Monroe Capital (MRCC) 10-K 1 Mar 23 2022 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Feb. 28, 2023	Jun. 30, 2022
Document and Entity Information [Abstract]
Document Type	10-K
Document Annual Report	true
Document Transition Report	false
Document Period End Date	Dec. 31, 2022
Entity File Number	814-00866
Entity Registrant Name	MONROE CAPITAL CORPORATION
Entity Incorporation, State or Country Code	MD
Entity Tax Identification Number	27-4895840
Entity Address State Or Province	IL
Entity Address, Address Line One	311 South Wacker Drive, Suite 6400
Entity Address, City or Town	Chicago
Entity Address, Postal Zip Code	60606
City Area Code	312
Local Phone Number	258-8300
Title of 12(b) Security	Common Stock, par value $0.001 per share
Trading Symbol	MRCC
Security Exchange Name	NASDAQ
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
ICFR Auditor Attestation Flag	false
Entity Shell Company	false
Entity Public Float			$ 188.9
Entity Common Stock, Shares Outstanding		21,666,340
Entity Central Index Key	0001512931
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2022
Document Fiscal Period Focus	FY
Amendment Flag	false
Auditor Name	RSM US LLP
Auditor Location	Chicago
Auditor Firm ID	49

CONSOLIDATED STATEMENTS OF ASSE

CONSOLIDATED STATEMENTS OF ASSETS AND LIABILITIES - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Assets
Total investments, at fair value (amortized cost of: $579,307 and $576,178, respectively)	$ 541,040	$ 561,693
Cash	5,450	2,622
Restricted cash		15,459
Unrealized gain on foreign currency forward contracts	1,507	781
Interest receivable	16,457	9,476
Other assets	541	427
Total assets	564,995	590,458
Debt:
Total debt	334,600	337,945
Less: Unamortized deferred financing costs	(4,486)	(5,794)
Total debt, less unamortized deferred financing costs	330,114	332,151
Interest payable	3,041	3,304
Management fees payable	2,221	2,454
Incentive fees payable	1,380	435
Accounts payable and accrued expenses	3,220	2,643
Total liabilities	339,976	340,987
Net assets	225,019	249,471
Commitments and contingencies (See Note 12)
ANALYSIS OF NET ASSETS
Common stock, $0.001 par value, 100,000 shares authorized, 21,666 and 21,666 shares issued and outstanding, respectively	22	22
Capital in excess of par value	298,700	298,687
Accumulated undistributed (overdistributed) earnings	(73,703)	(49,238)
Total net assets	$ 225,019	$ 249,471
Net asset value per share	$ 10.39	$ 11.51
Revolving credit facility
Debt:
Total debt	$ 204,600	$ 151,045
2026 Notes
Debt:
Total debt	130,000	130,000
SBA debentures payable
Debt:
Total debt		56,900
Non-controlled/non-affiliate company investments
Assets
Total investments, at fair value (amortized cost of: $579,307 and $576,178, respectively)	418,913	430,287
Non-controlled affiliate company investments
Assets
Total investments, at fair value (amortized cost of: $579,307 and $576,178, respectively)	86,618	90,281
Controlled affiliate company investments
Assets
Total investments, at fair value (amortized cost of: $579,307 and $576,178, respectively)	$ 35,509	$ 41,125

CONSOLIDATED STATEMENTS OF AS_2

CONSOLIDATED STATEMENTS OF ASSETS AND LIABILITIES (Parenthetical) - USD ($) shares in Thousands, $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
CONSOLIDATED STATEMENTS OF ASSETS AND LIABILITIES
Amortized Cost	$ 579,307	$ 576,178
Embedded Derivative Asset, Type [Extensible Enumeration]	Foreign currency forward contracts	Foreign currency forward contracts
Common stock, par value	$ 0.001	$ 0.001
Common stock, shares authorized	100,000	100,000
Common stock, shares issued	21,666	21,666
Common stock, shares outstanding	21,666	21,666

CONSOLIDATED STATEMENTS OF OPER

CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Thousands, $ in Thousands	3 Months Ended												12 Months Ended
	Dec. 31, 2022	Sep. 30, 2022	Jun. 30, 2022	Mar. 31, 2022	Dec. 31, 2021	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Investment income:
Payment-in-kind interest income													$ 6,689	$ 8,320	$ 8,776
Total investment income	$ 15,164	$ 15,916	$ 12,995	$ 12,491	$ 13,039	$ 15,214	$ 12,364	$ 13,213	$ 12,552	$ 13,385	$ 20,642	$ 15,002	56,566	53,830	61,581
Operating expenses:
Interest and other debt financing expenses													17,080	16,074	17,989
Base management fees													9,055	9,514	9,807
Incentive fees													4,127	3,690	712
Professional fees													894	1,013	1,023
Administrative service fees													1,163	1,357	1,300
General and administrative expenses													1,082	1,072	989
Directors' fees													148	144	145
Expenses before base management fee and incentive fee waivers													33,549	32,864	31,965
Base management fee waivers													(55)		(430)
Incentive fee waivers													(525)	(1,484)	(712)
Total operating expenses, net of base management fee and incentive fee waivers													32,969	31,380	30,823
Net investment income before income taxes													23,597	22,450	30,758
Income taxes, including excise taxes													1,405	282	370
Net investment income	5,520	6,260	5,014	5,398	5,373	6,312	5,157	5,326	5,326	5,644	12,636	6,782	22,192	22,168	30,388
Net realized gain (loss):
Realized gain (loss) on investments													(1,130)	(21,764)	2,551
Extinguishment of debt													(1,039)	(3,110)
Foreign currency forward contracts													119	(48)	(16)
Foreign currency and other transactions													(36)	(895)	(14)
Net realized gain (loss)													(2,086)	(25,817)	2,521
Net change in unrealized gain (loss):
Unrealized gain (loss) of investments													(23,782)	34,579	(30,559)
Foreign currency forward contracts													726	894	(54)
Foreign currency and other transactions													164	635	(650)
Net change in unrealized gain (loss)													(22,892)	36,108	(31,263)
Net gain (loss)	$ (1,040)	(7,009)	(12,378)	(4,551)	$ 1,462	927	6,173	1,729	$ 3,751	9,541	1,598	(43,632)	$ (24,978)	$ 10,291	$ (28,742)
Embedded Derivative Asset, Type [Extensible Enumeration]	Foreign currency forward contracts				Foreign currency forward contracts				Foreign currency forward contracts				Foreign currency forward contracts	Foreign currency forward contracts	Foreign currency forward contracts
Net increase (decrease) in net assets resulting from operations	$ 4,480	$ (749)	$ (7,364)	$ 847	$ 6,835	$ 7,239	$ 11,330	$ 7,055	$ 9,077	$ 15,185	$ 14,234	$ (36,850)	$ (2,786)	$ 32,459	$ 1,646
Per common share data:
Net investment income per share - basic	$ 0.25	$ 0.29	$ 0.23	$ 0.25	$ 0.25	$ 0.29	$ 0.24	$ 0.25	$ 0.25	$ 0.26	$ 0.61	$ 0.33	$ 1.02	$ 1.03	$ 1.45
Net investment income per share - diluted	0.25	0.29	0.23	0.25	0.25	0.29	0.24	0.25		0.26	0.61	0.33	1.02	1.03	1.45
Net increase (decrease) in net assets resulting from operations per share - basic	0.21	(0.03)	(0.34)	0.04	0.32	$ 0.34	0.53	0.33	0.42	0.71	0.69	(1.81)	(0.13)	1.51	0.08
Net increase (decrease) in net assets resulting from operations per share - diluted	$ 0.21	$ (0.03)	$ (0.34)	$ 0.04	$ 0.32		$ 0.53	$ 0.33	$ 0.42	$ 0.71	$ 0.69	$ (1.81)	$ (0.13)	$ 1.51	$ 0.08
Weighted average common shares outstanding - basic													21,666	21,453	20,924
Weighted average common shares outstanding - diluted													21,666	21,453	20,924
Non-controlled/non-affiliate company investments
Investment income:
Interest income													$ 35,751	$ 33,381	$ 42,928
Payment-in-kind interest income													3,009	1,836	3,928
Dividend income													372	400	10
Fee income													2,380	1,231	3,222
Total investment income													41,512	36,848	50,088
Net realized gain (loss):
Realized gain (loss) on investments													(1,129)	(16,127)	2,551
Net change in unrealized gain (loss):
Unrealized gain (loss) of investments													(12,287)	27,788	(20,397)
Non-controlled affiliate company investments
Investment income:
Interest income													7,585	5,150	2,098
Payment-in-kind interest income													3,680	6,484	4,848
Dividend income													189	987	147
Fee income														36
Total investment income													11,454	12,657	7,093
Net realized gain (loss):
Realized gain (loss) on investments													(1)	(5,637)
Net change in unrealized gain (loss):
Unrealized gain (loss) of investments													(5,379)	4,950	(7,034)
Controlled affiliate company investments
Investment income:
Dividend income													3,600	4,325	4,400
Total investment income													3,600	4,325	4,400
Net change in unrealized gain (loss):
Unrealized gain (loss) of investments													$ (6,116)	$ 1,841	$ (3,128)

CONSOLIDATED STATEMENTS OF CHAN

CONSOLIDATED STATEMENTS OF CHANGES IN NET ASSETS - USD ($) shares in Thousands, $ in Thousands	3 Months Ended						12 Months Ended
	Dec. 31, 2022	Mar. 31, 2022	Dec. 31, 2021	Mar. 31, 2021	Dec. 31, 2020	Mar. 31, 2020	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
CHANGES IN NET ASSETS
Balances at the beginning		$ 249,471		$ 234,434		$ 249,357	$ 249,471	$ 234,434	$ 249,357
Balances at the beginning (in shares)		21,666					21,666
Net investment income	$ 5,520	$ 5,398	$ 5,373	5,326	$ 5,326	6,782	$ 22,192	22,168	30,388
Net realized gain (loss)							(2,086)	(25,817)	2,521
Net change in unrealized gain (loss)							(22,892)	36,108	(31,263)
Issuance of common stock, net of offering and underwriting costs								4,092	6,495
Distributions to stockholders							(21,666)	(21,514)	(23,064)
Balances at the end	$ 225,019		$ 249,471		234,434		$ 225,019	$ 249,471	234,434
Balances at the end (in shares)	21,666		21,666				21,666	21,666
Common Stock
CHANGES IN NET ASSETS
Balances at the beginning		$ 22		$ 21		$ 20	$ 22	$ 21	$ 20
Balances at the beginning (in shares)		21,666		21,304		20,445	21,666	21,304	20,445
Issuance of common stock, net of offering and underwriting costs								$ 1	$ 1
Issuance of common stock, net of offering and underwriting costs (in shares)								362	859
Balances at the end	$ 22		$ 22		$ 21		$ 22	$ 22	$ 21
Balances at the end (in shares)	21,666		21,666		21,304		21,666	21,666	21,304
Capital in excess of par value
CHANGES IN NET ASSETS
Balances at the beginning		$ 298,687		$ 294,897		$ 288,850	$ 298,687	$ 294,897	$ 288,850
Issuance of common stock, net of offering and underwriting costs								4,091	6,494
Tax reclassification of stockholders' equity in accordance with generally accepted accounting principles							13	(301)	(447)
Balances at the end	$ 298,700		$ 298,687		$ 294,897		298,700	298,687	294,897
Accumulated undistributed (overdistributed) earnings
CHANGES IN NET ASSETS
Balances at the beginning		$ (49,238)		$ (60,484)		$ (39,513)	(49,238)	(60,484)	(39,513)
Net investment income							22,192	22,168	30,388
Net realized gain (loss)							(2,086)	(25,817)	2,521
Net change in unrealized gain (loss)							(22,892)	36,108	(31,263)
Distributions to stockholders							(21,666)	(21,514)	(23,064)
Tax reclassification of stockholders' equity in accordance with generally accepted accounting principles							(13)	301	447
Balances at the end	$ (73,703)		$ (49,238)		$ (60,484)		$ (73,703)	$ (49,238)	$ (60,484)

CONSOLIDATED STATEMENTS OF CASH

CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Cash flows from operating activities:
Net increase (decrease) in net assets resulting from operations	$ (2,786)	$ 32,459	$ 1,646
Adjustments to reconcile net increase (decrease) in net assets resulting from operations to net cash provided by (used in) operating activities:
Net realized (gain) loss on investments	1,130	21,764	$ (2,551)
Net realized (gain) loss on extinguishment of debt	$ 1,039	$ 3,110
Embedded Derivative Asset, Type [Extensible Enumeration]	Foreign currency forward contracts	Foreign currency forward contracts	Foreign currency forward contracts
Net realized (gain) loss on foreign currency forward contracts	$ (119)	$ 48	$ 16
Net realized (gain) loss on foreign currency and other transactions	36	895	14
Net change in unrealized (gain) loss on investments	23,782	(34,579)	30,559
Net change in unrealized (gain) loss on foreign currency forward contracts	(726)	(894)	54
Net change in unrealized (gain) loss on foreign currency and other transactions	(164)	(635)	650
Payment-in-kind interest income	(6,689)	(8,320)	(8,776)
Net accretion of discounts and amortization of premiums	(1,084)	(1,102)	(1,253)
Purchases of investments	(134,282)	(226,863)	(143,358)
Proceeds from principal payments, sales of investments and settlement of forward contracts	137,915	234,398	194,555
Amortization of deferred financing costs	2,126	2,205	2,181
Changes in operating assets and liabilities:
Interest receivable	(6,981)	(4,870)	4,083
Other assets	(114)	625	(557)
Interest payable	(263)	540	1
Management fees payable	(233)	476	(773)
Incentive fees payable	945	435	(1,374)
Accounts payable and accrued expenses	577	316	(186)
Net cash provided by (used in) operating activities	14,109	20,008	74,931
Cash flows from financing activities:
Payments of deferred financing costs	(1,857)	(4,057)	(1,180)
Proceeds from shares sold, net of offering and underwriting costs		4,092	6,495
Stockholder distributions paid, net of stock issued under the dividend reinvestment plan of $0, $0 and $0, respectively	(21,666)	(21,514)	(23,064)
Net cash provided by (used in) financing activities	(26,722)	(34,299)	(72,149)
Net increase (decrease) in Cash and Restricted cash	(12,613)	(14,291)	2,782
Effect of foreign currency exchange rates	(18)	(54)	1
Cash and Restricted cash, beginning of year	18,081	32,426	29,643
Cash and Restricted cash, end of year	5,450	18,081	32,426
Supplemental disclosure of cash flow information:
Cash interest paid during the year	15,072	13,221	15,721
Cash paid (refund received) for income taxes, including excise taxes during the year	1,587	400	85
Revolving credit facility
Cash flows from financing activities:
Proceeds from borrowings	185,300	309,300	96,200
Repayments of debt	(131,599)	(285,020)	$ (150,600)
2023 Notes
Cash flows from financing activities:
Repayments of debt		(109,000)
2026 Notes
Cash flows from financing activities:
Proceeds from borrowings		130,000
SBA debentures payable
Cash flows from financing activities:
Repayments of debt	$ (56,900)	$ (58,100)

CONSOLIDATED STATEMENTS OF CA_2

CONSOLIDATED STATEMENTS OF CASH FLOWS (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
CONSOLIDATED STATEMENTS OF CASH FLOWS
Value of stock issued under the dividend reinvestment plan	$ 0	$ 0	$ 0
Reconciliation of cash and restricted cash
Cash	5,450	2,622	6,769
Restricted cash		15,459	25,657
Total cash and restricted cash shown on the Consolidated Statements of Cash Flows	$ 5,450	$ 18,081	$ 32,426

CONSOLIDATED SCHEDULE OF INVEST

CONSOLIDATED SCHEDULE OF INVESTMENTS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Type [Extensible Enumeration]		Equity Securities [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Interest rate paid in cash	10.92%
Amortized Cost	$ 579,307	$ 576,178
Fair Value	$ 541,040	$ 561,693
% of Net Assets	240.40%	225.20%
Number of shares held	81
Investment, Restriction Status [true false]		true
Investment, Significant Unobservable Input [true false]		true
Investment, Non-income Producing [true false]		true
Number of units held	327,133
Investment, Identifier [Axis]: 360 Holdco, Inc. ( Delayed Draw), Senior Secured Loans, due 8/2/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:ThreeSixty360HoldcoIncMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Services: Consumer
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Spread Above Index	5%
Interest Rate	9.42%
Maturity	Aug. 02, 2025
Principal	$ 827
Fair Value	$ 252
Investment, Identifier [Axis]: 360 Holdco, Inc., Senior Secured Loans, due 8/2/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:ThreeSixty360HoldcoIncMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Services: Consumer
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Spread Above Index	5%
Interest Rate	9.42%
Maturity	Aug. 02, 2025
Principal	$ 2,145
Fair Value	$ 2,145
Investment, Identifier [Axis]: A P C O Worldwide, Inc, Equity Securities, Class A voting common stock
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:APCOWorldwideIncMember	mrcc:APCOWorldwideIncMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Equity Securities [Member]
Investment, Industry Sector [Extensible Enumeration]	Services: Business	Services: Business
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Acquisition Date	Nov. 01, 2017	Nov. 01, 2017
Amortized Cost	$ 395	$ 395
Fair Value	$ 921	$ 737
% of Net Assets	0.40%	0.30%
Number of shares held	100
Investment, Restriction Status [true false]	true	true
Investment, Significant Unobservable Input [true false]	true	true
Investment, Non-income Producing [true false]	false	true
Number of units held		100
Investment, Identifier [Axis]: A Q Carver Buyer, Inc., Senior Secured Loans, due 9/23/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:AQCarverBuyerIncMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Services: Business
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR
Spread Above Index	5%
Interest Rate	9.38%
Maturity	Sep. 23, 2025
Principal	$ 4,838
Fair Value	$ 4,834
Investment, Identifier [Axis]: A S G I I, L L C ( Delayed Draw), Unitranche Secured Loans, 5/25/2028
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:ASGIILLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Services: Business
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Spread Above Index	6.25%
Interest Rate	10.67%
Acquisition Date	May 25, 2022
Maturity	May 25, 2028
Principal	$ 285
Amortized Cost	51
Fair Value	$ 51
% of Net Assets	0%
Investment, Restriction Status [true false]	true
Investment, Significant Unobservable Input [true false]	true
Investment, Non-income Producing [true false]	false
Investment, Identifier [Axis]: A S G I I, L L C, Unitranche Secured Loans, due 5/25/2028
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:ASGIILLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Services: Business
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Spread Above Index	6.25%
Interest Rate	10.67%
Acquisition Date	May 25, 2022
Maturity	May 25, 2028
Principal	$ 1,900
Fair Value	$ 1,900
% of Net Assets	0.90%
Investment, Restriction Status [true false]	true
Investment, Significant Unobservable Input [true false]	true
Investment, Non-income Producing [true false]	false
Investment, Identifier [Axis]: Accelerate Auto Works Intermediate, L L C ( Delayed Draw), Senior Secured Loans, due 12/1/2027
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:AccelerateAutoWorksIntermediateLLCMember	mrcc:AccelerateAutoWorksIntermediateLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Automotive	Automotive
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR	LIBOR
Spread Above Index	4.50%	4.75%
Interest Rate	9.23%	5.75%
Maturity	Dec. 01, 2027	Dec. 01, 2027
Principal	$ 388	$ 388
Investment, Identifier [Axis]: Accelerate Auto Works Intermediate, L L C ( Revolver), Senior Secured Loans, due 12/1/2027
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:AccelerateAutoWorksIntermediateLLCMember	mrcc:AccelerateAutoWorksIntermediateLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Automotive	Automotive
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR	LIBOR
Spread Above Index	4.50%	4.75%
Interest Rate	9.23%	5.75%
Maturity	Dec. 01, 2027	Dec. 01, 2027
Principal	$ 132	$ 132
Investment, Identifier [Axis]: Accelerate Auto Works Intermediate, L L C, Senior Secured Loans, due 12/1/2027
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:AccelerateAutoWorksIntermediateLLCMember	mrcc:AccelerateAutoWorksIntermediateLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Automotive	Automotive
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR	LIBOR
Spread Above Index	4.50%	4.75%
Interest Rate	9.23%	5.75%
Maturity	Dec. 01, 2027	Dec. 01, 2027
Principal	$ 1,391	$ 1,454
Fair Value	$ 1,386	$ 1,436
Investment, Identifier [Axis]: Ad Theorent Holding Company, Inc. Equity Securities, common stock
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:AdTheorentHoldingCompanyIncMember	mrcc:AdTheorentHoldingCompanyIncMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Equity Securities [Member]
Investment, Industry Sector [Extensible Enumeration]	Media: Advertising, Printing & Publishing	Media: Advertising, Printing & Publishing
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Acquisition Date	Dec. 22, 2016	Dec. 22, 2016
Amortized Cost	$ 114	$ 114
Fair Value	$ 294	$ 1,041
% of Net Assets	0.20%	0.40%
Number of shares held		177,362
Investment, Restriction Status [true false]	true	true
Investment, Significant Unobservable Input [true false]	true	true
Investment, Non-income Producing [true false]	false	true
Number of units held	177,362
Investment, Identifier [Axis]: Amelia Holding II, LLC (Delayed Draw), Due 12/21/2027
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:AmeliaHoldingIiLlcDelayedDrawMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	High Tech Industries Sector [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Spread Above Index	10.26%
Interest rate paid in cash	13.77%
Interest rate paid in kind	1%
Acquisition Date	Dec. 21, 2022
Maturity	Dec. 21, 2027
Principal	$ 667
% of Net Assets	0%
Investment, Restriction Status [true false]	true
Investment, Significant Unobservable Input [true false]	true
Investment, Non-income Producing [true false]	false
Investment, Identifier [Axis]: Amelia Holding II, LLC (Revolver), Due 12/21/2027
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:AmeliaHoldingIiLlcRevolverMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	High Tech Industries Sector [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Spread Above Index	10.26%
Interest rate paid in cash	13.77%
Interest rate paid in kind	1%
Acquisition Date	Dec. 21, 2022
Maturity	Dec. 21, 2027
Principal	$ 133
% of Net Assets	0%
Investment, Restriction Status [true false]	true
Investment, Significant Unobservable Input [true false]	true
Investment, Non-income Producing [true false]	false
Investment, Identifier [Axis]: Amelia Holding II, LLC, Due 12/21/2027
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:AmeliaHoldingIiLlcMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	High Tech Industries Sector [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Spread Above Index	10.26%
Interest rate paid in cash	13.77%
Interest rate paid in kind	1%
Acquisition Date	Dec. 21, 2022
Maturity	Dec. 21, 2027
Principal	$ 2,000
Amortized Cost	1,940
Fair Value	$ 1,940
% of Net Assets	0.90%
Investment, Restriction Status [true false]	true
Investment, Significant Unobservable Input [true false]	true
Investment, Non-income Producing [true false]	false
Investment, Identifier [Axis]: Amelia Holding II, LLC, Equity Securities
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:AmeliaHoldingIiLlcMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	High Tech Industries Sector [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Acquisition Date	Dec. 21, 2022
Maturity	Dec. 21, 2027
% of Net Assets	0%
Investment, Restriction Status [true false]	true
Investment, Significant Unobservable Input [true false]	true
Investment, Non-income Producing [true false]	false
Warrants to Purchase Percentage of Equity	0.10%
Investment, Identifier [Axis]: American Broadband and Telecommunications Company L L C ( Delayed Draw), Senior Secured Loans, due 6/10/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:AmericanBroadbandandTelecommunicationsCompanyLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Telecommunications
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Prime Rate [Member]
Spread Above Index	12%
Interest rate paid in cash	17.50%
Interest rate paid in kind	2%
Acquisition Date	Jun. 10, 2022
Maturity	Jun. 10, 2025
Principal	$ 1,689
Amortized Cost	1,521
Fair Value	$ 1,539
% of Net Assets	0.70%
Investment, Restriction Status [true false]	true
Investment, Significant Unobservable Input [true false]	true
Investment, Non-income Producing [true false]	false
Investment, Identifier [Axis]: American Broadband and Telecommunications Company L L C ( Revolver), Senior Secured Loans, due 6/10/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:AmericanBroadbandandTelecommunicationsCompanyLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Telecommunications
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Prime Rate [Member]
Spread Above Index	12%
Interest rate paid in cash	17.50%
Interest rate paid in kind	2%
Acquisition Date	Jun. 10, 2022
Maturity	Jun. 10, 2025
Principal	$ 500
Amortized Cost	121
Fair Value	$ 118
% of Net Assets	0%
Investment, Restriction Status [true false]	true
Investment, Significant Unobservable Input [true false]	true
Investment, Non-income Producing [true false]	false
Investment, Identifier [Axis]: American Broadband and Telecommunications Company L L C, Equity Securities, Warrants
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:AmericanBroadbandandTelecommunicationsCompanyLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Telecommunications
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Acquisition Date	Jun. 10, 2022
Maturity	Jun. 10, 2032
Amortized Cost	$ 42
Fair Value	$ 69
% of Net Assets	0%
Investment, Restriction Status [true false]	true
Investment, Non-income Producing [true false]	false
Warrants to Purchase Percentage of Equity	0.20%
Investment, Identifier [Axis]: American Community Homes, Inc, Senior Secured Loans (Common stock)
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	American Community Homes, Inc. [ Member]
Number of shares held	4,940
Investment, Identifier [Axis]: American Community Homes, Inc. ( Revolver), Senior Secured Loans Due 12/31/2026
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	American Community Homes, Inc. [ Member]	American Community Homes, Inc. [ Member]
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	FIRE: Real Estate
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Spread Above Index	8.11%
Interest rate paid in kind	12.44%
Acquisition Date	Mar. 30, 2020
Maturity	Dec. 31, 2026
Principal	$ 2,500
% of Net Assets	0%
Investment, Restriction Status [true false]	true
Investment, Significant Unobservable Input [true false]	true
Investment, Non-income Producing [true false]	false
Investment, Identifier [Axis]: American Community Homes, Inc., Equity Securities Due 12/18/2024, Warrants
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	American Community Homes, Inc. [ Member]	American Community Homes, Inc. [ Member]
Investment, Type [Extensible Enumeration]		Equity Securities [Member]
Investment, Industry Sector [Extensible Enumeration]		FIRE: Real Estate
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Acquisition Date		Oct. 09, 2014
Maturity		Dec. 18, 2024
Fair Value		$ 264
% of Net Assets		0.10%
Investment, Restriction Status [true false]		true
Investment, Significant Unobservable Input [true false]		true
Investment, Non-income Producing [true false]		false
Warrants to Purchase Percentage of Equity	22.30%	22.30%
Investment, Identifier [Axis]: American Community Homes, Inc., Equity Securities, Common Stock
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	American Community Homes, Inc. [ Member]
Investment, Type [Extensible Enumeration]	Equity Securities [Member]
Investment, Industry Sector [Extensible Enumeration]	FIRE: Real Estate
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Acquisition Date	Dec. 29, 2022
% of Net Assets	0%
Number of shares held	4,940
Investment, Restriction Status [true false]	true
Investment, Significant Unobservable Input [true false]	true
Investment, Non-income Producing [true false]	true
Investment, Identifier [Axis]: American Community Homes, Inc., Loan Five
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	American Community Homes, Inc. [ Member]	American Community Homes, Inc. [ Member]
Fair Value			$ 335
Investment, Identifier [Axis]: American Community Homes, Inc., Loan Three
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	American Community Homes, Inc. [ Member]	American Community Homes, Inc. [ Member]
Fair Value			825
Investment, Identifier [Axis]: American Community Homes, Inc., Senior Secured Loans, Eight, Acquisition Date 9/30/2019
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	American Community Homes, Inc. [ Member]	American Community Homes, Inc. [ Member]
Fair Value	$ 17	$ 20	18
Investment, Identifier [Axis]: American Community Homes, Inc., Senior Secured Loans, Five, Due 12/31/2026
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	American Community Homes, Inc. [ Member]
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	FIRE: Real Estate
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Spread Above Index	8.11%
Interest rate paid in kind	12.44%
Acquisition Date	Mar. 29, 2019
Maturity	Dec. 31, 2026
Principal	$ 4,640
Amortized Cost	4,640
Fair Value	$ 3,694
% of Net Assets	1.70%
Investment, Restriction Status [true false]	true
Investment, Significant Unobservable Input [true false]	true
Investment, Non-income Producing [true false]	false
Investment, Identifier [Axis]: American Community Homes, Inc., Senior Secured Loans, Five, Due 3/31/2022
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		American Community Homes, Inc. [ Member]
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		FIRE: Real Estate
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Spread Above Index		10%
Interest rate paid in kind		11.50%
Acquisition Date		Mar. 29, 2019
Maturity		Mar. 31, 2022
Principal		$ 4,315
Amortized Cost		4,315
Fair Value		$ 4,357
% of Net Assets		1.80%
Investment, Restriction Status [true false]		true
Investment, Significant Unobservable Input [true false]		true
Investment, Non-income Producing [true false]		false
Investment, Identifier [Axis]: American Community Homes, Inc., Senior Secured Loans, Four, Acquisition Date 5/24/2017
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	American Community Homes, Inc. [ Member]	American Community Homes, Inc. [ Member]
Fair Value	$ 543	$ 634	570
Investment, Identifier [Axis]: American Community Homes, Inc., Senior Secured Loans, Four, Due 12/31/2026
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	American Community Homes, Inc. [ Member]
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	FIRE: Real Estate
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Spread Above Index	8.11%
Interest rate paid in kind	12.44%
Acquisition Date	Aug. 10, 2018
Maturity	Dec. 31, 2026
Principal	$ 2,507
Amortized Cost	2,507
Fair Value	$ 1,996
% of Net Assets	0.90%
Investment, Restriction Status [true false]	true
Investment, Significant Unobservable Input [true false]	true
Investment, Non-income Producing [true false]	false
Investment, Identifier [Axis]: American Community Homes, Inc., Senior Secured Loans, Four, Due 3/31/2022
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		American Community Homes, Inc. [ Member]
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		FIRE: Real Estate
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Spread Above Index		10%
Interest rate paid in kind		11.50%
Acquisition Date		Aug. 10, 2018
Maturity		Mar. 31, 2022
Principal		$ 2,331
Amortized Cost		2,331
Fair Value		$ 3,164
% of Net Assets		1.30%
Investment, Restriction Status [true false]		true
Investment, Significant Unobservable Input [true false]		true
Investment, Non-income Producing [true false]		false
Investment, Identifier [Axis]: American Community Homes, Inc., Senior Secured Loans, Nine, Acquisition Date 12/30/2019
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	American Community Homes, Inc. [ Member]	American Community Homes, Inc. [ Member]
Fair Value	$ 85	$ 99	89
Investment, Identifier [Axis]: American Community Homes, Inc., Senior Secured Loans, One, Acquisition Date 7/22/2014
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	American Community Homes, Inc. [ Member]	American Community Homes, Inc. [ Member]
Fair Value	$ 8,953	$ 10,457	9,401
Investment, Identifier [Axis]: American Community Homes, Inc., Senior Secured Loans, One, Due 12/31/2026
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	American Community Homes, Inc. [ Member]
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	FIRE: Real Estate
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Spread Above Index	8.11%
Interest rate paid in kind	12.44%
Acquisition Date	Jul. 22, 2014
Maturity	Dec. 31, 2026
Principal	$ 11,246
Amortized Cost	11,246
Fair Value	$ 8,953
% of Net Assets	4%
Investment, Restriction Status [true false]	true
Investment, Significant Unobservable Input [true false]	true
Investment, Non-income Producing [true false]	false
Investment, Identifier [Axis]: American Community Homes, Inc., Senior Secured Loans, One, Due 3/31/2022
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		American Community Homes, Inc. [ Member]
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		FIRE: Real Estate
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Spread Above Index		10%
Interest Rate		11.50%
Acquisition Date		Jul. 22, 2014
Maturity		Mar. 31, 2022
Principal		$ 10,457
Amortized Cost		10,457
Fair Value		$ 10,457
% of Net Assets		4.20%
Investment, Restriction Status [true false]		true
Investment, Significant Unobservable Input [true false]		true
Investment, Non-income Producing [true false]		false
Investment, Identifier [Axis]: American Community Homes, Inc., Senior Secured Loans, Seven, Acquisition Date 3/29/2019
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	American Community Homes, Inc. [ Member]	American Community Homes, Inc. [ Member]
Fair Value	$ 3,694	$ 4,357	3,879
Investment, Identifier [Axis]: American Community Homes, Inc., Senior Secured Loans, Seven, Due 12/31/2026
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	American Community Homes, Inc. [ Member]
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	FIRE: Real Estate
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Spread Above Index	8.11%
Interest rate paid in kind	12.44%
Acquisition Date	Dec. 30, 2019
Maturity	Dec. 31, 2026
Principal	$ 106
Amortized Cost	106
Fair Value	$ 85
% of Net Assets	0%
Investment, Restriction Status [true false]	true
Investment, Significant Unobservable Input [true false]	true
Investment, Non-income Producing [true false]	false
Investment, Identifier [Axis]: American Community Homes, Inc., Senior Secured Loans, Seven, Due 3/31/2022
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		American Community Homes, Inc. [ Member]
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		FIRE: Real Estate
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Spread Above Index		10%
Interest rate paid in kind		11.50%
Acquisition Date		Dec. 30, 2019
Maturity		Mar. 31, 2022
Principal		$ 99
Amortized Cost		99
Fair Value		$ 99
% of Net Assets		0%
Investment, Restriction Status [true false]		true
Investment, Significant Unobservable Input [true false]		true
Investment, Non-income Producing [true false]		false
Investment, Identifier [Axis]: American Community Homes, Inc., Senior Secured Loans, Six, Acquisition Date 8/10/2018
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	American Community Homes, Inc. [ Member]	American Community Homes, Inc. [ Member]
Fair Value	$ 1,996	$ 3,164	2,915
Investment, Identifier [Axis]: American Community Homes, Inc., Senior Secured Loans, Six, Due 12/31/2026
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	American Community Homes, Inc. [ Member]
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	FIRE: Real Estate
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Spread Above Index	8.11%
Interest rate paid in kind	12.44%
Acquisition Date	Sep. 30, 2019
Maturity	Dec. 31, 2026
Principal	$ 22
Amortized Cost	22
Fair Value	$ 17
% of Net Assets	0%
Investment, Restriction Status [true false]	true
Investment, Significant Unobservable Input [true false]	true
Investment, Non-income Producing [true false]	false
Investment, Identifier [Axis]: American Community Homes, Inc., Senior Secured Loans, Six, Due 3/31/2022
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		American Community Homes, Inc. [ Member]
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		FIRE: Real Estate
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Spread Above Index		10%
Interest rate paid in kind		11.50%
Acquisition Date		Sep. 30, 2019
Maturity		Mar. 31, 2022
Principal		$ 20
Amortized Cost		20
Fair Value		$ 20
% of Net Assets		0%
Investment, Restriction Status [true false]		true
Investment, Significant Unobservable Input [true false]		true
Investment, Non-income Producing [true false]		false
Investment, Identifier [Axis]: American Community Homes, Inc., Senior Secured Loans, Three, Due 12/31/2026
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	American Community Homes, Inc. [ Member]
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	FIRE: Real Estate
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Spread Above Index	8.11%
Interest rate paid in kind	12.44%
Acquisition Date	May 24, 2017
Maturity	Dec. 31, 2026
Principal	$ 682
Amortized Cost	682
Fair Value	$ 543
% of Net Assets	0.20%
Investment, Restriction Status [true false]	true
Investment, Significant Unobservable Input [true false]	true
Investment, Non-income Producing [true false]	false
Investment, Identifier [Axis]: American Community Homes, Inc., Senior Secured Loans, Three, Due 3/31/2022
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		American Community Homes, Inc. [ Member]
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		FIRE: Real Estate
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Spread Above Index		10%
Interest rate paid in kind		11.50%
Acquisition Date		May 24, 2017
Maturity		Mar. 31, 2022
Principal		$ 634
Amortized Cost		634
Fair Value		$ 634
% of Net Assets		0.30%
Investment, Restriction Status [true false]		true
Investment, Significant Unobservable Input [true false]		true
Investment, Non-income Producing [true false]		false
Investment, Identifier [Axis]: American Community Homes, Inc., Senior Secured Loans, Two, Acquisition Date 7/22/2014
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	American Community Homes, Inc. [ Member]	American Community Homes, Inc. [ Member]
Fair Value	$ 4,258	$ 4,753	6,239
Investment, Identifier [Axis]: American Community Homes, Inc., Senior Secured Loans, Two, Due 12/31/2026
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	American Community Homes, Inc. [ Member]
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	FIRE: Real Estate
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Spread Above Index	14.61%
Interest rate paid in kind	18.94%
Acquisition Date	Jul. 22, 2014
Maturity	Dec. 31, 2026
Principal	$ 5,348
Amortized Cost	5,348
Fair Value	$ 4,258
% of Net Assets	1.90%
Investment, Restriction Status [true false]	true
Investment, Significant Unobservable Input [true false]	true
Investment, Non-income Producing [true false]	false
Investment, Identifier [Axis]: American Community Homes, Inc., Senior Secured Loans, Two, Due 3/31/2022
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		American Community Homes, Inc. [ Member]
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		FIRE: Real Estate
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Spread Above Index		14.50%
Interest rate paid in kind		16%
Acquisition Date		Jul. 22, 2014
Maturity		Mar. 31, 2022
Principal		$ 4,753
Amortized Cost		4,753
Fair Value		$ 4,753
% of Net Assets		1.90%
Investment, Restriction Status [true false]		true
Investment, Significant Unobservable Input [true false]		true
Investment, Non-income Producing [true false]		false
Investment, Identifier [Axis]: Analogic Corporation, Senior Secured Loans, due 6/24/2024
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:AnalogicCorporationMember	mrcc:AnalogicCorporationMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Capital Equipment	Capital Equipment
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR	LIBOR
Spread Above Index		5.25%
Interest Rate		6.25%
Maturity		Jun. 24, 2024
Principal		$ 4,752
Fair Value		$ 4,702
Investment, Identifier [Axis]: Apotheco, L L C ( Revolver), Senior Secured Loans, due 4/8/2024
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:ApothecoLLCMember
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Healthcare & Pharmaceuticals Sector [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Spread Above Index		8.50%
Interest rate paid in cash		6.50%
Interest rate paid in kind		3%
Acquisition Date		Apr. 08, 2019
Maturity		Apr. 08, 2024
Principal		$ 955
Amortized Cost		955
Fair Value		$ 910
% of Net Assets		0.40%
Investment, Restriction Status [true false]		true
Investment, Significant Unobservable Input [true false]		true
Investment, Non-income Producing [true false]		false
Investment, Identifier [Axis]: Apotheco, L L C, Senior Secured Loans, due 4/8/2024
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:ApothecoLLCMember
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Healthcare & Pharmaceuticals Sector [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Spread Above Index		8.50%
Interest rate paid in cash		6.50%
Interest rate paid in kind		3%
Acquisition Date		Apr. 08, 2019
Maturity		Apr. 08, 2024
Principal		$ 3,632
Amortized Cost		3,597
Fair Value		$ 3,462
% of Net Assets		1.40%
Investment, Restriction Status [true false]		true
Investment, Significant Unobservable Input [true false]		true
Investment, Non-income Producing [true false]		false
Investment, Identifier [Axis]: Aras Corporation ( Revolver), Senior Secured Loans, due 4/13/2027
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:ArasCorporationMember	mrcc:ArasCorporationMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Services: Business	Services: Business
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR	LIBOR
Spread Above Index	6.50%	7%
Interest Rate	9.50%
Interest rate paid in cash		4.25%
Interest rate paid in kind		3.75%
Acquisition Date	Apr. 13, 2021	Apr. 13, 2021
Maturity	Apr. 13, 2027	Apr. 13, 2027
Principal	$ 150	$ 150
Amortized Cost	50
Fair Value	$ 50
% of Net Assets	0%	0%
Investment, Restriction Status [true false]	true	true
Investment, Significant Unobservable Input [true false]	true	true
Investment, Non-income Producing [true false]	false	false
Investment, Identifier [Axis]: Aras Corporation, Senior Secured Loans, due 4/13/2027
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:ArasCorporationMember	mrcc:ArasCorporationMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Services: Business	Services: Business
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR	LIBOR
Spread Above Index	7%	7%
Interest rate paid in cash	7.16%	4.25%
Interest rate paid in kind	3.75%	3.75%
Acquisition Date	Apr. 13, 2021	Apr. 13, 2021
Maturity	Apr. 13, 2027	Apr. 13, 2027
Principal	$ 2,155	$ 2,079
Amortized Cost	2,127	2,044
Fair Value	$ 2,167	$ 2,103
% of Net Assets	1%	0.80%
Investment, Restriction Status [true false]	true	true
Investment, Significant Unobservable Input [true false]	true	true
Investment, Non-income Producing [true false]	false	false
Investment, Identifier [Axis]: Arcstor Midco, L L C, Senior Secured Loans, due 3/16/2027
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:ArcstorMidcoLLCMember	mrcc:ArcstorMidcoLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	High Tech Industries Sector [Member]	High Tech Industries Sector [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]	LIBOR
Spread Above Index	7.60%	7%
Interest Rate		8%
Interest rate paid in cash	8.17%
Interest rate paid in kind	3.75%
Acquisition Date	Mar. 16, 2021	Mar. 16, 2021
Maturity	Mar. 16, 2027	Mar. 16, 2027
Principal	$ 4,528	$ 4,466
Amortized Cost	4,461	4,386
Fair Value	$ 4,122	$ 4,433
% of Net Assets	1.80%	1.80%
Investment, Restriction Status [true false]	true	true
Investment, Significant Unobservable Input [true false]	true	true
Investment, Non-income Producing [true false]	false	false
Investment, Identifier [Axis]: Ascent Midco, L L C ( Revolver), Senior Secured Loans Due 2/5/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	Ascent Midco, L L C [ Member]	Ascent Midco, L L C [ Member]
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Healthcare & Pharmaceuticals	Healthcare & Pharmaceuticals
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR	LIBOR
Spread Above Index	5.75%	5.50%
Interest Rate	10.14%	6.50%
Acquisition Date	Feb. 05, 2020	Feb. 05, 2020
Maturity	Feb. 05, 2025	Feb. 05, 2025
Principal	$ 1,129	$ 1,129
% of Net Assets	0%	0%
Investment, Restriction Status [true false]	true	true
Investment, Significant Unobservable Input [true false]	true	true
Investment, Non-income Producing [true false]	false	false
Investment, Identifier [Axis]: Ascent Midco, L L C, ( Delayed Draw) Loan
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	Ascent Midco, L L C [ Member]	Ascent Midco, L L C [ Member]
Investment, Identifier [Axis]: Ascent Midco, L L C, Equity Securities, Class A units
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	Ascent Midco, L L C [ Member]	Ascent Midco, L L C [ Member]
Investment, Type [Extensible Enumeration]	Equity Securities [Member]	Equity Securities [Member]
Investment, Industry Sector [Extensible Enumeration]		Healthcare & Pharmaceuticals
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Interest rate paid in cash		8%
Interest rate paid in kind	8%
Acquisition Date	Feb. 05, 2020	Feb. 05, 2020
Amortized Cost	$ 2,032	$ 2,032
Fair Value	$ 1,969	$ 2,554	3,016
% of Net Assets	0.90%	1%
Investment, Restriction Status [true false]	true	true
Investment, Significant Unobservable Input [true false]	true	true
Investment, Non-income Producing [true false]	false	false
Number of units held	2,032,258	2,032,258
Investment, Identifier [Axis]: Ascent Midco, L L C, Senior Secured Loans Due 2/5/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	Ascent Midco, L L C [ Member]	Ascent Midco, L L C [ Member]
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Healthcare & Pharmaceuticals	Healthcare & Pharmaceuticals
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR	LIBOR
Spread Above Index	5.75%	5.50%
Interest Rate	10.14%	6.50%
Acquisition Date	Feb. 05, 2020	Feb. 05, 2020
Maturity	Feb. 05, 2025	Feb. 05, 2025
Principal	$ 6,217	$ 6,392
Amortized Cost	6,159	6,308
Fair Value	$ 6,217	$ 6,392	6,997
% of Net Assets	2.80%	2.60%
Investment, Restriction Status [true false]	true	true
Investment, Significant Unobservable Input [true false]	true	true
Investment, Non-income Producing [true false]	false	false
Investment, Identifier [Axis]: Attom Intermediate Holdco, L L C ( Revolver), Senior Secured Loans, due 1/4/2024
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:AttomIntermediateHoldcoLLCMember
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Media: Diversified & Production
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]		us-gaap:LondonInterbankOfferedRateLiborSwapRateMember
Spread Above Index		5.75%
Interest Rate		6.75%
Acquisition Date		Jan. 04, 2019
Maturity		Jan. 04, 2024
Principal		$ 320
Amortized Cost		160
Fair Value		$ 160
% of Net Assets		0.10%
Investment, Restriction Status [true false]		true
Investment, Significant Unobservable Input [true false]		true
Investment, Non-income Producing [true false]		false
Investment, Identifier [Axis]: Attom Intermediate Holdco, L L C, Equity Securities, Class A units
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:AttomIntermediateHoldcoLLCMember	mrcc:AttomIntermediateHoldcoLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Equity Securities [Member]
Investment, Industry Sector [Extensible Enumeration]	Media: Diversified & Production	Media: Diversified & Production
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Acquisition Date	Jan. 04, 2019	Jan. 04, 2019
Amortized Cost	$ 297	$ 297
Fair Value	$ 522	$ 446
% of Net Assets	0.20%	0.20%
Investment, Restriction Status [true false]	true	true
Investment, Significant Unobservable Input [true false]	true	true
Investment, Non-income Producing [true false]	false	true
Number of units held	297,197	297,197
Investment, Identifier [Axis]: Attom Intermediate Holdco, L L C, Senior Secured Loans, Five, due 7/3/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:AttomIntermediateHoldcoLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Media: Diversified & Production
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Spread Above Index	6.25%
Interest Rate	11.39%
Acquisition Date	Dec. 22, 2022
Maturity	Jul. 03, 2025
Principal	$ 400
Amortized Cost	388
Fair Value	$ 399
% of Net Assets	0.20%
Investment, Restriction Status [true false]	true
Investment, Significant Unobservable Input [true false]	true
Investment, Non-income Producing [true false]	false
Investment, Identifier [Axis]: Attom Intermediate Holdco, L L C, Senior Secured Loans, Four, due 7/3/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:AttomIntermediateHoldcoLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Media: Diversified & Production
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Spread Above Index	6.25%
Interest Rate	10.69%
Acquisition Date	Aug. 04, 2022
Maturity	Jul. 03, 2025
Principal	$ 796
Amortized Cost	784
Fair Value	$ 794
% of Net Assets	0.30%
Investment, Restriction Status [true false]	true
Investment, Significant Unobservable Input [true false]	true
Investment, Non-income Producing [true false]	false
Investment, Identifier [Axis]: Attom Intermediate Holdco, L L C, Senior Secured Loans, One, due 1/4/2024
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:AttomIntermediateHoldcoLLCMember
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Media: Diversified & Production
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]		us-gaap:LondonInterbankOfferedRateLiborSwapRateMember
Spread Above Index		6.15%
Interest Rate		7.15%
Acquisition Date		Jan. 04, 2019
Maturity		Jan. 04, 2024
Principal		$ 1,940
Amortized Cost		1,923
Fair Value		$ 1,937
% of Net Assets		0.80%
Investment, Restriction Status [true false]		true
Investment, Significant Unobservable Input [true false]		true
Investment, Non-income Producing [true false]		false
Investment, Identifier [Axis]: Attom Intermediate Holdco, L L C, Senior Secured Loans, One, due 7/3/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:AttomIntermediateHoldcoLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Media: Diversified & Production
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Spread Above Index	6.25%
Interest Rate	10.69%
Acquisition Date	Jan. 04, 2019
Maturity	Jul. 03, 2025
Principal	$ 1,920
Amortized Cost	1,911
Fair Value	$ 1,915
% of Net Assets	0.90%
Investment, Restriction Status [true false]	true
Investment, Significant Unobservable Input [true false]	true
Investment, Non-income Producing [true false]	false
Investment, Identifier [Axis]: Attom Intermediate Holdco, L L C, Senior Secured Loans, Three, due 1/4/2024
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:AttomIntermediateHoldcoLLCMember
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Media: Diversified & Production
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]		us-gaap:LondonInterbankOfferedRateLiborSwapRateMember
Spread Above Index		6.15%
Interest Rate		7.15%
Acquisition Date		Jul. 01, 2021
Maturity		Jan. 04, 2024
Principal		$ 279
Amortized Cost		273
Fair Value		$ 278
% of Net Assets		0.10%
Investment, Restriction Status [true false]		true
Investment, Significant Unobservable Input [true false]		true
Investment, Non-income Producing [true false]		false
Investment, Identifier [Axis]: Attom Intermediate Holdco, L L C, Senior Secured Loans, Three, due 7/3/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:AttomIntermediateHoldcoLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Media: Diversified & Production
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Spread Above Index	6.25%
Interest Rate	10.69%
Acquisition Date	Jul. 01, 2021
Maturity	Jul. 03, 2025
Principal	$ 276
Amortized Cost	272
Fair Value	$ 275
% of Net Assets	0.10%
Investment, Restriction Status [true false]	true
Investment, Significant Unobservable Input [true false]	true
Investment, Non-income Producing [true false]	false
Investment, Identifier [Axis]: Attom Intermediate Holdco, L L C, Senior Secured Loans, Two, due 1/4/2024
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:AttomIntermediateHoldcoLLCMember
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Media: Diversified & Production
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]		us-gaap:LondonInterbankOfferedRateLiborSwapRateMember
Spread Above Index		6.15%
Interest Rate		7.15%
Acquisition Date		Jun. 25, 2020
Maturity		Jan. 04, 2024
Principal		$ 473
Amortized Cost		467
Fair Value		$ 472
% of Net Assets		0.20%
Investment, Restriction Status [true false]		true
Investment, Significant Unobservable Input [true false]		true
Investment, Non-income Producing [true false]		false
Investment, Identifier [Axis]: Attom Intermediate Holdco, L L C, Senior Secured Loans, Two, due 7/3/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:AttomIntermediateHoldcoLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Media: Diversified & Production
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Spread Above Index	6.25%
Interest Rate	10.69%
Acquisition Date	Jun. 25, 2020
Maturity	Jul. 03, 2025
Principal	$ 468
Amortized Cost	465
Fair Value	$ 467
% of Net Assets	0.20%
Investment, Restriction Status [true false]	true
Investment, Significant Unobservable Input [true false]	true
Investment, Non-income Producing [true false]	false
Investment, Identifier [Axis]: Attom Intermediate Holdco, LLC (Revolver), Senior Secured Loans, due 7/3/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:AttomIntermediateHoldcoLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Media: Diversified & Production
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Spread Above Index	6.25%
Interest Rate	10.69%
Acquisition Date	Jan. 04, 2019
Maturity	Jul. 03, 2025
Principal	$ 320
% of Net Assets	0%
Investment, Restriction Status [true false]	true
Investment, Significant Unobservable Input [true false]	true
Investment, Non-income Producing [true false]	false
Investment, Identifier [Axis]: Avalara, Inc. (Revolver), Senior Secured Loans, due 10/19/2028
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:AvalaraInc.Member
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	mrcc:FireFinanceMember
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Spread Above Index	7.25%
Interest Rate	11.83%
Acquisition Date	Oct. 19, 2022
Maturity	Oct. 19, 2028
Principal	$ 400
% of Net Assets	0%
Investment, Restriction Status [true false]	true
Investment, Significant Unobservable Input [true false]	true
Investment, Non-income Producing [true false]	false
Investment, Identifier [Axis]: Avalara, Inc. Senior Secured Loans, due 10/19/2028
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:AvalaraInc.Member
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	mrcc:FireFinanceMember
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Spread Above Index	7.25%
Interest Rate	11.83%
Acquisition Date	Oct. 19, 2022
Maturity	Oct. 19, 2028
Principal	$ 4,000
Amortized Cost	3,902
Fair Value	$ 3,900
% of Net Assets	1.70%
Investment, Restriction Status [true false]	true
Investment, Significant Unobservable Input [true false]	true
Investment, Non-income Producing [true false]	false
Investment, Identifier [Axis]: Avison Young ( U S A) Inc., Senior Secured Loans, due 1/30/2026
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:AvisonYoungUSAIncMember	mrcc:AvisonYoungUSAIncMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	FIRE Real Estate Sector [Member]	FIRE Real Estate Sector [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]	us-gaap:LondonInterbankOfferedRateLiborSwapRateMember
Spread Above Index	5.75%	5.75%
Interest Rate	10.19%	5.97%
Maturity	Jan. 30, 2026	Jan. 30, 2026
Principal	$ 4,800	$ 4,850
Fair Value	$ 4,020	$ 4,824
Investment, Identifier [Axis]: B L S T Operating Company, L L C, Equity Securities, Class A units
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:BLSTOperatingCompanyLLCMember	mrcc:BLSTOperatingCompanyLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Equity Securities [Member]
Investment, Industry Sector [Extensible Enumeration]	Retail	Retail
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Acquisition Date	Aug. 28, 2020	Aug. 28, 2020
Amortized Cost	$ 712	$ 712
Fair Value	$ 420	$ 420
% of Net Assets	0.20%	0.20%
Investment, Restriction Status [true false]	true	true
Investment, Significant Unobservable Input [true false]	true	true
Investment, Non-income Producing [true false]	false	true
Number of units held	139,883	139,883
Investment, Identifier [Axis]: B L S T Operating Company, L L C, Senior Secured Loans, due 8/28/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:BLSTOperatingCompanyLLCMember
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Retail
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]		us-gaap:LondonInterbankOfferedRateLiborSwapRateMember
Spread Above Index		8.50%
Interest rate paid in cash		1%
Interest rate paid in kind		9%
Acquisition Date		Aug. 28, 2020
Maturity		Aug. 28, 2025
Principal		$ 1,147
Amortized Cost		1,025
Fair Value		$ 1,143
% of Net Assets		0.50%
Investment, Restriction Status [true false]		true
Investment, Significant Unobservable Input [true false]		true
Investment, Non-income Producing [true false]		false
Investment, Identifier [Axis]: BLST Operating Company, LLC, Due 8/28/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:BLSTOperatingCompanyLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Retail
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR
Spread Above Index	8.50%
Interest Rate	12.62%
Acquisition Date	Aug. 28, 2020
Maturity	Aug. 28, 2025
Principal	$ 588
Amortized Cost	351
Fair Value	$ 571
% of Net Assets	0.20%
Investment, Restriction Status [true false]	true
Investment, Significant Unobservable Input [true false]	true
Investment, Non-income Producing [true false]	false
Investment, Identifier [Axis]: Bonterra, L L C (fka Cybergrants Holdings) ( Delayed Draw) , Senior Secured Loans, due 9/8/2027
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:BonterraLLCfkaCybergrantsHoldingsMember	mrcc:BonterraLLCfkaCybergrantsHoldingsMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Media: Diversified & Production	Media: Diversified & Production
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR	us-gaap:LondonInterbankOfferedRateLiborSwapRateMember
Spread Above Index	6.25%	6.50%
Interest Rate	10.98%	7.25%
Acquisition Date	Sep. 08, 2021	Sep. 08, 2021
Maturity	Sep. 08, 2027	Sep. 08, 2027
Principal	$ 1,906	$ 1,069
% of Net Assets	0%	0%
Investment, Restriction Status [true false]	true	true
Investment, Significant Unobservable Input [true false]	true	true
Investment, Non-income Producing [true false]	false	false
Investment, Identifier [Axis]: Bonterra, L L C (fka Cybergrants Holdings) ( Revolver), Senior Secured Loans, due 9/8/2027
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:BonterraLLCfkaCybergrantsHoldingsMember	mrcc:BonterraLLCfkaCybergrantsHoldingsMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Media: Diversified & Production	Media: Diversified & Production
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR	us-gaap:LondonInterbankOfferedRateLiborSwapRateMember
Spread Above Index	6.25%	6.50%
Interest Rate	10.98%	7.25%
Acquisition Date	Sep. 08, 2021	Sep. 08, 2021
Maturity	Sep. 08, 2027	Sep. 08, 2027
Principal	$ 1,069	$ 1,069
Amortized Cost	397
Fair Value	$ 389
% of Net Assets	0.20%	0%
Investment, Restriction Status [true false]	true	true
Investment, Significant Unobservable Input [true false]	true	true
Investment, Non-income Producing [true false]	false	false
Investment, Identifier [Axis]: Bonterra, L L C (fka Cybergrants Holdings), Senior Secured Loans, due 9/8/2027
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:BonterraLLCfkaCybergrantsHoldingsMember	mrcc:BonterraLLCfkaCybergrantsHoldingsMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Media: Diversified & Production	Media: Diversified & Production
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR	us-gaap:LondonInterbankOfferedRateLiborSwapRateMember
Spread Above Index	6.25%	6.50%
Interest Rate	10.98%	7.25%
Acquisition Date	Sep. 08, 2021	Sep. 08, 2021
Maturity	Sep. 08, 2027	Sep. 08, 2027
Principal	$ 13,195	$ 10,900
Amortized Cost	13,042	10,744
Fair Value	$ 12,898	$ 10,900
% of Net Assets	5.70%	4.40%
Investment, Restriction Status [true false]	true	true
Investment, Significant Unobservable Input [true false]	true	true
Investment, Non-income Producing [true false]	false	false
Investment, Identifier [Axis]: Born To Run, L L C ( Delayed Draw) Senior Secured Loans, due 4/1/2027
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:BornToRunLLCMember	mrcc:BornToRunLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Automotive	Automotive
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR	LIBOR
Spread Above Index	6%	6%
Interest Rate	10.73%	7%
Acquisition Date	Apr. 01, 2021	Apr. 01, 2021
Maturity	Apr. 01, 2027	Apr. 01, 2027
Principal	$ 470	$ 569
Amortized Cost	470	33
Fair Value	$ 452	$ 34
% of Net Assets	0.20%	0%
Investment, Restriction Status [true false]	true	true
Investment, Significant Unobservable Input [true false]	true	true
Investment, Non-income Producing [true false]	false	false
Investment, Identifier [Axis]: Born To Run, L L C, Equity Securities, Class A units
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:BornToRunLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Automotive
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Spread Above Index	0%
Interest Rate	0%
Acquisition Date	Apr. 01, 2021	Apr. 01, 2021
Principal	$ 0
Amortized Cost	269	$ 269
Fair Value	$ 233	$ 293
% of Net Assets	0.10%	0.10%
Investment, Restriction Status [true false]	true
Investment, Significant Unobservable Input [true false]	true
Number of units held	269,438	269,438
Investment, Identifier [Axis]: Born To Run, L L C, Senior Secured Loans, due 4/1/2027
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:BornToRunLLCMember	mrcc:BornToRunLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Automotive	Automotive
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR	LIBOR
Spread Above Index	6%	6%
Interest Rate	10.73%	7%
Acquisition Date	Apr. 01, 2021	Apr. 01, 2021
Maturity	Apr. 01, 2027	Apr. 01, 2027
Principal	$ 3,448	$ 3,483
Amortized Cost	3,395	3,419
Fair Value	$ 3,318	$ 3,544
% of Net Assets	1.50%	1.40%
Investment, Restriction Status [true false]	true	true
Investment, Significant Unobservable Input [true false]	true	true
Investment, Non-income Producing [true false]	false	false
Investment, Identifier [Axis]: Brickell Bay Acquisition Corp, Senior Secured Loans, due 2/12/2026
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:BrickellBayAcquisitionCorpMember	mrcc:BrickellBayAcquisitionCorpMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Healthcare & Pharmaceuticals Sector [Member]	Healthcare & Pharmaceuticals Sector [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR	LIBOR
Spread Above Index	6.50%	6.50%
Interest Rate	10.24%	7.50%
Acquisition Date	Feb. 12, 2021	Feb. 12, 2021
Maturity	Feb. 12, 2026	Feb. 12, 2026
Principal	$ 1,880	$ 1,899
Amortized Cost	1,850	1,865
Fair Value	$ 1,847	$ 1,889
% of Net Assets	0.80%	0.70%
Investment, Restriction Status [true false]		true
Investment, Significant Unobservable Input [true false]		true
Investment, Non-income Producing [true false]		false
Investment, Identifier [Axis]: Brickell Bay Acquisition Corp. ( Delayed Draw), Senior Secured Loans, due 2/12/2026
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:BrickellBayAcquisitionCorpMember
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Healthcare & Pharmaceuticals Sector [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Spread Above Index		6.50%
Interest Rate		7.50%
Acquisition Date		Feb. 12, 2021
Maturity		Feb. 12, 2026
Principal		$ 382
% of Net Assets		0%
Investment, Restriction Status [true false]		true
Investment, Significant Unobservable Input [true false]		true
Investment, Non-income Producing [true false]		false
Investment, Identifier [Axis]: Brickell Bay Acquisition Corp., Senior Secured Loans, due 6/30/2027
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:BrickellBayAcquisitionCorpMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Healthcare & Pharmaceuticals Sector [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Interest rate paid in cash	8.97%
Acquisition Date	Jun. 30, 2021
Maturity	Jun. 30, 2027
Principal	$ 5,016
Amortized Cost	4,935
Fair Value	$ 4,630
% of Net Assets	2.10%
Investment, Identifier [Axis]: Brightly Software Holdings, Inc. (fka Dude Solutions Holdings, Inc.), Senior Secured Loans, ( Revolver), due 6/13/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:BrightlySoftwareHoldingsInc.fkaDudeSolutionsHoldingsInc.Member
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Construction & Building
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Spread Above Index		6.25%
Interest Rate		7.25%
Acquisition Date		Jun. 14, 2019
Maturity		Jun. 13, 2025
Principal		$ 1,304
% of Net Assets		0%
Investment, Restriction Status [true false]		true
Investment, Significant Unobservable Input [true false]		true
Investment, Non-income Producing [true false]		false
Investment, Identifier [Axis]: Brightly Software Holdings, Inc. (fka Dude Solutions Holdings, Inc.), Senior Secured Loans, due 6/13/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:BrightlySoftwareHoldingsInc.fkaDudeSolutionsHoldingsInc.Member
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Construction & Building
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Spread Above Index		6.25%
Interest Rate		7.25%
Acquisition Date		Jun. 14, 2019
Maturity		Jun. 13, 2025
Principal		$ 9,900
Amortized Cost		9,755
Fair Value		$ 9,870
% of Net Assets		4%
Investment, Restriction Status [true false]		true
Investment, Significant Unobservable Input [true false]		true
Investment, Non-income Producing [true false]		false
Investment, Identifier [Axis]: Bromford Industries Limited, Senior Secured Loans, One, due 11/5/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:BromfordIndustriesLimitedMember	mrcc:BromfordIndustriesLimitedMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Aerospace & Defense	Aerospace & Defense
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	Non-US [Member]
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Prime Rate [Member]	Prime Rate [Member]
Spread Above Index	5.25%	4.25%
Interest Rate	12.75%	7.50%
Maturity	Nov. 05, 2025	Nov. 05, 2025
Principal	$ 2,744	$ 2,744
Fair Value	$ 2,581	$ 2,692
Investment, Identifier [Axis]: Bromford Industries Limited, Senior Secured Loans, Two, due 11/5/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:BromfordIndustriesLimitedMember	mrcc:BromfordIndustriesLimitedMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Aerospace & Defense	Aerospace & Defense
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	Non-US [Member]
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Prime Rate [Member]	Prime Rate [Member]
Spread Above Index	5.25%	4.25%
Interest Rate	12.75%	7.50%
Maturity	Nov. 05, 2025	Nov. 05, 2025
Principal	$ 1,829	$ 1,829
Fair Value	$ 1,720	$ 1,794
Investment, Identifier [Axis]: Burroughs, Inc. ( Revolver), Senior Secured Loans, due 12/22/2022
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:BurroughsInc.Member
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Services: Business
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Spread Above Index		6.50%
Interest Rate		7.50%
Acquisition Date		Dec. 22, 2017
Maturity		Dec. 22, 2022
Principal		$ 1,220
% of Net Assets		0%
Investment, Restriction Status [true false]		true
Investment, Significant Unobservable Input [true false]		true
Investment, Non-income Producing [true false]		false
Investment, Identifier [Axis]: Burroughs, Inc. ( Revolver), Senior Secured Loans, due 12/22/2023
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:BurroughsInc.Member
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Services: Business
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Spread Above Index	6.50%
Interest Rate	10.72%
Acquisition Date	Dec. 22, 2017
Maturity	Dec. 22, 2023
Principal	$ 1,215
% of Net Assets	0%
Investment, Restriction Status [true false]	true
Investment, Significant Unobservable Input [true false]	true
Investment, Non-income Producing [true false]	false
Investment, Identifier [Axis]: Burroughs, Inc., Senior Secured Loans, due 12/22/2022
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:BurroughsInc.Member
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Services: Business
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Spread Above Index		6.50%
Interest Rate		7.50%
Acquisition Date		Dec. 22, 2017
Maturity		Dec. 22, 2022
Principal		$ 5,501
Amortized Cost		5,477
Fair Value		$ 5,480
% of Net Assets		2.20%
Investment, Restriction Status [true false]		true
Investment, Significant Unobservable Input [true false]		true
Investment, Non-income Producing [true false]		false
Investment, Identifier [Axis]: Burroughs, Inc., Senior Secured Loans, due 12/22/2023
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:BurroughsInc.Member
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Services: Business
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Spread Above Index	6.50%
Interest Rate	10.72%
Acquisition Date	Dec. 22, 2017
Maturity	Dec. 22, 2023
Principal	$ 5,201
Amortized Cost	5,201
Fair Value	$ 5,201
% of Net Assets	2.30%
Investment, Restriction Status [true false]	true
Investment, Significant Unobservable Input [true false]	true
Investment, Non-income Producing [true false]	false
Investment, Identifier [Axis]: C B C Restaurant Corp., Senior Secured Loans, due 12/30/2022
Schedule of Investments [Line Items]
Investment, Issuer Name [Extensible Enumeration]		mrcc:CBCRestaurantCorpMember
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		mrcc:BeverageFoodAndTobaccoSectorMember
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Interest Rate	5%
Interest rate paid in kind		5%
Maturity		Dec. 30, 2022
Principal	$ 1,066	$ 1,116
Fair Value	$ 415	$ 1,072
Investment, Identifier [Axis]: C H A Holdings, Inc, Senior Secured Loans, One, due 4/10/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:CHAHoldingsIncMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Services: Business
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR
Spread Above Index	4.50%
Interest Rate	9.23%
Maturity	Apr. 10, 2025
Principal	$ 1,960
Fair Value	$ 1,886
Investment, Identifier [Axis]: C H A Holdings, Inc, Senior Secured Loans, Two, due 4/10/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:CHAHoldingsIncMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Services: Business
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR
Spread Above Index	4.50%
Interest Rate	9.23%
Maturity	Apr. 10, 2025
Principal	$ 413
Fair Value	$ 398
Investment, Identifier [Axis]: C Parent Holdings, LLC. (fka Curion Holdings, LLC), Equity Securities, Common Stock
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:CParentHoldingsLlc.Member
Investment, Type [Extensible Enumeration]	Equity Securities [Member]
Investment, Industry Sector [Extensible Enumeration]	Services: Business
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Acquisition Date	Aug. 17, 2018
% of Net Assets	0%
Number of shares held	58,779
Investment, Restriction Status [true false]	true
Investment, Significant Unobservable Input [true false]	true
Investment, Non-income Producing [true false]	true
Investment, Identifier [Axis]: C Parent Holdings, LLC. (fka Curion Holdings, LLC), Senior Secured Loan
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:CParentHoldingsLlc.Member
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Services: Business
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Acquisition Date	May 02, 2017
Fair Value	$ 146
% of Net Assets	0.10%
Investment, Restriction Status [true false]	true
Investment, Significant Unobservable Input [true false]	true
Investment, Non-income Producing [true false]	false
Investment, Identifier [Axis]: CGI Automated Manufacturing, LLC, Senior Secured Loans, One, due 12/17/2026
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:CgiAutomatedManufacturingLlcMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Capital Equipment
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Spread Above Index	6.50%
Interest Rate	11.34%
Acquisition Date	Sep. 09, 2022
Maturity	Dec. 17, 2026
Principal	$ 3,975
Amortized Cost	3,863
Fair Value	$ 3,975
% of Net Assets	1.80%
Investment, Restriction Status [true false]	true
Investment, Significant Unobservable Input [true false]	true
Investment, Non-income Producing [true false]	false
Investment, Identifier [Axis]: CGI Automated Manufacturing, LLC, Senior Secured Loans, Two, due 12/17/2026
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:CgiAutomatedManufacturingLlcMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Capital Equipment
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Spread Above Index	6.50%
Interest Rate	11.34%
Acquisition Date	Sep. 30, 2022
Maturity	Dec. 17, 2026
Principal	$ 1,141
Amortized Cost	1,114
Fair Value	$ 1,141
% of Net Assets	0.50%
Investment, Restriction Status [true false]	true
Investment, Significant Unobservable Input [true false]	true
Investment, Non-income Producing [true false]	false
Investment, Identifier [Axis]: Cadent, L L C ( Revolver), Senior Secured Loans, due 9/11/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:CadentLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Media: Advertising, Printing & Publishing
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR
Spread Above Index	6.50%
Interest Rate	11.23%
Maturity	Sep. 11, 2025
Principal	$ 167
Investment, Identifier [Axis]: Cadent, L L C, Senior Secured Loans, due 9/11/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:CadentLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Media: Advertising, Printing & Publishing
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR
Spread Above Index	6.50%
Interest Rate	11.23%
Maturity	Sep. 11, 2025
Principal	$ 4,237
Fair Value	$ 4,131
Investment, Identifier [Axis]: Calabrio, Inc. ( Revolver), Senior Secured Loans, due 4/16/2027
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:CalabrioIncMember	mrcc:CalabrioIncMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Telecommunications	Telecommunications
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR	LIBOR
Spread Above Index	7%	7%
Interest Rate	11.75%	8%
Acquisition Date	Apr. 16, 2021	Apr. 16, 2021
Maturity	Apr. 16, 2027	Apr. 16, 2027
Principal	$ 409	$ 409
Amortized Cost	234
Fair Value	$ 233
% of Net Assets	0.10%	0%
Investment, Restriction Status [true false]	true	true
Investment, Significant Unobservable Input [true false]	true	true
Investment, Non-income Producing [true false]	false	false
Investment, Identifier [Axis]: Calabrio, Inc., Senior Secured Loans, due 4/16/2027
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:CalabrioIncMember	mrcc:CalabrioIncMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Telecommunications	Telecommunications
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR	LIBOR
Spread Above Index	7%	7%
Interest Rate	11.73%	8%
Acquisition Date	Apr. 16, 2021	Apr. 16, 2021
Maturity	Apr. 16, 2027	Apr. 16, 2027
Principal	$ 3,400	$ 3,400
Amortized Cost	3,334	3,322
Fair Value	$ 3,379	$ 3,400
% of Net Assets	1.50%	1.40%
Investment, Restriction Status [true false]	true	true
Investment, Significant Unobservable Input [true false]	true	true
Investment, Non-income Producing [true false]	false	false
Investment, Identifier [Axis]: California Pizza Kitchen, Inc., Equity Securities, Common units
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:CaliforniaPizzaKitchenInc.Member	mrcc:CaliforniaPizzaKitchenInc.Member
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Equity Securities [Member]
Investment, Industry Sector [Extensible Enumeration]	mrcc:BeverageFoodAndTobaccoSectorMember	Beverage, Food & Tobacco
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Acquisition Date	Aug. 19, 2016	Aug. 19, 2016
Amortized Cost	$ 5,468	$ 5,468
Fair Value	$ 1,266	$ 3,699
% of Net Assets	0.60%	1.50%
Number of shares held	78,699
Investment, Restriction Status [true false]	true	true
Investment, Significant Unobservable Input [true false]	true	true
Investment, Non-income Producing [true false]	false	true
Number of units held		78,699
Investment, Identifier [Axis]: Cano Health, L L C, Senior Secured Loans, due 11/23/2027
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:CanoHealthLLMember	mrcc:CanoHealthLLMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Healthcare & Pharmaceuticals Sector [Member]	Healthcare & Pharmaceuticals Sector [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Spread Above Index	4%	4%
Interest Rate	8.42%	4.51%
Maturity	Nov. 23, 2027	Nov. 23, 2027
Principal	$ 1,970	$ 1,995
Fair Value	$ 1,572	$ 1,997
Investment, Identifier [Axis]: Caravel Autism Health, L L C ( Delayed Draw), Senior Secured Loans, due 6/30/2027
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:CaravelAutismHealthLLCMember	mrcc:CaravelAutismHealthLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Healthcare & Pharmaceuticals Sector [Member]	Healthcare & Pharmaceuticals Sector [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]	LIBOR
Spread Above Index	8.75%	5.75%
Interest Rate		6.75%
Interest rate paid in cash	8.97%
Interest rate paid in kind	3%
Acquisition Date	Jun. 30, 2021	Jun. 30, 2021
Maturity	Jun. 30, 2027	Jun. 30, 2027
Principal	$ 3,750	$ 3,750
Amortized Cost	188	187
Fair Value	$ 173	$ 176
% of Net Assets	0.10%	0.10%
Investment, Restriction Status [true false]		true
Investment, Significant Unobservable Input [true false]		true
Investment, Non-income Producing [true false]		false
Investment, Identifier [Axis]: Caravel Autism Health, L L C ( Revolver), Senior Secured Loans, due 6/30/2027
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:CaravelAutismHealthLLCMember	mrcc:CaravelAutismHealthLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Healthcare & Pharmaceuticals Sector [Member]	Healthcare & Pharmaceuticals Sector [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]	LIBOR
Spread Above Index	8.75%	5.75%
Interest Rate		6.75%
Interest rate paid in kind	3%
Acquisition Date	Jun. 30, 2021	Jun. 30, 2021
Maturity	Jun. 30, 2027	Jun. 30, 2027
Principal	$ 1,260	$ 1,250
Amortized Cost	1,135	625
Fair Value	$ 1,048	$ 587
% of Net Assets	0.50%	0.20%
Investment, Restriction Status [true false]		true
Investment, Significant Unobservable Input [true false]		true
Investment, Non-income Producing [true false]		false
Investment, Identifier [Axis]: Caravel Autism Health, L L C, Senior Secured Loans, due 6/30/2027
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:CaravelAutismHealthLLCMember	mrcc:CaravelAutismHealthLLCMember
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Healthcare & Pharmaceuticals Sector [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]	LIBOR
Spread Above Index	8.75%	5.75%
Interest Rate		6.75%
Interest rate paid in cash	8.97%
Interest rate paid in kind	3%
Acquisition Date		Jun. 30, 2021
Maturity		Jun. 30, 2027
Principal		$ 5,000
Amortized Cost		4,906
Fair Value		$ 4,699
% of Net Assets		1.90%
Investment, Restriction Status [true false]		true
Investment, Significant Unobservable Input [true false]		true
Investment, Non-income Producing [true false]		false
Investment, Identifier [Axis]: Cassavant Holdings, L L C, Unitranche Secured Loans, due 9/8/2026
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:CassavantHoldingsLLCMember	mrcc:CassavantHoldingsLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Unitranche Debt [Member]
Investment, Industry Sector [Extensible Enumeration]	Aerospace & Defense	Aerospace & Defense
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR	LIBOR
Spread Above Index	6.50%	6.50%
Interest Rate	10.62%	7.50%
Acquisition Date	Sep. 08, 2021	Sep. 08, 2021
Maturity	Sep. 08, 2026	Sep. 08, 2026
Principal	$ 7,580	$ 7,980
Amortized Cost	7,461	7,828
Fair Value	$ 7,436	$ 7,972
% of Net Assets	3.30%	3.20%
Investment, Restriction Status [true false]	true	true
Investment, Significant Unobservable Input [true false]	true	true
Investment, Non-income Producing [true false]	false	false
Investment, Identifier [Axis]: Centaur ( Palm Beach) Owner L L C and Panther National Golf Club L L C ( Delayed Draw), Senior Secured Loans, due 4/30/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:CentaurPalmBeachOwnerLLCandPantherNationalGolfClubLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	FIRE Real Estate Sector [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Spread Above Index	8.25%
Interest Rate	12.43%
Acquisition Date	May 03, 2022
Maturity	Apr. 30, 2025
Principal	$ 337
Amortized Cost	337
Fair Value	$ 337
% of Net Assets	0.10%
Investment, Identifier [Axis]: Centaur ( Palm Beach) Owner L L C and Panther National Golf Club L L C ( Revolver), Senior Secured Loans, due 4/30/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:CentaurPalmBeachOwnerLLCandPantherNationalGolfClubLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	FIRE Real Estate Sector [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Spread Above Index	8.25%
Interest Rate	12.43%
Acquisition Date	May 03, 2022
Maturity	Apr. 30, 2025
Principal	$ 1,653
Amortized Cost	720
Fair Value	$ 719
% of Net Assets	0.30%
Investment, Identifier [Axis]: Centaur ( Palm Beach) Owner L L C and Panther National Golf Club L L C, Senior Secured Loans, due 4/30/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:CentaurPalmBeachOwnerLLCandPantherNationalGolfClubLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	FIRE Real Estate Sector [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Spread Above Index	8.25%
Interest Rate	12.43%
Acquisition Date	May 03, 2022
Maturity	Apr. 30, 2025
Principal	$ 3,300
Amortized Cost	3,245
Fair Value	$ 3,296
% of Net Assets	1.50%
Investment, Identifier [Axis]: Certify, Inc, Senior Secured Loans, One, due 2/28/2024
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:CertifyIncMember
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Services: Business
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Spread Above Index		5.50%
Interest Rate		6.50%
Acquisition Date		Feb. 28, 2019
Maturity		Feb. 28, 2024
Principal		$ 9,000
Amortized Cost		8,935
Fair Value		$ 9,000
% of Net Assets		3.60%
Investment, Restriction Status [true false]		true
Investment, Significant Unobservable Input [true false]		true
Investment, Non-income Producing [true false]		false
Investment, Identifier [Axis]: Certify, Inc, Senior Secured Loans, Two, due 2/28/2024
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:CertifyIncMember
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Services: Business
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Spread Above Index		5.50%
Interest Rate		6.50%
Acquisition Date		Feb. 28, 2019
Maturity		Feb. 28, 2024
Principal		$ 1,227
Amortized Cost		1,227
Fair Value		$ 1,227
% of Net Assets		0.50%
Investment, Restriction Status [true false]		true
Investment, Significant Unobservable Input [true false]		true
Investment, Non-income Producing [true false]		false
Investment, Identifier [Axis]: Certify, Inc. (Revolver), Senior Secured Loans, due 2/28/2024
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:CertifyIncMember
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Services: Business
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Spread Above Index		5.50%
Interest Rate		6.50%
Acquisition Date		Feb. 28, 2019
Maturity		Feb. 28, 2024
Principal		$ 409
Amortized Cost		102
Fair Value		$ 102
% of Net Assets		0%
Investment, Restriction Status [true false]		true
Investment, Significant Unobservable Input [true false]		true
Investment, Non-income Producing [true false]		false
Investment, Identifier [Axis]: Chess.com, L L C ( Revolver), Senior Secured Loans, due 12/31/2027
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:Chess.comLLCMember	mrcc:Chess.comLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Media: Diversified & Production	Media: Diversified & Production
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR	us-gaap:LondonInterbankOfferedRateLiborSwapRateMember
Spread Above Index	6.50%	6.50%
Interest Rate	11.23%	7.50%
Acquisition Date	Dec. 31, 2021	Dec. 31, 2021
Maturity	Dec. 31, 2027	Dec. 31, 2027
Principal	$ 652	$ 652
% of Net Assets	0%	0%
Investment, Restriction Status [true false]	true	true
Investment, Significant Unobservable Input [true false]	true	true
Investment, Non-income Producing [true false]	false	false
Investment, Identifier [Axis]: Chess.com, L L C, Equity Securities, Class A units
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:Chess.comLLCMember	mrcc:Chess.comLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Equity Securities [Member]
Investment, Industry Sector [Extensible Enumeration]	Media: Diversified & Production	Media: Diversified & Production
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Acquisition Date	Dec. 31, 2021	Dec. 31, 2021
Amortized Cost	$ 87	$ 87
Fair Value	$ 50	$ 87
% of Net Assets	0%	0%
Investment, Restriction Status [true false]	true	true
Investment, Significant Unobservable Input [true false]	true	true
Investment, Non-income Producing [true false]	false	true
Number of units held		2
Investment, Identifier [Axis]: Chess.com, L L C, Senior Secured Loans, due 12/31/2027
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:Chess.comLLCMember	mrcc:Chess.comLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Media: Diversified & Production	Media: Diversified & Production
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR	us-gaap:LondonInterbankOfferedRateLiborSwapRateMember
Spread Above Index	6.50%	6.50%
Interest Rate	11.23%	7.50%
Acquisition Date	Dec. 31, 2021	Dec. 31, 2021
Maturity	Dec. 31, 2027	Dec. 31, 2027
Principal	$ 5,955	$ 6,000
Amortized Cost	5,852	5,880
Fair Value	$ 5,866	$ 5,880
% of Net Assets	2.60%	2.30%
Investment, Restriction Status [true false]	true	true
Investment, Significant Unobservable Input [true false]	true	true
Investment, Non-income Producing [true false]	false	false
Investment, Identifier [Axis]: Corel Inc. (c), Senior Secured Loans, due 7/2/2026
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:CorelIncMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	High Tech Industries Sector [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR
Spread Above Index	5%
Interest Rate	9.73%
Maturity	Jul. 02, 2026
Principal	$ 3,600
Fair Value	$ 3,365
Investment, Identifier [Axis]: Crownpeak Technology Inc. (Revolver) Senior Secured Loans, Due 2/28/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:CrownpeakTechnologyIncMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Media: Diversified & Production
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Spread Above Index	7.25%
Interest Rate	11.47%
Acquisition Date	Feb. 28, 2019
Maturity	Feb. 28, 2025
Principal	$ 500
% of Net Assets	0%
Investment, Restriction Status [true false]	true
Investment, Significant Unobservable Input [true false]	true
Investment, Non-income Producing [true false]	false
Investment, Identifier [Axis]: Crownpeak Technology Inc. Senior Secured Loans Four, Due 2/28/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:CrownpeakTechnologyIncMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Media: Diversified & Production
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Spread Above Index	7.25%
Interest Rate	11.41%
Acquisition Date	Sep. 27, 2022
Maturity	Feb. 28, 2025
Principal	$ 3,333
Amortized Cost	3,333
Fair Value	$ 3,333
% of Net Assets	1.50%
Investment, Restriction Status [true false]	true
Investment, Significant Unobservable Input [true false]	true
Investment, Non-income Producing [true false]	false
Investment, Identifier [Axis]: Crownpeak Technology Inc. Senior Secured Loans One, Due 2/28/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:CrownpeakTechnologyIncMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Media: Diversified & Production
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Spread Above Index	7.25%
Interest Rate	11.47%
Acquisition Date	Feb. 28, 2019
Maturity	Feb. 28, 2025
Principal	$ 4,000
Amortized Cost	3,979
Fair Value	$ 4,000
% of Net Assets	1.80%
Investment, Restriction Status [true false]	true
Investment, Significant Unobservable Input [true false]	true
Investment, Non-income Producing [true false]	false
Investment, Identifier [Axis]: Crownpeak Technology Inc. Senior Secured Loans Three, Due 2/28/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:CrownpeakTechnologyIncMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Media: Diversified & Production
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Spread Above Index	7.25%
Interest Rate	11.47%
Acquisition Date	Feb. 28, 2019
Maturity	Feb. 28, 2025
Principal	$ 60
Amortized Cost	60
Fair Value	$ 60
% of Net Assets	0%
Investment, Restriction Status [true false]	true
Investment, Significant Unobservable Input [true false]	true
Investment, Non-income Producing [true false]	false
Investment, Identifier [Axis]: Crownpeak Technology Inc. Senior Secured Loans Two, Due 2/28/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:CrownpeakTechnologyIncMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Media: Diversified & Production
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Spread Above Index	7.25%
Interest Rate	11.47%
Acquisition Date	Sep. 27, 2022
Maturity	Feb. 28, 2025
Principal	$ 1,273
Amortized Cost	1,252
Fair Value	$ 1,273
% of Net Assets	0.60%
Investment, Restriction Status [true false]	true
Investment, Significant Unobservable Input [true false]	true
Investment, Non-income Producing [true false]	false
Investment, Identifier [Axis]: Crownpeak Technology, Inc. ( Revolver), Senior Secured Loans, due 2/28/2024
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:CrownpeakTechnologyIncMember
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Media: Diversified & Production
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]		us-gaap:LondonInterbankOfferedRateLiborSwapRateMember
Spread Above Index		5.75%
Interest Rate		6.75%
Acquisition Date		Feb. 28, 2019
Maturity		Feb. 28, 2024
Principal		$ 167
% of Net Assets		0%
Investment, Restriction Status [true false]		true
Investment, Significant Unobservable Input [true false]		true
Investment, Non-income Producing [true false]		false
Investment, Identifier [Axis]: Crownpeak Technology, Inc., Senior Secured Loans, One, due 2/28/2024
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:CrownpeakTechnologyIncMember
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Media: Diversified & Production
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]		us-gaap:LondonInterbankOfferedRateLiborSwapRateMember
Spread Above Index		5.75%
Interest Rate		6.75%
Acquisition Date		Feb. 28, 2019
Maturity		Feb. 28, 2024
Principal		$ 4,000
Amortized Cost		3,962
Fair Value		$ 4,000
% of Net Assets		1.60%
Investment, Restriction Status [true false]		true
Investment, Significant Unobservable Input [true false]		true
Investment, Non-income Producing [true false]		false
Investment, Identifier [Axis]: Crownpeak Technology, Inc., Senior Secured Loans, Two, due 2/28/2024
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:CrownpeakTechnologyIncMember
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Media: Diversified & Production
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]		us-gaap:LondonInterbankOfferedRateLiborSwapRateMember
Spread Above Index		5.75%
Interest Rate		6.75%
Acquisition Date		Feb. 28, 2019
Maturity		Feb. 28, 2024
Principal		$ 60
Amortized Cost		60
Fair Value		$ 60
% of Net Assets		0%
Investment, Restriction Status [true false]		true
Investment, Significant Unobservable Input [true false]		true
Investment, Non-income Producing [true false]		false
Investment, Identifier [Axis]: Curion Holdings, L L C ( Revolver), Senior Secured Loans, Due 8/31/2022
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		Curion Holdings, L L C [ Member]
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Services: Business
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Interest rate paid in kind		14%
Acquisition Date		May 02, 2017
Maturity		Aug. 31, 2022
Principal		$ 871
Amortized Cost		528
Fair Value		$ 550
% of Net Assets		0.20%
Investment, Restriction Status [true false]		true
Investment, Significant Unobservable Input [true false]		true
Investment, Non-income Producing [true false]		false
Investment, Identifier [Axis]: Curion Holdings, L L C, Equity Securities, Common stock
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	Curion Holdings, L L C [ Member]	Curion Holdings, L L C [ Member]
Investment, Type [Extensible Enumeration]		Equity Securities [Member]
Investment, Industry Sector [Extensible Enumeration]		Services: Business
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Acquisition Date		Aug. 17, 2018
% of Net Assets		0%
Number of shares held	58,779	58,779
Investment, Restriction Status [true false]		true
Investment, Significant Unobservable Input [true false]		true
Investment, Non-income Producing [true false]		true
Investment, Identifier [Axis]: Curion Holdings, L L C, Junior Secured Loans, One, Due 1/2/2023
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	Curion Holdings, L L C [ Member]	Curion Holdings, L L C [ Member]
Investment, Type [Extensible Enumeration]		Junior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Services: Business
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Interest rate paid in kind		15%
Acquisition Date		Aug. 17, 2018
Maturity		Jan. 02, 2023
Principal		$ 1,720
Amortized Cost		$ 1
% of Net Assets		0%
Investment, Restriction Status [true false]		true
Investment, Significant Unobservable Input [true false]		true
Investment, Non-income Producing [true false]		false
Investment, Identifier [Axis]: Curion Holdings, L L C, Junior Secured Loans, Two, Due 1/2/2023
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	Curion Holdings, L L C [ Member]	Curion Holdings, L L C [ Member]
Investment, Type [Extensible Enumeration]		Junior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Services: Business
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Interest rate paid in kind		15%
Acquisition Date		Aug. 17, 2018
Maturity		Jan. 02, 2023
Principal		$ 44
% of Net Assets		0%
Investment, Restriction Status [true false]		true
Investment, Significant Unobservable Input [true false]		true
Investment, Non-income Producing [true false]		false
Investment, Identifier [Axis]: Curion Holdings, L L C, Senior Secured Loans, Due 8/31/2022
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		Curion Holdings, L L C [ Member]
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Services: Business
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Interest rate paid in kind		14%
Acquisition Date		May 02, 2017
Maturity		Aug. 31, 2022
Principal		$ 4,533
Amortized Cost		4,497
Fair Value		$ 4,561
% of Net Assets		1.80%
Investment, Restriction Status [true false]		true
Investment, Significant Unobservable Input [true false]		true
Investment, Non-income Producing [true false]		false
Investment, Identifier [Axis]: Curion Holdings, L L C, Senior Secured Loans, One, Acquisition Date 5/2/2017
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	Curion Holdings, L L C [ Member]	Curion Holdings, L L C [ Member]
Fair Value	$ 146	$ 4,561	3,159
Investment, Identifier [Axis]: Curion Holdings, LLC (Revolver), Senior Secured Loans, Two, Acquisition Date 5/2/2017
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	Curion Holdings, L L C [ Member]	Curion Holdings, L L C [ Member]
Fair Value		$ 550	820
Investment, Identifier [Axis]: D S Parent, Inc., Senior Secured Loans, due 12/8/2028
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:DSParentIncMember	mrcc:DSParentIncMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Capital Equipment	Capital Equipment
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR	LIBOR
Spread Above Index		5.75%
Interest Rate		6.50%
Maturity		Dec. 08, 2028
Principal		$ 3,000
Fair Value		$ 2,970
Investment, Identifier [Axis]: Destination Media, Inc (Revolver), Senior Secured Loans, due 4/7/2023
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:DestinationMediaIncMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Media: Advertising, Printing & Publishing
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Spread Above Index	5.50%
Interest Rate	9.94%
Acquisition Date	Apr. 07, 2017
Maturity	Apr. 07, 2023
Principal	$ 542
% of Net Assets	0%
Investment, Restriction Status [true false]	true
Investment, Significant Unobservable Input [true false]	true
Investment, Non-income Producing [true false]	false
Investment, Identifier [Axis]: Destination Media, Inc, Senior Secured Loans, due 4/7/2023
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:DestinationMediaIncMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Media: Advertising, Printing & Publishing
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Spread Above Index	5.50%
Interest Rate	9.94%
Acquisition Date	Apr. 07, 2017
Maturity	Apr. 07, 2023
Principal	$ 377
Amortized Cost	377
Fair Value	$ 377
% of Net Assets	0.20%
Investment, Restriction Status [true false]	true
Investment, Significant Unobservable Input [true false]	true
Investment, Non-income Producing [true false]	false
Investment, Identifier [Axis]: Destination Media, Inc. ( Revolver), Senior Secured Loans, due 4/7/2022
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:DestinationMediaIncMember
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Media: Advertising, Printing & Publishing
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]		us-gaap:LondonInterbankOfferedRateLiborSwapRateMember
Spread Above Index		5.50%
Interest Rate		6.50%
Acquisition Date		Apr. 07, 2017
Maturity		Apr. 07, 2022
Principal		$ 542
% of Net Assets		0%
Investment, Restriction Status [true false]		true
Investment, Significant Unobservable Input [true false]		true
Investment, Non-income Producing [true false]		false
Investment, Identifier [Axis]: Destination Media, Inc., Senior Secured Loans, due 4/7/2022
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:DestinationMediaIncMember
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Media: Advertising, Printing & Publishing
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]		us-gaap:LondonInterbankOfferedRateLiborSwapRateMember
Spread Above Index		5.50%
Interest Rate		6.50%
Acquisition Date		Apr. 07, 2017
Maturity		Apr. 07, 2022
Principal		$ 1,738
Amortized Cost		1,736
Fair Value		$ 1,738
% of Net Assets		0.70%
Investment, Restriction Status [true false]		true
Investment, Significant Unobservable Input [true false]		true
Investment, Non-income Producing [true false]		false
Investment, Identifier [Axis]: Dorado Acquisition, Inc, Equity Securities, One, Class A-1 units
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:DoradoAcquisitionIncMember	mrcc:DoradoAcquisitionIncMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Equity Securities [Member]
Investment, Industry Sector [Extensible Enumeration]	Healthcare & Pharmaceuticals Sector [Member]	Healthcare & Pharmaceuticals
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Acquisition Date	Jun. 30, 2021	Jun. 30, 2021
Amortized Cost	$ 207	$ 179
Fair Value	$ 215	$ 179
% of Net Assets	0.10%	0.10%
Investment, Restriction Status [true false]	true	true
Investment, Significant Unobservable Input [true false]	true	true
Investment, Non-income Producing [true false]	false	true
Number of units held	189,922	178,891
Investment, Identifier [Axis]: Dorado Acquisition, Inc, Equity Securities, Two, Class A-2 units
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:DoradoAcquisitionIncMember	mrcc:DoradoAcquisitionIncMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Equity Securities [Member]
Investment, Industry Sector [Extensible Enumeration]	Healthcare & Pharmaceuticals Sector [Member]	Healthcare & Pharmaceuticals
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Acquisition Date	Jun. 30, 2021	Jun. 30, 2021
Fair Value	$ 224	$ 9
% of Net Assets	0.10%	0%
Investment, Restriction Status [true false]	true	true
Investment, Significant Unobservable Input [true false]	true	true
Investment, Non-income Producing [true false]	false	true
Number of units held	189,922	178,891
Investment, Identifier [Axis]: Dorado Acquisition, Inc. ( Delayed Draw) , Senior Secured Loans, due 6/30/2026
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:DoradoAcquisitionInc.Member	mrcc:DoradoAcquisitionInc.Member
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Healthcare & Pharmaceuticals Sector [Member]	Healthcare & Pharmaceuticals Sector [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]	LIBOR
Spread Above Index	6.50%	6.75%
Interest Rate	10.72%	7.75%
Acquisition Date	Jun. 30, 2021	Jun. 30, 2021
Maturity	Jun. 30, 2026	Jun. 30, 2026
Principal	$ 216	$ 216
% of Net Assets	0%	0%
Investment, Restriction Status [true false]		true
Investment, Significant Unobservable Input [true false]		true
Investment, Non-income Producing [true false]		false
Investment, Identifier [Axis]: Dorado Acquisition, Inc. ( Revolver) , Senior Secured Loans, due 6/30/2026
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:DoradoAcquisitionInc.Member	mrcc:DoradoAcquisitionInc.Member
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Healthcare & Pharmaceuticals Sector [Member]	Healthcare & Pharmaceuticals Sector [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]	LIBOR
Spread Above Index	6.50%	6.75%
Interest Rate	10.92%	7.75%
Interest rate paid in cash	8.08%
Acquisition Date	Jun. 30, 2021	Jun. 30, 2021
Maturity	Jun. 30, 2026	Jun. 30, 2026
Principal	$ 596	$ 596
Amortized Cost	596
Fair Value	$ 596
% of Net Assets	0.30%	0%
Investment, Restriction Status [true false]		true
Investment, Significant Unobservable Input [true false]		true
Investment, Non-income Producing [true false]		false
Investment, Identifier [Axis]: Dorado Acquisition, Inc., Senior Secured Loans, One, due 6/30/2026
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:DoradoAcquisitionInc.Member
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Healthcare & Pharmaceuticals Sector [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Spread Above Index	6.76%
Interest Rate	11.34%
Acquisition Date	Nov. 27, 2022
Maturity	Jun. 30, 2026
Principal	$ 4,082
Amortized Cost	3,980
Fair Value	$ 4,074
% of Net Assets	1.80%
Investment, Identifier [Axis]: Dorado Acquisition, Inc., Senior Secured Loans, due 6/30/2026
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:DoradoAcquisitionInc.Member	mrcc:DoradoAcquisitionInc.Member
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Healthcare & Pharmaceuticals Sector [Member]	Healthcare & Pharmaceuticals Sector [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]	LIBOR
Spread Above Index	6.50%	6.75%
Interest Rate	10.72%	7.75%
Acquisition Date	Jun. 30, 2021	Jun. 30, 2021
Maturity	Jun. 30, 2026	Jun. 30, 2026
Principal	$ 4,938	$ 4,988
Amortized Cost	4,862	4,895
Fair Value	$ 4,928	$ 4,983
% of Net Assets	2.20%	2%
Investment, Restriction Status [true false]		true
Investment, Significant Unobservable Input [true false]		true
Investment, Non-income Producing [true false]		false
Investment, Identifier [Axis]: Drawbridge Partners, LLC (Delayed Draw), Senior Secured Loans, due 9/1/2028
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:DrawbridgePartnersLlcMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	High Tech Industries Sector [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Spread Above Index	7%
Interest rate paid in kind	11.56%
Acquisition Date	Sep. 01, 2022
Maturity	Sep. 01, 2028
Principal	$ 330
Amortized Cost	103
Fair Value	$ 102
% of Net Assets	0%
Investment, Restriction Status [true false]	true
Investment, Significant Unobservable Input [true false]	true
Investment, Non-income Producing [true false]	false
Investment, Identifier [Axis]: Drawbridge Partners, LLC (Revolver), Senior Secured Loans, due 9/1/2028
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:DrawbridgePartnersLlcMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	High Tech Industries Sector [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Spread Above Index	7%
Interest Rate	11.56%
Acquisition Date	Sep. 01, 2022
Maturity	Sep. 01, 2028
Principal	$ 522
% of Net Assets	0%
Investment, Restriction Status [true false]	true
Investment, Significant Unobservable Input [true false]	true
Investment, Non-income Producing [true false]	false
Investment, Identifier [Axis]: Drawbridge Partners, LLC, Equity Securities, Class A Units
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:DrawbridgePartnersLlcMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	High Tech Industries Sector [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Acquisition Date	Sep. 01, 2022
Amortized Cost	$ 130
Fair Value	$ 126
% of Net Assets	0.10%
Investment, Restriction Status [true false]	true
Investment, Significant Unobservable Input [true false]	true
Investment, Non-income Producing [true false]	false
Number of units held	130,433
Investment, Identifier [Axis]: Drawbridge Partners, LLC, Senior Secured Loans, due 9/1/2028
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:DrawbridgePartnersLlcMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	High Tech Industries Sector [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Spread Above Index	7%
Interest rate paid in kind	11.56%
Acquisition Date	Sep. 01, 2022
Maturity	Sep. 01, 2028
Principal	$ 3,000
Amortized Cost	2,943
Fair Value	$ 2,971
% of Net Assets	1.30%
Investment, Restriction Status [true false]	true
Investment, Significant Unobservable Input [true false]	true
Investment, Non-income Producing [true false]	false
Investment, Identifier [Axis]: Dresser Utility Solutions, L L C (fka N G S U S Finco, L L C), Senior Secured Loans, One, due 10/1/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:DresserUtilitySolutionsLLCfkaNGSUSFincoLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Utilities, Oil & Gas Sector [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR
Spread Above Index	4.25%
Interest Rate	8.63%
Maturity	Oct. 01, 2025
Principal	$ 1,678
Fair Value	$ 1,619
Investment, Identifier [Axis]: Dresser Utility Solutions, L L C (fka N G S U S Finco, L L C), Senior Secured Loans, Two, due 10/1/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:DresserUtilitySolutionsLLCfkaNGSUSFincoLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Utilities, Oil & Gas Sector [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR
Spread Above Index	5.25%
Interest Rate	9.63%
Maturity	Oct. 01, 2025
Principal	$ 245
Fair Value	$ 239
Investment, Identifier [Axis]: Drilling Info Holdings, Inc., Senior Secured Loans, due 7/30/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:DrillingInfoHoldingsIncMember	mrcc:DrillingInfoHoldingsIncMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	us-gaap-supplement:EnergySectorMember	Utilities, Oil & Gas Sector [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR	LIBOR
Spread Above Index		4.25%
Interest Rate		4.35%
Maturity		Jul. 30, 2025
Principal		$ 4,516
Fair Value		$ 4,471
Investment, Identifier [Axis]: Education Corporation of America, Equity Securities, Series G Preferred Stock
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:EducationCorporationofAmericaMember	mrcc:EducationCorporationofAmericaMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Equity Securities [Member]
Investment, Industry Sector [Extensible Enumeration]	Services: Consumer	Services: Consumer
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Interest rate paid in kind	12%	12%
Acquisition Date	Sep. 03, 2015	Sep. 03, 2015
Amortized Cost	$ 7,492	$ 7,492
Fair Value		$ 2,281
% of Net Assets	0%	0.90%
Number of shares held		8,333
Investment, Restriction Status [true false]	true	true
Investment, Significant Unobservable Input [true false]	true	true
Investment, Non-income Producing [true false]	false	false
Number of units held	8,333
Investment, Identifier [Axis]: Education Corporation of America, Junior Secured Loans
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:EducationCorporationofAmericaMember	mrcc:EducationCorporationofAmericaMember
Investment, Type [Extensible Enumeration]	Junior Loans [Member]	Junior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Services: Consumer	Services: Consumer
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR	LIBOR
Spread Above Index	11%	11%
Interest rate paid in cash		5.72%
Interest rate paid in kind	5.50%	5.50%
Acquisition Date	Sep. 03, 2015	Sep. 03, 2015
Principal	$ 833	$ 833
Amortized Cost	831	831
Fair Value	$ 1,882	$ 576
% of Net Assets	0.80%	0.20%
Investment, Restriction Status [true false]	true	true
Investment, Significant Unobservable Input [true false]	true	true
Investment, Non-income Producing [true false]	false	false
Investment, Identifier [Axis]: Eliassen Group, L L C ( Delayed Draw), Senior Secured Loans, due 4/14/2028
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:EliassenGroupLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Services: Business
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Spread Above Index	5.50%
Interest Rate	8.88%
Maturity	Apr. 14, 2028
Principal	$ 740
Fair Value	$ 109
Investment, Identifier [Axis]: Eliassen Group, L L C, Senior Secured Loans, due 4/14/2028
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:EliassenGroupLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Services: Business
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Spread Above Index	5.50%
Interest Rate	10.08%
Maturity	Apr. 14, 2028
Principal	$ 3,251
Fair Value	$ 3,194
Investment, Identifier [Axis]: Energy Services Group, L L C, Unitranche Secured Loans, One, Due 5/4/2022
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:EnergyServicesGroupLLCMember
Investment, Type [Extensible Enumeration]		Unitranche Debt [Member]
Investment, Industry Sector [Extensible Enumeration]		High Tech Industries
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Spread Above Index		8.42%
Interest Rate		9.42%
Acquisition Date		May 04, 2017
Maturity		May 04, 2022
Principal		$ 3,725
Amortized Cost		3,720
Fair Value		$ 3,725
% of Net Assets		1.50%
Investment, Restriction Status [true false]		true
Investment, Significant Unobservable Input [true false]		true
Investment, Non-income Producing [true false]		false
Investment, Identifier [Axis]: Energy Services Group, L L C, Unitranche Secured Loans, Three, Due 5/4/2022
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:EnergyServicesGroupLLCMember
Investment, Type [Extensible Enumeration]		Unitranche Debt [Member]
Investment, Industry Sector [Extensible Enumeration]		High Tech Industries
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Spread Above Index		8.42%
Interest Rate		9.42%
Acquisition Date		May 04, 2017
Maturity		May 04, 2022
Principal		$ 1,060
Amortized Cost		1,047
Fair Value		$ 1,060
% of Net Assets		0.40%
Investment, Restriction Status [true false]		true
Investment, Significant Unobservable Input [true false]		true
Investment, Non-income Producing [true false]		false
Investment, Identifier [Axis]: Energy Services Group, L L C, Unitranche Secured Loans, Two, Due 5/4/2022
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:EnergyServicesGroupLLCMember
Investment, Type [Extensible Enumeration]		Unitranche Debt [Member]
Investment, Industry Sector [Extensible Enumeration]		High Tech Industries
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]		Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Spread Above Index		8.42%
Interest Rate		9.42%
Acquisition Date		May 04, 2017
Maturity		May 04, 2022
Principal		$ 4,541
Amortized Cost		4,458
Fair Value		$ 4,541
% of Net Assets		1.80%
Investment, Restriction Status [true false]		true
Investment, Significant Unobservable Input [true false]		true
Investment, Non-income Producing [true false]		false
Investment, Identifier [Axis]: Engage2 Excel, Inc. ( Revolver), Senior Secured Loans, due 3/7/2023
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:Engage2ExcelIncMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Services: Business
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR
Spread Above Index	6.25%
Interest Rate	13.75%
Maturity	Mar. 07, 2023
Principal	$ 554
Fair Value	$ 509
Investment, Identifier [Axis]: Engage2 Excel, Inc., Senior Secured Loans, One, due 3/7/2023
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:Engage2ExcelIncMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Services: Business
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR
Spread Above Index	7.25%
Interest Rate	11.98%
Maturity	Mar. 07, 2023
Principal	$ 4,283
Fair Value	$ 4,242
Investment, Identifier [Axis]: Engage2 Excel, Inc., Senior Secured Loans, Two,due 3/7/2023
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:Engage2ExcelIncMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Services: Business
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR
Spread Above Index	7.25%
Interest Rate	11.98%
Maturity	Mar. 07, 2023
Principal	$ 773
Fair Value	$ 766
Investment, Identifier [Axis]: Equine Network, L L C ( Delayed Draw), Senior Secured Loans, due 12/13/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:EquineNetworkLLCMember
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Hotels, Gaming & Leisure
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Spread Above Index		8%
Interest Rate		9%
Acquisition Date		Dec. 31, 2020
Maturity		Dec. 31, 2025
Principal		$ 427
% of Net Assets		0%
Investment, Restriction Status [true false]		true
Investment, Significant Unobservable Input [true false]		true
Investment, Non-income Producing [true false]		false
Investment, Identifier [Axis]: Equine Network, L L C ( Revolver) , Senior Secured Loans, due 12/13/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:EquineNetworkLLCMember
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Hotels, Gaming & Leisure
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Spread Above Index		8%
Interest Rate		9%
Acquisition Date		Dec. 31, 2020
Maturity		Dec. 31, 2025
Principal		$ 171
Amortized Cost		85
Fair Value		$ 85
% of Net Assets		0.10%
Investment, Restriction Status [true false]		true
Investment, Significant Unobservable Input [true false]		true
Investment, Non-income Producing [true false]		false
Investment, Identifier [Axis]: Equine Network, L L C, (Delayed Draw), Senior Secured Loans, due 12/31/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:EquineNetworkLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Hotels, Gaming & Leisure
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Spread Above Index	6%
Interest Rate	10.24%
Acquisition Date	Dec. 31, 2020
Maturity	Dec. 31, 2025
Principal	$ 427
% of Net Assets	0%
Investment, Restriction Status [true false]	true
Investment, Significant Unobservable Input [true false]	true
Investment, Non-income Producing [true false]	false
Investment, Identifier [Axis]: Equine Network, L L C, (Revolver), Senior Secured Loans, due 12/31/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:EquineNetworkLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Hotels, Gaming & Leisure
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Spread Above Index	6%
Interest Rate	10.30%
Acquisition Date	Dec. 31, 2020
Maturity	Dec. 31, 2025
Principal	$ 171
Amortized Cost	128
Fair Value	$ 127
% of Net Assets	0.10%
Investment, Restriction Status [true false]	true
Investment, Significant Unobservable Input [true false]	true
Investment, Non-income Producing [true false]	false
Investment, Identifier [Axis]: Equine Network, L L C, Equity Securities, Class A units
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:EquineNetworkLLCMember	mrcc:EquineNetworkLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Equity Securities [Member]
Investment, Industry Sector [Extensible Enumeration]	Hotels, Gaming & Leisure	Hotels, Gaming & Leisure
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Acquisition Date	Dec. 31, 2020	Dec. 31, 2020
Amortized Cost	$ 111	$ 99
Fair Value	$ 109	$ 102
% of Net Assets	0%	0%
Investment, Restriction Status [true false]	true	true
Investment, Significant Unobservable Input [true false]	true	true
Investment, Non-income Producing [true false]	false	true
Number of units held	108	99
Investment, Identifier [Axis]: Equine Network, L L C, Senior Secured Loans, One, due 12/13/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:EquineNetworkLLCMember
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Hotels, Gaming & Leisure
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Spread Above Index		8%
Interest Rate		9%
Acquisition Date		Dec. 31, 2020
Maturity		Dec. 31, 2025
Principal		$ 1,737
Amortized Cost		1,704
Fair Value		$ 1,733
% of Net Assets		0.70%
Investment, Restriction Status [true false]		true
Investment, Significant Unobservable Input [true false]		true
Investment, Non-income Producing [true false]		false
Investment, Identifier [Axis]: Equine Network, L L C, Senior Secured Loans, One, due 12/31/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:EquineNetworkLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Hotels, Gaming & Leisure
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Spread Above Index	6%
Interest Rate	10.24%
Acquisition Date	Dec. 31, 2020
Maturity	Dec. 31, 2025
Principal	$ 1,719
Amortized Cost	1,694
Fair Value	$ 1,709
% of Net Assets	0.70%
Investment, Restriction Status [true false]	true
Investment, Significant Unobservable Input [true false]	true
Investment, Non-income Producing [true false]	false
Investment, Identifier [Axis]: Equine Network, L L C, Senior Secured Loans, Two, due 12/13/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:EquineNetworkLLCMember
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Hotels, Gaming & Leisure
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Spread Above Index		8%
Interest Rate		9%
Acquisition Date		Jan. 29, 2021
Maturity		Dec. 31, 2025
Principal		$ 788
Amortized Cost		774
Fair Value		$ 786
% of Net Assets		0.30%
Investment, Restriction Status [true false]		true
Investment, Significant Unobservable Input [true false]		true
Investment, Non-income Producing [true false]		false
Investment, Identifier [Axis]: Equine Network, L L C, Senior Secured Loans, Two, due 12/31/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:EquineNetworkLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Hotels, Gaming & Leisure
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Spread Above Index	6%
Interest Rate	10.24%
Acquisition Date	Jan. 29, 2021
Maturity	Dec. 31, 2025
Principal	$ 780
Amortized Cost	769
Fair Value	$ 775
% of Net Assets	0.30%
Investment, Restriction Status [true false]	true
Investment, Significant Unobservable Input [true false]	true
Investment, Non-income Producing [true false]	false
Investment, Identifier [Axis]: Excel Fitness Holdings, Inc. ( Revolver), Senior Secured Loans, due 4/28/2028
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:ExcelFitnessHoldingsIncMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Hotels, Gaming & Leisure
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Spread Above Index	5.25%
Interest Rate	9.67%
Maturity	Apr. 28, 2028
Principal	$ 625
Fair Value	$ 306
Investment, Identifier [Axis]: Excel Fitness Holdings, Inc., Senior Secured Loans, due 4/27/2029
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:ExcelFitnessHoldingsIncMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Hotels, Gaming & Leisure
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Spread Above Index	5.25%
Interest Rate	10.29%
Maturity	Apr. 27, 2029
Principal	$ 4,364
Fair Value	$ 4,102
Investment, Identifier [Axis]: Express Wash Acquisition Company, L L C ( Delayed Draw), Senior Secured Loans, Four, due 12/26/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:ExpressWashAcquisitionCompanyLLCMember
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Services: Consumer
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Spread Above Index		6.50%
Interest Rate		7.50%
Acquisition Date		Sep. 03, 2021
Maturity		Dec. 26, 2025
Principal		$ 2,500
Amortized Cost		925
Fair Value		$ 925
% of Net Assets		0.40%
Investment, Restriction Status [true false]		true
Investment, Significant Unobservable Input [true false]		true
Investment, Non-income Producing [true false]		false
Investment, Identifier [Axis]: Express Wash Acquisition Company, L L C ( Revolver), Senior Secured Loans, due 12/26/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:ExpressWashAcquisitionCompanyLLCMember
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Services: Consumer
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Spread Above Index		6.50%
Interest Rate		7.50%
Acquisition Date		Dec. 28, 2020
Maturity		Dec. 26, 2025
Principal		$ 750
Amortized Cost		400
Fair Value		$ 400
% of Net Assets		0.20%
Investment, Restriction Status [true false]		true
Investment, Significant Unobservable Input [true false]		true
Investment, Non-income Producing [true false]		false
Investment, Identifier [Axis]: Express Wash Acquisition Company, L L C, Equity Securities, Class A units
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:ExpressWashAcquisitionCompanyLLCMember	mrcc:ExpressWashAcquisitionCompanyLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Equity Securities [Member]
Investment, Industry Sector [Extensible Enumeration]	Services: Consumer	Services: Consumer
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Interest rate paid in kind	8%	8%
Acquisition Date	Dec. 28, 2020	Dec. 28, 2020
Amortized Cost	$ 125	$ 125
Fair Value	$ 118	$ 208
% of Net Assets	0.10%	0.10%
Investment, Restriction Status [true false]	true	true
Investment, Significant Unobservable Input [true false]	true	true
Investment, Non-income Producing [true false]	false	false
Number of units held	121,311	121,311
Investment, Identifier [Axis]: Express Wash Acquisition Company, L L C, Senior Secured Loans, One, due 12/26/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:ExpressWashAcquisitionCompanyLLCMember
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Services: Consumer
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Spread Above Index		6.50%
Interest Rate		7.50%
Acquisition Date		Dec. 28, 2020
Maturity		Dec. 26, 2025
Principal		$ 3,203
Amortized Cost		3,156
Fair Value		$ 3,203
% of Net Assets		1.30%
Investment, Restriction Status [true false]		true
Investment, Significant Unobservable Input [true false]		true
Investment, Non-income Producing [true false]		false
Investment, Identifier [Axis]: Express Wash Acquisition Company, L L C, Senior Secured Loans, Three, due 12/26/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:ExpressWashAcquisitionCompanyLLCMember
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Services: Consumer
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Spread Above Index		6.50%
Interest Rate		7.50%
Acquisition Date		Sep. 03, 2021
Maturity		Dec. 26, 2025
Principal		$ 3,500
Amortized Cost		3,500
Fair Value		$ 3,500
% of Net Assets		1.40%
Investment, Restriction Status [true false]		true
Investment, Significant Unobservable Input [true false]		true
Investment, Non-income Producing [true false]		false
Investment, Identifier [Axis]: Express Wash Acquisition Company, L L C, Senior Secured Loans, Two, due 12/26/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:ExpressWashAcquisitionCompanyLLCMember
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Services: Consumer
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Spread Above Index		6.50%
Interest Rate		7.50%
Acquisition Date		Sep. 03, 2021
Maturity		Dec. 26, 2025
Principal		$ 7,275
Amortized Cost		7,156
Fair Value		$ 7,275
% of Net Assets		2.90%
Investment, Restriction Status [true false]		true
Investment, Significant Unobservable Input [true false]		true
Investment, Non-income Producing [true false]		false
Investment, Identifier [Axis]: Express Wash Acquisition Company, LLC (Revolver), Senior Secured Loans, due 7/14/2028
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:ExpressWashAcquisitionCompanyLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Services: Consumer
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Spread Above Index	6.50%
Interest Rate	10.83%
Acquisition Date	Jul. 14, 2022
Maturity	Jul. 14, 2028
Principal	$ 379
Amortized Cost	209
Fair Value	$ 208
% of Net Assets	0.10%
Investment, Restriction Status [true false]	true
Investment, Significant Unobservable Input [true false]	true
Investment, Non-income Producing [true false]	false
Investment, Identifier [Axis]: Express Wash Acquisition Company, LLC, Senior Secured Loans, One, Due 7/14/2028
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:ExpressWashAcquisitionCompanyLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Services: Consumer
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Spread Above Index	6.50%
Interest Rate	10.32%
Acquisition Date	Jul. 14, 2022
Maturity	Jul. 14, 2028
Principal	$ 8,160
Amortized Cost	8,114
Fair Value	$ 8,119
% of Net Assets	3.60%
Investment, Restriction Status [true false]	true
Investment, Significant Unobservable Input [true false]	true
Investment, Non-income Producing [true false]	false
Investment, Identifier [Axis]: Express Wash Acquisition Company, LLC, Senior Secured Loans, Two, Due 7/14/2028
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:ExpressWashAcquisitionCompanyLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Services: Consumer
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Spread Above Index	6.50%
Interest Rate	10.43%
Acquisition Date	Jul. 14, 2022
Maturity	Jul. 14, 2028
Principal	$ 1,528
Amortized Cost	1,528
Fair Value	$ 1,521
% of Net Assets	0.70%
Investment, Restriction Status [true false]	true
Investment, Significant Unobservable Input [true false]	true
Investment, Non-income Producing [true false]	false
Investment, Identifier [Axis]: Familia Dental Group Holdings, L L C, Equity Securities, Class A units
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	Familia Dental Group Holdings, LLC	Familia Dental Group Holdings, LLC
Investment, Type [Extensible Enumeration]	Equity Securities [Member]	Equity Securities [Member]
Investment, Industry Sector [Extensible Enumeration]	Healthcare & Pharmaceuticals	Healthcare & Pharmaceuticals
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Acquisition Date	Apr. 08, 2016	Apr. 08, 2016
Amortized Cost	$ 4,030	$ 3,785
Fair Value	$ 2,625	$ 1,919	3,118
% of Net Assets	1.20%	0.80%
Investment, Restriction Status [true false]	true	true
Investment, Significant Unobservable Input [true false]	true	true
Investment, Non-income Producing [true false]	true	true
Number of units held	1,176	1,105
Investment, Identifier [Axis]: Florida East Coast Industries, L L C, Junior Secured Loans, due 6/28/2024
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:FloridaEastCoastIndustriesLLCMember
Investment, Type [Extensible Enumeration]	Junior Loans [Member]	Junior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	FIRE: Real Estate	FIRE: Real Estate
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Interest rate paid in cash	8%
Interest rate paid in kind	16%	16%
Acquisition Date	Aug. 09, 2021	Aug. 09, 2021
Maturity	Jun. 28, 2024	Jun. 28, 2024
Principal	$ 1,778	$ 1,520
Amortized Cost	1,753	1,482
Fair Value	$ 1,784	$ 1,530
% of Net Assets	0.80%	0.60%
Investment, Restriction Status [true false]	true	true
Investment, Significant Unobservable Input [true false]	true	true
Investment, Non-income Producing [true false]	false	false
Investment, Identifier [Axis]: Florida East Coast Industries, L L C, Senior Secured Loans, due 6/28/2024
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:FloridaEastCoastIndustriesLLCMember
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		FIRE Real Estate Sector [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Interest Rate	10.50%	10.50%
Acquisition Date	Aug. 09, 2021	Aug. 09, 2021
Maturity	Jun. 28, 2024	Jun. 28, 2024
Principal	$ 617	$ 3,572
Amortized Cost	606	3,477
Fair Value	$ 619	$ 3,571
% of Net Assets	0.30%	1.40%
Investment, Restriction Status [true false]		true
Investment, Significant Unobservable Input [true false]		true
Investment, Non-income Producing [true false]		false
Investment, Identifier [Axis]: Forman Mills, Inc, Equity Securities, Warrants
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:FormanMillsIncMember	mrcc:FormanMillsInc.Member
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Equity Securities [Member]
Investment, Industry Sector [Extensible Enumeration]	Retail	Retail
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Acquisition Date	Jan. 14, 2020	Jan. 14, 2020
Maturity	Jan. 14, 2029	Jan. 14, 2029
Fair Value	$ 155	$ 702
% of Net Assets	0.10%	0.30%
Investment, Restriction Status [true false]	true	true
Investment, Significant Unobservable Input [true false]	true	true
Investment, Non-income Producing [true false]	false	true
Warrants to Purchase Percentage of Equity		2.60%
Percentage of interests	2.60%
Investment, Identifier [Axis]: Forman Mills, Inc, Senior Secured Loans, One, due 4/30/2024
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:FormanMillsIncMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Retail
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Spread Above Index	9.50%
Interest rate paid in cash	11.94%
Interest rate paid in kind	2%
Acquisition Date	Jan. 14, 2020
Maturity	Apr. 30, 2024
Principal	$ 1,275
Amortized Cost	1,275
Fair Value	$ 1,253
% of Net Assets	0.60%
Investment, Restriction Status [true false]	true
Investment, Significant Unobservable Input [true false]	true
Investment, Non-income Producing [true false]	false
Investment, Identifier [Axis]: Forman Mills, Inc, Senior Secured Loans, Two, due 4/30/2024
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:FormanMillsIncMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Retail
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Spread Above Index	9.50%
Interest rate paid in cash	11.94%
Interest rate paid in kind	2%
Acquisition Date	Apr. 10, 2016
Maturity	Apr. 30, 2024
Principal	$ 6,909
Amortized Cost	6,909
Fair Value	$ 6,698
% of Net Assets	3%
Investment, Restriction Status [true false]	true
Investment, Significant Unobservable Input [true false]	true
Investment, Non-income Producing [true false]	false
Investment, Identifier [Axis]: Forman Mills, Inc., Senior Secured Loans, One, due 12/30/2022
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:FormanMillsInc.Member
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Retail
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]		us-gaap:LondonInterbankOfferedRateLiborSwapRateMember
Spread Above Index		9.50%
Interest rate paid in cash		8.50%
Interest rate paid in kind		2%
Acquisition Date		Jan. 14, 2020
Maturity		Dec. 30, 2022
Principal		$ 1,336
Amortized Cost		1,336
Fair Value		$ 1,330
% of Net Assets		0.50%
Investment, Restriction Status [true false]		true
Investment, Significant Unobservable Input [true false]		true
Investment, Non-income Producing [true false]		false
Investment, Identifier [Axis]: Forman Mills, Inc., Senior Secured Loans, Three, due 12/30/2022
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:FormanMillsInc.Member
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Retail
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]		us-gaap:LondonInterbankOfferedRateLiborSwapRateMember
Spread Above Index		9.50%
Interest rate paid in cash		8.50%
Interest rate paid in kind		2%
Acquisition Date		Oct. 04, 2016
Maturity		Dec. 30, 2022
Principal		$ 7,623
Amortized Cost		7,600
Fair Value		$ 7,524
% of Net Assets		3%
Investment, Restriction Status [true false]		true
Investment, Significant Unobservable Input [true false]		true
Investment, Non-income Producing [true false]		false
Investment, Identifier [Axis]: Forman Mills, Inc., Senior Secured Loans, Two, due 12/30/2022
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:FormanMillsInc.Member
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Retail
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]		us-gaap:LondonInterbankOfferedRateLiborSwapRateMember
Spread Above Index		9.50%
Interest rate paid in cash		8.50%
Interest rate paid in kind		2%
Acquisition Date		Oct. 04, 2016
Maturity		Dec. 30, 2022
Principal		$ 282
Amortized Cost		281
Fair Value		$ 281
% of Net Assets		0.10%
Investment, Restriction Status [true false]		true
Investment, Significant Unobservable Input [true false]		true
Investment, Non-income Producing [true false]		false
Investment, Identifier [Axis]: GC Champion Acquisition LLC (Delayed Draw), Senior Notes, Due 8/18/2028
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:GCChampionAcquisitionLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	mrcc:FireFinanceMember
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Spread Above Index	6.75%
Interest Rate	11.15%
Acquisition Date	Aug. 19, 2022
Maturity	Aug. 18, 2028
Principal	$ 704
% of Net Assets	0%
Investment, Restriction Status [true false]	true
Investment, Significant Unobservable Input [true false]	true
Investment, Non-income Producing [true false]	false
Investment, Identifier [Axis]: GC Champion Acquisition LLC, Senior Notes, Due 8/18/2028
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:GCChampionAcquisitionLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	mrcc:FireFinanceMember
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Spread Above Index	6.75%
Interest Rate	11.15%
Acquisition Date	Aug. 19, 2022
Maturity	Aug. 18, 2028
Principal	$ 2,528
Amortized Cost	2,480
Fair Value	$ 2,503
% of Net Assets	1.10%
Investment, Restriction Status [true false]	true
Investment, Significant Unobservable Input [true false]	true
Investment, Non-income Producing [true false]	false
Investment, Identifier [Axis]: H A H Group Holding Company L L C, Senior Secured Loans, due 10/29/2027
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:HAHGroupHoldingCompanyLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Healthcare & Pharmaceuticals Sector [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Spread Above Index	5%
Interest Rate	9.43%
Maturity	Oct. 29, 2027
Principal	$ 2,978
Fair Value	$ 2,847
Investment, Identifier [Axis]: H A L O Buyer, Inc., Senior Secured Loans, due 6/30/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:HALOBuyerIncMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR
Spread Above Index	4.50%
Interest Rate	8.88%
Maturity	Jun. 30, 2025
Principal	$ 4,774
Fair Value	$ 4,219
Investment, Identifier [Axis]: H F Z Capital Group L L C, Senior Secured Loans , Two
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:HFZCapitalGroupLLCMember	mrcc:HFZCapitalGroupLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	FIRE: Real Estate	FIRE: Real Estate
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR	LIBOR
Spread Above Index	12.50%	12.50%
Interest rate paid in kind	16.62%	14%
Acquisition Date	Oct. 20, 2017	Oct. 20, 2017
Principal	$ 4,758	$ 4,758
Amortized Cost	4,758	4,758
Fair Value	$ 5,805	$ 5,420	4,709
% of Net Assets	2.60%	2.20%
Investment, Restriction Status [true false]	true	true
Investment, Significant Unobservable Input [true false]	true	true
Investment, Non-income Producing [true false]	false	false
Investment, Identifier [Axis]: H F Z Capital Group L L C, Senior Secured Loans, One
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:HFZCapitalGroupLLCMember	mrcc:HFZCapitalGroupLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	FIRE: Real Estate	FIRE: Real Estate
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR	LIBOR
Spread Above Index	12.50%	12.50%
Interest rate paid in kind	16.62%	14%
Acquisition Date	Oct. 20, 2017	Oct. 20, 2017
Principal	$ 13,242	$ 13,242
Amortized Cost	13,242	13,242
Fair Value	$ 16,159	$ 15,084	13,106
% of Net Assets	7.20%	6%
Investment, Restriction Status [true false]	true	true
Investment, Significant Unobservable Input [true false]	true	true
Investment, Non-income Producing [true false]	false	false
Investment, Identifier [Axis]: H S4 Acquisitionco, Inc. ( Revolver), Senior Secured Loans, due 7/9/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:HS4AcquisitioncoIncMember	mrcc:HS4AcquisitioncoIncMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Services: Business	Services: Business
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR	LIBOR
Spread Above Index	6.75%	6.75%
Interest Rate	11.14%	7.75%
Acquisition Date	Jul. 09, 2019	Jul. 09, 2019
Maturity	Jul. 09, 2025	Jul. 09, 2025
Principal	$ 817	$ 817
Amortized Cost	409
Fair Value	$ 407
% of Net Assets	0.20%	0%
Investment, Restriction Status [true false]	true	true
Investment, Significant Unobservable Input [true false]	true	true
Investment, Non-income Producing [true false]	false	false
Investment, Identifier [Axis]: H S4 Acquisitionco, Inc., Senior Secured Loans, due 7/9/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:HS4AcquisitioncoIncMember	mrcc:HS4AcquisitioncoIncMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Services: Business	Services: Business
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR	LIBOR
Spread Above Index	6.75%	6.75%
Interest Rate	11.14%	7.75%
Acquisition Date	Jul. 09, 2019	Jul. 09, 2019
Maturity	Jul. 09, 2025	Jul. 09, 2025
Principal	$ 9,899	$ 10,000
Amortized Cost	9,801	9,869
Fair Value	$ 9,855	$ 9,910
% of Net Assets	4.40%	4%
Investment, Restriction Status [true false]	true	true
Investment, Significant Unobservable Input [true false]	true	true
Investment, Non-income Producing [true false]	false	false
Investment, Identifier [Axis]: Harbour Benefit Holdings, Inc., Senior Secured Loans, One, due 12/13/2024
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:HarbourBenefitHoldingsIncMember	mrcc:HarbourBenefitHoldingsIncMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	mrcc:FireFinanceMember	mrcc:FireFinanceMember
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR	us-gaap:LondonInterbankOfferedRateLiborSwapRateMember
Spread Above Index	5.25%	5.25%
Interest Rate	9.98%	6.25%
Maturity	Dec. 13, 2024	Dec. 13, 2024
Principal	$ 2,901	$ 2,948
Fair Value	$ 2,898	$ 2,932
Investment, Identifier [Axis]: Harbour Benefit Holdings, Inc., Senior Secured Loans, Two, due 12/13/2024
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:HarbourBenefitHoldingsIncMember	mrcc:HarbourBenefitHoldingsIncMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	mrcc:FireFinanceMember	mrcc:FireFinanceMember
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR	us-gaap:LondonInterbankOfferedRateLiborSwapRateMember
Spread Above Index	5.25%	5.25%
Interest Rate	9.63%	6.25%
Maturity	Dec. 13, 2024	Dec. 13, 2024
Principal	$ 61	$ 66
Fair Value	$ 61	$ 65
Investment, Identifier [Axis]: Hastings Manufacturing Company, Senior Secured Loans, due 4/24/2023
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:HastingsManufacturingCompanyMember	mrcc:HastingsManufacturingCompanyMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Automotive	Automotive
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR	LIBOR
Spread Above Index	7.25%	7.25%
Interest Rate	11.64%	8.25%
Acquisition Date	Apr. 24, 2018	Apr. 24, 2018
Maturity	Apr. 24, 2023	Apr. 24, 2023
Principal	$ 2,026	$ 2,524
Amortized Cost	2,023	2,508
Fair Value	$ 2,026	$ 2,524
% of Net Assets	0.90%	1%
Investment, Restriction Status [true false]	true	true
Investment, Significant Unobservable Input [true false]	true	true
Investment, Non-income Producing [true false]	false	false
Investment, Identifier [Axis]: I D I G Parent, L L C ( Revolver), Senior Secured Loans, due 12/15/2026
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		I D I G Parent, L L C [ Member]
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Services: Consumer
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Spread Above Index		6%
Interest Rate		7%
Acquisition Date		Dec. 15, 2020
Maturity		Dec. 15, 2026
Principal		$ 429
% of Net Assets		0%
Investment, Restriction Status [true false]		true
Investment, Significant Unobservable Input [true false]		true
Investment, Non-income Producing [true false]		false
Investment, Identifier [Axis]: I D I G Parent, L L C, Equity Securities, Common stock
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	I D I G Parent, L L C [ Member]	I D I G Parent, L L C [ Member]
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Equity Securities [Member]
Investment, Industry Sector [Extensible Enumeration]	Services: Consumer	Services: Consumer
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Acquisition Date	Jan. 04, 2021	Jan. 04, 2021
Amortized Cost	$ 248	$ 248
Fair Value	$ 324	$ 428
% of Net Assets	0.10%	0.20%
Number of shares held	245,958	245,958
Investment, Restriction Status [true false]	true	true
Investment, Significant Unobservable Input [true false]	true	true
Investment, Non-income Producing [true false]	false	true
Investment, Identifier [Axis]: I D I G Parent, L L C, Senior Secured Loans, One, due 12/15/2026
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		I D I G Parent, L L C [ Member]
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Services: Consumer
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Spread Above Index		6%
Interest Rate		7%
Acquisition Date		Dec. 15, 2020
Maturity		Dec. 15, 2026
Principal		$ 5,517
Amortized Cost		5,423
Fair Value		$ 5,530
% of Net Assets		2.20%
Investment, Restriction Status [true false]		true
Investment, Significant Unobservable Input [true false]		true
Investment, Non-income Producing [true false]		false
Investment, Identifier [Axis]: I D I G Parent, L L C, Senior Secured Loans, Two, due 12/15/2026
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		I D I G Parent, L L C [ Member]
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Services: Consumer
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Spread Above Index		6%
Interest Rate		7%
Acquisition Date		Dec. 15, 2020
Maturity		Dec. 15, 2026
Principal		$ 918
Amortized Cost		918
Fair Value		$ 920
% of Net Assets		0.40%
Investment, Restriction Status [true false]		true
Investment, Significant Unobservable Input [true false]		true
Investment, Non-income Producing [true false]		false
Investment, Identifier [Axis]: I N H Buyer, Inc., Senior Secured Loans, due 6/28/2028
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:INHBuyerInc.Member	mrcc:INHBuyerInc.Member
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Healthcare & Pharmaceuticals Sector [Member]	Healthcare & Pharmaceuticals Sector [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]	LIBOR
Spread Above Index	7%	6%
Interest Rate		7%
Interest rate paid in kind	3.50%
Acquisition Date	Jun. 30, 2021	Jun. 30, 2021
Maturity	Jun. 28, 2028	Jun. 28, 2028
Principal	$ 2,950	$ 2,939
Amortized Cost	2,925	2,911
Fair Value	$ 2,832	$ 2,857
% of Net Assets	1.30%	1.10%
Investment, Restriction Status [true false]		true
Investment, Significant Unobservable Input [true false]		true
Investment, Non-income Producing [true false]		false
Investment, Identifier [Axis]: I T Global Holding L L C ( Revolver), Senior Secured Loans, due 11/10/2023
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:ITGlobalHoldingLLCMember
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Services: Business
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Spread Above Index		9%
Interest Rate		10%
Acquisition Date		Nov. 15, 2018
Maturity		Nov. 10, 2023
Principal		$ 875
Amortized Cost		875
Fair Value		$ 1,060
% of Net Assets		0.40%
Investment, Restriction Status [true false]		true
Investment, Significant Unobservable Input [true false]		true
Investment, Non-income Producing [true false]		false
Investment, Identifier [Axis]: I T Global Holding L L C, Senior Secured Loans, One, due 11/10/2023
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:ITGlobalHoldingLLCMember
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Services: Business
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Spread Above Index		9%
Interest Rate		10%
Acquisition Date		Nov. 15, 2018
Maturity		Nov. 10, 2023
Principal		$ 3,405
Amortized Cost		3,374
Fair Value		$ 4,411
% of Net Assets		1.80%
Investment, Restriction Status [true false]		true
Investment, Significant Unobservable Input [true false]		true
Investment, Non-income Producing [true false]		false
Investment, Identifier [Axis]: I T Global Holding L L C, Senior Secured Loans, Two, due 11/10/2023
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:ITGlobalHoldingLLCMember
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Services: Business
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Spread Above Index		9%
Interest Rate		10%
Acquisition Date		Jul. 19, 2019
Maturity		Nov. 10, 2023
Principal		$ 1,270
Amortized Cost		1,255
Fair Value		$ 1,645
% of Net Assets		0.70%
Investment, Restriction Status [true false]		true
Investment, Significant Unobservable Input [true false]		true
Investment, Non-income Producing [true false]		false
Investment, Identifier [Axis]: In Mobi Pte, Ltd, Media: Equity Securities, due 9/18/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:InMobiPteLtdMember	mrcc:InMobiPteLtdMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Equity Securities [Member]
Investment, Industry Sector [Extensible Enumeration]	Media: Advertising, Printing & Publishing	Media: Advertising, Printing & Publishing
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	Non-US [Member]
Acquisition Date	Sep. 18, 2015	Sep. 18, 2015
Maturity	Sep. 18, 2025	Sep. 18, 2025
Fair Value	$ 1,816	$ 2,204
% of Net Assets	0.80%	0.90%
Investment, Restriction Status [true false]	true	true
Investment, Significant Unobservable Input [true false]	true	true
Investment, Non-income Producing [true false]	false	true
Warrants to Purchase Percentage of Equity	2.80%	2.80%
Number of units held	40
Investment, Identifier [Axis]: Independence Buyer, Inc, Senior Secured Loans, due 8/3/2026
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:IndependenceBuyerInc.Member	mrcc:IndependenceBuyerInc.Member
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Consumer Goods: Durable	Consumer Goods: Durable
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]	LIBOR
Spread Above Index	5.50%	5.75%
Interest Rate	9.74%	6.75%
Acquisition Date	Aug. 03, 2021	Aug. 03, 2021
Maturity	Aug. 03, 2026	Aug. 03, 2026
Principal	$ 5,940	$ 6,000
Amortized Cost	5,849	5,887
Fair Value	$ 5,866	$ 6,000
% of Net Assets	2.60%	2.40%
Investment, Restriction Status [true false]	true	true
Investment, Significant Unobservable Input [true false]	true	true
Investment, Non-income Producing [true false]	false	false
Investment, Identifier [Axis]: Independence Buyer, Inc. ( Revolver), Senior Secured Loans, due 8/3/2026
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:IndependenceBuyerInc.Member	mrcc:IndependenceBuyerInc.Member
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Consumer Goods: Durable	Consumer Goods: Durable
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR	LIBOR
Spread Above Index	5.50%	5.75%
Interest Rate	9.74%	6.75%
Acquisition Date	Aug. 03, 2021	Aug. 03, 2021
Maturity	Aug. 03, 2026	Aug. 03, 2026
Principal	$ 1,423	$ 1,423
% of Net Assets	0%	0%
Investment, Restriction Status [true false]	true	true
Investment, Significant Unobservable Input [true false]	true	true
Investment, Non-income Producing [true false]	false	false
Investment, Identifier [Axis]: Independence Buyer, Inc., Equity Securities, Class A units
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:IndependenceBuyerInc.Member	mrcc:IndependenceBuyerInc.Member
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Equity Securities [Member]
Investment, Industry Sector [Extensible Enumeration]	Consumer Goods: Durable	Consumer Goods: Durable
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Acquisition Date	Aug. 03, 2021	Aug. 03, 2021
Amortized Cost	$ 81	$ 81
Fair Value	$ 102	$ 101
% of Net Assets	0%	0%
Investment, Restriction Status [true false]	true	true
Investment, Significant Unobservable Input [true false]	true	true
Investment, Non-income Producing [true false]	false	true
Number of units held		81
Investment, Identifier [Axis]: Intermedia Holdings, Inc., Senior Secured Loans, due 7/21/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:IntermediaHoldingsIncMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Telecommunications
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR
Spread Above Index	6%
Interest Rate	10.38%
Maturity	Jul. 21, 2025
Principal	$ 1,760
Fair Value	$ 1,360
Investment, Identifier [Axis]: International Textile Group, Inc., Senior Secured Loans, due 5/1/2024
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:InternationalTextileGroupIncMember	mrcc:InternationalTextileGroupIncMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Consumer Goods: Durable	Consumer Goods: Durable
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR	LIBOR
Spread Above Index		5%
Interest Rate		5.13%
Maturity		May 01, 2024
Principal		$ 1,711
Fair Value		$ 1,590
Investment, Identifier [Axis]: J2 B W A Funding L L C ( Delayed Draw), Senior Secured Loans, due 12/24/2026
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:J2BWAFundingLLCMember
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		mrcc:FireFinanceMember
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Interest Rate		9%
Acquisition Date		Dec. 24, 2020
Maturity		Dec. 24, 2026
Principal		$ 2,710
Amortized Cost		677
Fair Value		$ 677
% of Net Assets		0.30%
Investment, Restriction Status [true false]		true
Investment, Significant Unobservable Input [true false]		true
Investment, Non-income Producing [true false]		false
Investment, Identifier [Axis]: J2 B W A Funding L L C, Equity Securities
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:J2BWAFundingLLCMember	mrcc:J2BWAFundingLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Equity Securities [Member]
Investment, Industry Sector [Extensible Enumeration]	FIRE: Finance	FIRE: Finance
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Acquisition Date	Dec. 24, 2020	Dec. 24, 2020
% of Net Assets	0%	0%
Investment, Restriction Status [true false]	true	true
Investment, Significant Unobservable Input [true false]	true	true
Investment, Non-income Producing [true false]	false	true
Percentage of profit sharing	0.70%	0.70%
Investment, Identifier [Axis]: J2 BWA Funding LLC (Delayed Draw), Senior Notes, Due 12/24/2026
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:J2BWAFundingLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	mrcc:FireFinanceMember
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Interest Rate	9%
Acquisition Date	Dec. 24, 2020
Maturity	Dec. 24, 2026
Principal	$ 2,750
Amortized Cost	1,303
Fair Value	$ 1,298
% of Net Assets	0.60%
Investment, Restriction Status [true false]	true
Investment, Significant Unobservable Input [true false]	true
Investment, Non-income Producing [true false]	false
Investment, Identifier [Axis]: Kar Wash Holdings, L L C ( Delayed Draw), Senior Secured Loans, due 2/26/2027
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:KarWashHoldingsLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Services: Consumer
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Spread Above Index	6%
Interest Rate	10.77%
Acquisition Date	Aug. 03, 2022
Maturity	Feb. 26, 2027
Principal	$ 2,667
Amortized Cost	1,790
Fair Value	$ 1,782
% of Net Assets	0.80%
Investment, Restriction Status [true false]	true
Investment, Significant Unobservable Input [true false]	true
Investment, Non-income Producing [true false]	false
Investment, Identifier [Axis]: Kar Wash Holdings, L L C ( Revolver), Senior Secured Loans, due 2/26/2027
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:KarWashHoldingsLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Services: Consumer
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Spread Above Index	6%
Interest Rate	10.77%
Acquisition Date	Feb. 28, 2022
Maturity	Feb. 26, 2027
Principal	$ 572
Amortized Cost	305
Fair Value	$ 303
% of Net Assets	0.10%
Investment, Restriction Status [true false]	true
Investment, Significant Unobservable Input [true false]	true
Investment, Non-income Producing [true false]	false
Investment, Identifier [Axis]: Kar Wash Holdings, L L C, Equity Securities, Class A units
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:KarWashHoldingsLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Services: Consumer
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Acquisition Date	Feb. 28, 2022
Amortized Cost	$ 103
Fair Value	$ 111
% of Net Assets	0%
Investment, Restriction Status [true false]	true
Investment, Significant Unobservable Input [true false]	true
Investment, Non-income Producing [true false]	false
Number of units held	99,807
Investment, Identifier [Axis]: Kar Wash Holdings, LLC, Senior Secured Loans, One, due 2/26/2027
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:KarWashHoldingsLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Services: Consumer
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Spread Above Index	6%
Interest Rate	9.82%
Acquisition Date	Feb. 28, 2022
Maturity	Feb. 26, 2027
Principal	$ 1,592
Amortized Cost	1,565
Fair Value	$ 1,585
% of Net Assets	0.70%
Investment, Restriction Status [true false]	true
Investment, Significant Unobservable Input [true false]	true
Investment, Non-income Producing [true false]	false
Investment, Identifier [Axis]: Kar Wash Holdings, LLC, Senior Secured Loans, Two, due 2/26/2027
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:KarWashHoldingsLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Services: Consumer
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Spread Above Index	6%
Interest Rate	10.35%
Acquisition Date	Feb. 28, 2022
Maturity	Feb. 26, 2027
Principal	$ 1,140
Amortized Cost	1,140
Fair Value	$ 1,135
% of Net Assets	0.50%
Investment, Restriction Status [true false]	true
Investment, Significant Unobservable Input [true false]	true
Investment, Non-income Producing [true false]	false
Investment, Identifier [Axis]: Keystone Purchaser, L L C, Senior Secured Loans, due 5/7/2027
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:KeystonePurchaserLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Transportation Sector [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR
Spread Above Index	5.50%
Interest Rate	10.60%
Maturity	May 07, 2027
Principal	$ 4,955
Fair Value	$ 4,955
Investment, Identifier [Axis]: Kingsley Gate Partners, LLC (Delayed Draw), One, Due 12/11/2028
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:KingsleyGatePartnersLlcMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Services: Business
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Spread Above Index	6.65%
Interest Rate	11.12%
Acquisition Date	Dec. 09, 2022
Maturity	Dec. 11, 2028
Principal	$ 720
% of Net Assets	0%
Investment, Restriction Status [true false]	true
Investment, Significant Unobservable Input [true false]	true
Investment, Non-income Producing [true false]	false
Investment, Identifier [Axis]: Kingsley Gate Partners, LLC (Delayed Draw), Two, Due 12/11/2028
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:KingsleyGatePartnersLlcMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Services: Business
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Spread Above Index	6.65%
Interest Rate	11.12%
Acquisition Date	Dec. 09, 2022
Maturity	Dec. 11, 2028
Principal	$ 600
% of Net Assets	0%
Investment, Restriction Status [true false]	true
Investment, Significant Unobservable Input [true false]	true
Investment, Non-income Producing [true false]	false
Investment, Identifier [Axis]: Kingsley Gate Partners, LLC (Revolver), Due 12/11/2028
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:KingsleyGatePartnersLlcMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Services: Business
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Spread Above Index	6.65%
Interest Rate	11.12%
Acquisition Date	Dec. 09, 2022
Maturity	Dec. 11, 2028
Principal	$ 240
% of Net Assets	0%
Investment, Restriction Status [true false]	true
Investment, Significant Unobservable Input [true false]	true
Investment, Non-income Producing [true false]	false
Investment, Identifier [Axis]: Kingsley Gate Partners, LLC, Due 12/11/2028
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:KingsleyGatePartnersLlcMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Services: Business
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Spread Above Index	6.65%
Interest Rate	11.12%
Acquisition Date	Dec. 09, 2022
Maturity	Dec. 11, 2028
Principal	$ 600
Amortized Cost	588
Fair Value	$ 588
% of Net Assets	0.30%
Investment, Restriction Status [true false]	true
Investment, Significant Unobservable Input [true false]	true
Investment, Non-income Producing [true false]	false
Investment, Identifier [Axis]: L S C S Holdings, Inc., Senior Secured Loans, due 12/15/2028
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:LSCSHoldingsIncMember	mrcc:LSCSHoldingsIncMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Healthcare & Pharmaceuticals Sector [Member]	Healthcare & Pharmaceuticals Sector [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR	LIBOR
Spread Above Index	4.50%	4.50%
Interest Rate	8.88%	5%
Maturity	Dec. 15, 2028	Dec. 15, 2028
Principal	$ 1,828	$ 1,846
Fair Value	$ 1,751	$ 1,849
Investment, Identifier [Axis]: L V F Holdings, Inc. ( Revolver), Senior Secured Loans, due 6/10/2027
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:LVFHoldingsIncMember	mrcc:LVFHoldingsIncMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	mrcc:BeverageFoodAndTobaccoSectorMember	Beverage, Food & Tobacco
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR	LIBOR
Spread Above Index	6.25%	6.25%
Interest Rate	10.98%	7.25%
Acquisition Date	Jun. 10, 2021	Oct. 06, 2021
Maturity	Jun. 10, 2027	Jun. 10, 2027
Principal	$ 238	$ 238
Amortized Cost	157	119
Fair Value	$ 152	$ 119
% of Net Assets	0.10%	0%
Investment, Restriction Status [true false]	true	true
Investment, Significant Unobservable Input [true false]	true	true
Investment, Non-income Producing [true false]		false
Investment, Identifier [Axis]: L V F Holdings, Inc., Senior Secured Loans, ( Delayed Draw) due 6/10/2027
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:LVFHoldingsIncMember	mrcc:LVFHoldingsIncMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	mrcc:BeverageFoodAndTobaccoSectorMember	Beverage, Food & Tobacco
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR	LIBOR
Spread Above Index	6.25%	6.25%
Interest Rate	8.45%	7.25%
Acquisition Date	Jun. 10, 2021	Oct. 06, 2021
Maturity	Jun. 10, 2027	Jun. 10, 2027
Principal	$ 344	$ 344
% of Net Assets	0%	0%
Investment, Restriction Status [true false]	true	true
Investment, Significant Unobservable Input [true false]	true	true
Investment, Non-income Producing [true false]	false	false
Investment, Identifier [Axis]: L V F Holdings, Inc., Senior Secured Loans, One, due 6/10/2027
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:LVFHoldingsIncMember	mrcc:LVFHoldingsIncMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	mrcc:BeverageFoodAndTobaccoSectorMember	Beverage, Food & Tobacco
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR	LIBOR
Spread Above Index	6.25%	6.25%
Interest Rate	8.45%	7.25%
Acquisition Date	Jun. 10, 2021	Jun. 10, 2021
Maturity	Jun. 10, 2027	Jun. 10, 2027
Principal	$ 1,481	$ 1,496
Amortized Cost	1,458	1,468
Fair Value	$ 1,437	$ 1,496
% of Net Assets	0.60%	0.60%
Investment, Restriction Status [true false]	true	true
Investment, Significant Unobservable Input [true false]	true	true
Investment, Non-income Producing [true false]	false	false
Investment, Identifier [Axis]: L V F Holdings, Inc., Senior Secured Loans, Two, due 6/10/2027
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:LVFHoldingsIncMember	mrcc:LVFHoldingsIncMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	mrcc:BeverageFoodAndTobaccoSectorMember	Beverage, Food & Tobacco
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR	LIBOR
Spread Above Index	6.25%	6.25%
Interest Rate	8.45%	7.25%
Acquisition Date	Jun. 10, 2021	Jun. 10, 2021
Maturity	Jun. 10, 2027	Jun. 10, 2027
Principal	$ 1,418	$ 1,432
Amortized Cost	1,418	1,432
Fair Value	$ 1,375	$ 1,432
% of Net Assets	0.60%	0.60%
Investment, Restriction Status [true false]	true	true
Investment, Significant Unobservable Input [true false]	true	true
Investment, Non-income Producing [true false]	false	false
Investment, Identifier [Axis]: L X/ J T Intermediate Holdings, Inc. ( Revolver), Senior Secured Loans, due 3/11/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:LXJTIntermediateHoldingsIncMember	mrcc:LXJTIntermediateHoldingsIncMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	mrcc:BeverageFoodAndTobaccoSectorMember	Beverage, Food & Tobacco
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]	LIBOR
Spread Above Index	6%	6%
Interest Rate	10.42%	7.50%
Acquisition Date	Mar. 11, 2020	Mar. 11, 2020
Maturity	Mar. 11, 2025	Mar. 11, 2025
Principal	$ 833	$ 833
% of Net Assets	0%	0%
Investment, Restriction Status [true false]	true	true
Investment, Significant Unobservable Input [true false]	true	true
Investment, Non-income Producing [true false]	false	false
Investment, Identifier [Axis]: L X/ J T Intermediate Holdings, Inc., Senior Secured Loans, due 3/11/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:LXJTIntermediateHoldingsIncMember	mrcc:LXJTIntermediateHoldingsIncMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	mrcc:BeverageFoodAndTobaccoSectorMember	Beverage, Food & Tobacco
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]	LIBOR
Spread Above Index	6%	6%
Interest Rate	10.42%	7.50%
Acquisition Date	Mar. 11, 2020	Nov. 03, 2020
Maturity	Mar. 11, 2025	Mar. 11, 2025
Principal	$ 5,468	$ 9,375
Amortized Cost	5,413	9,246
Fair Value	$ 5,394	$ 9,239
% of Net Assets	2.40%	3.70%
Investment, Restriction Status [true false]	true	true
Investment, Significant Unobservable Input [true false]	true	true
Investment, Non-income Producing [true false]	false	false
Investment, Identifier [Axis]: Laseraway Intermediate Holdings I I, L L C, Senior Secured Loans, due 10/14/2027
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:LaserawayIntermediateHoldingsIILLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Services: Consumer
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR
Spread Above Index	5.75%
Interest Rate	9.76%
Maturity	Oct. 14, 2027
Principal	$ 2,200
Fair Value	$ 2,161
Investment, Identifier [Axis]: Lifted Trucks Holdings, L L C ( Delayed Draw), Senior Secured Loans, due 8/2/2027
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:LiftedTrucksHoldingsLLCMember	mrcc:LiftedTrucksHoldingsLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Automotive	Automotive
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR	LIBOR
Spread Above Index	5.75%	5.75%
Interest Rate	9.49%	6.75%
Acquisition Date	Aug. 02, 2021	Aug. 02, 2021
Maturity	Aug. 02, 2027	Aug. 02, 2027
Principal	$ 1,400	$ 1,400
% of Net Assets	0%	0%
Investment, Restriction Status [true false]	true	true
Investment, Significant Unobservable Input [true false]	true	true
Investment, Non-income Producing [true false]	false	false
Investment, Identifier [Axis]: Lifted Trucks Holdings, L L C ( Revolver), Senior Secured Loans, due 8/2/2027
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:LiftedTrucksHoldingsLLCMember	mrcc:LiftedTrucksHoldingsLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Automotive	Automotive
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR	LIBOR
Spread Above Index	5.75%	5.75%
Interest Rate	9.49%	6.75%
Acquisition Date	Aug. 02, 2021	Aug. 02, 2021
Maturity	Aug. 02, 2027	Aug. 02, 2027
Principal	$ 1,667	$ 1,667
Amortized Cost		444
Fair Value		$ 443
% of Net Assets	0%	0.20%
Investment, Restriction Status [true false]	true	true
Investment, Significant Unobservable Input [true false]	true	true
Investment, Non-income Producing [true false]	false	false
Investment, Identifier [Axis]: Lifted Trucks Holdings, L L C, Equity Securities, Class A units
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:LiftedTrucksHoldingsLLCMember	mrcc:LiftedTrucksHoldingsLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Automotive	Automotive
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Spread Above Index	0%
Interest Rate	0%
Acquisition Date	Aug. 02, 2021	Aug. 02, 2021
Principal	$ 0
Amortized Cost	111	$ 111
Fair Value	$ 78	$ 109
% of Net Assets	0%	0.10%
Number of shares held	111,111
Investment, Restriction Status [true false]	true
Investment, Significant Unobservable Input [true false]	true
Number of units held		111,111
Investment, Identifier [Axis]: Lifted Trucks Holdings, L L C, Senior Secured Loans, due 8/2/2027
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:LiftedTrucksHoldingsLLCMember	mrcc:LiftedTrucksHoldingsLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Automotive	Automotive
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR	LIBOR
Spread Above Index	5.75%	5.75%
Interest Rate	9.49%	6.75%
Acquisition Date	Aug. 02, 2021	Aug. 02, 2021
Maturity	Aug. 02, 2027	Aug. 02, 2027
Principal	$ 6,930	$ 7,000
Amortized Cost	6,816	6,866
Fair Value	$ 6,840	$ 6,979
% of Net Assets	3.10%	2.80%
Investment, Restriction Status [true false]	true	true
Investment, Significant Unobservable Input [true false]	true	true
Investment, Non-income Producing [true false]	false	false
Investment, Identifier [Axis]: Liftforward S P V I I, L L C, Senior Secured Loans, due 9/30/2022
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:LiftforwardSPVIILLCMember
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		mrcc:FireFinanceMember
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Spread Above Index		10.75%
Interest Rate		11.25%
Acquisition Date		Nov. 10, 2016
Maturity		Sep. 30, 2022
Principal		$ 744
Amortized Cost		744
Fair Value		$ 713
% of Net Assets		0.30%
Investment, Restriction Status [true false]		true
Investment, Significant Unobservable Input [true false]		true
Investment, Non-income Producing [true false]		false
Investment, Identifier [Axis]: Liftforward SPV II, LLC, Senior Secured Loans, due 3/31/2023
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:LiftforwardSPVIILLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	mrcc:FireFinanceMember
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR
Spread Above Index	10.75%
Interest Rate	15.14%
Acquisition Date	Nov. 10, 2016
Maturity	Mar. 31, 2023
Principal	$ 413
Amortized Cost	413
Fair Value	$ 403
% of Net Assets	0.20%
Investment, Restriction Status [true false]	true
Investment, Significant Unobservable Input [true false]	true
Investment, Non-income Producing [true false]	false
Investment, Identifier [Axis]: Lightbox Intermediate, L. P., Senior Secured Loans, due 5/11/2026
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:LightboxIntermediateL.PMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	High Tech Industries Sector [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR
Spread Above Index	5%
Interest Rate	9.73%
Maturity	May 11, 2026
Principal	$ 4,825
Fair Value	$ 4,656
Investment, Identifier [Axis]: Liqui- Box Holdings, Inc., Senior Secured Loans, due 2/26/2027
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:Liqui-BoxHoldingsIncMember	mrcc:Liqui-BoxHoldingsIncMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Container and Packaging Sector [Member]	Container and Packaging Sector [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR	LIBOR
Spread Above Index		4.50%
Interest Rate		5.50%
Maturity		Feb. 26, 2027
Principal		$ 4,268
Fair Value		$ 3,991
Investment, Identifier [Axis]: Luxury Optical Holdings Co. ( Delayed Draw)
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	Luxury Optical Holdings Co [ Member]	Luxury Optical Holdings Co [ Member]
Fair Value			624
Investment, Identifier [Axis]: Luxury Optical Holdings Co. Investment, One
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	Luxury Optical Holdings Co [ Member]	Luxury Optical Holdings Co [ Member]
Fair Value			1,430
Investment, Identifier [Axis]: Luxury Optical Holdings Co.( Revolver)
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	Luxury Optical Holdings Co [ Member]	Luxury Optical Holdings Co [ Member]
Fair Value			66
Investment, Identifier [Axis]: Luxury Optical Holdings Co., Equity Securities
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	Luxury Optical Holdings Co [ Member]	mrcc:LuxuryOpticalHoldingsCo.Member
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Equity Securities [Member]
Investment, Industry Sector [Extensible Enumeration]	Retail	Retail
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Acquisition Date	Sep. 12, 2014	Sep. 12, 2014
Fair Value	$ 209	$ 78
% of Net Assets	0.10%	0%
Investment, Restriction Status [true false]	true	true
Investment, Significant Unobservable Input [true false]	true	true
Investment, Non-income Producing [true false]	false	true
Investment, Identifier [Axis]: Luxury Optical Holdings Co., Equity Securities, Common Stock
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	Luxury Optical Holdings Co [ Member]	Luxury Optical Holdings Co [ Member]
Number of shares held		86
Investment, Identifier [Axis]: Luxury Optical Holdings Co., Equity Securities, Preferred Units
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	Luxury Optical Holdings Co [ Member]	Luxury Optical Holdings Co [ Member]
Fair Value			2,476
Number of units held		91
Investment, Identifier [Axis]: M C Asset Management ( Corporate), L L C ( Delayed Draw), Senior Secured Loans Due 1/26/2024
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:MCAssetManagementCorporateLLCMember	mrcc:MCAssetManagementCorporateLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	FIRE: Real Estate	FIRE: Real Estate
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR	LIBOR
Spread Above Index	15%	15%
Interest rate paid in kind	18.74%	16%
Acquisition Date	Apr. 26, 2021	Apr. 26, 2021
Maturity	Jan. 26, 2024	Jan. 26, 2024
Principal	$ 1,793	$ 1,643
Amortized Cost	1,000	850
Fair Value	$ 1,000	$ 850
% of Net Assets	0.40%	0.30%
Investment, Restriction Status [true false]	true	true
Investment, Significant Unobservable Input [true false]	true	true
Investment, Non-income Producing [true false]	false	false
Investment, Identifier [Axis]: M C Asset Management ( Corporate), L L C, Equity Securites
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:MCAssetManagementCorporateLLCMember	mrcc:MCAssetManagementCorporateLLCMember
Investment, Type [Extensible Enumeration]	Equity Securities [Member]	Equity Securities [Member]
Investment, Industry Sector [Extensible Enumeration]	FIRE: Real Estate	FIRE: Real Estate
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Acquisition Date	Jun. 11, 2019	Jun. 11, 2019
Amortized Cost	$ 793	$ 793
Fair Value	$ 1,291	$ 644
% of Net Assets	0.60%	0.20%
Investment, Restriction Status [true false]	true	true
Investment, Significant Unobservable Input [true false]	true	true
Investment, Non-income Producing [true false]	true	false
Warrants to Purchase Percentage of Equity		15.90%
Percentage of interests	15.90%
Investment, Identifier [Axis]: M C Asset Management ( Corporate), L L C, Equity Securities
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:MCAssetManagementCorporateLLCMember	mrcc:MCAssetManagementCorporateLLCMember
Fair Value	$ 1,291	$ 644	785
Percentage of interests	15.90%	15.90%
Investment, Identifier [Axis]: M C Asset Management ( Corporate), L L C, Senior Secured Loans Due 1/26/2024
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:MCAssetManagementCorporateLLCMember	mrcc:MCAssetManagementCorporateLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	FIRE: Real Estate	FIRE: Real Estate
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR	LIBOR
Spread Above Index	15%	15%
Interest rate paid in kind	18.74%	16%
Acquisition Date	Jan. 26, 2021	Jan. 26, 2021
Maturity	Jan. 26, 2024	Jan. 26, 2024
Principal	$ 8,421	$ 7,154
Amortized Cost	8,421	7,154
Fair Value	$ 8,421	$ 7,154
% of Net Assets	3.70%	2.90%
Investment, Restriction Status [true false]	true	true
Investment, Significant Unobservable Input [true false]	true	true
Investment, Non-income Producing [true false]	false	false
Investment, Identifier [Axis]: M C Asset Management ( Industrial), L L C Promissory Note
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:MCAssetManagementIndustrialLLCMember	mrcc:MCAssetManagementIndustrialLLCMember
Fair Value			11,579
Investment, Identifier [Axis]: M C P Shaw Acquisitionco, L L C ( Delayed Draw), Senior Secured Loans, due 11/28/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:MCPShawAcquisitioncoLLCMember	mrcc:MCPShawAcquisitioncoLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Capital Equipment	Capital Equipment
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Spread Above Index	6.50%	6.50%
Interest Rate	11.06%	7.50%
Acquisition Date	Dec. 29, 2021	Dec. 29, 2021
Maturity	Nov. 28, 2025	Nov. 28, 2025
Principal	$ 978	$ 983
Amortized Cost	978
Fair Value	$ 979
% of Net Assets	0.40%	0%
Investment, Restriction Status [true false]	true	true
Investment, Significant Unobservable Input [true false]	true	true
Investment, Non-income Producing [true false]	false	false
Investment, Identifier [Axis]: M C P Shaw Acquisitionco, L L C ( Revolver), Senior Secured Loans, due 11/28/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:MCPShawAcquisitioncoLLCMember	mrcc:MCPShawAcquisitioncoLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Capital Equipment	Capital Equipment
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Spread Above Index	6.50%	6.50%
Interest Rate	11.06%	7.50%
Acquisition Date	Feb. 28, 2020	Feb. 28, 2020
Maturity	Nov. 28, 2025	Nov. 28, 2025
Principal	$ 1,784	$ 1,784
% of Net Assets	0%	0%
Investment, Restriction Status [true false]	true	true
Investment, Significant Unobservable Input [true false]	true	true
Investment, Non-income Producing [true false]	false	false
Investment, Identifier [Axis]: M C P Shaw Acquisitionco, L L C , Equity Securities, Class A-2 units
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:MCPShawAcquisitioncoLLCMember	mrcc:MCPShawAcquisitioncoLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Equity Securities [Member]
Investment, Industry Sector [Extensible Enumeration]	Capital Equipment	Capital Equipment
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Acquisition Date	Feb. 28, 2020	Feb. 28, 2020
Amortized Cost	$ 119	$ 119
Fair Value	$ 204	$ 148
% of Net Assets	0.10%	0.10%
Number of shares held	118,906
Investment, Restriction Status [true false]	true	true
Investment, Significant Unobservable Input [true false]	true	true
Investment, Non-income Producing [true false]	false	true
Number of units held		118,906
Investment, Identifier [Axis]: M C P Shaw Acquisitionco, L L C, Senior Secured Loans, One, due 11/28/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:MCPShawAcquisitioncoLLCMember	mrcc:MCPShawAcquisitioncoLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Capital Equipment	Capital Equipment
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Spread Above Index	6.50%	6.50%
Interest Rate	11.06%	7.50%
Acquisition Date	Feb. 28, 2020	Feb. 28, 2020
Maturity	Nov. 28, 2025	Nov. 28, 2025
Principal	$ 9,722	$ 9,733
Amortized Cost	9,615	9,595
Fair Value	$ 9,736	$ 9,699
% of Net Assets	4.40%	3.90%
Investment, Restriction Status [true false]	true	true
Investment, Significant Unobservable Input [true false]	true	true
Investment, Non-income Producing [true false]	false	false
Investment, Identifier [Axis]: M C P Shaw Acquisitionco, L L C, Senior Secured Loans, Two, due 11/28/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:MCPShawAcquisitioncoLLCMember	mrcc:MCPShawAcquisitioncoLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Capital Equipment	Capital Equipment
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Spread Above Index	6.50%	6.50%
Interest Rate	11.06%	7.50%
Acquisition Date	Dec. 29, 2021	Dec. 29, 2021
Maturity	Nov. 28, 2025	Nov. 28, 2025
Principal	$ 2,972	$ 3,002
Amortized Cost	2,926	2,942
Fair Value	$ 2,977	$ 2,992
% of Net Assets	1.30%	1.20%
Investment, Restriction Status [true false]	true	true
Investment, Significant Unobservable Input [true false]	true	true
Investment, Non-income Producing [true false]	false	false
Investment, Identifier [Axis]: M F G Chemical, L L C, Unitranche Secured Loans, One, Due 6/23/2022
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:MFGChemicalLLCMember
Investment, Type [Extensible Enumeration]		Unitranche Debt [Member]
Investment, Industry Sector [Extensible Enumeration]		Chemicals, Plastics & Rubber
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Spread Above Index		8%
Interest Rate		9%
Acquisition Date		Jun. 23, 2017
Maturity		Jun. 23, 2022
Principal		$ 5,555
Amortized Cost		5,546
Fair Value		$ 5,555
% of Net Assets		2.20%
Investment, Restriction Status [true false]		true
Investment, Significant Unobservable Input [true false]		true
Investment, Non-income Producing [true false]		false
Investment, Identifier [Axis]: M F G Chemical, L L C, Unitranche Secured Loans, Two, Due 6/23/2022
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:MFGChemicalLLCMember
Investment, Type [Extensible Enumeration]		Unitranche Debt [Member]
Investment, Industry Sector [Extensible Enumeration]		Chemicals, Plastics & Rubber
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Spread Above Index		8%
Interest Rate		9%
Acquisition Date		Mar. 15, 2018
Maturity		Jun. 23, 2022
Principal		$ 543
Amortized Cost		543
Fair Value		$ 543
% of Net Assets		0.20%
Investment, Restriction Status [true false]		true
Investment, Significant Unobservable Input [true false]		true
Investment, Non-income Producing [true false]		false
Investment, Identifier [Axis]: M R C C Senior Loan Fund I, L L C, Equity Securities
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Controlled affiliate company investments	Controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	MRCC Senior Loan Fund I, LLC	MRCC Senior Loan Fund I, LLC
Investment, Type [Extensible Enumeration]	Equity Securities [Member]	Equity Securities [Member]
Investment, Industry Sector [Extensible Enumeration]	mrcc:InvestmentFundsVehiclesMember	mrcc:InvestmentFundsVehiclesMember
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Acquisition Date	Oct. 31, 2017	Oct. 31, 2017
Amortized Cost	$ 42,650	$ 42,150
Fair Value	$ 35,509	$ 41,125	39,284
% of Net Assets	15.80%	16.50%
Investment, Restriction Status [true false]	true	true
Investment, Significant Unobservable Input [true false]	true	true
Investment, Non-income Producing [true false]	false	false
Percentage of interests	50%	50%
Investment, Identifier [Axis]: M V Receivables I I, L L C ( Delayed Draw), Senior Secured Loans, due 7/29/2026
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:MVReceivablesIILLCMember	mrcc:MVReceivablesIILLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Banking	Banking
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR	LIBOR
Spread Above Index	9.75%	9.75%
Interest Rate	13.87%	11.25%
Acquisition Date	Jul. 29, 2021	Jul. 29, 2021
Maturity	Jul. 29, 2026	Jul. 29, 2026
Principal	$ 8,115	$ 8,000
Amortized Cost	7,752	971
Fair Value	$ 7,968	$ 1,289
% of Net Assets	3.60%	0.50%
Investment, Restriction Status [true false]	true	true
Investment, Significant Unobservable Input [true false]	true	true
Investment, Non-income Producing [true false]	false	false
Investment, Identifier [Axis]: M V Receivables I I, L L C, Equity Securities, Common units
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:MVReceivablesIILLCMember	mrcc:MVReceivablesIILLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Banking	Banking
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Acquisition Date	Jul. 29, 2021	Jul. 29, 2021
Amortized Cost	$ 600	$ 300
Fair Value	$ 1,154	$ 558
% of Net Assets	0.50%	0.20%
Number of shares held	1,458
Investment, Restriction Status [true false]	true
Investment, Significant Unobservable Input [true false]	true
Investment, Non-income Producing [true false]	false
Number of units held		729
Investment, Identifier [Axis]: M V Receivables I I, L L C, Equity Securities, Due 7/28/2031, Warrants
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:MVReceivablesIILLCMember	mrcc:MVReceivablesIILLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Banking	Banking
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Acquisition Date	Jul. 28, 2021	Jul. 28, 2021
Maturity	Jul. 28, 2031	Jul. 28, 2031
Amortized Cost	$ 363	$ 363
Fair Value	$ 1,655	$ 1,007
% of Net Assets	0.80%	0.40%
Investment, Restriction Status [true false]	true
Investment, Significant Unobservable Input [true false]	true
Investment, Non-income Producing [true false]	false
Warrants to Purchase Percentage of Equity	0.80%	0.80%
Investment, Identifier [Axis]: MC Asset Management (Corporate), LLC (Delayed Draw)
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:MCAssetManagementCorporateLLCMember
Fair Value	$ 1,000	$ 850
Investment, Identifier [Axis]: Mac Queen Equipment, L L C ( Delayed Draw), Senior Secured Loans, due 1/7/2028
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:MacQueenEquipmentLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Capital Equipment
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR
Investment, Identifier [Axis]: Mac Queen Equipment, L L C ( Revolver), Senior Secured Loans, due 1/7/2028
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:MacQueenEquipmentLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Capital Equipment
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR
Investment, Identifier [Axis]: Mac Queen Equipment, L L C, Senior Secured Loans, due 1/7/2028
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:MacQueenEquipmentLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Capital Equipment
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR
Investment, Identifier [Axis]: Magneto & Diesel Acquisition, Inc, Senior Secured Loans, One, due 12/18/2023
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:MagnetoDieselAcquisitionInc.Member
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Automotive
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Spread Above Index		5.50%
Interest Rate		6.50%
Acquisition Date		Dec. 18, 2018
Maturity		Dec. 18, 2023
Principal		$ 4,850
Amortized Cost		4,812
Fair Value		$ 4,850
% of Net Assets		1.90%
Investment, Restriction Status [true false]		true
Investment, Significant Unobservable Input [true false]		true
Investment, Non-income Producing [true false]		false
Investment, Identifier [Axis]: Magneto & Diesel Acquisition, Inc, Senior Secured Loans, Three, due 12/8/2023
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:MagnetoDieselAcquisitionInc.Member
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Automotive
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Spread Above Index		5.50%
Interest Rate		6.50%
Acquisition Date		Aug. 04, 2021
Maturity		Dec. 18, 2023
Principal		$ 829
Amortized Cost		815
Fair Value		$ 842
% of Net Assets		0.40%
Investment, Restriction Status [true false]		true
Investment, Significant Unobservable Input [true false]		true
Investment, Non-income Producing [true false]		false
Investment, Identifier [Axis]: Magneto & Diesel Acquisition, Inc, Senior Secured Loans, Two, due 12/8/2023
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:MagnetoDieselAcquisitionInc.Member
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Automotive
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Spread Above Index		5.50%
Interest Rate		6.50%
Acquisition Date		Jul. 06, 2020
Maturity		Dec. 18, 2023
Principal		$ 1,908
Amortized Cost		1,885
Fair Value		$ 1,938
% of Net Assets		0.80%
Investment, Restriction Status [true false]		true
Investment, Significant Unobservable Input [true false]		true
Investment, Non-income Producing [true false]		false
Investment, Identifier [Axis]: Magneto & Diesel Acquisition, Inc. ( Revolver), Senior Secured Loans, due 12/8/2023
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:MagnetoDieselAcquisitionInc.Member
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Automotive
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Spread Above Index		5.50%
Interest Rate		6.50%
Acquisition Date		Dec. 18, 2018
Maturity		Dec. 18, 2023
Principal		$ 500
% of Net Assets		0%
Investment, Restriction Status [true false]		true
Investment, Significant Unobservable Input [true false]		true
Investment, Non-income Producing [true false]		false
Investment, Identifier [Axis]: Mammoth Holdings, L L C ( Delayed Draw), Senior Secured Loans, due 10/16/2023
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:MammothHoldingsLLCMember
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Services: Consumer
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Spread Above Index		6%
Interest Rate		7%
Acquisition Date		Jun. 15, 2021
Maturity		Oct. 16, 2023
Principal		$ 1,646
Amortized Cost		988
Fair Value		$ 989
% of Net Assets		0.40%
Investment, Restriction Status [true false]		true
Investment, Significant Unobservable Input [true false]		true
Investment, Non-income Producing [true false]		false
Investment, Identifier [Axis]: Mammoth Holdings, L L C ( Revolver), Senior Secured Loans, due 10/16/2023
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:MammothHoldingsLLCMember
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Services: Consumer
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Spread Above Index		6%
Interest Rate		7%
Acquisition Date		Oct. 16, 2018
Maturity		Oct. 16, 2023
Principal		$ 657
% of Net Assets		0%
Investment, Restriction Status [true false]		true
Investment, Significant Unobservable Input [true false]		true
Investment, Non-income Producing [true false]		false
Investment, Identifier [Axis]: Mammoth Holdings, L L C, Senior Secured Loans, One, due 10/16/2023
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:MammothHoldingsLLCMember
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Services: Consumer
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Spread Above Index		6%
Interest Rate		7%
Acquisition Date		Oct. 16, 2018
Maturity		Oct. 16, 2023
Principal		$ 1,940
Amortized Cost		1,924
Fair Value		$ 1,940
% of Net Assets		0.80%
Investment, Restriction Status [true false]		true
Investment, Significant Unobservable Input [true false]		true
Investment, Non-income Producing [true false]		false
Investment, Identifier [Axis]: Mammoth Holdings, L L C, Senior Secured Loans, Three, due 10/16/2023
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:MammothHoldingsLLCMember
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Services: Consumer
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Spread Above Index		6%
Interest Rate		7%
Acquisition Date		Mar. 12, 2021
Maturity		Oct. 16, 2023
Principal		$ 6,355
Amortized Cost		6,355
Fair Value		$ 6,368
% of Net Assets		2.60%
Investment, Restriction Status [true false]		true
Investment, Significant Unobservable Input [true false]		true
Investment, Non-income Producing [true false]		false
Investment, Identifier [Axis]: Mammoth Holdings, L L C, Senior Secured Loans, Two, due 10/16/2023
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:MammothHoldingsLLCMember
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Services: Consumer
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Spread Above Index		6%
Interest Rate		7%
Acquisition Date		Oct. 16, 2018
Maturity		Oct. 16, 2023
Principal		$ 4,073
Amortized Cost		4,073
Fair Value		$ 4,073
% of Net Assets		1.50%
Investment, Restriction Status [true false]		true
Investment, Significant Unobservable Input [true false]		true
Investment, Non-income Producing [true false]		false
Investment, Identifier [Axis]: Mammoth Holdings, LLC (Revolver), Senior Secured Loans, Due, 10/16/2024
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:MammothHoldingsLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Services: Consumer
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Spread Above Index	6%
Interest Rate	9.82%
Acquisition Date	Oct. 16, 2018
Maturity	Oct. 16, 2024
Principal	$ 657
% of Net Assets	0%
Investment, Restriction Status [true false]	true
Investment, Significant Unobservable Input [true false]	true
Investment, Non-income Producing [true false]	false
Investment, Identifier [Axis]: Mammoth Holdings, LLC, Senior Secured Loans, Four, due 10/16/2024
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:MammothHoldingsLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Services: Consumer
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Spread Above Index	6%
Interest Rate	9.82%
Acquisition Date	Jun. 15, 2021
Maturity	Oct. 16, 2024
Principal	$ 1,633
Amortized Cost	1,633
Fair Value	$ 1,630
% of Net Assets	0.70%
Investment, Restriction Status [true false]	true
Investment, Significant Unobservable Input [true false]	true
Investment, Non-income Producing [true false]	false
Investment, Identifier [Axis]: Mammoth Holdings, LLC, Senior Secured Loans, One, due 10/16/2024
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:MammothHoldingsLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Services: Consumer
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Spread Above Index	6%
Interest Rate	9.82%
Acquisition Date	Oct. 16, 2018
Maturity	Oct. 16, 2024
Principal	$ 1,920
Amortized Cost	1,911
Fair Value	$ 1,917
% of Net Assets	0.90%
Investment, Restriction Status [true false]	true
Investment, Significant Unobservable Input [true false]	true
Investment, Non-income Producing [true false]	false
Investment, Identifier [Axis]: Mammoth Holdings, LLC, Senior Secured Loans, Three, due 10/16/2024
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:MammothHoldingsLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Services: Consumer
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Spread Above Index	6%
Interest Rate	9.82%
Acquisition Date	Mar. 12, 2021
Maturity	Oct. 16, 2024
Principal	$ 6,291
Amortized Cost	6,291
Fair Value	$ 6,282
% of Net Assets	2.80%
Investment, Restriction Status [true false]	true
Investment, Significant Unobservable Input [true false]	true
Investment, Non-income Producing [true false]	false
Investment, Identifier [Axis]: Mammoth Holdings, LLC, Senior Secured Loans, Two, due 10/16/2024
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:MammothHoldingsLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Services: Consumer
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Spread Above Index	6%
Interest Rate	9.82%
Acquisition Date	Oct. 16, 2018
Maturity	Oct. 16, 2024
Principal	$ 4,031
Amortized Cost	4,031
Fair Value	$ 4,025
% of Net Assets	1.80%
Investment, Restriction Status [true false]	true
Investment, Significant Unobservable Input [true false]	true
Investment, Non-income Producing [true false]	false
Investment, Identifier [Axis]: Mark Logic Corporation ( Revolver), Senior Secured Loans, due 10/20/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:MarkLogicCorporationMember	mrcc:MarkLogicCorporationMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	High Tech Industries Sector [Member]	High Tech Industries Sector [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]	LIBOR
Spread Above Index	6.50%	6%
Interest Rate	10.85%	7%
Acquisition Date	Oct. 20, 2020	Oct. 20, 2020
Maturity	Oct. 20, 2025	Oct. 20, 2025
Principal	$ 269	$ 269
% of Net Assets	0%	0%
Investment, Restriction Status [true false]	true	true
Investment, Significant Unobservable Input [true false]	true	true
Investment, Non-income Producing [true false]	false	false
Investment, Identifier [Axis]: Mark Logic Corporation, Equity Securities, Class A units
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:MarkLogicCorporationMember	mrcc:MarkLogicCorporationMember
Investment, Type [Extensible Enumeration]	Equity Securities [Member]	Equity Securities [Member]
Investment, Industry Sector [Extensible Enumeration]	High Tech Industries Sector [Member]	High Tech Industries Sector [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Acquisition Date	Oct. 20, 2020	Oct. 20, 2020
Amortized Cost		$ 290
Fair Value	$ 426	$ 423
% of Net Assets	0.20%	0.20%
Number of shares held	290,239
Investment, Restriction Status [true false]	true	true
Investment, Significant Unobservable Input [true false]	true	true
Investment, Non-income Producing [true false]	true	true
Number of units held		290,239
Investment, Identifier [Axis]: Mark Logic Corporation, Senior Secured Loans, Four, due 10/20/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:MarkLogicCorporationMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	High Tech Industries Sector [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Spread Above Index	6.50%
Interest Rate	10.85%
Acquisition Date	Nov. 23, 2021
Maturity	Oct. 20, 2025
Principal	$ 214
Amortized Cost	214
Fair Value	$ 213
% of Net Assets	0.10%
Investment, Restriction Status [true false]	true
Investment, Significant Unobservable Input [true false]	true
Investment, Non-income Producing [true false]	false
Investment, Identifier [Axis]: Mark Logic Corporation, Senior Secured Loans, One, due 10/20/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:MarkLogicCorporationMember	mrcc:MarkLogicCorporationMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	High Tech Industries Sector [Member]	High Tech Industries Sector [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]	LIBOR
Spread Above Index	6.50%	6%
Interest Rate	10.85%	7%
Acquisition Date	Oct. 20, 2020	Oct. 20, 2020
Maturity	Oct. 20, 2025	Oct. 20, 2025
Principal	$ 3,430	$ 3,465
Amortized Cost	3,377	3,396
Fair Value	$ 3,414	$ 3,517
% of Net Assets	1.50%	1.40%
Investment, Restriction Status [true false]	true	true
Investment, Significant Unobservable Input [true false]	true	true
Investment, Non-income Producing [true false]	false	false
Investment, Identifier [Axis]: Mark Logic Corporation, Senior Secured Loans, Three, due 10/20/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:MarkLogicCorporationMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	High Tech Industries Sector [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Spread Above Index	6.50%
Interest Rate	10.85%
Acquisition Date	May 10, 2022
Maturity	Oct. 20, 2025
Principal	$ 2,669
Amortized Cost	2,623
Fair Value	$ 2,656
% of Net Assets	1.20%
Investment, Restriction Status [true false]	true
Investment, Significant Unobservable Input [true false]	true
Investment, Non-income Producing [true false]	false
Investment, Identifier [Axis]: Mark Logic Corporation, Senior Secured Loans, Two, due 10/20/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:MarkLogicCorporationMember	mrcc:MarkLogicCorporationMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	High Tech Industries Sector [Member]	High Tech Industries Sector [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]	LIBOR
Spread Above Index	6.50%	6%
Interest Rate	10.85%	7%
Acquisition Date	Nov. 23, 2021	Nov. 23, 2021
Maturity	Oct. 20, 2025	Oct. 20, 2025
Principal	$ 320	$ 323
Amortized Cost	315	317
Fair Value	$ 318	$ 330
% of Net Assets	0.20%	0.10%
Investment, Restriction Status [true false]	true	true
Investment, Significant Unobservable Input [true false]	true	true
Investment, Non-income Producing [true false]	false	false
Investment, Identifier [Axis]: MarkLogic Corporation (Delayed Draw), Senior Secured Loans 10/20/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:MarkLogicCorporationMember
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		High Tech Industries Sector [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Spread Above Index		6%
Interest Rate		7%
Acquisition Date		Nov. 23, 2021
Maturity		Oct. 20, 2025
Principal		$ 215
% of Net Assets		0%
Investment, Restriction Status [true false]		true
Investment, Significant Unobservable Input [true false]		true
Investment, Non-income Producing [true false]		false
Investment, Identifier [Axis]: Mavenir Systems, Inc., Senior Secured Loans, due 8/18/2028
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:MavenirSystemsIncMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Telecommunications
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR
Spread Above Index	4.75%
Interest Rate	9.42%
Maturity	Aug. 18, 2028
Principal	$ 1,654
Fair Value	$ 1,350
Investment, Identifier [Axis]: Mc Kissock Investment Holdings, L L C, Senior Secured Loans, due 3/9/2029
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:McKissockInvestmentHoldingsLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Services: Consumer
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Spread Above Index	5%
Interest Rate	8.87%
Maturity	Mar. 09, 2029
Principal	$ 2,481
Fair Value	$ 2,322
Investment, Identifier [Axis]: Medallia, Inc, Senior Secured Loans, due 10/27/2028
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:MedalliaIncMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	High Tech Industries Sector [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR
Spread Above Index	6.50%
Interest rate paid in kind	10.88%
Acquisition Date	Aug. 15, 2022
Maturity	Oct. 27, 2028
Principal	$ 2,049
Amortized Cost	2,011
Fair Value	$ 2,041
% of Net Assets	0.90%
Investment, Restriction Status [true false]	true
Investment, Significant Unobservable Input [true false]	true
Investment, Non-income Producing [true false]	false
Investment, Identifier [Axis]: Mindbody, Inc. ( Revolver) (f), Senior Secured Loans, due 2/14/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:MindbodyIncMember	mrcc:MindbodyIncMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	High Tech Industries Sector [Member]	High Tech Industries Sector [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR	LIBOR
Spread Above Index	7%	8%
Interest Rate	11.73%	9%
Acquisition Date	Feb. 15, 2019	Feb. 15, 2019
Maturity	Feb. 14, 2025	Feb. 14, 2025
Principal	$ 667	$ 667
% of Net Assets	0%	0%
Investment, Restriction Status [true false]	true	true
Investment, Significant Unobservable Input [true false]	true	true
Investment, Non-income Producing [true false]	false	false
Investment, Identifier [Axis]: Mindbody, Inc., Senior Secured Loans, One, due 2/14/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:MindbodyIncMember	mrcc:MindbodyIncMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	High Tech Industries Sector [Member]	High Tech Industries Sector [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR	LIBOR
Spread Above Index	7%	8.50%
Interest Rate	11.73%
Interest rate paid in cash		8%
Interest rate paid in kind		1.50%
Acquisition Date	Feb. 15, 2019	Feb. 15, 2019
Maturity	Feb. 14, 2025	Feb. 14, 2025
Principal	$ 6,536	$ 6,487
Amortized Cost	6,485	6,415
Fair Value	$ 6,526	$ 6,438
% of Net Assets	2.90%	2.60%
Investment, Restriction Status [true false]	true	true
Investment, Significant Unobservable Input [true false]	true	true
Investment, Non-income Producing [true false]	false	false
Investment, Identifier [Axis]: Mindbody, Inc., Senior Secured Loans, Two, due 2/14/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:MindbodyIncMember	mrcc:MindbodyIncMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	High Tech Industries Sector [Member]	High Tech Industries Sector [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR	LIBOR
Spread Above Index	7%	8.50%
Interest Rate	11.73%
Interest rate paid in cash		8%
Interest rate paid in kind		1.50%
Acquisition Date	Sep. 22, 2021	Sep. 22, 2021
Maturity	Feb. 14, 2025	Feb. 14, 2025
Principal	$ 674	$ 669
Amortized Cost	674	669
Fair Value	$ 673	$ 664
% of Net Assets	0.30%	0.30%
Investment, Restriction Status [true false]	true	true
Investment, Significant Unobservable Input [true false]	true	true
Investment, Non-income Producing [true false]	false	false
Investment, Identifier [Axis]: Minotaur Acquisition, Inc., Senior Secured Loans, due 3/27/2026
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:MinotaurAcquisitionIncMember	mrcc:MinotaurAcquisitionIncMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	mrcc:FireFinanceMember	mrcc:FireFinanceMember
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]	us-gaap:LondonInterbankOfferedRateLiborSwapRateMember
Spread Above Index	4.75%	4.75%
Interest Rate	9.17%	4.85%
Maturity	Mar. 27, 2026	Mar. 27, 2026
Principal	$ 4,857	$ 4,912
Fair Value	$ 4,656	$ 4,894
Investment, Identifier [Axis]: Mnine Holdings Inc. (Revolver)
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	Mnine Holdings, Inc [ Member]
Fair Value	$ 214
Investment, Identifier [Axis]: Mnine Holdings, Inc. (Revolver), Senior Secured Loans
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	Mnine Holdings, Inc [ Member]	Mnine Holdings, Inc [ Member]
Investment, Identifier [Axis]: Mnine Holdings, Inc. (Revolver), Senior Secured Loans, due 12/30/2023
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	Mnine Holdings, Inc [ Member]
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	High Tech Industries Sector [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Spread Above Index	8%
Interest rate paid in cash	7.84%
Interest rate paid in kind	5%
Acquisition Date	Aug. 09, 2022
Maturity	Dec. 30, 2023
Principal	$ 533
Amortized Cost	214
Fair Value	$ 214
% of Net Assets	0.10%
Investment, Restriction Status [true false]	true
Investment, Significant Unobservable Input [true false]	true
Investment, Non-income Producing [true false]	false
Investment, Identifier [Axis]: Mnine Holdings, Inc., Equity Securities, Class B units
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	Mnine Holdings, Inc [ Member]	Mnine Holdings, Inc [ Member]
Investment, Type [Extensible Enumeration]	Equity Securities [Member]	Equity Securities [Member]
Investment, Industry Sector [Extensible Enumeration]	High Tech Industries	High Tech Industries
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Acquisition Date	Jun. 30, 2020	Jun. 30, 2020
% of Net Assets	0%	0%
Investment, Restriction Status [true false]	true	true
Investment, Significant Unobservable Input [true false]	true	true
Investment, Non-income Producing [true false]	true	true
Number of units held	6,400	6,400
Investment, Identifier [Axis]: Mnine Holdings, Inc., Senior Secured Loans Due 12/30/2022
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	Mnine Holdings, Inc [ Member]	Mnine Holdings, Inc [ Member]
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	High Tech Industries Sector [Member]	High Tech Industries
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]	LIBOR
Spread Above Index	8%	8%
Interest rate paid in cash	7.84%	4%
Interest rate paid in kind	5%	5%
Acquisition Date	Nov. 02, 2018	Nov. 02, 2018
Maturity	Dec. 30, 2022	Dec. 30, 2022
Principal	$ 5,492	$ 5,193
Amortized Cost	5,477	5,165
Fair Value	$ 5,492	$ 5,771	12,356
% of Net Assets	2.40%	2.30%
Investment, Restriction Status [true false]	true	true
Investment, Significant Unobservable Input [true false]	true	true
Investment, Non-income Producing [true false]	false	false
Investment, Identifier [Axis]: Money Lion, Inc. ( Delayed Draw), Junior Secured Loans, due 3/24/2026
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:MoneyLionIncMember
Investment, Type [Extensible Enumeration]	Junior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Banking
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Spread Above Index	9.25%
Interest Rate	14.07%
Acquisition Date	Mar. 25, 2022
Maturity	Mar. 24, 2026
Principal	$ 1,500
% of Net Assets	0%
Investment, Restriction Status [true false]	true
Investment, Significant Unobservable Input [true false]	true
Investment, Non-income Producing [true false]	false
Investment, Identifier [Axis]: Money Lion, Inc., Junior Secured Loans, due 3/24/2026
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:MoneyLionIncMember
Investment, Type [Extensible Enumeration]	Junior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Banking
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Spread Above Index	9.25%
Interest Rate	14.07%
Acquisition Date	Mar. 25, 2022
Maturity	Mar. 24, 2026
Principal	$ 5,250
Amortized Cost	5,203
Fair Value	$ 5,165
% of Net Assets	2.30%
Investment, Restriction Status [true false]	true
Investment, Significant Unobservable Input [true false]	true
Investment, Non-income Producing [true false]	false
Investment, Identifier [Axis]: Money Lion, Inc., Junior Secured Loans, due 5/1/2023
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:MoneyLionIncMember	mrcc:MoneyLionIncMember
Investment, Type [Extensible Enumeration]	Junior Loans [Member]	Junior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Banking	Banking
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Prime Rate [Member]
Spread Above Index	5.75%
Interest Rate	13.25%	12%
Acquisition Date	Aug. 27, 2021	Aug. 27, 2021
Maturity	May 01, 2023	May 01, 2023
Principal	$ 1,500	$ 1,500
Amortized Cost	1,490	1,488
Fair Value	$ 1,498	$ 1,522
% of Net Assets	0.60%	0.60%
Investment, Restriction Status [true false]	true	true
Investment, Significant Unobservable Input [true false]	true	true
Investment, Non-income Producing [true false]	false	false
Investment, Identifier [Axis]: N C B P Property, L L C, Senior Secured Loans, due 12/16/2022
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:NCBPPropertyLLCMember	mrcc:NCBPPropertyLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	FIRE Real Estate Sector [Member]	FIRE Real Estate Sector [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR	LIBOR
Spread Above Index	9.50%	9.50%
Interest Rate	13.62%	10.50%
Acquisition Date	Dec. 18, 2020	Dec. 18, 2020
Maturity	Jun. 16, 2023	Dec. 16, 2022
Principal	$ 1,950	$ 1,950
Amortized Cost	1,945	1,940
Fair Value	$ 1,955	$ 1,955
% of Net Assets	0.90%	0.80%
Investment, Restriction Status [true false]		true
Investment, Significant Unobservable Input [true false]		true
Investment, Non-income Producing [true false]		false
Investment, Identifier [Axis]: N E C B Collections, L L C ( Revolver), Senior Secured Loans
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	N E C B Collections, L L C [ Member]	N E C B Collections, L L C [ Member]
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Services: Consumer	Services: Consumer
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR	LIBOR
Spread Above Index	11%	11%
Interest rate paid in kind	14.61%	12%
Acquisition Date	Jun. 25, 2019	Jun. 25, 2019
Principal	$ 1,356	$ 1,356
Amortized Cost	1,312	1,312
Fair Value	$ 382	$ 632	834
% of Net Assets	0.20%	0.30%
Investment, Restriction Status [true false]	true	true
Investment, Significant Unobservable Input [true false]	true	true
Investment, Non-income Producing [true false]	false	false
Investment, Identifier [Axis]: N E C B Collections, L L C, Equity Securities
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	N E C B Collections, L L C [ Member]	N E C B Collections, L L C [ Member]
Investment, Type [Extensible Enumeration]		Equity Securities [Member]
Investment, Industry Sector [Extensible Enumeration]		Services: Consumer
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Acquisition Date		Jun. 21, 2019
Amortized Cost		$ 1,458
% of Net Assets		0%
Investment, Significant Unobservable Input [true false]		true
Investment, Non-income Producing [true false]		true
Percentage of units held	20.80%	20.80%
Investment, Identifier [Axis]: N E C B Collections, L L C, Equity Securities, Common stock
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	N E C B Collections, L L C [ Member]
Investment, Type [Extensible Enumeration]	Equity Securities [Member]
Investment, Industry Sector [Extensible Enumeration]	Services: Consumer
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Acquisition Date	Jun. 21, 2019
Amortized Cost	$ 1,458
% of Net Assets	0%
Investment, Restriction Status [true false]	true
Investment, Significant Unobservable Input [true false]	true
Investment, Non-income Producing [true false]	true
Percentage of units held	20.80%
Investment, Identifier [Axis]: NQ PE Project Colosseum Midco Inc. (Delayed Draw), Senior Secured Loans, Due 10/4/2028
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:NqPeProjectColosseumMidcoInc.Member
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Healthcare & Pharmaceuticals Sector [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Spread Above Index	6%
Interest Rate	10.59%
Acquisition Date	Oct. 04, 2022
Maturity	Oct. 04, 2028
Principal	$ 778
% of Net Assets	0%
Investment, Identifier [Axis]: NQ PE Project Colosseum Midco Inc. (Revolver), Senior Secured Loans, Due 10/4/2028
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:NqPeProjectColosseumMidcoInc.Member
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Healthcare & Pharmaceuticals Sector [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Spread Above Index	6%
Interest Rate	10.59%
Acquisition Date	Oct. 04, 2022
Maturity	Oct. 04, 2028
Principal	$ 438
% of Net Assets	0%
Investment, Identifier [Axis]: NQ PE Project Colosseum Midco Inc., Equity Securities, Common Units
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:NqPeProjectColosseumMidcoInc.Member
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Healthcare & Pharmaceuticals Sector [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Acquisition Date	Oct. 04, 2022
Amortized Cost	$ 327
Fair Value	$ 327
% of Net Assets	0.10%
Number of shares held	327,133
Investment, Restriction Status [true false]	true
Investment, Significant Unobservable Input [true false]	true
Investment, Non-income Producing [true false]	false
Investment, Identifier [Axis]: NQ PE Project Colosseum Midco Inc., Senior Secured Loans, Due 10/4/2028
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:NqPeProjectColosseumMidcoInc.Member
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Healthcare & Pharmaceuticals Sector [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Spread Above Index	6%
Interest Rate	10.59%
Acquisition Date	Oct. 04, 2022
Maturity	Oct. 04, 2028
Principal	$ 3,500
Amortized Cost	3,432
Fair Value	$ 3,430
% of Net Assets	1.50%
Investment, Identifier [Axis]: Nations Benefits L L C, Senior Secured Loans, One, Due 8/26/2027
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:NationsBenefitsLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Healthcare & Pharmaceuticals Sector [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Spread Above Index	7%
Interest Rate	11.22%
Acquisition Date	Aug. 20, 2021
Maturity	Aug. 26, 2027
Principal	$ 3,960
Amortized Cost	3,898
Fair Value	$ 4,039
% of Net Assets	1.80%
Investment, Identifier [Axis]: Nations Benefits L L C, Senior Secured Loans, Two, Due 8/26/2027
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:NationsBenefitsLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Healthcare & Pharmaceuticals Sector [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Spread Above Index	7%
Interest Rate	11.22%
Acquisition Date	Aug. 26, 2022
Maturity	Aug. 26, 2027
Principal	$ 4,719
Amortized Cost	4,719
Fair Value	$ 4,813
% of Net Assets	2.10%
Investment, Identifier [Axis]: Nations Benefits LLC Delayed Draw
Schedule of Investments [Line Items]
Number of shares held	106,667
Investment, Identifier [Axis]: Nations Benefits LLC Delayed Draw, Senior Secured Loans Due 8/26/2027
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:NationsBenefitsLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Healthcare & Pharmaceuticals Sector [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Spread Above Index	7%
Interest Rate	11.22%
Acquisition Date	Aug. 26, 2022
Maturity	Aug. 26, 2027
Principal	$ 5,089
Amortized Cost	942
Fair Value	$ 961
% of Net Assets	0.40%
Investment, Identifier [Axis]: Nations Benefits, L L C ( Revolver), Senior Secured Loans, due 8/20/2026
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:NationsBenefitsLLCMember
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Healthcare & Pharmaceuticals Sector [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Spread Above Index		7%
Interest Rate		8%
Acquisition Date		Aug. 20, 2021
Maturity		Aug. 20, 2026
Principal		$ 445
% of Net Assets		0%
Investment, Restriction Status [true false]		true
Investment, Significant Unobservable Input [true false]		true
Investment, Non-income Producing [true false]		false
Investment, Identifier [Axis]: Nations Benefits, L L C (Revolver), Senior Secured Loans, Due 8/26/2027
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:NationsBenefitsLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Healthcare & Pharmaceuticals Sector [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Spread Above Index	7%
Interest Rate	11.42%
Acquisition Date	Aug. 20, 2021
Maturity	Aug. 26, 2027
Principal	$ 2,222
Amortized Cost	889
Fair Value	$ 889
% of Net Assets	0.40%
Investment, Identifier [Axis]: Nations Benefits, L L C, Equity Securities, One, Series B units
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:NationsBenefitsLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Healthcare & Pharmaceuticals Sector [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Interest rate paid in kind	5%
Acquisition Date	Aug. 20, 2021
Amortized Cost	$ 781
Fair Value	$ 934
% of Net Assets	0.40%
Number of shares held	116,460
Investment, Restriction Status [true false]	true
Investment, Significant Unobservable Input [true false]	true
Investment, Non-income Producing [true false]	false
Investment, Identifier [Axis]: Nations Benefits, L L C, Equity Securities, Three, Series A units
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:NationsBenefitsLLCMember
Investment, Type [Extensible Enumeration]		Equity Securities [Member]
Investment, Industry Sector [Extensible Enumeration]		Healthcare & Pharmaceuticals
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Interest rate paid in kind		9%
Acquisition Date		Aug. 20, 2021
Amortized Cost		$ 736
Fair Value		$ 714
% of Net Assets		0.30%
Investment, Restriction Status [true false]		true
Investment, Significant Unobservable Input [true false]		true
Investment, Non-income Producing [true false]		false
Number of units held		888,889
Investment, Identifier [Axis]: Nations Benefits, L L C, Equity Securities, Two, common units
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:NationsBenefitsLLCMember	mrcc:NationsBenefitsLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Equity Securities [Member]
Investment, Industry Sector [Extensible Enumeration]	Healthcare & Pharmaceuticals Sector [Member]	Healthcare & Pharmaceuticals
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Acquisition Date	Aug. 20, 2021	Aug. 20, 2021
Amortized Cost	$ 153	$ 153
Fair Value	$ 66	$ 67
% of Net Assets	0%	0%
Investment, Restriction Status [true false]	true	true
Investment, Significant Unobservable Input [true false]	true	true
Investment, Non-income Producing [true false]	false	true
Number of units held		106,667
Investment, Identifier [Axis]: Nations Benefits, L L C, Senior Secured Loans, due 8/20/2026
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:NationsBenefitsLLCMember
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Healthcare & Pharmaceuticals Sector [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Spread Above Index		7%
Interest Rate		8%
Acquisition Date		Aug. 20, 2021
Maturity		Aug. 20, 2026
Principal		$ 4,000
Amortized Cost		3,924
Fair Value		$ 3,993
% of Net Assets		1.60%
Investment, Restriction Status [true false]		true
Investment, Significant Unobservable Input [true false]		true
Investment, Non-income Producing [true false]		false
Investment, Identifier [Axis]: Natus Medical Incorporated, Senior Secured Loans, due 7/20/2029
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:NatusMedicalIncorporatedMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Healthcare & Pharmaceuticals Sector [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Spread Above Index	5.50%
Interest Rate	8.68%
Maturity	Jul. 20, 2029
Principal	$ 5,000
Fair Value	$ 4,650
Investment, Identifier [Axis]: Nearly Natural Inc. (Revolver) Senior Secured Loans due 3/31/2024
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:NearlyNaturalIncMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Wholesale
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Spread Above Index	11.50%
Interest rate paid in cash	12.32%
Interest rate paid in kind	4%
Acquisition Date	Dec. 15, 2017
Maturity	Mar. 31, 2024
Principal	$ 2,505
Amortized Cost	2,505
Fair Value	$ 2,241
% of Net Assets	1%
Investment, Restriction Status [true false]	true
Investment, Significant Unobservable Input [true false]	true
Investment, Non-income Producing [true false]	false
Investment, Identifier [Axis]: Nearly Natural Inc. Senior Secured Loans Four due 3/31/2024
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:NearlyNaturalIncMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Wholesale
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Spread Above Index	11.50%
Interest rate paid in cash	12.32%
Interest rate paid in kind	4%
Acquisition Date	Aug. 28, 2019
Maturity	Mar. 31, 2024
Principal	$ 1,868
Amortized Cost	1,868
Fair Value	$ 1,672
% of Net Assets	0.80%
Investment, Restriction Status [true false]	true
Investment, Significant Unobservable Input [true false]	true
Investment, Non-income Producing [true false]	false
Investment, Identifier [Axis]: Nearly Natural Inc. Senior Secured Loans One due 3/31/2024
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:NearlyNaturalIncMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Wholesale
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Spread Above Index	11.50%
Interest rate paid in cash	12.32%
Interest rate paid in kind	4%
Acquisition Date	Dec. 15, 2017
Maturity	Mar. 31, 2024
Principal	$ 6,628
Amortized Cost	6,628
Fair Value	$ 5,931
% of Net Assets	2.60%
Investment, Restriction Status [true false]	true
Investment, Significant Unobservable Input [true false]	true
Investment, Non-income Producing [true false]	false
Investment, Identifier [Axis]: Nearly Natural Inc. Senior Secured Loans Three due 3/31/2024
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:NearlyNaturalIncMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Wholesale
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Spread Above Index	11.50%
Interest rate paid in cash	12.32%
Interest rate paid in kind	4%
Acquisition Date	Feb. 16, 2021
Maturity	Mar. 31, 2024
Principal	$ 3,115
Amortized Cost	3,115
Fair Value	$ 2,787
% of Net Assets	1.20%
Investment, Restriction Status [true false]	true
Investment, Significant Unobservable Input [true false]	true
Investment, Non-income Producing [true false]	false
Investment, Identifier [Axis]: Nearly Natural Inc. Senior Secured Loans Two due 3/31/2024
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:NearlyNaturalIncMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Wholesale
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Spread Above Index	11.50%
Interest rate paid in cash	12.32%
Interest rate paid in kind	4%
Acquisition Date	Sep. 22, 2020
Maturity	Mar. 31, 2024
Principal	$ 1,714
Amortized Cost	1,714
Fair Value	$ 1,534
% of Net Assets	0.70%
Investment, Restriction Status [true false]	true
Investment, Significant Unobservable Input [true false]	true
Investment, Non-income Producing [true false]	false
Investment, Identifier [Axis]: Nearly Natural, Inc, Equity Securities, One, Class A units
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:NearlyNaturalIncMember	mrcc:NearlyNaturalInc.Member
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Equity Securities [Member]
Investment, Industry Sector [Extensible Enumeration]	Wholesale	Wholesale
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Acquisition Date	Dec. 15, 2017	Dec. 15, 2017
Amortized Cost	$ 153	$ 153
Fair Value		$ 69
% of Net Assets	0%	0%
Investment, Restriction Status [true false]	true	true
Investment, Significant Unobservable Input [true false]	true	true
Investment, Non-income Producing [true false]	false	true
Number of units held	152,174	152,174
Investment, Identifier [Axis]: Nearly Natural, Inc, Equity Securities, Two, Class A A units
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:NearlyNaturalIncMember	mrcc:NearlyNaturalInc.Member
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Equity Securities [Member]
Investment, Industry Sector [Extensible Enumeration]	Wholesale	Wholesale
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Acquisition Date	Aug. 27, 2021	Aug. 27, 2021
Amortized Cost	$ 61	$ 39
Fair Value		$ 5
% of Net Assets	0%	0%
Investment, Restriction Status [true false]	true	true
Investment, Significant Unobservable Input [true false]	true	true
Investment, Non-income Producing [true false]	false	true
Number of units held	61,087	39,394
Investment, Identifier [Axis]: Nearly Natural, Inc.( Revolver), Senior Secured loans, due 12/15/2022
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:NearlyNaturalIncMember
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Wholesale
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Spread Above Index		11.50%
Interest rate paid in cash		8.50%
Interest rate paid in kind		4%
Acquisition Date		Dec. 15, 2017
Maturity		Dec. 15, 2022
Principal		$ 2,430
Amortized Cost		2,430
Fair Value		$ 2,400
% of Net Assets		1%
Investment, Restriction Status [true false]		true
Investment, Significant Unobservable Input [true false]		true
Investment, Non-income Producing [true false]		false
Investment, Identifier [Axis]: Nearly Natural, Inc., Senior Secured loans, Four, due 12/15/2022
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:NearlyNaturalIncMember
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Wholesale
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Spread Above Index		11.50%
Interest rate paid in cash		8.50%
Interest rate paid in kind		4%
Acquisition Date		Aug. 28, 2019
Maturity		Dec. 15, 2022
Principal		$ 1,859
Amortized Cost		1,859
Fair Value		$ 1,836
% of Net Assets		0.70%
Investment, Restriction Status [true false]		true
Investment, Significant Unobservable Input [true false]		true
Investment, Non-income Producing [true false]		false
Investment, Identifier [Axis]: Nearly Natural, Inc., Senior Secured loans, One, due 12/15/2022
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:NearlyNaturalIncMember
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Wholesale
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Spread Above Index		11.50%
Interest rate paid in cash		8.50%
Interest rate paid in kind		4%
Acquisition Date		Dec. 15, 2017
Maturity		Dec. 15, 2022
Principal		$ 6,601
Amortized Cost		6,572
Fair Value		$ 6,520
% of Net Assets		2.60%
Investment, Restriction Status [true false]		true
Investment, Significant Unobservable Input [true false]		true
Investment, Non-income Producing [true false]		false
Investment, Identifier [Axis]: Nearly Natural, Inc., Senior Secured loans, Three, due 12/15/2022
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:NearlyNaturalIncMember
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Wholesale
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Spread Above Index		11.50%
Interest rate paid in cash		8.50%
Interest rate paid in kind		4%
Acquisition Date		Sep. 22, 2020
Maturity		Dec. 15, 2022
Principal		$ 1,706
Amortized Cost		1,691
Fair Value		$ 1,685
% of Net Assets		0.70%
Investment, Restriction Status [true false]		true
Investment, Significant Unobservable Input [true false]		true
Investment, Non-income Producing [true false]		false
Investment, Identifier [Axis]: Nearly Natural, Inc., Senior Secured loans, Two, due 12/15/2022
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:NearlyNaturalIncMember
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Wholesale
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Spread Above Index		11.50%
Interest rate paid in cash		8.50%
Interest rate paid in kind		4%
Acquisition Date		Feb. 16, 2021
Maturity		Dec. 15, 2022
Principal		$ 3,099
Amortized Cost		3,066
Fair Value		$ 3,061
% of Net Assets		1.20%
Investment, Restriction Status [true false]		true
Investment, Significant Unobservable Input [true false]		true
Investment, Non-income Producing [true false]		false
Investment, Identifier [Axis]: Newforma, Inc. ( Revolver), Senior Secured Loans, due 6/30/2022
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:NewformaIncMember
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		High Tech Industries Sector [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Spread Above Index		5.50%
Interest Rate		6.50%
Acquisition Date		Jun. 30, 2017
Maturity		Jun. 30, 2022
Principal		$ 1,250
% of Net Assets		0%
Investment, Restriction Status [true false]		true
Investment, Significant Unobservable Input [true false]		true
Investment, Non-income Producing [true false]		false
Investment, Identifier [Axis]: Newforma, Inc. ( Revolver) (f), Senior Secured Loans, due 3/31/2023
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:NewformaIncMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	High Tech Industries Sector [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR
Spread Above Index	5.50%
Interest Rate	10.23%
Acquisition Date	Jun. 30, 2017
Maturity	Mar. 31, 2023
Principal	$ 1,250
% of Net Assets	0%
Investment, Restriction Status [true false]	true
Investment, Significant Unobservable Input [true false]	true
Investment, Non-income Producing [true false]	false
Investment, Identifier [Axis]: Newforma, Inc., Senior Secured Loans, due 3/31/2023
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:NewformaIncMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	High Tech Industries Sector [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR
Spread Above Index	5.50%
Interest Rate	10.23%
Acquisition Date	Jun. 30, 2017
Maturity	Mar. 31, 2023
Principal	$ 938
Amortized Cost	937
Fair Value	$ 938
% of Net Assets	0.40%
Investment, Restriction Status [true false]	true
Investment, Significant Unobservable Input [true false]	true
Investment, Non-income Producing [true false]	false
Investment, Identifier [Axis]: Newforma, Inc., Senior Secured Loans, due 6/30/2022
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:NewformaIncMember
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		High Tech Industries Sector [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Spread Above Index		5.50%
Interest Rate		6.50%
Acquisition Date		Jun. 30, 2017
Maturity		Jun. 30, 2022
Principal		$ 3,890
Amortized Cost		3,882
Fair Value		$ 3,890
% of Net Assets		1.60%
Investment, Restriction Status [true false]		true
Investment, Significant Unobservable Input [true false]		true
Investment, Non-income Producing [true false]		false
Investment, Identifier [Axis]: North Haven Spartan U S Holdco, L L C, Senior Secured Loans, due 6/6/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:NorthHavenSpartanUSHoldcoLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Hotels, Gaming & Leisure
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Spread Above Index	6.25%
Interest Rate	10.71%
Maturity	Jun. 06, 2025
Principal	$ 2,280
Fair Value	$ 2,202
Investment, Identifier [Axis]: North Haven U S H C Acquisition, Inc. ( Delayed Draw), Senior Secured Loans, due, 10/30/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:NorthHavenUSHCAcquisitionIncMember	mrcc:NorthHavenUSHCAcquisitionIncMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Media: Advertising, Printing & Publishing	Media: Advertising, Printing & Publishing
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]	us-gaap:LondonInterbankOfferedRateLiborSwapRateMember
Spread Above Index	6.50%	6%
Interest Rate	11.18%	7%
Acquisition Date	Jul. 29, 2022	Sep. 03, 2021
Maturity	Oct. 30, 2025	Oct. 30, 2025
Principal	$ 1,056	$ 1,441
Amortized Cost		482
Fair Value		$ 487
% of Net Assets	0%	0.20%
Investment, Restriction Status [true false]	true	true
Investment, Significant Unobservable Input [true false]	true	true
Investment, Non-income Producing [true false]	false	false
Investment, Identifier [Axis]: North Haven U S H C Acquisition, Inc. ( Revolver), Senior Secured Loans, due, 10/30/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:NorthHavenUSHCAcquisitionIncMember	mrcc:NorthHavenUSHCAcquisitionIncMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Media: Advertising, Printing & Publishing	Media: Advertising, Printing & Publishing
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]	us-gaap:LondonInterbankOfferedRateLiborSwapRateMember
Spread Above Index	6.50%	6%
Interest Rate	11.13%	7%
Acquisition Date	Oct. 30, 2020	Oct. 30, 2020
Maturity	Oct. 30, 2025	Oct. 30, 2025
Principal	$ 416	$ 240
Amortized Cost	187
Fair Value	$ 187
% of Net Assets	0.10%	0%
Investment, Restriction Status [true false]	true	true
Investment, Significant Unobservable Input [true false]	true	true
Investment, Non-income Producing [true false]	false	false
Investment, Identifier [Axis]: North Haven U S H C Acquisition, Inc., Senior Secured Loans, due, One, 10/30/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:NorthHavenUSHCAcquisitionIncMember	mrcc:NorthHavenUSHCAcquisitionIncMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Media: Advertising, Printing & Publishing	Media: Advertising, Printing & Publishing
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]	us-gaap:LondonInterbankOfferedRateLiborSwapRateMember
Spread Above Index	6.50%	6%
Interest Rate	11.18%	7%
Acquisition Date	Oct. 30, 2020	Oct. 30, 2020
Maturity	Oct. 30, 2025	Oct. 30, 2025
Principal	$ 2,450	$ 2,475
Amortized Cost	2,419	2,435
Fair Value	$ 2,448	$ 2,475
% of Net Assets	1.10%	1%
Investment, Restriction Status [true false]	true	true
Investment, Significant Unobservable Input [true false]	true	true
Investment, Non-income Producing [true false]	false	false
Investment, Identifier [Axis]: North Haven U S H C Acquisition, Inc., Senior Secured Loans, due, Two, 10/30/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:NorthHavenUSHCAcquisitionIncMember	mrcc:NorthHavenUSHCAcquisitionIncMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Media: Advertising, Printing & Publishing	Media: Advertising, Printing & Publishing
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]	us-gaap:LondonInterbankOfferedRateLiborSwapRateMember
Spread Above Index	6.25%	6%
Interest Rate	10.41%	7%
Acquisition Date	Jul. 29, 2022	Mar. 12, 2021
Maturity	Oct. 30, 2025	Oct. 30, 2025
Principal	$ 2,592	$ 717
Amortized Cost	2,556	717
Fair Value	$ 2,575	$ 717
% of Net Assets	1.10%	0.30%
Investment, Restriction Status [true false]	true	true
Investment, Significant Unobservable Input [true false]	true	true
Investment, Non-income Producing [true false]	false	false
Investment, Identifier [Axis]: North Haven USHC Acquisition, Inc, Senior Secured Loans, Four, due 10/30/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:NorthHavenUSHCAcquisitionIncMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Media: Advertising, Printing & Publishing
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Spread Above Index	6.50%
Interest Rate	11.18%
Acquisition Date	Sep. 03, 2021
Maturity	Oct. 30, 2025
Principal	$ 1,434
Amortized Cost	1,434
Fair Value	$ 1,433
% of Net Assets	0.60%
Investment, Restriction Status [true false]	true
Investment, Significant Unobservable Input [true false]	true
Investment, Non-income Producing [true false]	false
Investment, Identifier [Axis]: North Haven USHC Acquisition, Inc, Senior Secured Loans, Three, due 10/30/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:NorthHavenUSHCAcquisitionIncMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Media: Advertising, Printing & Publishing
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Spread Above Index	6.50%
Interest Rate	11.18%
Acquisition Date	Mar. 12, 2021
Maturity	Oct. 30, 2025
Principal	$ 710
Amortized Cost	710
Fair Value	$ 709
% of Net Assets	0.30%
Investment, Restriction Status [true false]	true
Investment, Significant Unobservable Input [true false]	true
Investment, Non-income Producing [true false]	false
Investment, Identifier [Axis]: Oceana Australian Fixed Income Trust, Senior Secured Loans, One, due 6/29/2026
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:OceanaAustralianFixedIncomeTrustMember	mrcc:OceanaAustralianFixedIncomeTrustMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	mrcc:FireFinanceMember	mrcc:FireFinanceMember
Investment, Issuer Geographic Region [Extensible Enumeration]	Non-US [Member]	Non-US [Member]
Interest Rate	10.75%	10.75%
Acquisition Date	Jun. 29, 2021	Jun. 29, 2021
Maturity	Jun. 29, 2026	Jun. 29, 2026
Principal	$ 3,084	$ 3,288
Amortized Cost	3,400	3,400
Fair Value	$ 3,084	$ 3,288
% of Net Assets	1.40%	1.30%
Investment, Restriction Status [true false]	true	true
Investment, Significant Unobservable Input [true false]	true	true
Investment, Non-income Producing [true false]	false	false
Investment, Identifier [Axis]: Oceana Australian Fixed Income Trust, Senior Secured Loans, Two, due 2/25/2026
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:OceanaAustralianFixedIncomeTrustMember	mrcc:OceanaAustralianFixedIncomeTrustMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	mrcc:FireFinanceMember	mrcc:FireFinanceMember
Investment, Issuer Geographic Region [Extensible Enumeration]	Non-US [Member]	Non-US [Member]
Interest Rate	11.50%	11.50%
Acquisition Date	Feb. 25, 2021	Feb. 25, 2021
Maturity	Feb. 25, 2026	Feb. 25, 2026
Principal	$ 7,321	$ 7,805
Amortized Cost	8,460	8,460
Fair Value	$ 7,321	$ 7,805
% of Net Assets	3.20%	3.10%
Investment, Restriction Status [true false]	true	true
Investment, Significant Unobservable Input [true false]	true	true
Investment, Non-income Producing [true false]	false	false
Investment, Identifier [Axis]: Offen, Inc., Senior Secured Loans, One, due 6/22/2026
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:OffenIncMember	mrcc:OffenIncMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	us-gaap-supplement:EnergySectorMember	Utilities, Oil & Gas Sector [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR	LIBOR
Spread Above Index		5%
Interest Rate		5.10%
Maturity		Jun. 22, 2026
Principal		$ 2,388
Fair Value		$ 2,387
Investment, Identifier [Axis]: Offen, Inc., Senior Secured Loans, Two, due 6/22/2026
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:OffenIncMember	mrcc:OffenIncMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	us-gaap-supplement:EnergySectorMember	Utilities, Oil & Gas Sector [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR	LIBOR
Spread Above Index		5%
Interest Rate		5.10%
Maturity		Jun. 22, 2026
Principal		$ 876
Fair Value		$ 876
Investment, Identifier [Axis]: Onit, Inc., Unitranche Secured Loans, due 5/2/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:OnitInc.Member	mrcc:OnitInc.Member
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Unitranche Debt [Member]
Investment, Industry Sector [Extensible Enumeration]	Services: Business	Services: Business
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]	LIBOR
Spread Above Index	7.25%	7.25%
Interest Rate	12.30%	8.25%
Acquisition Date	Dec. 20, 2021	Dec. 20, 2021
Maturity	May 02, 2025	May 02, 2025
Principal	$ 1,680	$ 1,500
Amortized Cost	1,656	1,472
Fair Value	$ 1,663	$ 1,472
% of Net Assets	0.70%	0.60%
Investment, Restriction Status [true false]	true	true
Investment, Significant Unobservable Input [true false]	true	true
Investment, Non-income Producing [true false]	false	false
Investment, Identifier [Axis]: Orbit Purchaser L L C, Senior Secured Loans, One, due 10/21/2024
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:OrbitPurchaserLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Services: Business
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR
Spread Above Index	4.50%
Interest Rate	9.23%
Maturity	Oct. 21, 2024
Principal	$ 2,406
Fair Value	$ 2,190
Investment, Identifier [Axis]: Orbit Purchaser L L C, Senior Secured Loans, Three, due 10/21/2024
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:OrbitPurchaserLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Services: Business
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR
Spread Above Index	4.50%
Interest Rate	9.23%
Maturity	Oct. 21, 2024
Principal	$ 543
Fair Value	$ 494
Investment, Identifier [Axis]: Orbit Purchaser L L C, Senior Secured Loans, Two, due 10/21/2024
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:OrbitPurchaserLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Services: Business
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR
Spread Above Index	4.50%
Interest Rate	9.23%
Maturity	Oct. 21, 2024
Principal	$ 1,858
Fair Value	$ 1,691
Investment, Identifier [Axis]: Output Services Group Inc. Senior Secured Loans Due 6/29/2026
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:OutputServicesGroupIncMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Services: Business
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Spread Above Index	6.75%
Interest rate paid in kind	1.50%
Maturity	Jun. 29, 2026
Principal	$ 4,807
Fair Value	$ 3,275
Investment, Identifier [Axis]: Output Services Group, Inc., Senior Secured Loans, due 3/27/2024
Schedule of Investments [Line Items]
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Services: Business
Interest rate paid in cash	9.80%
Investment, Identifier [Axis]: P H Beauty Holdings I I I, I N C., Senior Secured Loans, due 9/26/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:PHBeautyHoldingsIIIINCMember	mrcc:PHBeautyHoldingsIIIINCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Consumer Goods: Non-Durable	Consumer Goods: Non-Durable
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR	LIBOR
Spread Above Index		5%
Interest Rate		5.18%
Maturity		Sep. 26, 2025
Principal		$ 2,418
Fair Value		$ 2,284
Investment, Identifier [Axis]: P K S Holdings, L L C, Equity Securities, Four, Preferred units
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:PKSHoldingsLLCMember	mrcc:PKSHoldingsLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Equity Securities [Member]
Investment, Industry Sector [Extensible Enumeration]	FIRE: Finance	FIRE: Finance
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Interest Rate	12%
Interest rate paid in kind		12%
Acquisition Date	Nov. 30, 2017	Nov. 30, 2017
Amortized Cost	$ 9	$ 9
Fair Value	$ 46	$ 34
% of Net Assets	0%	0%
Investment, Restriction Status [true false]	true	true
Investment, Significant Unobservable Input [true false]	true	true
Investment, Non-income Producing [true false]	false	false
Number of units held	916	916
Investment, Identifier [Axis]: P K S Holdings, L L C, Equity Securities, One, Preferred units
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:PKSHoldingsLLCMember	mrcc:PKSHoldingsLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Equity Securities [Member]
Investment, Industry Sector [Extensible Enumeration]	FIRE: Finance	FIRE: Finance
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Interest Rate	12%
Interest rate paid in kind		12%
Acquisition Date	Nov. 30, 2017	Nov. 30, 2017
Amortized Cost	$ 58	$ 58
Fair Value	$ 298	$ 219
% of Net Assets	0.20%	0.10%
Number of shares held	5,680
Investment, Restriction Status [true false]	true	true
Investment, Significant Unobservable Input [true false]	true	true
Investment, Non-income Producing [true false]	false	false
Number of units held		5,680
Investment, Identifier [Axis]: P K S Holdings, L L C, Equity Securities, Three, Preferred units
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:PKSHoldingsLLCMember	mrcc:PKSHoldingsLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Equity Securities [Member]
Investment, Industry Sector [Extensible Enumeration]	FIRE: Finance	FIRE: Finance
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Interest Rate	12%
Interest rate paid in kind		12%
Acquisition Date	Nov. 30, 2017	Nov. 30, 2017
Amortized Cost	$ 1	$ 1
Fair Value	$ 7	$ 5
% of Net Assets	0%	0%
Investment, Restriction Status [true false]	true	true
Investment, Significant Unobservable Input [true false]	true	true
Investment, Non-income Producing [true false]	false	false
Number of units held	132	132
Investment, Identifier [Axis]: P K S Holdings, L L C, Equity Securities, Two, Preferred units
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:PKSHoldingsLLCMember	mrcc:PKSHoldingsLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Equity Securities [Member]
Investment, Industry Sector [Extensible Enumeration]	FIRE: Finance	FIRE: Finance
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Interest Rate	12%
Interest rate paid in kind		12%
Acquisition Date	Nov. 30, 2017	Nov. 30, 2017
Amortized Cost	$ 9	$ 9
Fair Value	$ 46	$ 34
% of Net Assets	0%	0%
Investment, Restriction Status [true false]	true	true
Investment, Significant Unobservable Input [true false]	true	true
Investment, Non-income Producing [true false]	false	false
Number of units held	5,714	5,714
Investment, Identifier [Axis]: P V H C Holding Corp, Senior Secured Loans, due 8/5/2024
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:PVHCHoldingCorpMember	mrcc:PVHCHoldingCorpMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Container and Packaging Sector [Member]	Container and Packaging Sector [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR	LIBOR
Spread Above Index		4.75%
Interest Rate		5.75%
Maturity		Aug. 05, 2024
Principal		$ 3,217
Fair Value		$ 2,976
Investment, Identifier [Axis]: Panda Acquisition, LLC, Senior Secured Loans, due 10/18/2028
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:PandaAcquisitionLlcMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Automotive
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Spread Above Index	6.35%
Interest Rate	10.28%
Acquisition Date	Dec. 20, 2022
Maturity	Oct. 18, 2028
Principal	$ 4,500
Amortized Cost	3,691
Fair Value	$ 3,690
% of Net Assets	1.60%
Investment, Restriction Status [true false]	true
Investment, Significant Unobservable Input [true false]	true
Investment, Non-income Producing [true false]	false
Investment, Identifier [Axis]: Paragon Healthcare Inc. Senior Secured Loan Due 1/19/2027
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:ParagonHealthcareIncMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Healthcare & Pharmaceuticals Sector [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Spread Above Index	5.75%
Interest Rate	9.81%
Maturity	Jan. 19, 2027
Principal	$ 2,127
Fair Value	$ 2,109
Investment, Identifier [Axis]: Paragon HealthcareInc. Delayed Draw Senior Secured Loans due 1/19/2027
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:ParagonHealthcareIncMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Healthcare & Pharmaceuticals Sector [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Spread Above Index	5.75%
Interest Rate	10.06%
Maturity	Jan. 19, 2027
Principal	$ 366
Fair Value	$ 242
Investment, Identifier [Axis]: Paragon HealthcareInc. Revolver Senior Secured Loan Due 1/19/2027
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:ParagonHealthcareIncMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Healthcare & Pharmaceuticals Sector [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Spread Above Index	5.75%
Interest Rate	10.26%
Maturity	Jan. 19, 2027
Principal	$ 490
Fair Value	$ 61
Investment, Identifier [Axis]: Phoenix Chemical Holding Company L L C (fka Polymer Solutions Group), Senior Secured Loans, due 1/3/2023
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:PhoenixChemicalHoldingCompanyLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Chemicals, Plastics & Rubber
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR
Investment, Identifier [Axis]: Planful Inc. Senior Secured Loans, One, due 12/30/2024
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:PlanfulIncMember
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		High Tech Industries Sector [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Spread Above Index		6.50%
Interest Rate		7.50%
Acquisition Date		Dec. 28, 2018
Maturity		Dec. 30, 2024
Principal		$ 9,500
Amortized Cost		9,414
Fair Value		$ 9,472
% of Net Assets		3.80%
Investment, Restriction Status [true false]		true
Investment, Significant Unobservable Input [true false]		true
Investment, Non-income Producing [true false]		false
Investment, Identifier [Axis]: Planful Inc. Senior Secured Loans, Two, due 12/30/2024
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:PlanfulIncMember
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		High Tech Industries Sector [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Spread Above Index		6.50%
Interest Rate		7.50%
Acquisition Date		Jan. 11, 2021
Maturity		Dec. 30, 2024
Principal		$ 1,325
Amortized Cost		1,325
Fair Value		$ 1,322
% of Net Assets		0.50%
Investment, Restriction Status [true false]		true
Investment, Significant Unobservable Input [true false]		true
Investment, Non-income Producing [true false]		false
Investment, Identifier [Axis]: Planful, Inc, Equity Securities, Class A units
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:PlanfulIncMember
Investment, Type [Extensible Enumeration]		Equity Securities [Member]
Investment, Industry Sector [Extensible Enumeration]		High Tech Industries Sector [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Interest rate paid in kind		8%
Acquisition Date		Dec. 28, 2018
Amortized Cost		$ 473
Fair Value		$ 557
% of Net Assets		0.20%
Investment, Restriction Status [true false]		true
Investment, Significant Unobservable Input [true false]		true
Investment, Non-income Producing [true false]		false
Number of units held		473,082
Investment, Identifier [Axis]: Planful, Inc, Senior Secured Loans, Four, due 12/28/2026
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:PlanfulIncMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	High Tech Industries Sector [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Spread Above Index	6.50%
Interest Rate	10.32%
Acquisition Date	Feb. 11, 2022
Maturity	Dec. 28, 2026
Principal	$ 884
Amortized Cost	884
Fair Value	$ 878
% of Net Assets	0.40%
Investment, Restriction Status [true false]	true
Investment, Significant Unobservable Input [true false]	true
Investment, Non-income Producing [true false]	false
Investment, Identifier [Axis]: Planful, Inc, Senior Secured Loans, One, due 12/28/2026
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:PlanfulIncMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	High Tech Industries Sector [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Spread Above Index	6.50%
Interest Rate	10.32%
Acquisition Date	Dec. 28, 2018
Maturity	Dec. 28, 2026
Principal	$ 9,500
Amortized Cost	9,456
Fair Value	$ 9,443
% of Net Assets	4.20%
Investment, Restriction Status [true false]	true
Investment, Significant Unobservable Input [true false]	true
Investment, Non-income Producing [true false]	false
Investment, Identifier [Axis]: Planful, Inc, Senior Secured Loans, Three, due 12/28/2026
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:PlanfulIncMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	High Tech Industries Sector [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Spread Above Index	6.50%
Interest Rate	10.32%
Acquisition Date	Jan. 11, 2021
Maturity	Dec. 28, 2026
Principal	$ 1,325
Amortized Cost	1,325
Fair Value	$ 1,318
% of Net Assets	0.60%
Investment, Restriction Status [true false]	true
Investment, Significant Unobservable Input [true false]	true
Investment, Non-income Producing [true false]	false
Investment, Identifier [Axis]: Planful, Inc, Senior Secured Loans, Two, due 12/28/2026
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:PlanfulIncMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	High Tech Industries Sector [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Spread Above Index	6.50%
Interest Rate	9.90%
Acquisition Date	Sep. 12, 2022
Maturity	Dec. 28, 2026
Principal	$ 530
Amortized Cost	519
Fair Value	$ 527
% of Net Assets	0.20%
Investment, Restriction Status [true false]	true
Investment, Significant Unobservable Input [true false]	true
Investment, Non-income Producing [true false]	false
Investment, Identifier [Axis]: Planful, Inc. ( Revolver), Senior Secured Loans, due 12/28/2026
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:PlanfulIncMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	High Tech Industries Sector [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Spread Above Index	6.50%
Interest Rate	10.32%
Acquisition Date	Dec. 28, 2018
Maturity	Dec. 28, 2026
Principal	$ 442
Amortized Cost	442
Fair Value	$ 439
% of Net Assets	0.20%
Investment, Restriction Status [true false]	true
Investment, Significant Unobservable Input [true false]	true
Investment, Non-income Producing [true false]	false
Investment, Identifier [Axis]: Planful, Inc. ( Revolver), Senior Secured Loans, due 12/30/2024
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:PlanfulIncMember
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		High Tech Industries Sector [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Spread Above Index		6.50%
Interest Rate		7.50%
Acquisition Date		Dec. 28, 2018
Maturity		Dec. 30, 2024
Principal		$ 442
Amortized Cost		88
Fair Value		$ 88
% of Net Assets		0%
Investment, Restriction Status [true false]		true
Investment, Significant Unobservable Input [true false]		true
Investment, Non-income Producing [true false]		false
Investment, Identifier [Axis]: Planful, Inc., Equity Securities, Class A Units
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:PlanfulInc.Member
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	High Tech Industries Sector [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Interest rate paid in kind	8%
Acquisition Date	Dec. 28, 2018
Amortized Cost	$ 473
Fair Value	$ 563
% of Net Assets	0.20%
Investment, Restriction Status [true false]	true
Investment, Significant Unobservable Input [true false]	true
Investment, Non-income Producing [true false]	false
Number of units held	473,082
Investment, Identifier [Axis]: Polychem Acquisition, L L C, Senior Secured Loans, due 3/17/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:PolychemAcquisitionLLCMember	mrcc:PolychemAcquisitionLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Container and Packaging Sector [Member]	Container and Packaging Sector [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR	LIBOR
Spread Above Index		5%
Interest Rate		5.50%
Maturity		Mar. 17, 2025
Principal		$ 2,918
Fair Value		$ 2,917
Investment, Identifier [Axis]: Polymer Solutions Group Senior Secured Loans Due 1/3/2023
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:PhoenixChemicalHoldingCompanyLLCMember
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Chemicals, Plastics & Rubber
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Spread Above Index		7%
Interest Rate		8%
Maturity		Jan. 03, 2023
Principal		$ 1,178
Fair Value		$ 1,169
Investment, Identifier [Axis]: Port Townsend Holdings Company, Inc. and Crown Corrugated Company, Senior Secured Loans, due 4/3/2024
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:PortTownsendHoldingsCompanyInc.andCrownCorrugatedCompanyMember
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Container and Packaging Sector [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Spread Above Index		6.75%
Interest rate paid in cash		5.75%
Interest rate paid in kind		2%
Maturity		Apr. 03, 2024
Principal		$ 4,751
Fair Value		$ 4,238
Investment, Identifier [Axis]: Priority Ambulance, L L C, Unitranche Secured Loans, Four, due 4/12/2022
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:PriorityAmbulanceLLCMember
Investment, Type [Extensible Enumeration]		Unitranche Debt [Member]
Investment, Industry Sector [Extensible Enumeration]		Healthcare & Pharmaceuticals
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Spread Above Index		6.50%
Interest Rate		7.50%
Acquisition Date		Oct. 22, 2020
Maturity		Apr. 12, 2022
Principal		$ 990
Amortized Cost		990
Fair Value		$ 989
% of Net Assets		0.40%
Investment, Restriction Status [true false]		true
Investment, Significant Unobservable Input [true false]		true
Investment, Non-income Producing [true false]		false
Investment, Identifier [Axis]: Priority Ambulance, L L C, Unitranche Secured Loans, One, due 4/12/2022
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:PriorityAmbulanceLLCMember
Investment, Type [Extensible Enumeration]		Unitranche Debt [Member]
Investment, Industry Sector [Extensible Enumeration]		Healthcare & Pharmaceuticals
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Spread Above Index		6.50%
Interest Rate		7.50%
Acquisition Date		Jul. 18, 2018
Maturity		Apr. 12, 2022
Principal		$ 10,015
Amortized Cost		10,015
Fair Value		$ 10,010
% of Net Assets		4%
Investment, Restriction Status [true false]		true
Investment, Significant Unobservable Input [true false]		true
Investment, Non-income Producing [true false]		false
Investment, Identifier [Axis]: Priority Ambulance, L L C, Unitranche Secured Loans, Three, due 4/12/2022
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:PriorityAmbulanceLLCMember
Investment, Type [Extensible Enumeration]		Unitranche Debt [Member]
Investment, Industry Sector [Extensible Enumeration]		Healthcare & Pharmaceuticals
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Spread Above Index		6.50%
Interest Rate		7.50%
Acquisition Date		Dec. 13, 2018
Maturity		Apr. 12, 2022
Principal		$ 655
Amortized Cost		655
Fair Value		$ 655
% of Net Assets		0.30%
Investment, Restriction Status [true false]		true
Investment, Significant Unobservable Input [true false]		true
Investment, Non-income Producing [true false]		false
Investment, Identifier [Axis]: Priority Ambulance, L L C, Unitranche Secured Loans, Two, due 4/12/2022
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:PriorityAmbulanceLLCMember
Investment, Type [Extensible Enumeration]		Unitranche Debt [Member]
Investment, Industry Sector [Extensible Enumeration]		Healthcare & Pharmaceuticals
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Spread Above Index		6.50%
Interest Rate		7.50%
Acquisition Date		Apr. 12, 2017
Maturity		Apr. 12, 2022
Principal		$ 1,253
Amortized Cost		1,251
Fair Value		$ 1,253
% of Net Assets		0.50%
Investment, Restriction Status [true false]		true
Investment, Significant Unobservable Input [true false]		true
Investment, Non-income Producing [true false]		false
Investment, Identifier [Axis]: Prototek LLC (Delayed Draw), Due 12/8/2027
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:PrototekLlcMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Services: Business
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Spread Above Index	6.50%
Interest Rate	10.83%
Acquisition Date	Dec. 08, 2022
Maturity	Dec. 08, 2027
Principal	$ 768
% of Net Assets	0%
Investment, Restriction Status [true false]	true
Investment, Significant Unobservable Input [true false]	true
Investment, Non-income Producing [true false]	false
Investment, Identifier [Axis]: Prototek LLC (Revolver), Due,12/8/2027
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:PrototekLlcMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Services: Business
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Spread Above Index	6.50%
Interest Rate	10.83%
Acquisition Date	Dec. 08, 2022
Maturity	Dec. 08, 2027
Principal	$ 576
% of Net Assets	0%
Investment, Restriction Status [true false]	true
Investment, Significant Unobservable Input [true false]	true
Investment, Non-income Producing [true false]	false
Investment, Identifier [Axis]: Prototek LLC, Due 12/8/2027
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:PrototekLlcMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Services: Business
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Spread Above Index	6.50%
Interest Rate	10.83%
Acquisition Date	Dec. 08, 2022
Maturity	Dec. 08, 2027
Principal	$ 2,500
Amortized Cost	2,425
Fair Value	$ 2,425
% of Net Assets	1.10%
Investment, Restriction Status [true false]	true
Investment, Significant Unobservable Input [true false]	true
Investment, Non-income Producing [true false]	false
Investment, Identifier [Axis]: Quest Resource Management Group, L L C ( Delayed Draw), Senior Secured Loans, due 10/20/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:QuestResourceManagementGroupLLCMember	mrcc:QuestResourceManagementGroupLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Environmental Industries	Environmental Industries
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR	LIBOR
Spread Above Index	6.50%	6.50%
Interest Rate	10.62%	7.50%
Acquisition Date	Dec. 07, 2021	Dec. 07, 2021
Maturity	Oct. 20, 2025	Oct. 20, 2025
Principal	$ 1,772	$ 1,778
Amortized Cost	383
Fair Value	$ 381
% of Net Assets	0.20%	0%
Investment, Restriction Status [true false]	true	true
Investment, Significant Unobservable Input [true false]	true	true
Investment, Non-income Producing [true false]	false	false
Investment, Identifier [Axis]: Quest Resource Management Group, L L C, Equity Securites, Two, Warrants
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:QuestResourceManagementGroupLLCMember	mrcc:QuestResourceManagementGroupLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Equity Securities [Member]
Investment, Industry Sector [Extensible Enumeration]	Environmental Industries	Environmental Industries
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Acquisition Date	Oct. 19, 2021	Oct. 19, 2021
Maturity	Mar. 19, 2028	Mar. 19, 2028
Fair Value	$ 147	$ 169
% of Net Assets	0.10%	0.10%
Investment, Restriction Status [true false]	true	true
Investment, Significant Unobservable Input [true false]	true	true
Investment, Non-income Producing [true false]	false	true
Warrants to Purchase Percentage of Equity	0.20%	0.20%
Investment, Identifier [Axis]: Quest Resource Management Group, L L C, Equity Securities, One, Warrants
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:QuestResourceManagementGroupLLCMember	mrcc:QuestResourceManagementGroupLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Equity Securities [Member]
Investment, Industry Sector [Extensible Enumeration]	Environmental Industries	Environmental Industries
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Acquisition Date	Oct. 19, 2020	Oct. 19, 2020
Maturity	Mar. 19, 2028	Mar. 19, 2028
Amortized Cost	$ 67	$ 67
Fair Value	$ 210	$ 286
% of Net Assets	0.10%	0.10%
Investment, Restriction Status [true false]	true	true
Investment, Significant Unobservable Input [true false]	true	true
Investment, Non-income Producing [true false]	false	true
Warrants to Purchase Percentage of Equity	0.20%	0.20%
Investment, Identifier [Axis]: Quest Resource Management Group, L L C, Senior Secured Loans, One, due 10/20/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:QuestResourceManagementGroupLLCMember	mrcc:QuestResourceManagementGroupLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Environmental Industries	Environmental Industries
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR	LIBOR
Spread Above Index	6.50%	6.50%
Interest Rate	10.62%	7.50%
Acquisition Date	Oct. 19, 2020	Oct. 19, 2020
Maturity	Oct. 20, 2025	Oct. 20, 2025
Principal	$ 972	$ 990
Amortized Cost	908	924
Fair Value	$ 972	$ 989
% of Net Assets	0.40%	0.40%
Investment, Restriction Status [true false]	true	true
Investment, Significant Unobservable Input [true false]	true	true
Investment, Non-income Producing [true false]	false	false
Investment, Identifier [Axis]: Quest Resource Management Group, L L C, Senior Secured Loans, Three, due 10/20/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:QuestResourceManagementGroupLLCMember	mrcc:QuestResourceManagementGroupLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Environmental Industries	Environmental Industries
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR	LIBOR
Spread Above Index	6.50%	6.50%
Interest Rate	10.62%	7.50%
Acquisition Date	Dec. 07, 2021	Dec. 07, 2021
Maturity	Oct. 20, 2025	Oct. 20, 2025
Principal	$ 3,796	$ 3,856
Amortized Cost	3,738	3,779
Fair Value	$ 3,781	$ 3,853
% of Net Assets	1.70%	1.60%
Investment, Restriction Status [true false]	true	true
Investment, Significant Unobservable Input [true false]	true	true
Investment, Non-income Producing [true false]	false	false
Investment, Identifier [Axis]: Quest Resource Management Group, L L C, Senior Secured Loans, Two, due 10/20/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:QuestResourceManagementGroupLLCMember	mrcc:QuestResourceManagementGroupLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Environmental Industries	Environmental Industries
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR	LIBOR
Spread Above Index	6.50%	6.50%
Interest Rate	10.62%	7.50%
Acquisition Date	Oct. 19, 2020	Oct. 19, 2020
Maturity	Oct. 20, 2025	Oct. 20, 2025
Principal	$ 1,068	$ 1,087
Amortized Cost	1,068	1,087
Fair Value	$ 1,067	$ 1,086
% of Net Assets	0.50%	0.40%
Investment, Restriction Status [true false]	true	true
Investment, Significant Unobservable Input [true false]	true	true
Investment, Non-income Producing [true false]	false	false
Investment, Identifier [Axis]: Radiology Partners, Inc., Senior Secured Loans, due 7/9/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:RadiologyPartnersIncMember	mrcc:RadiologyPartnersIncMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Healthcare & Pharmaceuticals Sector [Member]	Healthcare & Pharmaceuticals Sector [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR	LIBOR
Spread Above Index	4.25%	4.25%
Interest Rate	8.64%	4.35%
Maturity	Jul. 09, 2025	Jul. 09, 2025
Principal	$ 4,760	$ 4,760
Fair Value	$ 4,018	$ 4,700
Investment, Identifier [Axis]: Recorded Future, Inc, Equity Securities, Class A units
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	Recorded Future, Inc [ Member]	Recorded Future, Inc [ Member]
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Equity Securities [Member]
Investment, Industry Sector [Extensible Enumeration]	High Tech Industries Sector [Member]	High Tech Industries Sector [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Acquisition Date	Jul. 03, 2019	Jul. 03, 2019
Amortized Cost	$ 81	$ 81
Fair Value	$ 225	$ 203
% of Net Assets	0.10%	0.10%
Investment, Restriction Status [true false]	true	true
Investment, Significant Unobservable Input [true false]	true	true
Investment, Non-income Producing [true false]	false	true
Number of units held	80,486	80,486
Investment, Identifier [Axis]: Recycled Plastics Industries, L L C ( Revolver), Senior Secured Loans, due 8/4/2026
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:RecycledPlasticsIndustriesLLCMember	mrcc:RecycledPlasticsIndustriesLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Consumer Goods: Durable	Consumer Goods: Durable
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR	LIBOR
Spread Above Index	6.75%	6.75%
Interest Rate	10.87%	7.75%
Acquisition Date	Aug. 04, 2021	Aug. 04, 2021
Maturity	Aug. 04, 2026	Aug. 04, 2026
Principal	$ 473	$ 473
Amortized Cost		142
Fair Value		$ 142
% of Net Assets	0%	0.10%
Investment, Restriction Status [true false]	true	true
Investment, Significant Unobservable Input [true false]	true	true
Investment, Non-income Producing [true false]	false	false
Investment, Identifier [Axis]: Recycled Plastics Industries, L L C, Senior Secured Loans, due 8/4/2026
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:RecycledPlasticsIndustriesLLCMember	mrcc:RecycledPlasticsIndustriesLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Consumer Goods: Durable	Consumer Goods: Durable
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR	LIBOR
Spread Above Index	6.75%	6.75%
Interest Rate	10.87%	7.75%
Acquisition Date	Aug. 04, 2021	Aug. 04, 2021
Maturity	Aug. 04, 2026	Aug. 04, 2026
Principal	$ 3,456	$ 3,491
Amortized Cost	3,403	3,426
Fair Value	$ 3,370	$ 3,491
% of Net Assets	1.50%	1.40%
Investment, Restriction Status [true false]	true	true
Investment, Significant Unobservable Input [true false]	true	true
Investment, Non-income Producing [true false]	false	false
Investment, Identifier [Axis]: Red Zone Robotics, Inc. ( Revolver) , Senior Secured Loans, due 6/5/2023
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:RedZoneRoboticsIncMember
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Services: Business
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Spread Above Index		6.75%
Interest Rate		7.75%
Acquisition Date		Jun. 01, 2018
Maturity		Jun. 05, 2023
Principal		$ 158
% of Net Assets		0%
Investment, Restriction Status [true false]		true
Investment, Significant Unobservable Input [true false]		true
Investment, Non-income Producing [true false]		false
Investment, Identifier [Axis]: Red Zone Robotics, Inc., Senior Secured Loans, due 6/5/2023
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:RedZoneRoboticsIncMember
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Services: Business
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Spread Above Index		6.75%
Interest Rate		7.75%
Acquisition Date		Jun. 01, 2018
Maturity		Jun. 05, 2023
Principal		$ 213
Amortized Cost		211
Fair Value		$ 213
% of Net Assets		0.10%
Investment, Restriction Status [true false]		true
Investment, Significant Unobservable Input [true false]		true
Investment, Non-income Producing [true false]		false
Investment, Identifier [Axis]: Relativity O D A L L C ( Revolver), Senior Secured Loans, due 5/12/2027
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:RelativityODALLCMember	mrcc:RelativityODALLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Services: Business	Services: Business
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR	LIBOR
Spread Above Index	7.50%	7.50%
Interest rate paid in kind	11.89%	8.50%
Acquisition Date	May 12, 2021	May 12, 2021
Maturity	May 12, 2027	May 12, 2027
Principal	$ 180	$ 180
% of Net Assets	0%	0%
Investment, Restriction Status [true false]	true	true
Investment, Significant Unobservable Input [true false]	true	true
Investment, Non-income Producing [true false]	false	false
Investment, Identifier [Axis]: Relativity O D A L L C, Senior Secured Loans, due 5/12/2027
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:RelativityODALLCMember	mrcc:RelativityODALLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Services: Business	Services: Business
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR	LIBOR
Spread Above Index	7.50%	7.50%
Interest rate paid in kind	11.89%	8.50%
Acquisition Date	May 12, 2021	May 12, 2021
Maturity	May 12, 2027	May 12, 2027
Principal	$ 2,061	$ 1,896
Amortized Cost	2,024	1,854
Fair Value	$ 2,060	$ 1,894
% of Net Assets	0.90%	0.80%
Investment, Restriction Status [true false]	true	true
Investment, Significant Unobservable Input [true false]	true	true
Investment, Non-income Producing [true false]	false	false
Investment, Identifier [Axis]: Relevate Health Group, L L C ( Delayed Draw), Senior Secured Loans, due, 11/20/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:RelevateHealthGroupLLCMember	mrcc:RelevateHealthGroupLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Media: Advertising, Printing & Publishing	Media: Advertising, Printing & Publishing
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]	us-gaap:LondonInterbankOfferedRateLiborSwapRateMember
Spread Above Index	5.75%	6%
Interest Rate	9.97%	7%
Acquisition Date	Nov. 20, 2020	Nov. 20, 2020
Maturity	Nov. 20, 2025	Nov. 20, 2025
Principal	$ 778	$ 784
Amortized Cost	659	666
Fair Value	$ 648	$ 673
% of Net Assets	0.30%	0.30%
Investment, Restriction Status [true false]	true	true
Investment, Significant Unobservable Input [true false]	true	true
Investment, Non-income Producing [true false]	false	false
Investment, Identifier [Axis]: Relevate Health Group, L L C ( Revolver), Senior Secured Loans, due, 11/20/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:RelevateHealthGroupLLCMember	mrcc:RelevateHealthGroupLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Media: Advertising, Printing & Publishing	Media: Advertising, Printing & Publishing
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]	us-gaap:LondonInterbankOfferedRateLiborSwapRateMember
Spread Above Index	5.75%	6%
Interest Rate	9.97%	7%
Acquisition Date	Nov. 20, 2020	Nov. 20, 2020
Maturity	Nov. 20, 2025	Nov. 20, 2025
Principal	$ 316	$ 316
% of Net Assets	0%	0%
Investment, Restriction Status [true false]	true	true
Investment, Significant Unobservable Input [true false]	true	true
Investment, Non-income Producing [true false]	false	false
Investment, Identifier [Axis]: Relevate Health Group, L L C, Equity Securities, Class B common units
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:RelevateHealthGroupLLCMember	mrcc:RelevateHealthGroupLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Equity Securities [Member]
Investment, Industry Sector [Extensible Enumeration]	Media: Advertising, Printing & Publishing	Media: Advertising, Printing & Publishing
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Acquisition Date	Nov. 20, 2020	Nov. 20, 2020
% of Net Assets	0%	0%
Investment, Restriction Status [true false]	true	true
Investment, Significant Unobservable Input [true false]	true	true
Investment, Non-income Producing [true false]	false	true
Number of units held		40
Investment, Identifier [Axis]: Relevate Health Group, L L C, Equity Securities, preferred units
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:RelevateHealthGroupLLCMember	mrcc:RelevateHealthGroupLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Equity Securities [Member]
Investment, Industry Sector [Extensible Enumeration]	Media: Advertising, Printing & Publishing	Media: Advertising, Printing & Publishing
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Interest rate paid in kind	12%	12%
Acquisition Date	Nov. 20, 2020	Nov. 20, 2020
Amortized Cost	$ 40	$ 40
Fair Value	$ 36	$ 40
% of Net Assets	0%	0%
Number of shares held	40
Investment, Restriction Status [true false]	true	true
Investment, Significant Unobservable Input [true false]	true	true
Investment, Non-income Producing [true false]	false	false
Number of units held		40
Investment, Identifier [Axis]: Relevate Health Group, L L C, Senior Secured Loans, due, 11/20/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:RelevateHealthGroupLLCMember	mrcc:RelevateHealthGroupLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Media: Advertising, Printing & Publishing	Media: Advertising, Printing & Publishing
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]	us-gaap:LondonInterbankOfferedRateLiborSwapRateMember
Spread Above Index	5.75%	6%
Interest Rate	9.97%	7%
Acquisition Date	Nov. 20, 2020	Nov. 20, 2020
Maturity	Nov. 20, 2025	Nov. 20, 2025
Principal	$ 1,474	$ 1,489
Amortized Cost	1,455	1,465
Fair Value	$ 1,449	$ 1,504
% of Net Assets	0.60%	0.60%
Investment, Restriction Status [true false]	true	true
Investment, Significant Unobservable Input [true false]	true	true
Investment, Non-income Producing [true false]	false	false
Investment, Identifier [Axis]: Research Now Group, Inc. and Survey Sampling International, L L C, Senior Secured Loans, due 12/20/2024
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:ResearchNowGroupInc.andSurveySamplingInternationalLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Media: Diversified & Production
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR
Spread Above Index	5.50%
Interest Rate	8.84%
Maturity	Dec. 20, 2024
Principal	$ 6,650
Fair Value	$ 5,035
Investment, Identifier [Axis]: Rockdale Blackhawk, L L C, Senior Secured Loans, no stated maturity
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:RockdaleBlackhawkLLCMember
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Healthcare & Pharmaceuticals Sector [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Acquisition Date	Mar. 31, 2015	Mar. 31, 2015
Fair Value	$ 557	$ 1,681
% of Net Assets	0.20%	0.70%
Investment, Restriction Status [true false]		true
Investment, Significant Unobservable Input [true false]		true
Investment, Non-income Producing [true false]		true
Investment, Identifier [Axis]: Runner Buyer I N C., Senior Secured Loans, due 10/23/2028
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:RunnerBuyerINCMember	mrcc:RunnerBuyerINCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Consumer Goods: Durable	Consumer Goods: Durable
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR	LIBOR
Spread Above Index		5.50%
Interest Rate		6.25%
Maturity		Oct. 23, 2028
Principal		$ 3,000
Fair Value		2,970
Investment, Identifier [Axis]: S F R Holdco, L L C Equity Securities
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	S F R Holdco, L L C [ Member]
Investment, Type [Extensible Enumeration]	Equity Securities [Member]
Investment, Industry Sector [Extensible Enumeration]	FIRE: Real Estate
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Acquisition Date	Aug. 06, 2021
Amortized Cost	$ 3,900
Fair Value	$ 3,900	3,900
% of Net Assets	1.70%
Investment, Restriction Status [true false]	true
Investment, Significant Unobservable Input [true false]	true
Investment, Non-income Producing [true false]	true
Percentage of interests	24.40%
Investment, Identifier [Axis]: S F R Holdco, L L C, Junior Secured Loans Due 7/28/2028
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	S F R Holdco, L L C [ Member]
Investment, Type [Extensible Enumeration]	Junior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	FIRE: Real Estate
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Interest Rate	8%
Acquisition Date	Aug. 06, 2021
Maturity	Jul. 28, 2028
Principal	$ 5,850
Amortized Cost	5,850
Fair Value	$ 5,850	$ 5,850
% of Net Assets	2.60%
Investment, Restriction Status [true false]	true
Investment, Significant Unobservable Input [true false]	true
Investment, Non-income Producing [true false]	false
Investment, Identifier [Axis]: S H I Holdings, Inc. ( Common stock)
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	S H I Holdings, Inc [ Member]	S H I Holdings, Inc [ Member]
Number of shares held		24
Investment, Identifier [Axis]: S H I Holdings, Inc. ( Revolver)
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	S H I Holdings, Inc [ Member]	S H I Holdings, Inc [ Member]
Fair Value			297
Investment, Identifier [Axis]: S H I Holdings, Inc., Investment One
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	S H I Holdings, Inc [ Member]	S H I Holdings, Inc [ Member]
Fair Value			188
Investment, Identifier [Axis]: S I R V A Worldwide Inc., Senior Secured Loans, due 8/4/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:SIRVAWorldwideIncMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Services: Business
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR
Spread Above Index	5.50%
Interest Rate	10.23%
Maturity	Aug. 04, 2025
Principal	$ 1,800
Fair Value	$ 1,606
Investment, Identifier [Axis]: S T A T S Intermediate Holdings, L L C, Senior Secured Loans, due 7/10/2026
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:STATSIntermediateHoldingsLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Media: Diversified & Production
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR
Spread Above Index	5.25%
Interest Rate	9.90%
Maturity	Oct. 07, 2026
Principal	$ 4,850
Fair Value	$ 4,498
Investment, Identifier [Axis]: S W Ingredients Holdings, L L C, Senior Secured Loans, due 7/3/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:SWIngredientsHoldingsLLCMember	mrcc:SWIngredientsHoldingsLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	mrcc:BeverageFoodAndTobaccoSectorMember	mrcc:BeverageFoodAndTobaccoSectorMember
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR	LIBOR
Spread Above Index	4.75%	4.75%
Interest Rate	9.13%	5.75%
Maturity	Jul. 03, 2025	Jul. 03, 2025
Principal	$ 3,581	$ 3,619
Fair Value	$ 3,581	$ 3,619
Investment, Identifier [Axis]: SFR Holdco, LLC (Junior secured loan)
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	Second Avenue S F R Holdings I I L L C [ Member]	Second Avenue S F R Holdings I I L L C [ Member]
Investment, Identifier [Axis]: SFR Holdco, LLC (LLC interest)
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	Second Avenue S F R Holdings I I L L C [ Member]	Second Avenue S F R Holdings I I L L C [ Member]
Investment, Identifier [Axis]: Sandvine Corporation, Senior Secured Loans, due 10/31/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:SandvineCorporationMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Telecommunications
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR
Spread Above Index	4.50%
Interest Rate	8.88%
Maturity	Oct. 31, 2025
Principal	$ 2,000
Fair Value	$ 1,904
Investment, Identifier [Axis]: Second Avenue S F R Holdings I I L L C ( Revolver), Senior Secured Loans, Due 8/9/2024
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	Second Avenue S F R Holdings I I L L C [ Member]	Second Avenue S F R Holdings I I L L C [ Member]
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	FIRE: Real Estate	FIRE: Real Estate
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR	LIBOR
Spread Above Index	7%	7%
Interest Rate	11.12%	7.50%
Acquisition Date	Aug. 11, 2021	Aug. 11, 2021
Maturity	Aug. 09, 2024	Aug. 09, 2024
Principal	$ 4,875	$ 4,875
Amortized Cost	4,785	2,104
Fair Value	$ 4,755	$ 2,104
% of Net Assets	2.10%	0.80%
Investment, Restriction Status [true false]	true	true
Investment, Significant Unobservable Input [true false]	true	true
Investment, Non-income Producing [true false]	false	false
Investment, Identifier [Axis]: Second Avenue S F R Holdings I I L L C, Equity Securities
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		Second Avenue S F R Holdings I I L L C [ Member]
Investment, Type [Extensible Enumeration]		Equity Securities [Member]
Investment, Industry Sector [Extensible Enumeration]		FIRE: Real Estate
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Acquisition Date		Aug. 06, 2021
Amortized Cost		$ 3,900
Fair Value		$ 3,900
% of Net Assets		1.60%
Investment, Restriction Status [true false]		true
Investment, Significant Unobservable Input [true false]		true
Investment, Non-income Producing [true false]		false
Warrants to Purchase Percentage of Equity		24.40%
Percentage of interests		24.40%
Investment, Identifier [Axis]: Second Avenue S F R Holdings I I L L C, Junior Secured Loans, Due 7/28/2028
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		Second Avenue S F R Holdings I I L L C [ Member]
Investment, Type [Extensible Enumeration]		Junior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		FIRE: Real Estate
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Interest Rate		8%
Acquisition Date		Aug. 06, 2021
Maturity		Jul. 28, 2028
Principal		$ 5,850
Amortized Cost		5,850
Fair Value		$ 5,850
% of Net Assets		2.30%
Investment, Restriction Status [true false]		true
Investment, Significant Unobservable Input [true false]		true
Investment, Non-income Producing [true false]		false
Investment, Identifier [Axis]: Second Avenue SFR Holdings II LLC (Delayed Draw) Loan
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	Second Avenue S F R Holdings I I L L C [ Member]	Second Avenue S F R Holdings I I L L C [ Member]
Fair Value		$ 5,850
Investment, Identifier [Axis]: Secretariat Advisors L L C ( Delayed Draw), Senior Secured Loans, due 12/29/2028
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:SecretariatAdvisorsLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Services: Business
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR
Spread Above Index	4.75%
Interest Rate	9.48%
Maturity	Dec. 29, 2028
Principal	$ 270
Fair Value	$ 260
Investment, Identifier [Axis]: Secretariat Advisors L L C, Senior Secured Loans, due 12/29/2028
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:SecretariatAdvisorsLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Services: Business
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR
Spread Above Index	4.75%
Interest Rate	9.48%
Maturity	Dec. 29, 2028
Principal	$ 1,693
Fair Value	$ 1,634
Investment, Identifier [Axis]: Security Services Acquisition Sub Corp., Senior Secured Loans, Five, due 9/30/2026
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:SecurityServicesAcquisitionSubCorpMember	mrcc:SecurityServicesAcquisitionSubCorpMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Services: Business	Services: Business
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]	LIBOR
Spread Above Index	6%	6%
Interest Rate	10.40%	7%
Acquisition Date	Feb. 15, 2019	Feb. 15, 2019
Maturity	Sep. 30, 2026	Sep. 30, 2026
Principal	$ 1,535	$ 1,551
Amortized Cost	1,535	1,551
Fair Value	$ 1,532	$ 1,549
% of Net Assets	0.70%	0.60%
Investment, Restriction Status [true false]	true	true
Investment, Significant Unobservable Input [true false]	true	true
Investment, Non-income Producing [true false]	false	false
Investment, Identifier [Axis]: Security Services Acquisition Sub Corp., Senior Secured Loans, Four, due 9/30/2026
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:SecurityServicesAcquisitionSubCorpMember	mrcc:SecurityServicesAcquisitionSubCorpMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Services: Business	Services: Business
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]	LIBOR
Spread Above Index	6%	6%
Interest Rate	10.42%	7%
Acquisition Date	Feb. 15, 2019	Feb. 15, 2019
Maturity	Sep. 30, 2026	Sep. 30, 2026
Principal	$ 2,135	$ 2,157
Amortized Cost	2,135	2,157
Fair Value	$ 2,131	$ 2,154
% of Net Assets	0.90%	0.90%
Investment, Restriction Status [true false]	true	true
Investment, Significant Unobservable Input [true false]	true	true
Investment, Non-income Producing [true false]	false	false
Investment, Identifier [Axis]: Security Services Acquisition Sub Corp., Senior Secured Loans, One, due 9/30/2026
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:SecurityServicesAcquisitionSubCorpMember	mrcc:SecurityServicesAcquisitionSubCorpMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Services: Business	Services: Business
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]	LIBOR
Spread Above Index	6%	6%
Interest Rate	10.42%	7%
Acquisition Date	Feb. 15, 2019	Sep. 30, 2021
Maturity	Sep. 30, 2026	Sep. 30, 2026
Principal	$ 3,378	$ 7,980
Amortized Cost	3,353	7,872
Fair Value	$ 3,372	$ 7,972
% of Net Assets	1.50%	3.20%
Investment, Restriction Status [true false]	true	true
Investment, Significant Unobservable Input [true false]	true	true
Investment, Non-income Producing [true false]	false	false
Investment, Identifier [Axis]: Security Services Acquisition Sub Corp., Senior Secured Loans, Three, due 9/30/2026
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:SecurityServicesAcquisitionSubCorpMember	mrcc:SecurityServicesAcquisitionSubCorpMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Services: Business	Services: Business
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]	LIBOR
Spread Above Index	6%	6%
Interest Rate	10.42%	7%
Acquisition Date	Sep. 30, 2021	Feb. 15, 2019
Maturity	Sep. 30, 2026	Sep. 30, 2026
Principal	$ 7,900	$ 2,455
Amortized Cost	7,806	2,455
Fair Value	$ 7,884	$ 2,452
% of Net Assets	3.50%	1%
Investment, Restriction Status [true false]	true	true
Investment, Significant Unobservable Input [true false]	true	true
Investment, Non-income Producing [true false]	false	false
Investment, Identifier [Axis]: Security Services Acquisition Sub Corp., Senior Secured Loans, Two, due 9/30/2026
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:SecurityServicesAcquisitionSubCorpMember	mrcc:SecurityServicesAcquisitionSubCorpMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Services: Business	Services: Business
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]	LIBOR
Spread Above Index	6%	6%
Interest Rate	10.42%	7%
Acquisition Date	Feb. 15, 2019	Feb. 15, 2019
Maturity	Sep. 30, 2026	Sep. 30, 2026
Principal	$ 2,430	$ 3,413
Amortized Cost	2,430	3,382
Fair Value	$ 2,425	$ 3,409
% of Net Assets	1.10%	1.40%
Investment, Restriction Status [true false]	true	true
Investment, Significant Unobservable Input [true false]	true	true
Investment, Non-income Producing [true false]	false	false
Investment, Identifier [Axis]: Seran Bio Science, L L C ( Revolver), Senior Secured Loans, due 7/8/2027
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:SeranBioScienceLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Healthcare & Pharmaceuticals Sector [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Spread Above Index	6.25%
Interest Rate	9.96%
Interest rate paid in cash	7.86%
Acquisition Date	Dec. 31, 2020
Maturity	Jul. 08, 2027
Principal	$ 444
% of Net Assets	0%
Investment, Identifier [Axis]: Seran Bio Science, L L C (Revolver), Senior Secured Loans, Due 12/31/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:SeranBioScienceLLCMember
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Healthcare & Pharmaceuticals Sector [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Spread Above Index		6.25%
Interest Rate		7.25%
Acquisition Date		Dec. 31, 2020
Maturity		Dec. 31, 2025
Principal		$ 444
% of Net Assets		0%
Investment, Restriction Status [true false]		true
Investment, Significant Unobservable Input [true false]		true
Investment, Non-income Producing [true false]		false
Investment, Identifier [Axis]: Seran Bio Science, L L C, Equity Securities, common units
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:SeranBioScienceLLCMember
Investment, Type [Extensible Enumeration]		Equity Securities [Member]
Investment, Industry Sector [Extensible Enumeration]		Healthcare & Pharmaceuticals
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Acquisition Date		Dec. 31, 2020
Amortized Cost		$ 334
Fair Value		$ 714
% of Net Assets		0.30%
Investment, Restriction Status [true false]		true
Investment, Significant Unobservable Input [true false]		true
Investment, Non-income Producing [true false]		true
Number of units held		33,333
Investment, Identifier [Axis]: Seran Bio Science, L L C, Senior Secured Loans, Due 12/31/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:SeranBioScienceLLCMember
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Healthcare & Pharmaceuticals Sector [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Spread Above Index		6.25%
Interest Rate		7.25%
Acquisition Date		Dec. 31, 2020
Maturity		Dec. 31, 2025
Principal		$ 2,481
Amortized Cost		2,440
Fair Value		$ 2,487
% of Net Assets		1%
Investment, Restriction Status [true false]		true
Investment, Significant Unobservable Input [true false]		true
Investment, Non-income Producing [true false]		false
Investment, Identifier [Axis]: Seran Bio Science, L L C, Senior Secured Loans, due 7/8/2027
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:SeranBioScienceLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Healthcare & Pharmaceuticals Sector [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Spread Above Index	6.25%
Interest Rate	9.96%
Acquisition Date	Dec. 31, 2020
Maturity	Jul. 08, 2027
Principal	$ 2,456
Amortized Cost	2,424
Fair Value	$ 2,435
% of Net Assets	1.10%
Investment, Identifier [Axis]: Seran BioScience, LLC (Delayed Draw), Senior Secured Loans, Due 7/8/2027
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:SeranBioScienceLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Healthcare & Pharmaceuticals Sector [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Spread Above Index	6.25%
Interest Rate	10.67%
Acquisition Date	Jul. 08, 2022
Maturity	Jul. 08, 2027
Principal	$ 2,776
Amortized Cost	1,331
Fair Value	$ 1,320
% of Net Assets	0.60%
Investment, Identifier [Axis]: Seran BioScience, LLC, Equity Security, Common Units
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:SeranBioScienceLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Healthcare & Pharmaceuticals Sector [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Acquisition Date	Dec. 31, 2020
Amortized Cost	$ 334
Fair Value	$ 537
% of Net Assets	0.30%
Investment, Restriction Status [true false]	true
Investment, Significant Unobservable Input [true false]	true
Investment, Non-income Producing [true false]	false
Number of units held	33,333
Investment, Identifier [Axis]: Service Max, Inc. ( Revolver) , Senior Secured Loans, due 11/1/2027
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:ServiceMaxIncMember	mrcc:ServiceMaxIncMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Services: Business	Services: Business
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR	LIBOR
Spread Above Index	6%	7%
Interest Rate		8%
Interest rate paid in kind	10.27%
Acquisition Date	Nov. 01, 2021	Nov. 01, 2021
Maturity	Nov. 01, 2027	Nov. 01, 2027
Principal	$ 350	$ 350
Amortized Cost	175
Fair Value	$ 175
% of Net Assets	0.10%	0%
Investment, Restriction Status [true false]	true	true
Investment, Significant Unobservable Input [true false]	true	true
Investment, Non-income Producing [true false]	false	false
Investment, Identifier [Axis]: Service Max, Inc., Senior Secured Loans, due 11/1/2027
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:ServiceMaxIncMember	mrcc:ServiceMaxIncMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Services: Business	Services: Business
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR	LIBOR
Spread Above Index	7%	7%
Interest Rate		8%
Interest rate paid in kind	11.12%
Acquisition Date	Nov. 01, 2021	Nov. 01, 2021
Maturity	Nov. 01, 2027	Nov. 01, 2027
Principal	$ 3,846	$ 3,500
Amortized Cost	3,786	3,431
Fair Value	$ 3,884	$ 3,500
% of Net Assets	1.70%	1.40%
Investment, Restriction Status [true false]	true	true
Investment, Significant Unobservable Input [true false]	true	true
Investment, Non-income Producing [true false]	false	false
Investment, Identifier [Axis]: Spectrum Science Communications, L L C ( Revolver), Senior Secured Loans, due 1/25/2027
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:SpectrumScienceCommunicationsLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Media: Diversified & Production
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Spread Above Index	6.25%
Interest Rate	10.92%
Acquisition Date	Jan. 25, 2022
Maturity	Jan. 25, 2027
Principal	$ 200
% of Net Assets	0%
Investment, Restriction Status [true false]	true
Investment, Significant Unobservable Input [true false]	true
Investment, Non-income Producing [true false]	false
Investment, Identifier [Axis]: Spectrum Science Communications, L L C, Senior Secured Loans, due 1/25/2027
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:SpectrumScienceCommunicationsLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Media: Diversified & Production
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Spread Above Index	6.25%
Interest Rate	10.92%
Acquisition Date	Jan. 25, 2022
Maturity	Jan. 25, 2027
Principal	$ 995
Amortized Cost	979
Fair Value	$ 1,005
% of Net Assets	0.40%
Investment, Restriction Status [true false]	true
Investment, Significant Unobservable Input [true false]	true
Investment, Non-income Producing [true false]	false
Investment, Identifier [Axis]: Spherix Global Inc, Equity Securities, Class A units
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:SpherixGlobalInc.Member	mrcc:SpherixGlobalInc.Member
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Equity Securities [Member]
Investment, Industry Sector [Extensible Enumeration]	Media: Advertising, Printing & Publishing	Media: Advertising, Printing & Publishing
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Acquisition Date	Dec. 22, 2021	Dec. 22, 2021
Amortized Cost	$ 81	$ 81
Fair Value	$ 63	$ 81
% of Net Assets	0%	0%
Investment, Restriction Status [true false]	true	true
Investment, Significant Unobservable Input [true false]	true	true
Investment, Non-income Producing [true false]	false	true
Number of units held	81	81
Investment, Identifier [Axis]: Spherix Global Inc. ( Revolver), Senior Secured Loans, due, 12/22/2026
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:SpherixGlobalInc.Member	mrcc:SpherixGlobalInc.Member
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Media: Advertising, Printing & Publishing	Media: Advertising, Printing & Publishing
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Spread Above Index	6%	6%
Interest Rate	10.24%	7%
Acquisition Date	Dec. 22, 2021	Dec. 22, 2021
Maturity	Dec. 22, 2026	Dec. 22, 2026
Principal	$ 122	$ 122
% of Net Assets	0%	0%
Investment, Restriction Status [true false]	true	true
Investment, Significant Unobservable Input [true false]	true	true
Investment, Non-income Producing [true false]	false	false
Investment, Identifier [Axis]: Spherix Global Inc. , Senior Secured Loans, due, 12/22/2026
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:SpherixGlobalInc.Member	mrcc:SpherixGlobalInc.Member
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Media: Advertising, Printing & Publishing	Media: Advertising, Printing & Publishing
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Spread Above Index	6%	6%
Interest Rate	10.24%	7%
Acquisition Date	Dec. 22, 2021	Dec. 22, 2021
Maturity	Dec. 22, 2026	Dec. 22, 2026
Principal	$ 1,092	$ 1,100
Amortized Cost	1,076	1,081
Fair Value	$ 1,088	$ 1,081
% of Net Assets	0.50%	0.40%
Investment, Restriction Status [true false]	true	true
Investment, Significant Unobservable Input [true false]	true	true
Investment, Non-income Producing [true false]	false	false
Investment, Identifier [Axis]: Sports Operating Holdings II, LLC (Delayed Draw), Due 11/3/2027
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:SportsOperatingHoldingsIiLlcMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Media: Diversified & Production
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Spread Above Index	5.75%
Interest Rate	10.17%
Acquisition Date	Nov. 03, 2022
Maturity	Nov. 03, 2027
Principal	$ 2,400
% of Net Assets	0%
Investment, Restriction Status [true false]	true
Investment, Significant Unobservable Input [true false]	true
Investment, Non-income Producing [true false]	false
Investment, Identifier [Axis]: Sports Operating Holdings II, LLC (Revolver), Due, 11/3/2027
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:SportsOperatingHoldingsIiLlcMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Media: Diversified & Production
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Spread Above Index	5.75%
Interest Rate	10.17%
Acquisition Date	Nov. 03, 2022
Maturity	Nov. 03, 2027
Principal	$ 519
% of Net Assets	0%
Investment, Restriction Status [true false]	true
Investment, Significant Unobservable Input [true false]	true
Investment, Non-income Producing [true false]	false
Investment, Identifier [Axis]: Sports Operating Holdings II, LLC, Due, 11/3/2027
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:SportsOperatingHoldingsIiLlcMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Media: Diversified & Production
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Spread Above Index	5.75%
Interest Rate	10.17%
Acquisition Date	Nov. 03, 2022
Maturity	Nov. 03, 2027
Principal	$ 2,993
Amortized Cost	2,920
Fair Value	$ 2,918
% of Net Assets	1.30%
Investment, Restriction Status [true false]	true
Investment, Significant Unobservable Input [true false]	true
Investment, Non-income Producing [true false]	false
Investment, Identifier [Axis]: Star Compliance Mid Co, L L C, ( Revolver), Senior Secured Loans, due 1/12/2027
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:StarComplianceMidCoLLCMember	mrcc:StarComplianceMidCoLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Banking	Banking
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR	LIBOR
Spread Above Index	6.75%	6.75%
Interest Rate	11.14%	7.75%
Acquisition Date	Jan. 12, 2021	Jan. 12, 2021
Maturity	Jan. 12, 2027	Jan. 11, 2027
Principal	$ 322	$ 322
Amortized Cost	81
Fair Value	$ 79
% of Net Assets	0%	0%
Investment, Restriction Status [true false]	true	true
Investment, Significant Unobservable Input [true false]	true	true
Investment, Non-income Producing [true false]	false	false
Investment, Identifier [Axis]: Star Compliance Mid Co, L L C, Senior Secured Loans, One, due 1/12/2027
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:StarComplianceMidCoLLCMember	mrcc:StarComplianceMidCoLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Banking	Banking
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR	LIBOR
Spread Above Index	6.75%	6.75%
Interest Rate	11.48%	7.75%
Acquisition Date	Jan. 12, 2021	Jan. 12, 2021
Maturity	Jan. 12, 2027	Jan. 11, 2027
Principal	$ 2,000	$ 2,000
Amortized Cost	1,971	1,965
Fair Value	$ 1,968	$ 2,000
% of Net Assets	0.90%	0.80%
Investment, Restriction Status [true false]	true	true
Investment, Significant Unobservable Input [true false]	true	true
Investment, Non-income Producing [true false]	false	false
Investment, Identifier [Axis]: Star Compliance Mid Co, L L C, Senior Secured Loans, Two, due 1/12/2027
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:StarComplianceMidCoLLCMember	mrcc:StarComplianceMidCoLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Banking	Banking
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR	LIBOR
Spread Above Index	6.75%	6.75%
Interest Rate	11.48%	7.75%
Acquisition Date	Oct. 12, 2021	Oct. 12, 2021
Maturity	Jan. 12, 2027	Jan. 11, 2027
Principal	$ 336	$ 336
Amortized Cost	330	329
Fair Value	$ 330	$ 336
% of Net Assets	0.10%	0.10%
Investment, Restriction Status [true false]	true	true
Investment, Significant Unobservable Input [true false]	true	true
Investment, Non-income Producing [true false]	false	false
Investment, Identifier [Axis]: Storm Trap, L L C ( Revolver), Senior Secured Loans, due 12/8/2023
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:StormTrapLLCMember
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Environmental Industries
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Spread Above Index		5.50%
Interest Rate		6.50%
Acquisition Date		Dec. 10, 2018
Maturity		Dec. 08, 2023
Principal		$ 432
% of Net Assets		0%
Investment, Restriction Status [true false]		true
Investment, Significant Unobservable Input [true false]		true
Investment, Non-income Producing [true false]		false
Investment, Identifier [Axis]: Storm Trap, L L C, Senior Secured Loans, due 12/8/2023
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:StormTrapLLCMember
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Environmental Industries
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Spread Above Index		5.50%
Interest Rate		6.50%
Acquisition Date		Dec. 10, 2018
Maturity		Dec. 08, 2023
Principal		$ 7,170
Amortized Cost		7,114
Fair Value		$ 7,170
% of Net Assets		2.90%
Investment, Restriction Status [true false]		true
Investment, Significant Unobservable Input [true false]		true
Investment, Non-income Producing [true false]		false
Investment, Identifier [Axis]: Summit Container Corporation ( Revolver)
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	Summit Container Corporation [ Member]	Summit Container Corporation [ Member]
Fair Value			1,654
Investment, Identifier [Axis]: Summit Container Corporation, Equity Securities, Warrants
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	Summit Container Corporation [ Member]	Summit Container Corporation [ Member]
Fair Value			139
Warrants to Purchase Percentage of Equity		19.50%
Investment, Identifier [Axis]: Summit Container Corporation, Investment One
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	Summit Container Corporation [ Member]	Summit Container Corporation [ Member]
Fair Value			3,204
Investment, Identifier [Axis]: Synergy Environmental Corporation ( Revolver), Senior Secured Loans, due 9/29/2023
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:SynergyEnvironmentalCorporationMember
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Environmental Industries
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Spread Above Index		6%
Interest Rate		7%
Acquisition Date		Apr. 29, 2016
Maturity		Sep. 29, 2023
Principal		$ 671
% of Net Assets		0%
Investment, Restriction Status [true false]		true
Investment, Significant Unobservable Input [true false]		true
Investment, Non-income Producing [true false]		false
Investment, Identifier [Axis]: Synergy Environmental Corporation, Senior Secured Loans, One, due 9/29/2023
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:SynergyEnvironmentalCorporationMember
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Environmental Industries
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Spread Above Index		6%
Interest Rate		7%
Acquisition Date		Apr. 29, 2016
Maturity		Sep. 29, 2023
Principal		$ 2,853
Amortized Cost		2,846
Fair Value		$ 2,853
% of Net Assets		1.10%
Investment, Restriction Status [true false]		true
Investment, Significant Unobservable Input [true false]		true
Investment, Non-income Producing [true false]		false
Investment, Identifier [Axis]: Synergy Environmental Corporation, Senior Secured Loans, Three, due 9/29/2023
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:SynergyEnvironmentalCorporationMember
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Environmental Industries
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Spread Above Index		6%
Interest Rate		7%
Acquisition Date		Apr. 29, 2016
Maturity		Sep. 29, 2023
Principal		$ 810
Amortized Cost		810
Fair Value		$ 810
% of Net Assets		0.30%
Investment, Restriction Status [true false]		true
Investment, Significant Unobservable Input [true false]		true
Investment, Non-income Producing [true false]		false
Investment, Identifier [Axis]: Synergy Environmental Corporation, Senior Secured Loans, Two, due 9/29/2023
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:SynergyEnvironmentalCorporationMember
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Environmental Industries
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Spread Above Index		6%
Interest Rate		7%
Acquisition Date		Apr. 29, 2016
Maturity		Sep. 29, 2023
Principal		$ 477
Amortized Cost		476
Fair Value		$ 477
% of Net Assets		0.20%
Investment, Restriction Status [true false]		true
Investment, Significant Unobservable Input [true false]		true
Investment, Non-income Producing [true false]		false
Investment, Identifier [Axis]: T A T T Buyer, L L C, Senior Secured Loans, due 3/30/2029
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:TATTBuyerLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Media: Diversified & Production
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Spread Above Index	5%
Interest Rate	8.98%
Maturity	Mar. 30, 2029
Principal	$ 3,325
Fair Value	$ 3,242
Investment, Identifier [Axis]: T C F I I I O W L Buyer L L C, Senior Secured Loans, One, due 4/17/2026
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:TCFIIIOWLBuyerLLCMember	mrcc:TCFIIIOWLBuyerLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Construction & Building	Construction & Building
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]	LIBOR
Spread Above Index	5.50%	6%
Interest Rate	9.94%	7%
Acquisition Date	Apr. 19, 2021	Apr. 19, 2021
Maturity	Apr. 17, 2026	Apr. 17, 2026
Principal	$ 2,019	$ 2,040
Amortized Cost	1,994	2,008
Fair Value	$ 2,022	$ 2,040
% of Net Assets	0.90%	0.80%
Investment, Restriction Status [true false]	true	true
Investment, Significant Unobservable Input [true false]	true	true
Investment, Non-income Producing [true false]	false	false
Investment, Identifier [Axis]: T C F I I I O W L Buyer L L C, Senior Secured Loans, Three, due 4/17/2026
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:TCFIIIOWLBuyerLLCMember	mrcc:TCFIIIOWLBuyerLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Construction & Building	Construction & Building
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]	LIBOR
Spread Above Index	5.50%	6%
Interest Rate	9.94%	7%
Acquisition Date	Dec. 17, 2021	Dec. 17, 2021
Maturity	Apr. 17, 2026	Apr. 17, 2026
Principal	$ 2,213	$ 2,235
Amortized Cost	2,182	2,196
Fair Value	$ 2,215	$ 2,235
% of Net Assets	1%	0.90%
Investment, Restriction Status [true false]	true	true
Investment, Significant Unobservable Input [true false]	true	true
Investment, Non-income Producing [true false]	false	false
Investment, Identifier [Axis]: T C F I I I O W L Buyer L L C, Senior Secured Loans, Two, due 4/17/2026
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:TCFIIIOWLBuyerLLCMember	mrcc:TCFIIIOWLBuyerLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Construction & Building	Construction & Building
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]	LIBOR
Spread Above Index	5.50%	6%
Interest Rate	9.94%	7%
Acquisition Date	Apr. 19, 2021	Apr. 19, 2021
Maturity	Apr. 17, 2026	Apr. 17, 2026
Principal	$ 2,466	$ 2,491
Amortized Cost	2,466	2,491
Fair Value	$ 2,469	$ 2,491
% of Net Assets	1.10%	1%
Investment, Restriction Status [true false]	true	true
Investment, Significant Unobservable Input [true false]	true	true
Investment, Non-income Producing [true false]	false	false
Investment, Identifier [Axis]: T E A M Public Choices, L L C, Senior Secured Loans, due 12/17/2027
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:TEAMPublicChoicesLLCMember	mrcc:TEAMPublicChoicesLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	mrcc:FireFinanceMember	Healthcare & Pharmaceuticals Sector [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR	LIBOR
Spread Above Index	5%	5%
Interest Rate	9.93%	6%
Maturity	Dec. 17, 2027	Dec. 17, 2027
Principal	$ 2,955	$ 2,992
Fair Value	$ 2,822	$ 2,985
Investment, Identifier [Axis]: T G G T S Acquisition Company, Senior Secured Loans, due 12/12/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:TGGTSAcquisitionCompanyMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	High Tech Industries Sector [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR
Spread Above Index	6.50%
Interest Rate	10.88%
Maturity	Dec. 12, 2025
Principal	$ 3,190
Fair Value	$ 3,143
Investment, Identifier [Axis]: T J C Spartech Acquisition Corp., Senior Secured Loans, due 5/5/2028
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:TJCSpartechAcquisitionCorpMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Chemicals, Plastics & Rubber
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR
Investment, Identifier [Axis]: T J Management Hold Co L L C ( Revolver), Senior Secured Loans, Due 6/28/2024
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	T J Management Hold Co L L C [ Member]	T J Management Hold Co L L C [ Member]
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Beverage, Food & Tobacco	Beverage, Food & Tobacco
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR	LIBOR
Spread Above Index	5.50%	5.50%
Interest Rate	9.89%	6.50%
Acquisition Date	Sep. 09, 2020	Sep. 09, 2020
Maturity	Jun. 28, 2024	Jun. 28, 2024
Principal	$ 477	$ 477
Amortized Cost	80
Fair Value	$ 80
% of Net Assets	0%	0%
Investment, Restriction Status [true false]	true	true
Investment, Significant Unobservable Input [true false]	true	true
Investment, Non-income Producing [true false]	false	false
Investment, Identifier [Axis]: T J Management Hold Co L L C, Equity Securities, Common stock
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	T J Management Hold Co L L C [ Member]	T J Management Hold Co L L C [ Member]
Investment, Type [Extensible Enumeration]	Equity Securities [Member]	Equity Securities [Member]
Investment, Industry Sector [Extensible Enumeration]	Beverage, Food & Tobacco	Beverage, Food & Tobacco
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Acquisition Date	Sep. 09, 2020	Sep. 09, 2020
Amortized Cost	$ 1,631	$ 1,631
Fair Value	$ 2,766	$ 3,148	3,323
% of Net Assets	1.20%	1.30%
Number of shares held	16	16
Investment, Restriction Status [true false]	true	true
Investment, Significant Unobservable Input [true false]	true	true
Investment, Non-income Producing [true false]	true	false
Investment, Identifier [Axis]: Tait L L C ( Revolver), Senior Secured Loans, due 3/28/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:TaitLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Hotels, Gaming & Leisure
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Prime Rate [Member]
Spread Above Index	4%
Interest Rate	10.25%
Maturity	Mar. 28, 2025
Principal	$ 769
Investment, Identifier [Axis]: Tait L L C, Senior Secured Loans, due 3/28/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:TaitLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Hotels, Gaming & Leisure
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR
Spread Above Index	5%
Interest Rate	8.75%
Maturity	Mar. 28, 2025
Principal	$ 4,083
Fair Value	$ 3,972
Investment, Identifier [Axis]: Teneo Holdings L L C, Senior Secured Loans, due 7/11/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:TeneoHoldingsLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Services: Business
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Spread Above Index	5.25%
Interest Rate	9.67%
Maturity	Jul. 11, 2025
Principal	$ 4,837
Fair Value	$ 4,668
Investment, Identifier [Axis]: The Cook & Boardman Group L L C, Senior Secured Loans, due 10/20/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:TheCookBoardmanGroupLLCMember	mrcc:TheCookBoardmanGroupLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Construction & Building	Construction & Building
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]	LIBOR
Spread Above Index		5.75%
Interest Rate		6.75%
Maturity		Oct. 20, 2025
Principal		$ 2,910
Fair Value		$ 2,838
Investment, Identifier [Axis]: The Kleinfelder Group, Inc., Senior Secured Loans, due 11/29/2024
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:TheKleinfelderGroupIncMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Services: Business
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR
Spread Above Index	5.25%
Interest Rate	9.98%
Maturity	Nov. 29, 2024
Principal	$ 2,362
Fair Value	$ 2,362
Investment, Identifier [Axis]: The Kyjen Company, L L C ( Revolver), Senior Secured Loans, due 4/3/2026
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:TheKyjenCompanyLLCMember	mrcc:TheKyjenCompanyLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Consumer Goods: Non-Durable	Consumer Goods: Non-Durable
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]	LIBOR
Spread Above Index	7.10%	6.50%
Interest Rate		7.50%
Interest rate paid in kind	0.50%
Acquisition Date	May 14, 2021	May 14, 2021
Maturity	Apr. 03, 2026	Apr. 03, 2026
Principal	$ 105	$ 105
Amortized Cost	89	43
Fair Value	$ 88	$ 43
% of Net Assets	0%	0%
Investment, Restriction Status [true false]	true	true
Investment, Significant Unobservable Input [true false]	true	true
Investment, Non-income Producing [true false]	false	false
Investment, Identifier [Axis]: The Kyjen Company, L L C, Senior SEcured Loans, Two, Due 4/3/2026
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:TheKyjenCompanyLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Consumer Goods: Non-Durable
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Spread Above Index	7%
Interest rate paid in kind	11.42%
Acquisition Date	Sep. 13, 2022
Maturity	Apr. 03, 2026
% of Net Assets	0%
Investment, Restriction Status [true false]	true
Investment, Significant Unobservable Input [true false]	true
Investment, Non-income Producing [true false]	false
Investment, Identifier [Axis]: The Kyjen Company, L L C, Senior Secured Loans, due 4/3/2026
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:TheKyjenCompanyLLCMember	mrcc:TheKyjenCompanyLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Consumer Goods: Non-Durable	Consumer Goods: Non-Durable
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Spread Above Index	7.15%	6.50%
Interest Rate		7.50%
Interest rate paid in cash	11.15%
Interest rate paid in kind	0.50%
Acquisition Date	May 14, 2021	May 14, 2021
Maturity	Apr. 03, 2026	Apr. 03, 2026
Principal	$ 986	$ 993
Amortized Cost	979	983
Fair Value	$ 975	$ 997
% of Net Assets	0.50%	0.40%
Investment, Restriction Status [true false]	true	true
Investment, Significant Unobservable Input [true false]	true	true
Investment, Non-income Producing [true false]	false	false
Investment, Identifier [Axis]: Thrasio, L L C, Senior Secured Loans, due 12/18/2026
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:ThrasioLLCMember	mrcc:ThrasioLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Consumer Goods: Non-Durable	Consumer Goods: Non-Durable
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR	LIBOR
Spread Above Index	7%	7%
Interest Rate	11.73%	8%
Acquisition Date	Dec. 18, 2020	Dec. 18, 2020
Maturity	Dec. 18, 2026	Dec. 18, 2026
Principal	$ 2,445	$ 2,470
Amortized Cost	2,440	2,438
Fair Value	$ 2,445	$ 2,470
% of Net Assets	1.10%	1%
Investment, Restriction Status [true false]	true	true
Investment, Significant Unobservable Input [true false]	true	true
Investment, Non-income Producing [true false]	false	false
Investment, Identifier [Axis]: Tiger Connect, Inc. ( Delayed Draw), Senior Secured Loans, due 2/16/2028
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:TigerConnectIncMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Healthcare & Pharmaceuticals Sector [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Spread Above Index	7.25%
Interest rate paid in kind	3.63%
Acquisition Date	Feb. 16, 2022
Maturity	Feb. 16, 2028
Principal	$ 124
Amortized Cost	28
Fair Value	$ 27
% of Net Assets	0%
Investment, Identifier [Axis]: Tiger Connect, Inc. ( Revolver), Senior Secured Loans, due 2/16/2028
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:TigerConnectIncMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Healthcare & Pharmaceuticals Sector [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Spread Above Index	7.25%
Interest Rate	11.49%
Acquisition Date	Feb. 16, 2022
Maturity	Feb. 16, 2028
Principal	$ 429
% of Net Assets	0%
Investment, Identifier [Axis]: Tiger Connect, Inc., Senior Secured Loans, due 2/16/2028
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:TigerConnectIncMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Healthcare & Pharmaceuticals Sector [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Spread Above Index	7.25%
Interest rate paid in cash	7.86%
Interest rate paid in kind	3.63%
Acquisition Date	Feb. 16, 2022
Maturity	Feb. 16, 2028
Principal	$ 3,000
Amortized Cost	2,947
Fair Value	$ 2,963
% of Net Assets	1.30%
Investment, Identifier [Axis]: Toojay’s Management L L C ( Revolver), Senior Secured Loans, due 10/26/2022
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:ToojaysManagementLLCMember
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Beverage, Food & Tobacco
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Acquisition Date		Oct. 26, 2018
Maturity		Oct. 26, 2022
Principal		$ 66
Amortized Cost		$ 66
% of Net Assets		0%
Investment, Restriction Status [true false]		true
Investment, Significant Unobservable Input [true false]		true
Investment, Non-income Producing [true false]		false
Investment, Identifier [Axis]: Toojay’s Management L L C, Senior Secured Loans, One, due 10/26/2022
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:ToojaysManagementLLCMember
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Beverage, Food & Tobacco
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Acquisition Date		Oct. 26, 2018
Maturity		Oct. 26, 2022
Principal		$ 1,448
Amortized Cost		$ 1,407
% of Net Assets		0%
Investment, Restriction Status [true false]		true
Investment, Significant Unobservable Input [true false]		true
Investment, Non-income Producing [true false]		false
Investment, Identifier [Axis]: Toojay’s Management L L C, Senior Secured Loans, Two, due 10/26/2022
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:ToojaysManagementLLCMember
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Beverage, Food & Tobacco
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Acquisition Date		Oct. 26, 2018
Maturity		Oct. 26, 2022
Principal		$ 199
Amortized Cost		$ 199
% of Net Assets		0%
Investment, Restriction Status [true false]		true
Investment, Significant Unobservable Input [true false]		true
Investment, Non-income Producing [true false]		false
Investment, Identifier [Axis]: Trident Maritime Systems, Inc ( Revolver), Senior Secured Loans, due 2/26/2027
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:TridentMaritimeSystemsIncMember	mrcc:TridentMaritimeSystemsIncMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Aerospace & Defense	Aerospace & Defense
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR	LIBOR
Spread Above Index	4.75%	5.50%
Interest Rate	9.08%	6.50%
Maturity	Feb. 26, 2027	Feb. 26, 2027
Principal	$ 319	$ 265
Fair Value	$ 122
Investment, Identifier [Axis]: Trident Maritime Systems, Inc, Senior Secured Loans, One, due 2/26/2027
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:TridentMaritimeSystemsIncMember	mrcc:TridentMaritimeSystemsIncMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Aerospace & Defense	Aerospace & Defense
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR	LIBOR
Spread Above Index	4.75%	5.50%
Interest Rate	9.48%	6.50%
Maturity	Feb. 26, 2027	Feb. 26, 2027
Principal	$ 2,445	$ 2,467
Fair Value	$ 2,443	$ 2,478
Investment, Identifier [Axis]: Trident Maritime Systems, Inc, Senior Secured Loans, Two, due 2/26/2027
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:TridentMaritimeSystemsIncMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Aerospace & Defense
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR
Spread Above Index	4.75%
Interest Rate	9.48%
Maturity	Feb. 26, 2027
Principal	$ 746
Fair Value	$ 746
Investment, Identifier [Axis]: Truck- Lite Co., L L C, Senior Secured Loans, One, due 12/14/2026
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:Truck-LiteCo.LLCMember	mrcc:Truck-LiteCo.LLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Automotive	Automotive
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]	LIBOR
Spread Above Index	6.25%	6.25%
Interest Rate	11.14%	7.25%
Maturity	Dec. 14, 2026	Dec. 14, 2026
Principal	$ 1,691	$ 1,709
Fair Value	$ 1,690	$ 1,718
Investment, Identifier [Axis]: Truck- Lite Co., L L C, Senior Secured Loans, Two, due 12/14/2026
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:Truck-LiteCo.LLCMember	mrcc:Truck-LiteCo.LLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Automotive	Automotive
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]	LIBOR
Spread Above Index	6.25%	6.25%
Interest Rate	11.14%	7.25%
Maturity	Dec. 14, 2026	Dec. 14, 2026
Principal	$ 251	$ 253
Fair Value	$ 250	$ 255
Investment, Identifier [Axis]: Truck-Lite Co., LLC, Senior Secured Loans, Three, due 12/14/2026
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:Truck-LiteCo.LLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Automotive
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Spread Above Index	6.25%
Interest Rate	11.14%
Maturity	Dec. 14, 2026
Principal	$ 43
Fair Value	$ 43
Investment, Identifier [Axis]: V B E1, L L C ( Delayed Draw), Unitranche Secured Loans, due 11/18/2026
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:VBE1LLCMember
Investment, Type [Extensible Enumeration]		Unitranche Debt [Member]
Investment, Industry Sector [Extensible Enumeration]		Telecommunications
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Spread Above Index		7.65%
Interest Rate		8.15%
Acquisition Date		Nov. 18, 2020
Maturity		Nov. 18, 2026
Principal		$ 2,250
Amortized Cost		1,100
Fair Value		$ 1,118
% of Net Assets		0.40%
Investment, Restriction Status [true false]		true
Investment, Significant Unobservable Input [true false]		true
Investment, Non-income Producing [true false]		false
Investment, Identifier [Axis]: V B E1, L L C, Unitranche Secured Loans, due 11/18/2026
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:VBE1LLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Telecommunications
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR
Spread Above Index	7.65%
Interest Rate	12.38%
Acquisition Date	Nov. 18, 2020
Maturity	Nov. 18, 2026
Principal	$ 2,250
Amortized Cost	2,250
Fair Value	$ 2,257
% of Net Assets	1%
Investment, Restriction Status [true false]	true
Investment, Significant Unobservable Input [true false]	true
Investment, Non-income Producing [true false]	false
Investment, Identifier [Axis]: V H T Solutions ( Delayed Draw), Senior Secured Loans, due 12/21/2026
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:VHTAcquisitionsLLCMember
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Telecommunications
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Spread Above Index		7%
Interest rate paid in kind		8%
Acquisition Date		Dec. 21, 2021
Maturity		Dec. 21, 2026
Principal		$ 120
% of Net Assets		0%
Investment, Restriction Status [true false]		true
Investment, Significant Unobservable Input [true false]		true
Investment, Non-income Producing [true false]		false
Investment, Identifier [Axis]: V H T Solutions ( Revolver), Senior Secured Loans, due 12/21/2026
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:VHTAcquisitionsLLCMember
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Telecommunications
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Spread Above Index		7%
Interest rate paid in kind		8%
Acquisition Date		Dec. 21, 2021
Maturity		Dec. 21, 2026
Principal		$ 43
% of Net Assets		0%
Investment, Restriction Status [true false]		true
Investment, Significant Unobservable Input [true false]		true
Investment, Non-income Producing [true false]		false
Investment, Identifier [Axis]: V H T Solutions, Senior Secured Loans, due 12/21/2026
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:VHTAcquisitionsLLCMember
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Telecommunications
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Spread Above Index		7%
Interest rate paid in kind		8%
Acquisition Date		Dec. 21, 2021
Maturity		Dec. 21, 2026
Principal		$ 1,500
Amortized Cost		1,470
Fair Value		$ 1,470
% of Net Assets		0.60%
Investment, Restriction Status [true false]		true
Investment, Significant Unobservable Input [true false]		true
Investment, Non-income Producing [true false]		false
Investment, Identifier [Axis]: V P S Holdings, L L C ( Revolver), Senior Secured Loans, due 10/4/2024
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:VPSHoldingsLLCMember	mrcc:VPSHoldingsLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Services: Business	Services: Business
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR	LIBOR
Spread Above Index	9%	9%
Interest rate paid in cash	11.39%	8%
Interest rate paid in kind	2%	2%
Acquisition Date	Oct. 05, 2018	Oct. 05, 2018
Maturity	Oct. 04, 2024	Oct. 04, 2024
Principal	$ 1,002	$ 1,001
Amortized Cost	102	101
Fair Value	$ 102	$ 97
% of Net Assets	0%	0%
Investment, Restriction Status [true false]	true	true
Investment, Significant Unobservable Input [true false]	true	true
Investment, Non-income Producing [true false]	false	false
Investment, Identifier [Axis]: V P S Holdings, L L C, Senior Secured Loans, One, due 10/4/2024
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:VPSHoldingsLLCMember	mrcc:VPSHoldingsLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Services: Business	Services: Business
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR	LIBOR
Spread Above Index	9%	9%
Interest rate paid in cash	11.39%	8%
Interest rate paid in kind	2%	2%
Acquisition Date	Oct. 05, 2018	Oct. 05, 2018
Maturity	Oct. 04, 2024	Oct. 04, 2024
Principal	$ 3,246	$ 3,447
Amortized Cost	3,222	3,410
Fair Value	$ 3,252	$ 3,325
% of Net Assets	1.40%	1.30%
Investment, Restriction Status [true false]	true	true
Investment, Significant Unobservable Input [true false]	true	true
Investment, Non-income Producing [true false]	false	false
Investment, Identifier [Axis]: V P S Holdings, L L C, Senior Secured Loans, Two, due 10/4/2024
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:VPSHoldingsLLCMember	mrcc:VPSHoldingsLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Services: Business	Services: Business
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR	LIBOR
Spread Above Index	9%	9%
Interest rate paid in cash	11.39%	8%
Interest rate paid in kind	2%	2%
Acquisition Date	Oct. 05, 2018	Oct. 05, 2018
Maturity	Oct. 04, 2024	Oct. 04, 2024
Principal	$ 2,656	$ 2,817
Amortized Cost	2,656	2,817
Fair Value	$ 2,661	$ 2,717
% of Net Assets	1.20%	1.10%
Investment, Restriction Status [true false]	true	true
Investment, Significant Unobservable Input [true false]	true	true
Investment, Non-income Producing [true false]	false	false
Investment, Identifier [Axis]: Valudor Products L L C ( Revolver), Senior Secured Loans, due 6/19/2023
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:ValudorProductsLLCMember	mrcc:ValudorProductsLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Chemicals, Plastics & Rubber	Chemicals, Plastics & Rubber
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR	LIBOR
Spread Above Index	9.50%	9.50%
Interest Rate	13.89%	10.50%
Acquisition Date	Jun. 18, 2018	Jun. 18, 2018
Maturity	Jun. 19, 2023	Jun. 19, 2023
Principal	$ 1,095	$ 1,095
Amortized Cost	55	480
Fair Value	$ 55	$ 479
% of Net Assets	0%	0.20%
Investment, Restriction Status [true false]	true	true
Investment, Significant Unobservable Input [true false]	true	true
Investment, Non-income Producing [true false]	false	false
Investment, Identifier [Axis]: Valudor Products L L C , Equity Securities, Class A-1 units
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:ValudorProductsLLCMember	mrcc:ValudorProductsLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Equity Securities [Member]
Investment, Industry Sector [Extensible Enumeration]	Chemicals, Plastics & Rubber	Chemicals, Plastics & Rubber
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Interest Rate	10%
Interest rate paid in kind		10%
Acquisition Date	Jun. 18, 2018	Jun. 18, 2018
Amortized Cost	$ 501	$ 501
Fair Value	$ 555	$ 16
% of Net Assets	0.20%	0%
Number of shares held	501,014
Investment, Restriction Status [true false]	true	true
Investment, Significant Unobservable Input [true false]	true	true
Investment, Non-income Producing [true false]	false	false
Number of units held		501,014
Investment, Identifier [Axis]: Valudor Products L L C, Senior Secured Loans, One, due 6/19/2023,
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:ValudorProductsLLCMember	mrcc:ValudorProductsLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Chemicals, Plastics & Rubber	Chemicals, Plastics & Rubber
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR	LIBOR
Spread Above Index	7.50%	7.50%
Interest rate paid in cash	10.39%	7%
Interest rate paid in kind	1.50%	1.50%
Acquisition Date	Jun. 18, 2018	Jun. 18, 2018
Maturity	Jun. 19, 2023	Jun. 19, 2023
Principal	$ 1,609	$ 1,585
Amortized Cost	1,606	1,574
Fair Value	$ 1,958	$ 1,871
% of Net Assets	0.90%	0.70%
Investment, Restriction Status [true false]	true	true
Investment, Significant Unobservable Input [true false]	true	true
Investment, Non-income Producing [true false]	false	false
Investment, Identifier [Axis]: Valudor Products L L C, Senior Secured Loans, Three, due 6/19/2023
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:ValudorProductsLLCMember	mrcc:ValudorProductsLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Chemicals, Plastics & Rubber	Chemicals, Plastics & Rubber
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR	LIBOR
Spread Above Index	7.50%	7.50%
Interest Rate	11.89%
Interest rate paid in kind		8.50%
Acquisition Date	Dec. 22, 2021	Jun. 18, 2018
Maturity	Jun. 19, 2023	Jun. 19, 2023
Principal	$ 502	$ 237
Amortized Cost	502	234
Fair Value	$ 1,565	$ 230
% of Net Assets	0.70%	0.10%
Investment, Restriction Status [true false]	true	true
Investment, Significant Unobservable Input [true false]	true	true
Investment, Non-income Producing [true false]	false	false
Investment, Identifier [Axis]: Valudor Products L L C, Senior Secured Loans, Two, due 6/19/2023
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:ValudorProductsLLCMember	mrcc:ValudorProductsLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Chemicals, Plastics & Rubber	Chemicals, Plastics & Rubber
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR	LIBOR
Spread Above Index	7.50%	7.50%
Interest Rate		8.50%
Interest rate paid in kind	11.89%
Acquisition Date	Jun. 18, 2018	Dec. 22, 2021
Maturity	Jun. 19, 2023	Jun. 19, 2023
Principal	$ 260	$ 548
Amortized Cost	260	548
Fair Value	$ 312	$ 1,469
% of Net Assets	0.10%	0.60%
Investment, Restriction Status [true false]	true	true
Investment, Significant Unobservable Input [true false]	true	true
Investment, Non-income Producing [true false]	false	false
Investment, Identifier [Axis]: Vice Group Holding Inc., Senior Secured Loans, Four, due 5/12/2023
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:ViceGroupHoldingIncMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Media: Broadcasting & Subscription
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR
Spread Above Index	12%
Interest rate paid in cash	4.25%
Interest rate paid in kind	12%
Acquisition Date	May 02, 2019
Maturity	May 12, 2023
Principal	$ 200
Amortized Cost	200
Fair Value	$ 196
% of Net Assets	0.10%
Investment, Restriction Status [true false]	true
Investment, Significant Unobservable Input [true false]	true
Investment, Non-income Producing [true false]	false
Investment, Identifier [Axis]: Vice Group Holding Inc., Senior Secured Loans, Four, due, 11/2/2022
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:ViceGroupHoldingIncMember
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Media: Broadcasting & Subscription
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]		us-gaap:LondonInterbankOfferedRateLiborSwapRateMember
Spread Above Index		12%
Interest rate paid in cash		5.50%
Interest rate paid in kind		8%
Acquisition Date		May 02, 2019
Maturity		Nov. 02, 2022
Principal		$ 180
Amortized Cost		180
Fair Value		$ 180
% of Net Assets		0.10%
Investment, Restriction Status [true false]		true
Investment, Significant Unobservable Input [true false]		true
Investment, Non-income Producing [true false]		false
Investment, Identifier [Axis]: Vice Group Holding Inc., Senior Secured Loans, One, due 11/2/2022
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:ViceGroupHoldingIncMember
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Media: Broadcasting & Subscription
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]		us-gaap:LondonInterbankOfferedRateLiborSwapRateMember
Spread Above Index		12%
Interest rate paid in cash		5.50%
Interest rate paid in kind		8%
Acquisition Date		May 02, 2019
Maturity		Nov. 02, 2022
Principal		$ 1,526
Amortized Cost		1,523
Fair Value		$ 1,526
% of Net Assets		0.60%
Investment, Restriction Status [true false]		true
Investment, Significant Unobservable Input [true false]		true
Investment, Non-income Producing [true false]		false
Investment, Identifier [Axis]: Vice Group Holding Inc., Senior Secured Loans, One, due 5/12/2023
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:ViceGroupHoldingIncMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Media: Broadcasting & Subscription
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR
Spread Above Index	12%
Interest rate paid in cash	4.51%
Interest rate paid in kind	12%
Acquisition Date	May 02, 2019
Maturity	May 12, 2023
Principal	$ 1,691
Amortized Cost	1,691
Fair Value	$ 1,657
% of Net Assets	0.70%
Investment, Restriction Status [true false]	true
Investment, Significant Unobservable Input [true false]	true
Investment, Non-income Producing [true false]	false
Investment, Identifier [Axis]: Vice Group Holding Inc., Senior Secured Loans, Three, due 11/2/2022
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:ViceGroupHoldingIncMember
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Media: Broadcasting & Subscription
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]		us-gaap:LondonInterbankOfferedRateLiborSwapRateMember
Spread Above Index		12%
Interest rate paid in cash		5.50%
Interest rate paid in kind		8%
Acquisition Date		May 02, 2019
Maturity		Nov. 02, 2022
Principal		$ 478
Amortized Cost		478
Fair Value		$ 478
% of Net Assets		0.20%
Investment, Restriction Status [true false]		true
Investment, Significant Unobservable Input [true false]		true
Investment, Non-income Producing [true false]		false
Investment, Identifier [Axis]: Vice Group Holding Inc., Senior Secured Loans, Three, due 5/12/2023
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:ViceGroupHoldingIncMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Media: Broadcasting & Subscription
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR
Spread Above Index	12%
Interest rate paid in cash	4.42%
Interest rate paid in kind	12%
Acquisition Date	May 02, 2019
Maturity	May 12, 2023
Principal	$ 531
Amortized Cost	531
Fair Value	$ 520
% of Net Assets	0.20%
Investment, Restriction Status [true false]	true
Investment, Significant Unobservable Input [true false]	true
Investment, Non-income Producing [true false]	false
Investment, Identifier [Axis]: Vice Group Holding Inc., Senior Secured Loans, Two, due 11/2/2022
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:ViceGroupHoldingIncMember
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Media: Broadcasting & Subscription
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]		us-gaap:LondonInterbankOfferedRateLiborSwapRateMember
Spread Above Index		12%
Interest rate paid in cash		5.50%
Interest rate paid in kind		8%
Acquisition Date		Nov. 04, 2019
Maturity		Nov. 02, 2022
Principal		$ 293
Amortized Cost		291
Fair Value		$ 293
% of Net Assets		0.10%
Investment, Restriction Status [true false]		true
Investment, Significant Unobservable Input [true false]		true
Investment, Non-income Producing [true false]		false
Investment, Identifier [Axis]: Vice Group Holding Inc., Senior Secured Loans, Two, due 5/12/2023
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:ViceGroupHoldingIncMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Media: Broadcasting & Subscription
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR
Spread Above Index	12%
Interest rate paid in cash	4.51%
Interest rate paid in kind	12%
Acquisition Date	Nov. 04, 2019
Maturity	May 12, 2023
Principal	$ 325
Amortized Cost	325
Fair Value	$ 318
% of Net Assets	0.20%
Investment, Restriction Status [true false]	true
Investment, Significant Unobservable Input [true false]	true
Investment, Non-income Producing [true false]	false
Investment, Identifier [Axis]: Vinci Brands L L C (fka Incipio, L L C) ( Junior secured loan), One
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	Vinci Brands L L C (fka Incipio, L L C) [ Member]	Vinci Brands L L C (fka Incipio, L L C) [ Member]
Investment, Identifier [Axis]: Vinci Brands L L C (fka Incipio, L L C) ( Junior secured loan), Two
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	Vinci Brands L L C (fka Incipio, L L C) [ Member]	Vinci Brands L L C (fka Incipio, L L C) [ Member]
Investment, Identifier [Axis]: Vinci Brands L L C (fka Incipio, L L C), (Delayed Draw)
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	Vinci Brands L L C (fka Incipio, L L C) [ Member]
Investment, Identifier [Axis]: Vinci Brands L L C (fka Incipio, L L C), Equity Securities, Series C common units)
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	Vinci Brands L L C (fka Incipio, L L C) [ Member]	Vinci Brands L L C (fka Incipio, L L C) [ Member]
Number of shares held		1,774
Investment, Identifier [Axis]: Vinci Brands L L C (fka Incipio, L L C), Loan Five
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	Vinci Brands L L C (fka Incipio, L L C) [ Member]	Vinci Brands L L C (fka Incipio, L L C) [ Member]
Fair Value			1,519
Investment, Identifier [Axis]: Vinci Brands L L C (fka Incipio, L L C), Loan Four
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	Vinci Brands L L C (fka Incipio, L L C) [ Member]	Vinci Brands L L C (fka Incipio, L L C) [ Member]
Fair Value			761
Investment, Identifier [Axis]: Vinci Brands L L C (fka Incipio, L L C), Loan One
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	Vinci Brands L L C (fka Incipio, L L C) [ Member]	Vinci Brands L L C (fka Incipio, L L C) [ Member]
Fair Value			1,764
Investment, Identifier [Axis]: Vinci Brands L L C (fka Incipio, L L C), Loan Six
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		Vinci Brands L L C (fka Incipio, L L C) [ Member]
Fair Value			1,488
Investment, Identifier [Axis]: Vinci Brands L L C (fka Incipio, L L C), Loan Three
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	Vinci Brands L L C (fka Incipio, L L C) [ Member]	Vinci Brands L L C (fka Incipio, L L C) [ Member]
Fair Value			1,805
Investment, Identifier [Axis]: Vinci Brands L L C (fka Incipio, L L C), Loan Two
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	Vinci Brands L L C (fka Incipio, L L C) [ Member]	Vinci Brands L L C (fka Incipio, L L C) [ Member]
Fair Value			4,227
Investment, Identifier [Axis]: Vinci Brands L L C, Unitranche Secured Loans, Four, due 2/6/2024
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:VinciBrandsLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Unitranche Debt [Member]
Investment, Industry Sector [Extensible Enumeration]	Consumer Goods: Non-Durable	Consumer Goods: Non-Durable
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Interest rate paid in kind	2%	2%
Acquisition Date	Dec. 26, 2014	Dec. 26, 2014
Maturity	Feb. 06, 2024	Feb. 06, 2024
Principal	$ 1,149	$ 1,149
Amortized Cost	$ 1,149	$ 1,149
% of Net Assets	0%	0%
Investment, Restriction Status [true false]	true	true
Investment, Significant Unobservable Input [true false]	true	true
Investment, Non-income Producing [true false]	false	false
Investment, Identifier [Axis]: Vinci Brands L L C, Unitranche Secured Loans, One, due 2/6/2024
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:VinciBrandsLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Unitranche Debt [Member]
Investment, Industry Sector [Extensible Enumeration]	Consumer Goods: Non-Durable	Consumer Goods: Non-Durable
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Interest rate paid in kind	2%	2%
Acquisition Date	Jul. 06, 2018	Jul. 06, 2018
Maturity	Feb. 06, 2024	Feb. 06, 2024
Principal	$ 7,026	$ 7,026
Amortized Cost	$ 7,026	7,026
Fair Value		$ 4,950
% of Net Assets	0%	2%
Investment, Restriction Status [true false]	true	true
Investment, Significant Unobservable Input [true false]	false	true
Investment, Non-income Producing [true false]	false	false
Investment, Identifier [Axis]: Vinci Brands L L C, Unitranche Secured Loans, Three, due 2/6/2024
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:VinciBrandsLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Unitranche Debt [Member]
Investment, Industry Sector [Extensible Enumeration]	Consumer Goods: Non-Durable	Consumer Goods: Non-Durable
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Interest rate paid in kind	2%	2%
Acquisition Date	Dec. 26, 2014	Dec. 26, 2014
Maturity	Feb. 06, 2024	Feb. 06, 2024
Principal	$ 13,552	$ 13,552
Amortized Cost	$ 13,528	$ 13,528
% of Net Assets	0%	0%
Investment, Restriction Status [true false]	true	true
Investment, Significant Unobservable Input [true false]	true	true
Investment, Non-income Producing [true false]	false	false
Investment, Identifier [Axis]: Vinci Brands L L C, Unitranche Secured Loans, Two, due 2/6/2024
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:VinciBrandsLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Unitranche Debt [Member]
Investment, Industry Sector [Extensible Enumeration]	Consumer Goods: Non-Durable	Consumer Goods: Non-Durable
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Interest rate paid in kind	2%	2%
Acquisition Date	Mar. 09, 2018	Mar. 09, 2018
Maturity	Feb. 06, 2024	Feb. 06, 2024
Principal	$ 3,065	$ 3,065
Amortized Cost	$ 3,065	$ 3,065
% of Net Assets	0%	0%
Investment, Restriction Status [true false]	true	true
Investment, Significant Unobservable Input [true false]	true	true
Investment, Non-income Producing [true false]	false	false
Investment, Identifier [Axis]: W3 Monroe R E Debt L L C, Senior Secured Loans, due 2/4/2028
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:W3MonroeREDebtLLCMember	mrcc:W3MonroeREDebtLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	mrcc:FireFinanceMember	mrcc:FireFinanceMember
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Interest rate paid in kind	10%	10%
Acquisition Date	Feb. 05, 2021	Feb. 05, 2021
Maturity	Feb. 04, 2028	Feb. 04, 2028
Principal	$ 3,210	$ 2,906
Amortized Cost	3,210	2,906
Fair Value	$ 3,210	$ 2,906
% of Net Assets	1.40%	1.20%
Investment, Restriction Status [true false]	true	true
Investment, Significant Unobservable Input [true false]	true	true
Investment, Non-income Producing [true false]	false	false
Investment, Identifier [Axis]: Wheel Pros, Inc., Senior Secured Loans, due 5/11/2028
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:WheelProsIncMember	mrcc:WheelProsIncMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Automotive	Automotive
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR	LIBOR
Spread Above Index	4.50%	4.50%
Interest Rate	8.82%	5.25%
Maturity	May 11, 2028	May 11, 2028
Principal	$ 1,932	$ 1,952
Fair Value	$ 1,321	$ 1,951
Investment, Identifier [Axis]: Whistler Parent Holdings I I I, Inc. ( Delayed Draw), Senior Secured Loans, due 6/2/2028
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:WhistlerParentHoldingsIIIIncMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Healthcare & Pharmaceuticals Sector [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Spread Above Index	6.75%
Interest Rate	11.17%
Acquisition Date	Jun. 03, 2022
Maturity	Jun. 02, 2028
Principal	$ 1,406
Amortized Cost	56
Fair Value	$ 56
% of Net Assets	0%
Investment, Identifier [Axis]: Whistler Parent Holdings I I I, Inc. ( Revolver), Senior Secured Loans, due 6/2/2028
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:WhistlerParentHoldingsIIIIncMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Healthcare & Pharmaceuticals Sector [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Spread Above Index	6.75%
Interest Rate	11.17%
Acquisition Date	Jun. 03, 2022
Maturity	Jun. 02, 2028
Principal	$ 563
Amortized Cost	84
Fair Value	$ 84
% of Net Assets	0%
Investment, Identifier [Axis]: Whistler Parent Holdings I I I, Inc., Senior Secured Loans, due 6/2/2028
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:WhistlerParentHoldingsIIIIncMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Healthcare & Pharmaceuticals Sector [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Spread Above Index	6.75%
Interest Rate	11.17%
Acquisition Date	Jun. 03, 2022
Maturity	Jun. 02, 2028
Principal	$ 4,500
Amortized Cost	4,415
Fair Value	$ 4,457
% of Net Assets	2%
Investment, Identifier [Axis]: WillowTree, LLC, Unitranche Secured Loans, due 10/9/2023
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:WillowTreeLLCMember	mrcc:WillowTreeLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Unitranche Debt [Member]
Investment, Industry Sector [Extensible Enumeration]	High Tech Industries Sector [Member]	High Tech Industries Sector [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR	LIBOR
Spread Above Index	5%	5%
Interest Rate	9.39%	6%
Acquisition Date	Oct. 09, 2018	Oct. 09, 2018
Maturity	Oct. 09, 2023	Oct. 09, 2023
Principal	$ 7,326	$ 7,639
Amortized Cost		7,584
Fair Value	$ 7,326	$ 7,651
% of Net Assets	3.30%	3.10%
Investment, Restriction Status [true false]	true	true
Investment, Significant Unobservable Input [true false]	true	true
Investment, Non-income Producing [true false]	false	false
Investment, Identifier [Axis]: Witkoff/ Monroe 700 J V L L C ( Delayed Draw), Junior Secured Loans, due 7/2/2026
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:WitkoffMonroe700JVLLCMember
Investment, Type [Extensible Enumeration]	Junior Loans [Member]	Junior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	FIRE: Real Estate	FIRE: Real Estate
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Interest Rate	4%
Interest rate paid in cash	10.23%	8%
Interest rate paid in kind		4%
Acquisition Date	Jul. 02, 2021	Jul. 02, 2021
Maturity	Jul. 02, 2026	Jul. 02, 2026
Principal	$ 6,708	$ 5,576
Amortized Cost	6,014	4,665
Fair Value	$ 6,014	$ 4,886
% of Net Assets	2.70%	2%
Investment, Restriction Status [true false]	true	true
Investment, Significant Unobservable Input [true false]	true	true
Investment, Non-income Producing [true false]	false	false
Investment, Identifier [Axis]: Witkoff/ Monroe 700 J V L L C, Equity Securities, Preferred units
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:WitkoffMonroe700JVLLCMember	mrcc:WitkoffMonroe700JVLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Equity Securities [Member]
Investment, Industry Sector [Extensible Enumeration]	FIRE: Real Estate	FIRE: Real Estate
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Interest rate paid in cash	8%	8%
Interest rate paid in kind	4%	4%
Acquisition Date	Jul. 02, 2021	Jul. 02, 2021
Amortized Cost	$ 2	$ 2
Fair Value	$ 1,047	$ 2
% of Net Assets	0.50%	0%
Investment, Restriction Status [true false]	true	true
Investment, Significant Unobservable Input [true false]	true	true
Investment, Non-income Producing [true false]	false	false
Number of units held	2,141	2,141
Investment, Identifier [Axis]: Xan Edu Publishing, Inc, Equity Securities, Class A units
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:XanEduPublishingIncMember	mrcc:XanEduPublishingIncMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Equity Securities [Member]
Investment, Industry Sector [Extensible Enumeration]	Media: Advertising, Printing & Publishing	Media: Advertising, Printing & Publishing
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Interest rate paid in kind	8%	8%
Acquisition Date	Jan. 28, 2020	Jan. 28, 2020
Amortized Cost	$ 49	$ 49
Fair Value	$ 223	$ 106
% of Net Assets	0.10%	0%
Investment, Restriction Status [true false]	true	true
Investment, Significant Unobservable Input [true false]	true	true
Investment, Non-income Producing [true false]	false	false
Number of units held	49,479	49,479
Investment, Identifier [Axis]: Xan Edu Publishing, Inc. ( Revolver), Senior Secured Loans, due, 1/28/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:XanEduPublishingIncMember	mrcc:XanEduPublishingIncMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Media: Advertising, Printing & Publishing	Media: Advertising, Printing & Publishing
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]	us-gaap:LondonInterbankOfferedRateLiborSwapRateMember
Spread Above Index	6.50%	6.50%
Interest Rate	10.94%	7.50%
Acquisition Date	Jan. 28, 2020	Jan. 28, 2020
Maturity	Jan. 28, 2025	Jan. 28, 2025
Principal	$ 742	$ 742
% of Net Assets	0%	0%
Investment, Restriction Status [true false]	true	true
Investment, Significant Unobservable Input [true false]	true	true
Investment, Non-income Producing [true false]	false	false
Investment, Identifier [Axis]: Xan Edu Publishing, Inc., Senior Secured Loans, One, due, 1/28/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:XanEduPublishingIncMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Media: Advertising, Printing & Publishing
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Spread Above Index	6.50%
Interest Rate	10.94%
Acquisition Date	Jan. 28, 2020
Maturity	Jan. 28, 2025
Principal	$ 4,584
Amortized Cost	4,531
Fair Value	$ 4,602
% of Net Assets	2.10%
Investment, Restriction Status [true false]	true
Investment, Significant Unobservable Input [true false]	true
Investment, Non-income Producing [true false]	false
Investment, Identifier [Axis]: Xan Edu Publishing, Inc., Senior Secured Loans, Two, due, 1/28/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:XanEduPublishingIncMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Media: Advertising, Printing & Publishing
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Spread Above Index	6.50%
Interest Rate	10.94%
Acquisition Date	Aug. 31, 2022
Maturity	Jan. 28, 2025
Principal	$ 1,822
Amortized Cost	1,782
Fair Value	$ 1,829
% of Net Assets	0.80%
Investment, Restriction Status [true false]	true
Investment, Significant Unobservable Input [true false]	true
Investment, Non-income Producing [true false]	false
Investment, Identifier [Axis]: Xan Edu Publishing, Inc., Senior Secured Loans, due, 1/28/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:XanEduPublishingIncMember
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Media: Advertising, Printing & Publishing
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]		us-gaap:LondonInterbankOfferedRateLiborSwapRateMember
Spread Above Index		6.50%
Interest Rate		7.50%
Acquisition Date		Jan. 28, 2020
Maturity		Jan. 28, 2025
Principal		$ 4,631
Amortized Cost		4,555
Fair Value		$ 4,647
% of Net Assets		1.80%
Investment, Restriction Status [true false]		true
Investment, Significant Unobservable Input [true false]		true
Investment, Non-income Producing [true false]		false
Investment, Identifier [Axis]: Y S W H 4, L L C (Revolver), Senior Secured Loans, Due 11/20/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:YSWH4LLCRevolverMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	mrcc:FireFinanceMember
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Spread Above Index	7%
Interest Rate	11.44%
Acquisition Date	Jul. 20, 2022
Maturity	Nov. 20, 2025
Principal	$ 5,250
Amortized Cost	1,776
Fair Value	$ 1,776
% of Net Assets	0.80%
Investment, Restriction Status [true false]	true
Investment, Significant Unobservable Input [true false]	true
Investment, Non-income Producing [true false]	false
Investment, Identifier [Axis]: iCIMS, Inc, Due 8/18/2028
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:IcimsIncMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Services: Business
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Spread Above Index	7.25%
Interest Rate	11.52%
Acquisition Date	Oct. 24, 2022
Maturity	Aug. 18, 2028
Principal	$ 2,500
Amortized Cost	2,457
Fair Value	$ 2,456
% of Net Assets	1.10%
Investment, Restriction Status [true false]	true
Investment, Significant Unobservable Input [true false]	true
Investment, Non-income Producing [true false]	false
T J Management Hold Co L L C [ Member]
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Fair Value	$ 2,846	$ 3,148	3,323
American Community Homes, Inc. [ Member]
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Fair Value	$ 19,546	$ 23,748	24,271
Number of shares held	4,940
Percentage of interests	22.30%
Second Avenue S F R Holdings I I L L C [ Member]
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Fair Value		$ 11,854
Ascent Midco, L L C [ Member]
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Fair Value	$ 8,186	$ 8,946	10,013
Mnine Holdings, Inc [ Member]
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Fair Value	$ 5,706	$ 5,771	12,356
Curion Holdings, L L C [ Member]
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Fair Value	$ 146	$ 5,111	3,979
N E C B Collections, L L C [ Member]
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Fair Value	$ 382	$ 632	834
S F R Holdco, L L C [ Member]
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Fair Value	$ 9,750	$ 9,750
Familia Dental Group Holdings, LLC
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Fair Value	$ 2,625	$ 1,919	3,118
MRCC Senior Loan Fund I, LLC
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Controlled affiliate company investments	Controlled affiliate company investments
Fair Value	$ 35,509	$ 41,125	39,284
Non-US [Member]
Schedule of Investments [Line Items]
Amortized Cost	11,860	11,860
Fair Value	10,405	11,093
Automotive
Schedule of Investments [Line Items]
Amortized Cost	16,775	21,162
Fair Value	16,637	21,556
Banking
Schedule of Investments [Line Items]
Amortized Cost	17,790	5,416
Fair Value	19,817	6,712
Beverage, Food & Tobacco
Schedule of Investments [Line Items]
Amortized Cost	15,625	21,036
Fair Value	12,470	19,133
Capital Equipment
Schedule of Investments [Line Items]
Amortized Cost	18,615	12,656
Fair Value	19,012	12,839
Chemicals, Plastics & Rubber
Schedule of Investments [Line Items]
Amortized Cost	2,924	9,426
Fair Value	4,445	10,163
Construction & Building
Schedule of Investments [Line Items]
Amortized Cost	6,642	16,450
Fair Value	6,706	16,636
Environmental Industries
Schedule of Investments [Line Items]
Amortized Cost	6,164	17,103
Fair Value	$ 6,558	17,693
FIRE: Real Estate
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	FIRE Real Estate Sector [Member]
Principal	$ 7,857
Amortized Cost	6,853
Fair Value	$ 6,926
% of Net Assets	3.10%
Healthcare & Pharmaceuticals
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Healthcare & Pharmaceuticals Sector [Member]
Principal	$ 61,092
Amortized Cost	45,636
Fair Value	$ 46,159
% of Net Assets	20.50%
Hotels, Gaming & Leisure
Schedule of Investments [Line Items]
Amortized Cost	$ 2,702	2,662
Fair Value	2,720	2,706
Media: Advertising, Printing & Publishing
Schedule of Investments [Line Items]
Amortized Cost	17,470	13,421
Fair Value	19,777	16,794
Media: Broadcasting & Subscription
Schedule of Investments [Line Items]
Amortized Cost	2,747	2,472
Fair Value	2,691	2,477
Media: Diversified & Production
Schedule of Investments [Line Items]
Amortized Cost	36,018	23,853
Fair Value	36,164	24,220
Retail
Schedule of Investments [Line Items]
Amortized Cost	9,247	10,954
Fair Value	9,306	11,478
Telecommunications
Schedule of Investments [Line Items]
Amortized Cost	7,502	5,892
Fair Value	7,595	5,988
Wholesale
Schedule of Investments [Line Items]
Amortized Cost	16,044	15,810
Fair Value	14,165	15,576
Aerospace & Defense
Schedule of Investments [Line Items]
Amortized Cost	7,461	7,828
Fair Value	7,436	7,972
Senior Loans [Member]
Schedule of Investments [Line Items]
Amortized Cost	436,066	415,600
Fair Value	434,023	423,700
Unitranche Debt [Member]
Schedule of Investments [Line Items]
Amortized Cost	45,352	70,977
Fair Value	20,633	51,494
Unitranche Debt [Member] | Aerospace & Defense
Schedule of Investments [Line Items]
Principal	7,580
Amortized Cost	7,461
Fair Value	$ 7,436
% of Net Assets	3.30%
Junior Loans [Member]
Schedule of Investments [Line Items]
Amortized Cost	$ 21,141	14,317
Fair Value	22,193	14,364
Equity Securities [Member]
Schedule of Investments [Line Items]
Amortized Cost	34,098	33,134
Fair Value	28,682	31,010
Equity Securities [Member] | Healthcare & Pharmaceuticals
Schedule of Investments [Line Items]
Amortized Cost	6,062
Fair Value	$ 4,594
% of Net Assets	2.10%
Equity Securities [Member] | Services: Business
Schedule of Investments [Line Items]
% of Net Assets	0%
Non-controlled/non-affiliate company investments
Schedule of Investments [Line Items]
Amortized Cost	$ 446,964	446,051
Fair Value	$ 418,913	$ 430,287
% of Net Assets	186.10%	172.50%
Investment, Restriction Status [true false]		true
Investment, Significant Unobservable Input [true false]		true
Investment, Non-income Producing [true false]	false
Non-controlled/non-affiliate company investments | Senior Loans [Member]
Schedule of Investments [Line Items]
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Principal	$ 425,065	$ 398,010
Amortized Cost	366,067	347,073
Fair Value	$ 365,806	$ 351,698
% of Net Assets	162.60%	141.10%
Investment, Restriction Status [true false]		true
Investment, Significant Unobservable Input [true false]		true
Investment, Non-income Producing [true false]		false
Non-controlled/non-affiliate company investments | Senior Loans [Member] | Automotive
Schedule of Investments [Line Items]
Principal	$ 20,441	$ 24,730
Amortized Cost	16,395	20,782
Fair Value	$ 16,326	$ 21,154
% of Net Assets	7.30%	8.50%
Investment, Restriction Status [true false]		true
Investment, Significant Unobservable Input [true false]		true
Investment, Non-income Producing [true false]		false
Non-controlled/non-affiliate company investments | Senior Loans [Member] | Banking
Schedule of Investments [Line Items]
Principal	$ 10,773	$ 10,658
Amortized Cost	10,134	3,265
Fair Value	$ 10,345	$ 3,625
% of Net Assets	4.60%	1.40%
Investment, Restriction Status [true false]		true
Investment, Significant Unobservable Input [true false]		true
Investment, Non-income Producing [true false]		false
Non-controlled/non-affiliate company investments | Senior Loans [Member] | Beverage, Food & Tobacco
Schedule of Investments [Line Items]
Principal	$ 9,782	$ 15,431
Amortized Cost	8,446	13,937
Fair Value	$ 8,358	$ 12,286
% of Net Assets	3.70%	4.90%
Investment, Restriction Status [true false]		true
Investment, Significant Unobservable Input [true false]		true
Investment, Non-income Producing [true false]		false
Non-controlled/non-affiliate company investments | Senior Loans [Member] | Capital Equipment
Schedule of Investments [Line Items]
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Principal	$ 20,572	$ 15,502
Amortized Cost	18,496	12,537
Fair Value	$ 18,808	$ 12,691
% of Net Assets	8.40%	5.10%
Investment, Restriction Status [true false]		true
Investment, Significant Unobservable Input [true false]		true
Investment, Non-income Producing [true false]		false
Non-controlled/non-affiliate company investments | Senior Loans [Member] | Chemicals, Plastics & Rubber
Schedule of Investments [Line Items]
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Principal	$ 3,466	$ 3,465
Amortized Cost	2,423	2,836
Fair Value	$ 3,890	$ 4,049
% of Net Assets	1.70%	1.60%
Investment, Restriction Status [true false]		true
Investment, Significant Unobservable Input [true false]		true
Investment, Non-income Producing [true false]		false
Non-controlled/non-affiliate company investments | Senior Loans [Member] | Construction & Building
Schedule of Investments [Line Items]
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Principal	$ 6,698	$ 17,970
Amortized Cost	6,642	16,450
Fair Value	$ 6,706	$ 16,636
% of Net Assets	3%	6.70%
Investment, Restriction Status [true false]		true
Investment, Significant Unobservable Input [true false]		true
Investment, Non-income Producing [true false]		false
Non-controlled/non-affiliate company investments | Senior Loans [Member] | Consumer Goods: Durable
Schedule of Investments [Line Items]
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Principal	$ 11,292	$ 11,387
Amortized Cost	9,252	9,455
Fair Value	$ 9,236	$ 9,633
% of Net Assets	4.10%	3.90%
Investment, Restriction Status [true false]		true
Investment, Significant Unobservable Input [true false]		true
Investment, Non-income Producing [true false]		false
Non-controlled/non-affiliate company investments | Senior Loans [Member] | Consumer Goods: Non-Durable
Schedule of Investments [Line Items]
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Principal	$ 3,536	$ 3,568
Amortized Cost	3,508	3,464
Fair Value	$ 3,508	$ 3,510
% of Net Assets	1.60%	1.40%
Investment, Restriction Status [true false]		true
Investment, Significant Unobservable Input [true false]		true
Investment, Non-income Producing [true false]		false
Non-controlled/non-affiliate company investments | Senior Loans [Member] | Environmental Industries
Schedule of Investments [Line Items]
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Principal	$ 7,608	$ 20,124
Amortized Cost	6,097	17,036
Fair Value	$ 6,201	$ 17,238
% of Net Assets	2.80%	6.90%
Investment, Restriction Status [true false]		true
Investment, Significant Unobservable Input [true false]		true
Investment, Non-income Producing [true false]		false
Non-controlled/non-affiliate company investments | Senior Loans [Member] | FIRE: Finance
Schedule of Investments [Line Items]
Principal	$ 29,660	$ 17,453
Amortized Cost	24,944	16,187
Fair Value	$ 23,495	$ 15,389
% of Net Assets	10.40%	6.20%
Investment, Restriction Status [true false]		true
Investment, Significant Unobservable Input [true false]		true
Investment, Non-income Producing [true false]		false
Non-controlled/non-affiliate company investments | Senior Loans [Member] | FIRE: Real Estate
Schedule of Investments [Line Items]
Principal		$ 5,522
Amortized Cost		5,417
Fair Value		$ 5,526
% of Net Assets		2.20%
Investment, Restriction Status [true false]		true
Investment, Significant Unobservable Input [true false]		true
Investment, Non-income Producing [true false]		false
Non-controlled/non-affiliate company investments | Senior Loans [Member] | Healthcare & Pharmaceuticals
Schedule of Investments [Line Items]
Principal		$ 32,977
Amortized Cost		26,305
Fair Value		$ 27,724
% of Net Assets		11.10%
Investment, Restriction Status [true false]		true
Investment, Significant Unobservable Input [true false]		true
Non-controlled/non-affiliate company investments | Senior Loans [Member] | High Tech Industries
Schedule of Investments [Line Items]
Principal	$ 42,877	$ 32,968
Amortized Cost	38,709	29,892
Fair Value	$ 38,519	$ 30,154
% of Net Assets	17.10%	12.10%
Investment, Restriction Status [true false]	true	true
Investment, Significant Unobservable Input [true false]		true
Investment, Non-income Producing [true false]		false
Non-controlled/non-affiliate company investments | Senior Loans [Member] | Hotels, Gaming & Leisure
Schedule of Investments [Line Items]
Principal	$ 3,097	$ 3,123
Amortized Cost	2,591	2,563
Fair Value	$ 2,611	$ 2,604
% of Net Assets	1.10%	1.10%
Investment, Restriction Status [true false]		true
Investment, Significant Unobservable Input [true false]		true
Investment, Non-income Producing [true false]		false
Non-controlled/non-affiliate company investments | Senior Loans [Member] | Media: Advertising, Printing & Publishing
Schedule of Investments [Line Items]
Principal	$ 20,507
Amortized Cost	17,186
Fair Value	$ 17,345
% of Net Assets	7.70%
Non-controlled/non-affiliate company investments | Senior Loans [Member] | Media: Broadcasting & Subscription
Schedule of Investments [Line Items]
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Principal	$ 2,747	$ 2,477
Amortized Cost	2,747	2,472
Fair Value	$ 2,691	$ 2,477
% of Net Assets	1.20%	1%
Investment, Restriction Status [true false]		true
Investment, Significant Unobservable Input [true false]		true
Investment, Non-income Producing [true false]		false
Non-controlled/non-affiliate company investments | Senior Loans [Member] | Media: Diversified & Production
Schedule of Investments [Line Items]
Principal	$ 43,230	$ 26,929
Amortized Cost	35,634	23,469
Fair Value	$ 35,592	$ 23,687
% of Net Assets	15.80%	9.50%
Investment, Restriction Status [true false]		true
Investment, Significant Unobservable Input [true false]		true
Investment, Non-income Producing [true false]		false
Non-controlled/non-affiliate company investments | Senior Loans [Member] | Retail
Schedule of Investments [Line Items]
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Principal	$ 8,772	$ 10,388
Amortized Cost	8,535	10,242
Fair Value	$ 8,522	$ 10,278
% of Net Assets	3.80%	4.10%
Investment, Restriction Status [true false]		true
Investment, Non-income Producing [true false]		false
Non-controlled/non-affiliate company investments | Senior Loans [Member] | Services: Business
Schedule of Investments [Line Items]
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Principal	$ 58,660	$ 67,071
Amortized Cost	52,282	62,399
Fair Value	$ 52,627	$ 64,220
% of Net Assets	23.40%	25.80%
Investment, Restriction Status [true false]		true
Investment, Significant Unobservable Input [true false]		true
Investment, Non-income Producing [true false]		false
Non-controlled/non-affiliate company investments | Senior Loans [Member] | Services: Consumer
Schedule of Investments [Line Items]
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Principal	$ 30,570	$ 38,763
Amortized Cost	28,517	34,818
Fair Value	$ 28,507	$ 35,123
% of Net Assets	12.70%	14.10%
Investment, Restriction Status [true false]		true
Investment, Significant Unobservable Input [true false]		true
Investment, Non-income Producing [true false]		false
Non-controlled/non-affiliate company investments | Senior Loans [Member] | Telecommunications
Schedule of Investments [Line Items]
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Principal	$ 5,998	$ 5,472
Amortized Cost	5,210	4,792
Fair Value	$ 5,269	$ 4,870
% of Net Assets	2.30%	2%
Investment, Restriction Status [true false]		true
Investment, Significant Unobservable Input [true false]		true
Non-controlled/non-affiliate company investments | Senior Loans [Member] | Wholesale
Schedule of Investments [Line Items]
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Principal	$ 15,830	$ 15,695
Amortized Cost	15,830	15,618
Fair Value	$ 14,165	$ 15,502
% of Net Assets	6.30%	6.20%
Investment, Restriction Status [true false]		true
Investment, Significant Unobservable Input [true false]		true
Investment, Non-income Producing [true false]		false
Non-controlled/non-affiliate company investments | Unitranche Debt [Member]
Schedule of Investments [Line Items]
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Principal	$ 45,813	$ 72,498
Amortized Cost	45,352	70,977
Fair Value	$ 20,633	$ 51,494
% of Net Assets	9.20%	20.60%
Investment, Restriction Status [true false]		true
Investment, Significant Unobservable Input [true false]		true
Investment, Non-income Producing [true false]		false
Non-controlled/non-affiliate company investments | Unitranche Debt [Member] | Chemicals, Plastics & Rubber
Schedule of Investments [Line Items]
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Principal		$ 6,098
Amortized Cost		6,089
Fair Value		$ 6,098
% of Net Assets		2.40%
Investment, Restriction Status [true false]		true
Investment, Significant Unobservable Input [true false]		true
Investment, Non-income Producing [true false]		false
Non-controlled/non-affiliate company investments | Unitranche Debt [Member] | Consumer Goods: Durable
Schedule of Investments [Line Items]
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Principal		$ 24,792
Amortized Cost		24,768
Fair Value		$ 4,950
% of Net Assets		2%
Investment, Restriction Status [true false]		true
Investment, Significant Unobservable Input [true false]		true
Investment, Non-income Producing [true false]		false
Non-controlled/non-affiliate company investments | Unitranche Debt [Member] | Consumer Goods: Non-Durable
Schedule of Investments [Line Items]
Principal	$ 24,792
Amortized Cost	$ 24,768
% of Net Assets	0%
Non-controlled/non-affiliate company investments | Unitranche Debt [Member] | Healthcare & Pharmaceuticals
Schedule of Investments [Line Items]
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Principal		$ 12,913
Amortized Cost		12,911
Fair Value		$ 12,907
% of Net Assets		5.20%
Investment, Restriction Status [true false]		true
Investment, Significant Unobservable Input [true false]		true
Investment, Non-income Producing [true false]		false
Non-controlled/non-affiliate company investments | Unitranche Debt [Member] | High Tech Industries
Schedule of Investments [Line Items]
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Principal	$ 7,326	$ 16,965
Amortized Cost	7,301	16,809
Fair Value	$ 7,326	$ 16,977
% of Net Assets	3.30%	6.80%
Investment, Restriction Status [true false]		true
Investment, Significant Unobservable Input [true false]		true
Investment, Non-income Producing [true false]		false
Non-controlled/non-affiliate company investments | Unitranche Debt [Member] | Services: Business
Schedule of Investments [Line Items]
Investment, Type [Extensible Enumeration]		Unitranche Debt [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Principal	$ 3,865	$ 1,500
Amortized Cost	3,572	1,472
Fair Value	$ 3,614	$ 1,472
% of Net Assets	1.60%	0.60%
Investment, Restriction Status [true false]		true
Investment, Significant Unobservable Input [true false]		true
Investment, Non-income Producing [true false]		false
Non-controlled/non-affiliate company investments | Unitranche Debt [Member] | Telecommunications
Schedule of Investments [Line Items]
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Principal	$ 2,250	$ 2,250
Amortized Cost	2,250	1,100
Fair Value	$ 2,257	$ 1,118
% of Net Assets	1%	0.40%
Investment, Restriction Status [true false]		true
Investment, Significant Unobservable Input [true false]		true
Investment, Non-income Producing [true false]		false
Non-controlled/non-affiliate company investments | Unitranche Debt [Member] | Aerospace & Defense
Schedule of Investments [Line Items]
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Principal		$ 7,980
Amortized Cost		7,828
Fair Value		$ 7,972
% of Net Assets		3.20%
Investment, Restriction Status [true false]		true
Investment, Significant Unobservable Input [true false]		true
Investment, Non-income Producing [true false]		false
Non-controlled/non-affiliate company investments | Junior Loans [Member]
Schedule of Investments [Line Items]
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Principal	$ 17,569	$ 9,429
Amortized Cost	15,291	8,466
Fair Value	$ 16,343	$ 8,514
% of Net Assets	7.20%	3.40%
Investment, Restriction Status [true false]		true
Investment, Significant Unobservable Input [true false]		true
Investment, Non-income Producing [true false]		false
Non-controlled/non-affiliate company investments | Junior Loans [Member] | Banking
Schedule of Investments [Line Items]
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Principal	$ 8,250	$ 1,500
Amortized Cost	6,693	1,488
Fair Value	$ 6,663	$ 1,522
% of Net Assets	2.90%	0.60%
Investment, Restriction Status [true false]		true
Investment, Significant Unobservable Input [true false]		true
Investment, Non-income Producing [true false]		false
Non-controlled/non-affiliate company investments | Junior Loans [Member] | Consumer Goods: Durable
Schedule of Investments [Line Items]
Principal	$ 833
Amortized Cost	831
Fair Value	$ 1,882
% of Net Assets	0.80%
Non-controlled/non-affiliate company investments | Junior Loans [Member] | FIRE: Real Estate
Schedule of Investments [Line Items]
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Principal	$ 8,486	$ 7,096
Amortized Cost	7,767	6,147
Fair Value	$ 7,798	$ 6,416
% of Net Assets	3.50%	2.60%
Investment, Restriction Status [true false]		true
Investment, Significant Unobservable Input [true false]		true
Investment, Non-income Producing [true false]		false
Non-controlled/non-affiliate company investments | Junior Loans [Member] | Services: Consumer
Schedule of Investments [Line Items]
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Principal		$ 833
Amortized Cost		831
Fair Value		$ 576
% of Net Assets		0.20%
Investment, Restriction Status [true false]		true
Investment, Significant Unobservable Input [true false]		true
Investment, Non-income Producing [true false]		false
Non-controlled/non-affiliate company investments | Equity Securities [Member]
Schedule of Investments [Line Items]
Amortized Cost	$ 20,254	$ 19,535
Fair Value	$ 16,131	$ 18,581
% of Net Assets	7.10%	7.40%
Investment, Restriction Status [true false]		true
Investment, Significant Unobservable Input [true false]		true
Investment, Non-income Producing [true false]	false
Non-controlled/non-affiliate company investments | Equity Securities [Member] | Automotive
Schedule of Investments [Line Items]
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Amortized Cost	$ 380	$ 380
Fair Value	$ 311	$ 402
% of Net Assets	0.10%	0.20%
Investment, Significant Unobservable Input [true false]		true
Investment, Non-income Producing [true false]		false
Non-controlled/non-affiliate company investments | Equity Securities [Member] | Banking
Schedule of Investments [Line Items]
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Amortized Cost	$ 963	$ 663
Fair Value	$ 2,809	$ 1,565
% of Net Assets	1.30%	0.60%
Investment, Restriction Status [true false]	true	true
Investment, Significant Unobservable Input [true false]	true	true
Investment, Non-income Producing [true false]	true	true
Non-controlled/non-affiliate company investments | Equity Securities [Member] | Beverage, Food & Tobacco
Schedule of Investments [Line Items]
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Amortized Cost	$ 5,468	$ 5,468
Fair Value	$ 1,266	$ 3,699
% of Net Assets	0.60%	1.50%
Investment, Restriction Status [true false]	true	true
Investment, Significant Unobservable Input [true false]	true	true
Investment, Non-income Producing [true false]	true	true
Non-controlled/non-affiliate company investments | Equity Securities [Member] | Capital Equipment
Schedule of Investments [Line Items]
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Amortized Cost	$ 119	$ 119
Fair Value	$ 204	$ 148
% of Net Assets	0.10%	0.10%
Investment, Restriction Status [true false]	true	true
Investment, Significant Unobservable Input [true false]	true	true
Investment, Non-income Producing [true false]	true	true
Non-controlled/non-affiliate company investments | Equity Securities [Member] | Chemicals, Plastics & Rubber
Schedule of Investments [Line Items]
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Amortized Cost	$ 501	$ 501
Fair Value	$ 555	$ 16
% of Net Assets	0.20%	0%
Investment, Restriction Status [true false]	true	true
Investment, Significant Unobservable Input [true false]	true	true
Investment, Non-income Producing [true false]	false	false
Non-controlled/non-affiliate company investments | Equity Securities [Member] | Consumer Goods: Durable
Schedule of Investments [Line Items]
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Amortized Cost	$ 81	$ 81
Fair Value	$ 102	$ 101
% of Net Assets	0%	0%
Investment, Restriction Status [true false]	true	true
Investment, Significant Unobservable Input [true false]	true	true
Investment, Non-income Producing [true false]	true	true
Non-controlled/non-affiliate company investments | Equity Securities [Member] | Environmental Industries
Schedule of Investments [Line Items]
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Amortized Cost	$ 67	$ 67
Fair Value	$ 357	$ 455
% of Net Assets	0.20%	0.20%
Investment, Restriction Status [true false]	true	true
Investment, Significant Unobservable Input [true false]	true	true
Investment, Non-income Producing [true false]	true	true
Non-controlled/non-affiliate company investments | Equity Securities [Member] | FIRE: Finance
Schedule of Investments [Line Items]
Investment, Industry Sector [Extensible Enumeration]		FIRE: Finance
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Amortized Cost	$ 77	$ 77
Fair Value	$ 397	$ 292
% of Net Assets	0.20%	0.10%
Investment, Restriction Status [true false]	true	true
Investment, Significant Unobservable Input [true false]	true	true
Investment, Non-income Producing [true false]	false
Non-controlled/non-affiliate company investments | Equity Securities [Member] | FIRE: Real Estate
Schedule of Investments [Line Items]
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Amortized Cost	$ 2	$ 2
Fair Value	$ 1,047	$ 2
% of Net Assets	0.50%	0%
Investment, Restriction Status [true false]	true	true
Investment, Significant Unobservable Input [true false]	true	true
Investment, Non-income Producing [true false]	false	false
Non-controlled/non-affiliate company investments | Equity Securities [Member] | Healthcare & Pharmaceuticals
Schedule of Investments [Line Items]
Investment, Industry Sector [Extensible Enumeration]		Healthcare & Pharmaceuticals
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Amortized Cost	$ 1,802	$ 1,402
Fair Value	$ 2,303	$ 1,683
% of Net Assets	1%	0.70%
Investment, Restriction Status [true false]	true	true
Investment, Significant Unobservable Input [true false]	true	true
Investment, Non-income Producing [true false]	false
Non-controlled/non-affiliate company investments | Equity Securities [Member] | High Tech Industries
Schedule of Investments [Line Items]
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Amortized Cost	$ 684	$ 844
Fair Value	$ 1,340	$ 1,183
% of Net Assets	0.60%	0.50%
Investment, Restriction Status [true false]	true	true
Investment, Significant Unobservable Input [true false]	true	true
Investment, Non-income Producing [true false]	false
Non-controlled/non-affiliate company investments | Equity Securities [Member] | Hotels, Gaming & Leisure
Schedule of Investments [Line Items]
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Amortized Cost	$ 111	$ 99
Fair Value	$ 109	$ 102
% of Net Assets	0%	0%
Investment, Restriction Status [true false]	true	true
Investment, Significant Unobservable Input [true false]	true	true
Investment, Non-income Producing [true false]	true	true
Non-controlled/non-affiliate company investments | Equity Securities [Member] | Media: Advertising, Printing & Publishing
Schedule of Investments [Line Items]
Amortized Cost	$ 284	$ 284
Fair Value	$ 2,432	$ 3,472
% of Net Assets	1.10%	1.30%
Investment, Restriction Status [true false]	true	true
Investment, Significant Unobservable Input [true false]	true	true
Investment, Non-income Producing [true false]	false
Non-controlled/non-affiliate company investments | Equity Securities [Member] | Media: Diversified & Production
Schedule of Investments [Line Items]
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Amortized Cost	$ 384	$ 384
Fair Value	$ 572	$ 533
% of Net Assets	0.20%	0.20%
Investment, Restriction Status [true false]	true	true
Investment, Significant Unobservable Input [true false]	true	true
Investment, Non-income Producing [true false]	true	true
Non-controlled/non-affiliate company investments | Equity Securities [Member] | Retail
Schedule of Investments [Line Items]
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Amortized Cost	$ 712	$ 712
Fair Value	$ 784	$ 1,200
% of Net Assets	0.40%	0.50%
Investment, Restriction Status [true false]	true	true
Investment, Significant Unobservable Input [true false]	true	true
Investment, Non-income Producing [true false]	true	true
Non-controlled/non-affiliate company investments | Equity Securities [Member] | Services: Business
Schedule of Investments [Line Items]
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Amortized Cost	$ 395	$ 395
Fair Value	$ 921	$ 737
% of Net Assets	0.40%	0.30%
Investment, Restriction Status [true false]	true	true
Investment, Significant Unobservable Input [true false]	true	true
Investment, Non-income Producing [true false]	true	true
Non-controlled/non-affiliate company investments | Equity Securities [Member] | Services: Consumer
Schedule of Investments [Line Items]
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Amortized Cost	$ 7,968	$ 7,865
Fair Value	$ 553	$ 2,917
% of Net Assets	0.20%	1.20%
Investment, Restriction Status [true false]	true	true
Investment, Significant Unobservable Input [true false]	true	true
Investment, Non-income Producing [true false]	false	false
Non-controlled/non-affiliate company investments | Equity Securities [Member] | Telecommunications
Schedule of Investments [Line Items]
Amortized Cost	$ 42
Fair Value	$ 69
% of Net Assets	0%
Investment, Restriction Status [true false]	true
Investment, Significant Unobservable Input [true false]	true
Investment, Non-income Producing [true false]	true
Non-controlled/non-affiliate company investments | Equity Securities [Member] | Wholesale
Schedule of Investments [Line Items]
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Amortized Cost	$ 214	$ 192
Fair Value		$ 74
% of Net Assets	0%	0%
Investment, Restriction Status [true false]	true	true
Investment, Significant Unobservable Input [true false]	true	true
Investment, Non-income Producing [true false]	true	true
Non-controlled affiliate company investments
Schedule of Investments [Line Items]
Investment, Type [Extensible Enumeration]	Equity Securities [Member]
Amortized Cost	$ 89,693	$ 87,977
Fair Value	$ 86,618	$ 90,281	109,715
% of Net Assets	38.50%	36.20%
Investment, Restriction Status [true false]		true
Investment, Significant Unobservable Input [true false]		true
Investment, Non-income Producing [true false]		true
Non-controlled affiliate company investments | Healthcare & Pharmaceuticals
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled affiliate company investments
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Principal		$ 7,521
Amortized Cost		6,308
Fair Value		$ 6,392
% of Net Assets		2.60%
Investment, Restriction Status [true false]		true
Investment, Significant Unobservable Input [true false]		true
Investment, Non-income Producing [true false]		false
Non-controlled affiliate company investments | Senior Loans [Member]
Schedule of Investments [Line Items]
Principal	$ 75,344	$ 74,232
Amortized Cost	69,999	68,527
Fair Value	$ 68,217	$ 72,002
% of Net Assets	30.30%	28.90%
Non-controlled affiliate company investments | Senior Loans [Member] | Beverage, Food & Tobacco
Schedule of Investments [Line Items]
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Principal	$ 477	$ 477
Amortized Cost	80
Fair Value	$ 80
% of Net Assets	0%	0%
Investment, Restriction Status [true false]		true
Investment, Significant Unobservable Input [true false]		true
Investment, Non-income Producing [true false]		false
Non-controlled affiliate company investments | Senior Loans [Member] | FIRE: Real Estate
Schedule of Investments [Line Items]
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Principal	$ 60,140	$ 54,281
Amortized Cost	56,757	50,717
Fair Value	$ 55,686	$ 54,096
% of Net Assets	24.70%	21.70%
Investment, Restriction Status [true false]		true
Investment, Significant Unobservable Input [true false]		true
Investment, Non-income Producing [true false]		false
Non-controlled affiliate company investments | Senior Loans [Member] | Healthcare & Pharmaceuticals
Schedule of Investments [Line Items]
Principal	$ 7,346
Amortized Cost	6,159
Fair Value	$ 6,217
% of Net Assets	2.80%
Non-controlled affiliate company investments | Senior Loans [Member] | High Tech Industries
Schedule of Investments [Line Items]
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Principal	$ 6,025	$ 5,193
Amortized Cost	5,691	5,165
Fair Value	$ 5,706	$ 5,771
% of Net Assets	2.50%	2.30%
Investment, Restriction Status [true false]		true
Investment, Significant Unobservable Input [true false]		true
Investment, Non-income Producing [true false]		false
Non-controlled affiliate company investments | Senior Loans [Member] | Media: Advertising, Printing & Publishing
Schedule of Investments [Line Items]
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Principal		$ 16,337
Amortized Cost		13,137
Fair Value		$ 13,322
% of Net Assets		5.30%
Investment, Restriction Status [true false]		true
Investment, Significant Unobservable Input [true false]		true
Investment, Non-income Producing [true false]		false
Non-controlled affiliate company investments | Senior Loans [Member] | Services: Business
Schedule of Investments [Line Items]
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Principal		$ 5,404
Amortized Cost		5,025
Fair Value	$ 146	$ 5,111
% of Net Assets	0.10%	2%
Investment, Restriction Status [true false]		true
Investment, Significant Unobservable Input [true false]		true
Investment, Non-income Producing [true false]	false	false
Non-controlled affiliate company investments | Senior Loans [Member] | Services: Consumer
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled affiliate company investments
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Services: Consumer
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Principal	$ 1,356	$ 1,356
Amortized Cost	1,312	1,312
Fair Value	$ 382	$ 632
% of Net Assets	0.20%	0.30%
Investment, Restriction Status [true false]		true
Investment, Significant Unobservable Input [true false]		true
Investment, Non-income Producing [true false]		false
Non-controlled affiliate company investments | Junior Loans [Member]
Schedule of Investments [Line Items]
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Principal	$ 5,850	$ 7,614
Amortized Cost	5,850	5,851
Fair Value	$ 5,850	$ 5,850
% of Net Assets	2.60%	2.30%
Investment, Restriction Status [true false]		true
Investment, Significant Unobservable Input [true false]		true
Investment, Non-income Producing [true false]		false
Non-controlled affiliate company investments | Junior Loans [Member] | FIRE: Real Estate
Schedule of Investments [Line Items]
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Principal	$ 5,850	$ 5,850
Amortized Cost	5,850	5,850
Fair Value	$ 5,850	$ 5,850
% of Net Assets	2.60%	2.30%
Investment, Restriction Status [true false]		true
Investment, Significant Unobservable Input [true false]		true
Investment, Non-income Producing [true false]		false
Non-controlled affiliate company investments | Junior Loans [Member] | Services: Business
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled affiliate company investments
Investment, Type [Extensible Enumeration]		Junior Loans [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Principal		$ 1,764
Amortized Cost		$ 1
% of Net Assets		0%
Investment, Restriction Status [true false]		true
Investment, Significant Unobservable Input [true false]		true
Investment, Non-income Producing [true false]		false
Non-controlled affiliate company investments | Equity Securities [Member]
Schedule of Investments [Line Items]
Investment, Type [Extensible Enumeration]	Equity Securities [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Amortized Cost	$ 13,844	$ 13,599
Fair Value	$ 12,551	$ 12,429
% of Net Assets	5.60%	5%
Investment, Significant Unobservable Input [true false]		true
Investment, Non-income Producing [true false]		true
Non-controlled affiliate company investments | Equity Securities [Member] | Beverage, Food & Tobacco
Schedule of Investments [Line Items]
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Amortized Cost	$ 1,631	$ 1,631
Fair Value	$ 2,766	$ 3,148
% of Net Assets	1.20%	1.30%
Investment, Restriction Status [true false]		true
Investment, Significant Unobservable Input [true false]		true
Investment, Non-income Producing [true false]		false
Non-controlled affiliate company investments | Equity Securities [Member] | FIRE: Real Estate
Schedule of Investments [Line Items]
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Amortized Cost	$ 4,693	$ 4,693
Fair Value	$ 5,191	$ 4,808
% of Net Assets	2.30%	1.90%
Investment, Restriction Status [true false]		true
Investment, Significant Unobservable Input [true false]		true
Investment, Non-income Producing [true false]		false
Non-controlled affiliate company investments | Equity Securities [Member] | Healthcare & Pharmaceuticals
Schedule of Investments [Line Items]
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Amortized Cost		$ 5,817
Fair Value		$ 4,473
% of Net Assets		1.80%
Investment, Restriction Status [true false]		true
Investment, Significant Unobservable Input [true false]		true
Investment, Non-income Producing [true false]		true
Non-controlled affiliate company investments | Equity Securities [Member] | High Tech Industries
Schedule of Investments [Line Items]
% of Net Assets	0%	0%
Investment, Restriction Status [true false]		true
Investment, Significant Unobservable Input [true false]		true
Investment, Non-income Producing [true false]		true
Non-controlled affiliate company investments | Equity Securities [Member] | Services: Business
Schedule of Investments [Line Items]
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
% of Net Assets		0%
Investment, Restriction Status [true false]		true
Investment, Significant Unobservable Input [true false]		true
Investment, Non-income Producing [true false]		true
Non-controlled affiliate company investments | Equity Securities [Member] | Services: Consumer
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled affiliate company investments
Investment, Type [Extensible Enumeration]		Equity Securities [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Amortized Cost	$ 1,458	$ 1,458
% of Net Assets	0%	0%
Investment, Restriction Status [true false]		true
Investment, Significant Unobservable Input [true false]		true
Investment, Non-income Producing [true false]		true
Controlled affiliate company investments
Schedule of Investments [Line Items]
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Amortized Cost	$ 42,650	$ 42,150
Fair Value	$ 35,509	$ 41,125	$ 39,284
% of Net Assets	15.80%	16.50%
Investment, Restriction Status [true false]		true
Investment, Significant Unobservable Input [true false]		true
Investment, Non-income Producing [true false]		false
Controlled affiliate company investments | Equity Securities [Member]
Schedule of Investments [Line Items]
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Amortized Cost	$ 42,650	$ 42,150
Fair Value	$ 35,509	$ 41,125
% of Net Assets	15.80%	16.50%
Investment, Restriction Status [true false]		true
Investment, Significant Unobservable Input [true false]		true
Investment, Non-income Producing [true false]		false

CONSOLIDATED SCHEDULE OF INVE_2

CONSOLIDATED SCHEDULE OF INVESTMENTS (Foreign currency forward contracts) £ in Thousands, $ in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)	Dec. 31, 2022 AUD ($)	Dec. 31, 2021 AUD ($)	Dec. 31, 2021 GBP (£)
Open Forward Foreign Currency Contract [Line Items]
Unrealized Gain (Loss) on Derivatives	$ 1,507	$ 781
Open Forward Foreign Currency Contract, Identifier [Axis]: Foreign currency forward contract with settlement date 1/17/2024
Open Forward Foreign Currency Contract [Line Items]
Derivative Asset, Notional Amount	$ 115	$ 115
Derivative Liability, Notional Amount			$ 150	$ 150
Derivative Asset, Counterparty Name [Extensible Enumeration]	mrcc:BannockburnGlobalForexLlcMember	mrcc:BannockburnGlobalForexLlcMember	mrcc:BannockburnGlobalForexLlcMember	mrcc:BannockburnGlobalForexLlcMember	mrcc:BannockburnGlobalForexLlcMember
Derivative, Maturity Date	Jan. 17, 2024	Jan. 17, 2024
Unrealized Gain (Loss) on Derivatives	$ 13	$ 6
Open Forward Foreign Currency Contract, Identifier [Axis]: Foreign currency forward contract with settlement date 1/18/2023
Open Forward Foreign Currency Contract [Line Items]
Derivative Asset, Notional Amount	$ 118	$ 118
Derivative Liability, Notional Amount			$ 153	$ 153
Derivative Asset, Counterparty Name [Extensible Enumeration]	mrcc:BannockburnGlobalForexLlcMember	mrcc:BannockburnGlobalForexLlcMember	mrcc:BannockburnGlobalForexLlcMember	mrcc:BannockburnGlobalForexLlcMember	mrcc:BannockburnGlobalForexLlcMember
Derivative, Maturity Date	Jan. 18, 2023	Jan. 18, 2023
Unrealized Gain (Loss) on Derivatives	$ 14	$ 7
Open Forward Foreign Currency Contract, Identifier [Axis]: Foreign currency forward contract with settlement date 1/19/2022
Open Forward Foreign Currency Contract [Line Items]
Derivative Asset, Notional Amount		$ 121
Derivative Liability, Notional Amount				$ 156
Derivative Asset, Counterparty Name [Extensible Enumeration]		mrcc:BannockburnGlobalForexLlcMember		mrcc:BannockburnGlobalForexLlcMember	mrcc:BannockburnGlobalForexLlcMember
Derivative, Maturity Date		Jan. 19, 2022
Unrealized Gain (Loss) on Derivatives		$ 8
Open Forward Foreign Currency Contract, Identifier [Axis]: Foreign currency forward contract with settlement date 1/3/2022
Open Forward Foreign Currency Contract [Line Items]
Derivative Asset, Notional Amount		$ 101
Derivative Liability, Notional Amount | £					£ 82
Derivative Asset, Counterparty Name [Extensible Enumeration]		mrcc:BannockburnGlobalForexLlcMember		mrcc:BannockburnGlobalForexLlcMember	mrcc:BannockburnGlobalForexLlcMember
Derivative, Maturity Date		Jan. 03, 2022
Unrealized Gain (Loss) on Derivatives		$ (10)
Open Forward Foreign Currency Contract, Identifier [Axis]: Foreign currency forward contract with settlement date 10/18/2023
Open Forward Foreign Currency Contract [Line Items]
Derivative Asset, Notional Amount	$ 114	$ 114
Derivative Liability, Notional Amount			$ 148	$ 148
Derivative Asset, Counterparty Name [Extensible Enumeration]	mrcc:BannockburnGlobalForexLlcMember	mrcc:BannockburnGlobalForexLlcMember	mrcc:BannockburnGlobalForexLlcMember	mrcc:BannockburnGlobalForexLlcMember	mrcc:BannockburnGlobalForexLlcMember
Derivative, Maturity Date	Oct. 18, 2023	Oct. 18, 2023
Unrealized Gain (Loss) on Derivatives	$ 13	$ 6
Open Forward Foreign Currency Contract, Identifier [Axis]: Foreign currency forward contract with settlement date 10/19/2022
Open Forward Foreign Currency Contract [Line Items]
Derivative Asset, Notional Amount		$ 117
Derivative Liability, Notional Amount				$ 152
Derivative Asset, Counterparty Name [Extensible Enumeration]		mrcc:BannockburnGlobalForexLlcMember		mrcc:BannockburnGlobalForexLlcMember	mrcc:BannockburnGlobalForexLlcMember
Derivative, Maturity Date		Oct. 19, 2022
Unrealized Gain (Loss) on Derivatives		$ 7
Open Forward Foreign Currency Contract, Identifier [Axis]: Foreign currency forward contract with settlement date 11/16/2022
Open Forward Foreign Currency Contract [Line Items]
Derivative Asset, Notional Amount		$ 105
Derivative Liability, Notional Amount				$ 136
Derivative Asset, Counterparty Name [Extensible Enumeration]		mrcc:BannockburnGlobalForexLlcMember		mrcc:BannockburnGlobalForexLlcMember	mrcc:BannockburnGlobalForexLlcMember
Derivative, Maturity Date		Nov. 16, 2022
Unrealized Gain (Loss) on Derivatives		$ 6
Open Forward Foreign Currency Contract, Identifier [Axis]: Foreign currency forward contract with settlement date 11/16/2023
Open Forward Foreign Currency Contract [Line Items]
Derivative Asset, Notional Amount	$ 107	$ 107
Derivative Liability, Notional Amount			$ 140	$ 140
Derivative Asset, Counterparty Name [Extensible Enumeration]	mrcc:BannockburnGlobalForexLlcMember	mrcc:BannockburnGlobalForexLlcMember	mrcc:BannockburnGlobalForexLlcMember	mrcc:BannockburnGlobalForexLlcMember	mrcc:BannockburnGlobalForexLlcMember
Derivative, Maturity Date	Nov. 16, 2023	Nov. 16, 2023
Unrealized Gain (Loss) on Derivatives	$ 12	$ 6
Open Forward Foreign Currency Contract, Identifier [Axis]: Foreign currency forward contract with settlement date 12/16/2022
Open Forward Foreign Currency Contract [Line Items]
Derivative Asset, Notional Amount		$ 109
Derivative Liability, Notional Amount				$ 142
Derivative Asset, Counterparty Name [Extensible Enumeration]		mrcc:BannockburnGlobalForexLlcMember		mrcc:BannockburnGlobalForexLlcMember	mrcc:BannockburnGlobalForexLlcMember
Derivative, Maturity Date		Dec. 16, 2022
Unrealized Gain (Loss) on Derivatives		$ 7
Open Forward Foreign Currency Contract, Identifier [Axis]: Foreign currency forward contract with settlement date 12/18/2023
Open Forward Foreign Currency Contract [Line Items]
Derivative Asset, Notional Amount	$ 109	$ 109
Derivative Liability, Notional Amount			$ 142	$ 142
Derivative Asset, Counterparty Name [Extensible Enumeration]	mrcc:BannockburnGlobalForexLlcMember	mrcc:BannockburnGlobalForexLlcMember	mrcc:BannockburnGlobalForexLlcMember	mrcc:BannockburnGlobalForexLlcMember	mrcc:BannockburnGlobalForexLlcMember
Derivative, Maturity Date	Dec. 18, 2023	Dec. 18, 2023
Unrealized Gain (Loss) on Derivatives	$ 12	$ 6
Open Forward Foreign Currency Contract, Identifier [Axis]: Foreign currency forward contract with settlement date 2/16/2022
Open Forward Foreign Currency Contract [Line Items]
Derivative Asset, Notional Amount		$ 105
Derivative Liability, Notional Amount				$ 136
Derivative Asset, Counterparty Name [Extensible Enumeration]		mrcc:BannockburnGlobalForexLlcMember		mrcc:BannockburnGlobalForexLlcMember	mrcc:BannockburnGlobalForexLlcMember
Derivative, Maturity Date		Feb. 16, 2022
Unrealized Gain (Loss) on Derivatives		$ 7
Open Forward Foreign Currency Contract, Identifier [Axis]: Foreign currency forward contract with settlement date 2/16/2023
Open Forward Foreign Currency Contract [Line Items]
Derivative Asset, Notional Amount	$ 108	$ 108
Derivative Liability, Notional Amount			$ 140	$ 140
Derivative Asset, Counterparty Name [Extensible Enumeration]	mrcc:BannockburnGlobalForexLlcMember	mrcc:BannockburnGlobalForexLlcMember	mrcc:BannockburnGlobalForexLlcMember	mrcc:BannockburnGlobalForexLlcMember	mrcc:BannockburnGlobalForexLlcMember
Derivative, Maturity Date	Feb. 16, 2023	Feb. 16, 2023
Unrealized Gain (Loss) on Derivatives	$ 13	$ 6
Open Forward Foreign Currency Contract, Identifier [Axis]: Foreign currency forward contract with settlement date 2/16/2024
Open Forward Foreign Currency Contract [Line Items]
Derivative Asset, Notional Amount	$ 110	$ 110
Derivative Liability, Notional Amount			$ 143	$ 143
Derivative Asset, Counterparty Name [Extensible Enumeration]	mrcc:BannockburnGlobalForexLlcMember	mrcc:BannockburnGlobalForexLlcMember	mrcc:BannockburnGlobalForexLlcMember	mrcc:BannockburnGlobalForexLlcMember	mrcc:BannockburnGlobalForexLlcMember
Derivative, Maturity Date	Feb. 16, 2024	Feb. 16, 2024
Unrealized Gain (Loss) on Derivatives	$ 12	$ 6
Open Forward Foreign Currency Contract, Identifier [Axis]: Foreign currency forward contract with settlement date 3/16/2022
Open Forward Foreign Currency Contract [Line Items]
Derivative Asset, Notional Amount		$ 102
Derivative Liability, Notional Amount				$ 132
Derivative Asset, Counterparty Name [Extensible Enumeration]		mrcc:BannockburnGlobalForexLlcMember		mrcc:BannockburnGlobalForexLlcMember	mrcc:BannockburnGlobalForexLlcMember
Derivative, Maturity Date		Mar. 16, 2022
Unrealized Gain (Loss) on Derivatives		$ 6
Open Forward Foreign Currency Contract, Identifier [Axis]: Foreign currency forward contract with settlement date 3/16/2023
Open Forward Foreign Currency Contract [Line Items]
Derivative Asset, Notional Amount	$ 102	$ 102
Derivative Liability, Notional Amount			$ 132	$ 132
Derivative Asset, Counterparty Name [Extensible Enumeration]	mrcc:BannockburnGlobalForexLlcMember	mrcc:BannockburnGlobalForexLlcMember	mrcc:BannockburnGlobalForexLlcMember	mrcc:BannockburnGlobalForexLlcMember	mrcc:BannockburnGlobalForexLlcMember
Derivative, Maturity Date	Mar. 16, 2023	Mar. 16, 2023
Unrealized Gain (Loss) on Derivatives	$ 12	$ 6
Open Forward Foreign Currency Contract, Identifier [Axis]: Foreign currency forward contract with settlement date 3/18/2024
Open Forward Foreign Currency Contract [Line Items]
Derivative Asset, Notional Amount	$ 11,827	$ 11,827
Derivative Liability, Notional Amount			$ 15,410	$ 15,410
Derivative Asset, Counterparty Name [Extensible Enumeration]	mrcc:BannockburnGlobalForexLlcMember	mrcc:BannockburnGlobalForexLlcMember	mrcc:BannockburnGlobalForexLlcMember	mrcc:BannockburnGlobalForexLlcMember	mrcc:BannockburnGlobalForexLlcMember
Derivative, Maturity Date	Mar. 18, 2024	Mar. 18, 2024
Unrealized Gain (Loss) on Derivatives	$ 1,329	$ 635
Open Forward Foreign Currency Contract, Identifier [Axis]: Foreign currency forward contract with settlement date 4/19/2022
Open Forward Foreign Currency Contract [Line Items]
Derivative Asset, Notional Amount		$ 113
Derivative Liability, Notional Amount				$ 146
Derivative Asset, Counterparty Name [Extensible Enumeration]		mrcc:BannockburnGlobalForexLlcMember		mrcc:BannockburnGlobalForexLlcMember	mrcc:BannockburnGlobalForexLlcMember
Derivative, Maturity Date		Apr. 19, 2022
Unrealized Gain (Loss) on Derivatives		$ 7
Open Forward Foreign Currency Contract, Identifier [Axis]: Foreign currency forward contract with settlement date 4/20/2023
Open Forward Foreign Currency Contract [Line Items]
Derivative Asset, Notional Amount	$ 123	$ 123
Derivative Liability, Notional Amount			$ 160	$ 160
Derivative Asset, Counterparty Name [Extensible Enumeration]	mrcc:BannockburnGlobalForexLlcMember	mrcc:BannockburnGlobalForexLlcMember	mrcc:BannockburnGlobalForexLlcMember	mrcc:BannockburnGlobalForexLlcMember	mrcc:BannockburnGlobalForexLlcMember
Derivative, Maturity Date	Apr. 20, 2023	Apr. 20, 2023
Unrealized Gain (Loss) on Derivatives	$ 14	$ 7
Open Forward Foreign Currency Contract, Identifier [Axis]: Foreign currency forward contract with settlement date 4/4/2022
Open Forward Foreign Currency Contract [Line Items]
Derivative Asset, Notional Amount		$ 97
Derivative Liability, Notional Amount | £					£ 79
Derivative Asset, Counterparty Name [Extensible Enumeration]		mrcc:BannockburnGlobalForexLlcMember		mrcc:BannockburnGlobalForexLlcMember	mrcc:BannockburnGlobalForexLlcMember
Derivative, Maturity Date		Apr. 04, 2022
Unrealized Gain (Loss) on Derivatives		$ (10)
Open Forward Foreign Currency Contract, Identifier [Axis]: Foreign currency forward contract with settlement date 5/16/2023
Open Forward Foreign Currency Contract [Line Items]
Derivative Asset, Notional Amount	$ 93	$ 93
Derivative Liability, Notional Amount			$ 121	$ 121
Derivative Asset, Counterparty Name [Extensible Enumeration]	mrcc:BannockburnGlobalForexLlcMember	mrcc:BannockburnGlobalForexLlcMember	mrcc:BannockburnGlobalForexLlcMember	mrcc:BannockburnGlobalForexLlcMember	mrcc:BannockburnGlobalForexLlcMember
Derivative, Maturity Date	May 16, 2023	May 16, 2023
Unrealized Gain (Loss) on Derivatives	$ 11	$ 5
Open Forward Foreign Currency Contract, Identifier [Axis]: Foreign currency forward contract with settlement date 5/17/2022
Open Forward Foreign Currency Contract [Line Items]
Derivative Asset, Notional Amount		$ 107
Derivative Liability, Notional Amount				$ 138
Derivative Asset, Counterparty Name [Extensible Enumeration]		mrcc:BannockburnGlobalForexLlcMember		mrcc:BannockburnGlobalForexLlcMember	mrcc:BannockburnGlobalForexLlcMember
Derivative, Maturity Date		May 17, 2022
Unrealized Gain (Loss) on Derivatives		$ 7
Open Forward Foreign Currency Contract, Identifier [Axis]: Foreign currency forward contract with settlement date 5/6/2022
Open Forward Foreign Currency Contract [Line Items]
Derivative Asset, Notional Amount		$ 36
Derivative Liability, Notional Amount | £					£ 29
Derivative Asset, Counterparty Name [Extensible Enumeration]		mrcc:BannockburnGlobalForexLlcMember		mrcc:BannockburnGlobalForexLlcMember	mrcc:BannockburnGlobalForexLlcMember
Derivative, Maturity Date		May 06, 2022
Unrealized Gain (Loss) on Derivatives		$ (3)
Open Forward Foreign Currency Contract, Identifier [Axis]: Foreign currency forward contract with settlement date 6/17/2022
Open Forward Foreign Currency Contract [Line Items]
Derivative Asset, Notional Amount		$ 119
Derivative Liability, Notional Amount				$ 153
Derivative Asset, Counterparty Name [Extensible Enumeration]		mrcc:BannockburnGlobalForexLlcMember		mrcc:BannockburnGlobalForexLlcMember	mrcc:BannockburnGlobalForexLlcMember
Derivative, Maturity Date		Jun. 17, 2022
Unrealized Gain (Loss) on Derivatives		$ 7
Open Forward Foreign Currency Contract, Identifier [Axis]: Foreign currency forward contract with settlement date 6/19/2023
Open Forward Foreign Currency Contract [Line Items]
Derivative Asset, Notional Amount	$ 121	$ 121
Derivative Liability, Notional Amount			$ 156	$ 156
Derivative Asset, Counterparty Name [Extensible Enumeration]	mrcc:BannockburnGlobalForexLlcMember	mrcc:BannockburnGlobalForexLlcMember	mrcc:BannockburnGlobalForexLlcMember	mrcc:BannockburnGlobalForexLlcMember	mrcc:BannockburnGlobalForexLlcMember
Derivative, Maturity Date	Jun. 19, 2023	Jun. 19, 2023
Unrealized Gain (Loss) on Derivatives	$ 14	$ 7
Open Forward Foreign Currency Contract, Identifier [Axis]: Foreign currency forward contract with settlement date 7/18/2022
Open Forward Foreign Currency Contract [Line Items]
Derivative Asset, Notional Amount		$ 107
Derivative Liability, Notional Amount				$ 138
Derivative Asset, Counterparty Name [Extensible Enumeration]		mrcc:BannockburnGlobalForexLlcMember		mrcc:BannockburnGlobalForexLlcMember	mrcc:BannockburnGlobalForexLlcMember
Derivative, Maturity Date		Jul. 18, 2022
Unrealized Gain (Loss) on Derivatives		$ 7
Open Forward Foreign Currency Contract, Identifier [Axis]: Foreign currency forward contract with settlement date 7/18/2023
Open Forward Foreign Currency Contract [Line Items]
Derivative Asset, Notional Amount	$ 107	$ 107
Derivative Liability, Notional Amount			$ 138	$ 138
Derivative Asset, Counterparty Name [Extensible Enumeration]	mrcc:BannockburnGlobalForexLlcMember	mrcc:BannockburnGlobalForexLlcMember	mrcc:BannockburnGlobalForexLlcMember	mrcc:BannockburnGlobalForexLlcMember	mrcc:BannockburnGlobalForexLlcMember
Derivative, Maturity Date	Jul. 18, 2023	Jul. 18, 2023
Unrealized Gain (Loss) on Derivatives	$ 12	$ 6
Open Forward Foreign Currency Contract, Identifier [Axis]: Foreign currency forward contract with settlement date 8/16/2022
Open Forward Foreign Currency Contract [Line Items]
Derivative Asset, Notional Amount		$ 108
Derivative Liability, Notional Amount				$ 140
Derivative Asset, Counterparty Name [Extensible Enumeration]		mrcc:BannockburnGlobalForexLlcMember		mrcc:BannockburnGlobalForexLlcMember	mrcc:BannockburnGlobalForexLlcMember
Derivative, Maturity Date		Aug. 16, 2022
Unrealized Gain (Loss) on Derivatives		$ 7
Open Forward Foreign Currency Contract, Identifier [Axis]: Foreign currency forward contract with settlement date 8/16/2023
Open Forward Foreign Currency Contract [Line Items]
Derivative Asset, Notional Amount	$ 113	$ 113
Derivative Liability, Notional Amount			$ 146	$ 146
Derivative Asset, Counterparty Name [Extensible Enumeration]	mrcc:BannockburnGlobalForexLlcMember	mrcc:BannockburnGlobalForexLlcMember	mrcc:BannockburnGlobalForexLlcMember	mrcc:BannockburnGlobalForexLlcMember	mrcc:BannockburnGlobalForexLlcMember
Derivative, Maturity Date	Aug. 16, 2023	Aug. 16, 2023
Unrealized Gain (Loss) on Derivatives	$ 13	$ 6
Open Forward Foreign Currency Contract, Identifier [Axis]: Foreign currency forward contract with settlement date 9/16/2022
Open Forward Foreign Currency Contract [Line Items]
Derivative Asset, Notional Amount		$ 118
Derivative Liability, Notional Amount				$ 153
Derivative Asset, Counterparty Name [Extensible Enumeration]		mrcc:BannockburnGlobalForexLlcMember		mrcc:BannockburnGlobalForexLlcMember	mrcc:BannockburnGlobalForexLlcMember
Derivative, Maturity Date		Sep. 16, 2022
Unrealized Gain (Loss) on Derivatives		$ 7
Open Forward Foreign Currency Contract, Identifier [Axis]: Foreign currency forward contract with settlement date 9/18/2023
Open Forward Foreign Currency Contract [Line Items]
Derivative Asset, Notional Amount	$ 113	$ 113
Derivative Liability, Notional Amount			$ 146	$ 146
Derivative Asset, Counterparty Name [Extensible Enumeration]	mrcc:BannockburnGlobalForexLlcMember	mrcc:BannockburnGlobalForexLlcMember	mrcc:BannockburnGlobalForexLlcMember	mrcc:BannockburnGlobalForexLlcMember	mrcc:BannockburnGlobalForexLlcMember
Derivative, Maturity Date	Sep. 18, 2023	Sep. 18, 2023
Unrealized Gain (Loss) on Derivatives	$ 13	$ 6

CONSOLIDATED SCHEDULE OF INVE_3

CONSOLIDATED SCHEDULE OF INVESTMENTS (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
CONSOLIDATED SCHEDULE OF INVESTMENTS
Company investments as percentage of net assets		225.20%
Company investments as percentage of total assets		95.10%
Net assets	$ 225,019	$ 249,471	$ 234,434
Qualifying assets as percentage of total assets	70%
Non-qualifying assets as percentage of total assets		22.50%
Equity contribution	$ 4,758
IDIG Parent, LLC
CONSOLIDATED SCHEDULE OF INVESTMENTS
Commitment to fund equity investment	43	$ 43
Recorded Future, Inc.
CONSOLIDATED SCHEDULE OF INVESTMENTS
Commitment to fund equity investment	$ 16	16
Familia Dental Group Holdings, LLC
CONSOLIDATED SCHEDULE OF INVESTMENTS
Company investments as percentage of net assets	240.40%
Company investments as percentage of total assets	95.80%
Net assets	$ 225,019
Qualifying assets as percentage of total assets	70%
Non-qualifying assets as percentage of total assets	24.70%
Commitment to fund equity investment	$ 183	428
Monroe Capital Corporation SBIC, LP
CONSOLIDATED SCHEDULE OF INVESTMENTS
Amount of not collateral revolving credit facility	$ 4,226
Toojay's NewCo.
CONSOLIDATED SCHEDULE OF INVESTMENTS
Fair market value of loans		$ 0
Percentage of equity interest of parent	15.90%
Portion of credit bid	$ 2,386
MC Asset Management (Corporate), LLC ("Corporate")
CONSOLIDATED SCHEDULE OF INVESTMENTS
Percentage of equity interest of parent	15.90%
MC Asset Management (Corporate), LLC ("Corporate") | MC Asset Management (Corporate), LLC ("Corporate")
CONSOLIDATED SCHEDULE OF INVESTMENTS
Percentage of equity interest of parent			15.90%
MC Asset Management (Industrial), LLC ("Industrial"). | MC Asset Management (Corporate), LLC ("Corporate")
CONSOLIDATED SCHEDULE OF INVESTMENTS
Percentage of equity interest of parent	100%		100%
HFZ Capital Group LLC
CONSOLIDATED SCHEDULE OF INVESTMENTS
Equity contribution			$ 4,758
Vinci Brands LLC Fka Incipio, LLC Loan, Two | Monroe Capital Corporation SBIC, LP
CONSOLIDATED SCHEDULE OF INVESTMENTS
Amount of not collateral revolving credit facility	$ 54
Vinci Brands LLC Fka Incipio, LLC Loan, Three | Monroe Capital Corporation SBIC, LP
CONSOLIDATED SCHEDULE OF INVESTMENTS
Amount of not collateral revolving credit facility	4,969
Vinci Brands LLC Fka Incipio, LLC Loan, Four | Monroe Capital Corporation SBIC, LP
CONSOLIDATED SCHEDULE OF INVESTMENTS
Amount of not collateral revolving credit facility	421
Priority Ambulance, LLC, Loan, One | Monroe Capital Corporation SBIC, LP
CONSOLIDATED SCHEDULE OF INVESTMENTS
Amount of not collateral revolving credit facility	9,258
Priority Ambulance, LLC, Loan, Two | Monroe Capital Corporation SBIC, LP
CONSOLIDATED SCHEDULE OF INVESTMENTS
Amount of not collateral revolving credit facility	525
Curion Holdings, LLC
CONSOLIDATED SCHEDULE OF INVESTMENTS
Equity contribution	$ 0

Organization and Principal Busi

Organization and Principal Business	12 Months Ended
	Dec. 31, 2022
Organization and Principal Business
Organization and Principal Business	Note 1. Organization and Principal Business Monroe Capital Corporation (together with its subsidiaries, the “Company”) is an externally managed, non-diversified, closed-end management investment company and has elected to be regulated as a business development company (“BDC”) under the Investment Company Act of 1940, as amended (the “1940 Act”). The Company’s investment objective is to maximize the total return to its stockholders in the form of current income and capital appreciation through investment in senior secured, junior secured and unitranche secured (a combination of senior secured and junior secured debt in the same facility in which the Company syndicates a “first out” portion of the loan to an investor and retains a “last out” portion of the loan) debt and, to a lesser extent, unsecured subordinated debt and equity co-investments in preferred and common stock and warrants. The Company is managed by Monroe Capital BDC Advisors, LLC (“MC Advisors”), a registered investment adviser under the Investment Advisers Act of 1940, as amended. In addition, for U.S. federal income tax purposes, the Company has elected to be treated as a regulated investment company (“RIC”) under Subchapter M of the Internal Revenue Code of 1986, as amended (the “Code”). On February 28, 2014, the Company’s wholly-owned subsidiary, Monroe Capital Corporation SBIC, LP (“MRCC SBIC”), a Delaware limited partnership, received a license from the Small Business Administration (“SBA”) to operate as a Small Business Investment Company (“SBIC”) under Section 301(c) of the Small Business Investment Act of 1958, as amended. MRCC SBIC commenced operations on September 16, 2013. MRCC SBIC received approval from the SBA to surrender its SBIC license and on March 31, 2022, MRCC SBIC was dissolved. See Note 7 for additional information.

Summary of Significant Accounti

Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2022
Summary of Significant Accounting Policies
Summary of Significant Accounting Policies	Note 2. Summary of Significant Accounting Policies Basis of Presentation The accompanying consolidated financial statements of the Company have been prepared in accordance with generally accepted accounting principles in the United States of America (“GAAP”). The accompanying consolidated financial statements of the Company and related financial information have been prepared pursuant to the requirements for reporting on Form 10-K and Articles 6 and 10 of Regulation S-X. The Company has determined it meets the definition of an investment company and follows the accounting and reporting guidance in the Financial Accounting Standards Board (“FASB”) Accounting Standards Codification (“ASC”) Topic 946 – Financial Services – Investment Companies Use of Estimates The preparation of the consolidated financial statements in conformity with GAAP requires the Company to make estimates and assumptions that affect the reported amounts of assets and liabilities and the disclosure of contingent assets and liabilities as of the date of the consolidated financial statements and the reported amounts of revenue and expenses during the reporting period. Actual results could differ from those estimates. Consolidation As permitted under ASC Topic 946, the Company will generally not consolidate its investment in a portfolio company other than an investment company subsidiary or a controlled operating company whose business consists of providing services to the Company. Accordingly, the Company consolidated the results of the Company’s wholly-owned subsidiaries, including MRCC SBIC (through its dissolution date) and its wholly-owned general partner MCC SBIC GP, LLC, and the Company’s wholly-owned taxable subsidiaries (the “Taxable Subsidiaries”) in its consolidated financial statements. The purpose of the Taxable Subsidiaries is to permit the Company to hold equity investments in portfolio companies that are taxed as partnerships for U.S. federal income tax purposes while complying with the “source of income” requirements contained in the RIC tax provisions. The Taxable Subsidiaries are not consolidated with the Company for U.S. federal corporate income tax purposes, and each Taxable Subsidiary is subject to U.S. federal corporate income tax on its taxable income. All intercompany balances and transactions have been eliminated. The Company does not consolidate its non-controlling interest in MRCC Senior Loan Fund I, LLC (“SLF”). See further description of the Company’s investment in SLF in Note 3. Fair Value of Financial Instruments The Company applies fair value to substantially all of its financial instruments in accordance with ASC Topic 820 — Fair Value Measurements and Disclosures ASC Topic 820 requires disclosure of the fair value of financial instruments for which it is practical to estimate such value. The Company believes that the carrying amounts of its other financial instruments such as cash, receivables and payables approximate the fair value of such items due to the short maturity of such instruments. Revenue Recognition The Company’s revenue recognition policies are as follows: Investments and related investment income: Dividend income on preferred equity securities is recorded as dividend income on an accrual basis to the extent that such amounts are payable by the portfolio company and are expected to be collected. Dividend income on common equity securities is recorded on the record date for private portfolio companies. Each distribution received from limited liability company (“LLC”) and limited partnership (“LP”) investments is evaluated to determine if the distribution should be recorded as dividend income or a return of capital. Generally, the Company will not record distributions from equity investments in LLCs and LPs as dividend income unless there are sufficient accumulated tax-basis earnings and profits in the LLC or LP prior to the applicable distribution. Distributions that are classified as a return of capital are recorded as a reduction in the cost basis of the investment. For the years ended December 31, 2022, 2021 and 2020, the Company received return of capital distributions from its equity investments of $290, $1,177 and zero, respectively. The Company has certain investments in its portfolio that contain a payment-in-kind (“PIK”) provision, which represents contractual interest or dividends that are added to the principal balance and recorded as income. The Company stops accruing PIK interest or PIK dividends when it is determined that PIK interest or PIK dividends are no longer collectible. To maintain RIC tax treatment, and to avoid incurring corporate U.S. federal income tax, substantially all of this income must be paid out to stockholders in the form of distributions, even though the Company has not yet collected the cash. Loan origination fees, original issue discount and market discount or premiums are capitalized, and the Company then amortizes such amounts using the effective interest method as interest income over the life of the investment. Unamortized discounts and loan origination fees totaled $4,701 and $4,370 as of December 31, 2022 and 2021, respectively. Upfront loan origination and closing fees received for the years ended December 31, 2022, 2021 and 2020 totaled $3,475, $3,752 and $1,909, respectively. Upon the prepayment of a loan or debt security, any unamortized premium or discount or loan origination fees are recorded as interest income. The components of the Company’s investment income were as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ For the years ended December 31, ​ 2022 2021 2020 Interest income ​ $ 41,449 ​ $ 35,738 ​ $ 42,640 PIK interest income ​ 6,689 ​ 8,320 ​ ​ 8,776 Dividend income (1) ​ 4,161 ​ 5,712 ​ ​ 4,557 Fee income ​ 2,380 ​ 1,267 ​ ​ 3,222 Prepayment gain (loss) ​ 803 ​ 1,691 ​ ​ 1,133 Accretion of discounts and amortization of premium ​ 1,084 ​ 1,102 ​ ​ 1,253 Total investment income ​ $ 56,566 ​ $ 53,830 ​ $ 61,581 (1) During the years ended December 31, 2022, 2021 and 2020, includes PIK dividends of $475 , $1,164 and $157 , respectively. Investment transactions are recorded on a trade-date basis. Realized gains or losses on portfolio investments are calculated based upon the difference between the net proceeds from the disposition and the amortized cost basis of the investment, without regard to unrealized gains or losses previously recognized. Realized gains and losses are recorded within net realized gain (loss) on investments on the consolidated statements of operations. Changes in the fair value of investments from the prior period, as determined through the application of the Company’s valuation policy, are included within net change in unrealized gain (loss) on investments on the consolidated statements of operations. Non-accrual: Distributions Distributions to common stockholders are recorded on the applicable record date. The amount, if any, to be distributed to common stockholders is determined by the Company’s board of directors (the “Board”) each quarter and is generally based upon the Company’s earnings estimated by management. Net realized capital gains, if any, are generally distributed at least annually. The determination of the tax attributes for the Company’s distributions is made annually, based upon its taxable income for the full year and distributions paid for the full year. Ordinary dividend distributions from a RIC do not qualify for the preferential tax rate on qualified dividend income from domestic corporations and qualified foreign corporations, except to the extent that the RIC received the income in the form of qualifying dividends from domestic corporations and qualified foreign corporations. The tax attributes for distributions will generally include both ordinary income and capital gains, but may also include qualified dividends or return of capital. In October 2012, the Company adopted a dividend reinvestment plan (“DRIP”) that provides for the reinvestment of dividends on behalf of its stockholders, unless a stockholder has elected to receive dividends in cash. When the Company declares a cash dividend, the Company’s stockholders who have not “opted out” of the DRIP at least three days prior to the dividend payment date will have their cash dividend automatically reinvested into additional shares of the Company’s common stock. The Company has the option to satisfy the share requirements of the DRIP through the issuance of new shares of common stock or through open market purchases of common stock by the DRIP plan administrator. Newly issued shares are valued based upon the final closing price of the Company’s common stock on a date determined by the Board. Shares purchased in the open market to satisfy the DRIP requirements will be valued based upon the average price of the applicable shares purchased by the DRIP plan administrator, before any associated brokerage or other costs. See Note 10 for additional information on the Company’s distributions. Segments In accordance with ASC Topic 280 — Segment Reporting Cash The Company deposits its cash in a financial institution and, at times, such balances may be in excess of the Federal Deposit Insurance Corporation insurance limits. Restricted Cash Restricted cash included amounts held within MRCC SBIC. Cash held within an SBIC is generally restricted to the originations of new loans from the SBIC and the payment of SBA debentures and related interest expense. Unamortized Deferred Financing Costs Deferred financing costs represent fees and other direct incremental costs incurred in connection with the Company's borrowings. As of December 31, 2022 and 2021, the Company had unamortized deferred financing costs of $4,486 and $5,794, respectively, presented as a direct reduction of the carrying amount of debt on the consolidated statements of assets and liabilities. These amounts are amortized and included in interest and other debt financing expenses on the consolidated statements of operations over the estimated average life of the borrowings. Amortization of deferred financing costs for the years ended December 31, 2022, 2021 and 2020 was $2,126, $2,205 and $2,181, respectively. Offering Costs Offering costs include, among other things, fees paid in relation to legal, accounting, regulatory and printing work completed in preparation of debt and equity offerings. Offering costs from equity offerings are charged against the proceeds from the offering within the consolidated statements of changes in net assets. Offering costs from debt offerings are reclassified to unamortized deferred financing costs on the consolidated statements of assets and liabilities as noted above. As of December 31, 2022 and 2021, other assets on the consolidated statements of assets and liabilities included $184 and $123 of deferred offering costs, respectively, which will be charged against the proceeds from future debt or equity offerings when completed. Investments Denominated in Foreign Currency As of December 31, 2022, the Company held investments in one portfolio company that was denominated in Australian dollars. As of December 31, 2021, the Company held investments in one portfolio company that was denominated in Great Britain pounds and one portfolio company that was denominated in Australian dollars. At each balance sheet date, portfolio company investments denominated in foreign currencies are translated into U.S. dollars using the spot exchange rate on the last business day of the period. Purchases and sales of foreign portfolio company investments, and any income from such investments, are translated into U.S. dollars using the rates of exchange prevailing on the respective dates of such transactions. Although the fair values of foreign portfolio company investments and the fluctuation in such fair values are translated into U.S. dollars using the applicable foreign exchange rates described above, the Company does not isolate the portion of the change in fair value resulting from foreign currency exchange rates fluctuations from the change in fair value of the underlying investment. All fluctuations in fair value are included in net change in unrealized gain (loss) on investments on the Company’s consolidated statements of operations. Investments denominated in foreign currencies and foreign currency transactions may involve certain consideration and risks not typically associated with those of domestic origin, including unanticipated movements in the value of the foreign currency relative to the U.S. dollar. Derivative Instruments The Company may enter into foreign currency forward contracts to reduce the Company’s exposure to foreign currency exchange rate fluctuations. In a foreign currency forward contract, the Company agrees to receive or deliver a fixed quantity of one currency for another, at a pre-determined price at a future date. Foreign currency forward contracts are marked-to-market based on the difference between the forward rate and the exchange rate at the current period end. Unrealized gain (loss) on foreign currency forward contracts are recorded on the Company’s consolidated statements of assets and liabilities by counterparty on a net basis. The Company does not utilize hedge accounting and as such values its foreign currency forward contracts at fair value with the change in unrealized gain or loss recorded in net change in unrealized gain (loss) on foreign currency forward contracts and the realized gain or loss recorded in net realized gain (loss) on foreign currency forward contracts on the Company’s consolidated statements of operations. Income Taxes The Company has elected to be treated as a RIC under Subchapter M of the Code and operates in a manner so as to qualify for the tax treatment available to RICs. To maintain qualification as a RIC, the Company must, among other things, meet certain source-of-income and asset diversification requirements and distribute to stockholders, for each taxable year, at least 90% of the Company’s “investment company taxable income,” which is generally the Company’s net ordinary income plus the excess, if any, of realized net short-term capital gains over realized net long-term capital losses. If the Company qualifies as a RIC and satisfies the annual distribution requirement, the Company will not have to pay corporate-level federal income taxes on any income that the Company distributes to its stockholders. The Company intends to make distributions in an amount sufficient to maintain RIC status each year and to avoid any federal income taxes on income. The Company is also subject to nondeductible federal excise taxes if the Company does not distribute at least 98% of net ordinary income, 98.2% of any capital gain net income, if any, and any recognized and undistributed income from prior years for which it paid no federal income taxes. To the extent that the Company determines that its estimated current year annual taxable income may exceed estimated current year dividend distributions, the Company accrues excise tax, calculated as 4% of the estimated excess taxable income, if any, as taxable income is earned. For the years ended December 31, 2022, 2021 and 2020, the Company recorded a net expense (benefit) on the consolidated statements of operations of $94, $278, and $368, respectively, for U.S. federal excise tax. As of December 31, 2022 and 2021, the Company had payables for excise taxes of $1 and $183, respectively, which were included in accounts payable and accrued expenses on the Company’s consolidated statements of assets and liabilities. The Company’s consolidated Taxable Subsidiaries may be subject to U.S. federal and state corporate-level income taxes. For the years ended December 31, 2022, 2021 and 2020, the Company recorded a net tax expense of $1,311, $4 and $2, respectively, on the consolidated statements of operations for these subsidiaries. As of both December 31, 2022 and December 31, 2021, the Company did not have any payables for corporate-level income taxes. The Company accounts for income taxes in conformity with ASC Topic 740 — Income Taxes Subsequent Events The Company has evaluated the need for disclosures and/or adjustments resulting from subsequent events through the date the consolidated financial statements were issued. There have been no subsequent events that occurred during such period that would require disclosure in this Form 10-K or would be required to be recognized in the consolidated financial statements as of and for the year ended December 31, 2022, except as disclosed in Note 14. Recent Accounting Pronouncements In March 2020, the FASB issued ASU 2020-04, Reference Rate Reform

Investments

Investments	12 Months Ended
	Dec. 31, 2022
Investments
Investments	Note 3. Investments The following tables show the composition of the Company’s investment portfolio, at amortized cost and fair value (with corresponding percentage of total portfolio investments): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, 2022 ​ December 31, 2021 Amortized Cost: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Senior secured loans $ 436,066 75.3 % $ 415,600 72.1 % Unitranche secured loans ​ 45,352 7.8 ​ 70,977 12.3 ​ Junior secured loans ​ 21,141 3.6 ​ 14,317 2.5 ​ LLC equity interest in SLF ​ 42,650 7.4 ​ 42,150 7.3 ​ Equity securities ​ 34,098 5.9 ​ 33,134 5.8 ​ Total ​ $ 579,307 100.0 % $ 576,178 100.0 % ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, 2022 ​ December 31, 2021 Fair Value: ​ ​ ​ Senior secured loans ​ $ 434,023 80.2 % $ 423,700 75.4 % Unitranche secured loans ​ 20,633 3.8 ​ 51,494 9.2 ​ Junior secured loans ​ 22,193 4.1 ​ 14,364 2.6 ​ LLC equity interest in SLF ​ 35,509 6.6 ​ 41,125 7.3 ​ Equity securities ​ 28,682 5.3 ​ 31,010 5.5 ​ Total ​ $ 541,040 100.0 % $ 561,693 100.0 % ​ The following tables show the composition of the Company’s investment portfolio by geographic region, at amortized cost and fair value (with corresponding percentage of total portfolio investments). The geographic composition is determined by the location of the corporate headquarters of the portfolio company, which may not be indicative of the primary source of the portfolio company’s business: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, 2022 ​ December 31, 2021 Amortized Cost: ​ ​ ​ International ​ $ 11,860 2.1 % $ 11,860 2.0 % Midwest ​ 157,558 27.2 ​ 145,023 25.2 ​ Northeast ​ 100,961 17.4 ​ 107,828 18.7 ​ Southeast ​ 158,548 27.4 ​ 164,100 28.5 ​ Southwest ​ 27,348 4.7 ​ 40,121 7.0 ​ West ​ 123,032 21.2 ​ 107,246 18.6 ​ Total ​ $ 579,307 100.0 % $ 576,178 100.0 % ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, 2022 ​ December 31, 2021 Fair Value: ​ ​ ​ International ​ $ 10,405 1.9 % $ 11,093 2.0 % Midwest ​ 143,691 26.6 ​ 143,435 25.5 ​ Northeast ​ 104,157 19.2 ​ 112,175 20.0 ​ Southeast ​ 155,624 28.8 ​ 159,807 28.4 ​ Southwest ​ 28,287 5.2 ​ 44,380 7.9 ​ West ​ 98,876 18.3 ​ 90,803 16.2 ​ Total ​ $ 541,040 100.0 % $ 561,693 100.0 % ​ The following tables show the composition of the Company’s investment portfolio by industry, at amortized cost and fair value (with corresponding percentage of total portfolio investments): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, 2022 ​ December 31, 2021 Amortized Cost: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Aerospace & Defense $ 7,461 1.3 % $ 7,828 1.4 % Automotive ​ 16,775 2.9 ​ 21,162 3.7 ​ Banking ​ 17,790 3.1 ​ 5,416 1.0 ​ Beverage, Food & Tobacco ​ 15,625 2.7 ​ 21,036 3.7 ​ Capital Equipment ​ 18,615 3.2 ​ 12,656 2.2 ​ Chemicals, Plastics & Rubber ​ 2,924 0.5 ​ 9,426 1.6 ​ Construction & Building ​ 6,642 1.1 ​ 16,450 2.9 ​ Consumer Goods: Durable ​ 9,333 1.6 ​ 9,536 1.7 ​ Consumer Goods: Non-Durable ​ 28,276 4.9 ​ 28,232 4.9 ​ Environmental Industries ​ 6,164 1.1 ​ 17,103 3.0 ​ FIRE: Finance ​ 25,021 4.3 ​ 16,264 2.8 ​ FIRE: Real Estate ​ 81,922 14.1 ​ 72,826 12.6 ​ Healthcare & Pharmaceuticals ​ 59,659 10.3 ​ 52,743 9.2 ​ High Tech Industries ​ 52,385 9.0 ​ 52,710 9.1 ​ Hotels, Gaming & Leisure ​ 2,702 0.5 ​ 2,662 0.5 ​ Investment Funds & Vehicles ​ 42,650 7.4 ​ 42,150 7.3 ​ Media: Advertising, Printing & Publishing ​ 17,470 3.0 ​ 13,421 2.3 ​ Media: Broadcasting & Subscription ​ 2,747 0.5 ​ 2,472 0.4 ​ Media: Diversified & Production ​ 36,018 6.2 ​ 23,853 4.1 ​ Retail ​ 9,247 1.6 ​ 10,954 1.9 ​ Services: Business ​ 56,249 9.7 ​ 69,292 12.0 ​ Services: Consumer ​ 40,086 6.9 ​ 46,284 8.0 ​ Telecommunications ​ 7,502 1.3 ​ 5,892 1.0 ​ Wholesale ​ 16,044 2.8 ​ 15,810 2.7 ​ Total ​ $ 579,307 100.0 % $ 576,178 100.0 % ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, 2022 ​ December 31, 2021 Fair Value: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Aerospace & Defense $ 7,436 1.4 % $ 7,972 1.4 % Automotive ​ 16,637 3.1 ​ 21,556 3.8 ​ Banking ​ 19,817 3.7 ​ 6,712 1.2 ​ Beverage, Food & Tobacco ​ 12,470 2.3 ​ 19,133 3.4 ​ Capital Equipment ​ 19,012 3.5 ​ 12,839 2.3 ​ Chemicals, Plastics & Rubber ​ 4,445 0.8 ​ 10,163 1.8 ​ Construction & Building ​ 6,706 1.2 ​ 16,636 3.0 ​ Consumer Goods: Durable ​ 9,338 1.7 ​ 9,734 1.7 ​ Consumer Goods: Non-Durable ​ 3,508 0.6 ​ 8,460 1.5 ​ Environmental Industries ​ 6,558 1.2 ​ 17,693 3.2 ​ FIRE: Finance ​ 23,892 4.4 ​ 15,681 2.8 ​ FIRE: Real Estate ​ 82,498 15.2 ​ 76,698 13.6 ​ Healthcare & Pharmaceuticals ​ 59,273 11.0 ​ 53,179 9.5 ​ High Tech Industries ​ 52,891 9.8 ​ 54,085 9.6 ​ Hotels, Gaming & Leisure ​ 2,720 0.5 ​ 2,706 0.5 ​ Investment Funds & Vehicles ​ 35,509 6.6 ​ 41,125 7.3 ​ Media: Advertising, Printing & Publishing ​ 19,777 3.7 ​ 16,794 3.0 ​ Media: Broadcasting & Subscription ​ 2,691 0.5 ​ 2,477 0.5 ​ Media: Diversified & Production ​ 36,164 6.7 ​ 24,220 4.3 ​ Retail ​ 9,306 1.7 ​ 11,478 2.0 ​ Services: Business ​ 57,308 10.6 ​ 71,540 12.7 ​ Services: Consumer ​ 31,324 5.8 ​ 39,248 7.0 ​ Telecommunications ​ 7,595 1.4 ​ 5,988 1.1 ​ Wholesale ​ 14,165 2.6 ​ 15,576 2.8 ​ Total ​ $ 541,040 100.0 % $ 561,693 100.0 % ​ MRCC Senior Loan Fund I, LLC The Company co-invests with Life Insurance Company of the Southwest (“LSW”) in senior secured loans through SLF, an unconsolidated Delaware LLC. SLF is capitalized as underlying investment transactions are completed, taking into account available debt and equity commitments available for funding these investments. All portfolio and investment decisions in respect to SLF must be approved by the SLF investment committee, consisting of one representative from the Company and one representative from LSW. SLF may cease making new investments upon notification of either member but operations will continue until all investments have been sold or paid-off in the normal course of business. Investments held by SLF are measured at fair value using the same valuation methodologies as described in Note 4. The Company’s investment is illiquid in nature as SLF does not allow for withdrawal from the LLC or the sale of a member’s interest unless approved by the board members of SLF. The full withdrawal of a member would result in an orderly wind-down of SLF. SLF’s profits and losses are allocated to the Company and LSW in accordance with their respective ownership interests. As of both December 31, 2022 and December 31, 2021, the Company and LSW each owned 50.0% of the LLC equity interests of SLF. As of both December 31, 2022 and December 31, 2021, SLF had $100,000 in equity commitments from its members (in the aggregate), of which $85,300 and $84,300 was funded, respectively. As of both December 31, 2022 and December 31, 2021, the Company had committed to fund $50,000 of LLC equity interest subscriptions to SLF. As of December 31, 2022 and December 31, 2021, $42,650 and $42,150 of the Company's LLC equity interest subscriptions to SLF had been called and contributed, net of return of capital distributions subject to recall, respectively. For the years ended December 31, 2022, 2021 and 2020, the Company received $3,600, $4,325 and $4,400 of dividend income from its LLC equity interest in SLF, respectively. SLF has a senior secured revolving credit facility (as amended, the “SLF Credit Facility”) with Capital One, N.A., through its wholly-owned subsidiary MRCC Senior Loan Fund I Financing SPV, LLC (“SLF SPV”). The SLF Credit Facility allows SLF SPV to borrow up to $175,000, subject to leverage and borrowing base restrictions. Borrowings on the SLF Credit Facility bear interest at an annual rate of LIBOR (three-month) plus 2.10% and the SLF Credit Facility has a maturity date of November 23, 2031. SLF does not pay any fees to MC Advisors or its affiliates; however, SLF has entered into an administration agreement with Monroe Capital Management Advisors, LLC (“MC Management”), pursuant to which certain loan servicing and administrative functions are delegated to MC Management. SLF may reimburse MC Management for its allocable share of overhead and other expenses incurred by MC Management. For the years ended December 31, 2022, 2021, and 2020, SLF incurred $237, $211, and $209, of allocable expenses, respectively. There are no agreements or understandings by which the Company guarantees any SLF obligations. As of December 31, 2022 and December 31, 2021, SLF had total assets at fair value of $192,830 and $194,623, respectively. As of both December 31, 2022 and December 31, 2021, SLF had one portfolio company investment on non-accrual status with a fair value of $415 and $1,072, respectively. The portfolio companies in SLF are in industries and geographies similar to those in which the Company may invest directly. Additionally, as of December 31, 2022 and December 31, 2021, SLF had $4,579 and $2,061, respectively, in outstanding commitments to fund investments under undrawn revolvers and delayed draw commitments. Below is a summary of SLF’s portfolio, followed by a listing of the individual investments in SLF’s portfolio as of December 31, 2022 and 2021: ​ ​ ​ ​ ​ ​ ​ ​ As of ​ ​ December 31, 2022 ​ December 31, 2021 Senior secured loans (1) 197,867 193,062 ​ Weighted average current interest rate on senior secured loans (2) 9.7 % 5.9 % Number of portfolio company investments in SLF 60 57 ​ Largest portfolio company investment (1) 6,650 6,720 ​ Total of five largest portfolio company investments (1) 27,026 27,074 ​ (1) Represents outstanding principal amount, excluding unfunded commitments. (2) Computed as the (a) annual stated interest rate on accruing senior secured loans divided by (b) total senior secured loans at outstanding principal amount. ​ MRCC SENIOR LOAN FUND I, LLC CONSOLIDATED SCHEDULE OF INVESTMENTS December 31, 2022 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Portfolio Company (a) Index (b) Spread (b) Interest Rate (b) Maturity Principal Fair Value Non-Controlled/Non-Affiliate Company Investments ​ ​ Senior Secured Loans ​ ​ Aerospace & Defense ​ ​ ​ Bromford Industries Limited (c) P 5.25 % 12.75 % ​ 11/5/2025 2,744 ​ $ 2,581 Bromford Industries Limited (c) P 5.25 % 12.75 % ​ 11/5/2025 1,829 ​ 1,720 Trident Maritime Systems, Inc. L 4.75 % 9.48 % ​ 2/26/2027 2,445 ​ 2,443 Trident Maritime Systems, Inc. L 4.75 % 9.48 % ​ 2/26/2027 746 ​ 746 Trident Maritime Systems, Inc. (Revolver) (d) L 4.75 % 9.08 % ​ 2/26/2027 319 ​ 122 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 8,083 ​ 7,612 Automotive ​ ​ ​ Accelerate Auto Works Intermediate, LLC L 4.50 % 9.23 % ​ 12/1/2027 1,391 ​ 1,386 Accelerate Auto Works Intermediate, LLC (Delayed Draw) (d) L 4.50 % 9.23 % ​ 12/1/2027 388 ​ — Accelerate Auto Works Intermediate, LLC (Revolver) (d) L 4.50 % 9.23 % ​ 12/1/2027 132 ​ — Truck-Lite Co., LLC SF 6.25 % 11.14 % ​ 12/14/2026 1,691 ​ 1,690 Truck-Lite Co., LLC SF 6.25 % 11.14 % ​ 12/14/2026 251 ​ 250 Truck-Lite Co., LLC SF 6.25 % 11.14 % ​ 12/14/2026 43 ​ 43 Wheel Pros, Inc. L 4.50 % 8.82 % ​ 5/11/2028 1,932 ​ 1,321 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 5,828 ​ 4,690 Beverage, Food & Tobacco ​ ​ ​ CBC Restaurant Corp. n/a n/a 5.00 % PIK (e) n/a (f) 1,066 ​ 415 SW Ingredients Holdings, LLC L 4.75 % 9.13 % ​ 7/3/2025 3,581 ​ 3,581 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 4,647 ​ 3,996 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Portfolio Company (a) Index (b) Spread (b) Interest Rate (b) Maturity Principal Fair Value Capital Equipment ​ Analogic Corporation L 5.25 % 9.66 % 6/24/2024 4,703 ​ $ 4,433 DS Parent, Inc. L 5.75 % 9.92 % 12/8/2028 2,850 ​ 2,725 MacQueen Equipment, LLC L 5.25 % 9.98 % 1/7/2028 2,096 ​ 2,096 MacQueen Equipment, LLC (Delayed Draw) (d) L 5.25 % 9.98 % 1/7/2028 592 ​ 69 MacQueen Equipment, LLC (Revolver) (d) L 5.25 % 9.98 % 1/7/2028 296 ​ — ​ ​ ​ ​ ​ ​ ​ ​ ​ 10,537 ​ 9,323 Chemicals, Plastics & Rubber ​ ​ Phoenix Chemical Holding Company LLC (fka Polymer Solutions Group) L 7.00 % 11.39 % 6/15/2023 1,139 ​ 1,132 TJC Spartech Acquisition Corp. L 4.75 % 8.53 % 5/5/2028 4,253 ​ 4,131 ​ ​ ​ ​ ​ ​ ​ ​ ​ 5,392 ​ 5,263 Construction & Building ​ ​ The Cook & Boardman Group LLC SF 5.75 % 9.99 % 10/20/2025 2,879 ​ 2,458 ​ ​ ​ ​ ​ ​ ​ ​ ​ 2,879 ​ 2,458 Consumer Goods: Durable ​ ​ International Textile Group, Inc. L 5.00 % 9.21 % 5/1/2024 1,664 ​ 1,166 Runner Buyer INC. L 5.50 % 10.23 % 10/23/2028 2,978 ​ 2,114 ​ ​ ​ ​ ​ ​ ​ ​ ​ 4,642 ​ 3,280 Consumer Goods: Non-Durable ​ ​ PH Beauty Holdings III, INC. L 5.00 % 9.73 % 9/26/2025 2,393 ​ 1,950 ​ ​ ​ ​ ​ ​ ​ ​ ​ 2,393 ​ 1,950 Containers, Packaging & Glass ​ ​ Liqui-Box Holdings, Inc. L 4.50 % 9.23 % 2/26/2027 4,225 ​ 4,186 Polychem Acquisition, LLC L 5.00 % 9.38 % 3/17/2025 2,888 ​ 2,888 PVHC Holding Corp L 4.75 % 9.48 % 8/5/2024 3,184 ​ 3,072 ​ ​ ​ ​ ​ ​ ​ ​ ​ 10,297 ​ 10,146 Energy: Oil & Gas ​ ​ Drilling Info Holdings, Inc. L 4.25 % 8.63 % 7/30/2025 4,469 ​ 4,313 Offen, Inc. L 5.00 % 9.38 % 6/22/2026 2,249 ​ 2,249 Offen, Inc. L 5.00 % 9.38 % 6/22/2026 867 ​ 867 ​ ​ ​ ​ ​ ​ ​ ​ ​ 7,585 ​ 7,429 ​ ​ MRCC SENIOR LOAN FUND I, LLC CONSOLIDATED SCHEDULE OF INVESTMENTS - (continued) December 31, 2022 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Portfolio Company (a) Index (b) Spread (b) Interest Rate (b) Maturity Principal Fair Value FIRE: Finance ​ ​ Harbour Benefit Holdings, Inc. L 5.25 % 9.98 % ​ 12/13/2024 2,901 ​ $ 2,898 Harbour Benefit Holdings, Inc. L 5.25 % 9.63 % ​ 12/13/2024 61 ​ 61 Minotaur Acquisition, Inc. SF 4.75 % 9.17 % ​ 3/27/2026 4,857 ​ 4,656 TEAM Public Choices, LLC L 5.00 % 9.93 % ​ 12/17/2027 2,955 ​ 2,822 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 10,774 ​ 10,437 FIRE: Real Estate ​ ​ ​ Avison Young (USA) Inc. (c) SF 5.75 % 10.19 % ​ 1/30/2026 4,800 ​ 4,020 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 4,800 ​ 4,020 Healthcare & Pharmaceuticals ​ ​ ​ Cano Health, LLC SF 4.00 % 8.42 % ​ 11/23/2027 1,970 ​ 1,572 HAH Group Holding Company LLC SF 5.00 % 9.43 % ​ 10/29/2027 2,978 ​ 2,847 LSCS Holdings, Inc. L 4.50 % 8.88 % ​ 12/15/2028 1,828 ​ 1,751 Natus Medical Incorporated SF 5.50 % 8.68 % ​ 7/20/2029 5,000 ​ 4,650 Paragon Healthcare, Inc. SF 5.75 % 9.81 % ​ 1/19/2027 2,127 ​ 2,109 Paragon Healthcare, Inc. (Delayed Draw) (d) SF 5.75 % 10.06 % ​ 1/19/2027 366 ​ 242 Paragon Healthcare, Inc. (Revolver) (d) SF 5.75 % 10.26 % ​ 1/19/2027 490 ​ 61 Radiology Partners, Inc. L 4.25 % 8.64 % ​ 7/9/2025 4,760 ​ 4,018 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 19,519 ​ 17,250 High Tech Industries ​ ​ ​ Corel Inc. (c) L 5.00 % 9.73 % ​ 7/2/2026 3,600 ​ 3,365 Lightbox Intermediate, L.P. L 5.00 % 9.73 % ​ 5/11/2026 4,825 ​ 4,656 TGG TS Acquisition Company L 6.50 % 10.88 % ​ 12/12/2025 3,190 ​ 3,143 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 11,615 ​ 11,164 Hotels, Gaming & Leisure ​ ​ ​ Excel Fitness Holdings, Inc. SF 5.25 % 10.29 % ​ 4/27/2029 4,364 ​ 4,102 Excel Fitness Holdings, Inc. (Revolver) (d) SF 5.25 % 9.67 % ​ 4/28/2028 625 ​ 306 North Haven Spartan US Holdco, LLC SF 6.25 % 10.71 % ​ 6/6/2025 2,280 ​ 2,202 Tait LLC L 5.00 % 8.75 % ​ 3/28/2025 4,083 ​ 3,972 Tait LLC (Revolver) (d) P 4.00 % 10.25 % ​ 3/28/2025 769 ​ — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 12,121 ​ 10,582 Media: Advertising, Printing & Publishing ​ ​ ​ Cadent, LLC L 6.50 % 11.23 % ​ 9/11/2025 4,237 ​ 4,131 Cadent, LLC (Revolver) (d) L 6.50 % 11.23 % ​ 9/11/2025 167 ​ — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 4,404 ​ 4,131 Media: Diversified & Production ​ ​ ​ Research Now Group, Inc. and Survey Sampling International, LLC L 5.50 % 8.84 % ​ 12/20/2024 6,650 ​ 5,035 STATS Intermediate Holdings, LLC L 5.25 % 9.90 % ​ 7/10/2026 4,850 ​ 4,498 TA TT Buyer, LLC SF 5.00 % 8.98 % ​ 3/30/2029 3,325 ​ 3,242 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 14,825 ​ 12,775 Services: Business ​ ​ ​ AQ Carver Buyer, Inc. L 5.00 % 9.38 % ​ 9/23/2025 4,838 ​ 4,834 CHA Holdings, Inc L 4.50 % 9.23 % ​ 4/10/2025 1,960 ​ 1,886 CHA Holdings, Inc L 4.50 % 9.23 % ​ 4/10/2025 413 ​ 398 Eliassen Group, LLC SF 5.50 % 10.08 % ​ 4/14/2028 3,251 ​ 3,194 Eliassen Group, LLC (Delayed Draw) (d) SF 5.50 % 8.88 % ​ 4/14/2028 740 ​ 109 Engage2Excel, Inc. L 7.25 % 11.98 % ​ 3/7/2023 4,283 ​ 4,242 Engage2Excel, Inc. L 7.25 % 11.98 % ​ 3/7/2023 773 ​ 766 Engage2Excel, Inc. (Revolver) (d) P 6.25 % 13.75 % ​ 3/7/2023 554 ​ 509 Orbit Purchaser LLC L 4.50 % 9.23 % ​ 10/21/2024 2,406 ​ 2,190 Orbit Purchaser LLC L 4.50 % 9.23 % ​ 10/21/2024 1,858 ​ 1,691 Orbit Purchaser LLC L 4.50 % 9.23 % ​ 10/21/2024 543 ​ 494 ​ ​ ​ ​ ​ 9.80 % Cash/ ​ ​ ​ ​ ​ ​ ​ Output Services Group, Inc. ​ SF 6.75 % 1.50 % PIK ​ 6/29/2026 4,807 ​ 3,275 Secretariat Advisors LLC L 4.75 % 9.48 % ​ 12/29/2028 1,693 ​ 1,634 Secretariat Advisors LLC L 4.75 % 9.48 % ​ 12/29/2028 270 ​ 260 SIRVA Worldwide Inc. L 5.50 % 10.23 % ​ 8/4/2025 1,800 ​ 1,606 Teneo Holdings LLC SF 5.25 % 9.67 % ​ 7/11/2025 4,837 ​ 4,668 The Kleinfelder Group, Inc. L 5.25 % 9.98 % ​ 11/29/2024 2,362 ​ 2,362 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 37,388 ​ 34,118 Services: Consumer ​ ​ ​ 360Holdco, Inc. SF 5.00 % 9.42 % ​ 8/2/2025 2,145 ​ 2,145 360Holdco, Inc. (Delayed Draw) (d) SF 5.00 % 9.42 % ​ 8/2/2025 827 ​ 252 Laseraway Intermediate Holdings II, LLC L 5.75 % 9.76 % ​ 10/14/2027 2,200 ​ 2,161 McKissock Investment Holdings, LLC SF 5.00 % 8.87 % ​ 3/9/2029 2,481 ​ 2,322 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 7,653 ​ 6,880 Telecommunications ​ ​ ​ Intermedia Holdings, Inc. L 6.00 % 10.38 % ​ 7/21/2025 1,760 ​ 1,360 Mavenir Systems, Inc. L 4.75 % 9.42 % ​ 8/18/2028 1,654 ​ 1,350 Sandvine Corporation L 4.50 % 8.88 % ​ 10/31/2025 2,000 ​ 1,904 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 5,414 ​ 4,614 Transportation: Cargo ​ ​ ​ Keystone Purchaser, LLC L 5.50 % 10.60 % ​ 5/7/2027 4,955 ​ 4,955 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 4,955 ​ 4,955 Utilities: Oil & Gas ​ ​ ​ Dresser Utility Solutions, LLC (fka NGS US Finco, LLC) L 4.25 % 8.63 % ​ 10/1/2025 1,678 ​ 1,619 Dresser Utility Solutions, LLC (fka NGS US Finco, LLC) L 5.25 % 9.63 % ​ 10/1/2025 245 ​ 239 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 1,923 ​ 1,858 Wholesale ​ ​ ​ HALO Buyer, Inc. L 4.50 % 8.88 % ​ 6/30/2025 4,774 ​ 4,219 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 4,774 ​ 4,219 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ TOTAL INVESTMENTS ​ ​ $ 183,150 (a) All investments are U.S. companies unless otherwise noted. (b) The majority of investments bear interest at a rate that may be determined by reference to the London Interbank Offered Rate (“LIBOR” or “L”), Secured Overnight Financing Rate (“SOFR” or “SF”) or Prime (“P”) which reset daily, monthly, quarterly or semiannually. The Company has provided the spread over LIBOR, SOFR or Prime and the current contractual rate of interest in effect at December 31, 2022. Certain investments may be subject to an interest rate floor or cap. Certain investments contain a Payment-in-Kind (“PIK”) provision. (c) This is an international company. (d) All or a portion of this commitment was unfunded as of December 31, 2022. As such, interest is earned only on the funded portion of this commitment. Principal reflects the commitment outstanding. (e) This position was on non-accrual status as of December 31, 2022, meaning that the Company has ceased accruing interest income on the position. (f) This is a demand note with no stated maturity. ​ ​ MRCC SENIOR LOAN FUND I, LLC CONSOLIDATED SCHEDULE OF INVESTMENTS December 31, 2021 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Spread Above ​ ​ ​ ​ ​ ​ Portfolio Company (a) ​ Index (b) ​ Interest Rate (b) ​ ​ Maturity ​ Principal ​ Fair Value Non-Controlled/Non-Affiliate Company Investments ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Senior Secured Loans ​ ​ ​ Aerospace & Defense ​ ​ ​ Bromford Industries Limited (c) P+ 4.25 % 7.50 % ​ 11/5/2025 2,744 ​ $ 2,692 Bromford Industries Limited (c) P+ 4.25 % 7.50 % ​ 11/5/2025 1,829 ​ 1,794 Trident Maritime Systems, Inc. L+ 5.50 % 6.50 % ​ 02/26/2027 2,467 ​ 2,478 Trident Maritime Systems, Inc. (Revolver) (d) L+ 5.50 % 6.50 % ​ 02/26/2027 265 ​ — ​ ​ ​ ​ ​ ​ ​ ​ 7,305 ​ ​ 6,964 Automotive ​ ​ ​ Accelerate Auto Works Intermediate, LLC L+ 4.75 % 5.75 % ​ 12/1/2027 1,454 ​ 1,436 Accelerate Auto Works Intermediate, LLC (Delayed Draw) (d) L+ 4.75 % 5.75 % ​ 12/1/2027 388 ​ — Accelerate Auto Works Intermediate, LLC (Revolver) (d) L+ 4.75 % 5.75 % ​ 12/1/2027 132 ​ — Truck-Lite Co., LLC L+ 6.25 % 7.25 % ​ 12/14/2026 1,709 ​ 1,718 Truck-Lite Co., LLC L+ 6.25 % 7.25 % ​ 12/14/2026 253 ​ 255 Wheel Pros, Inc. L+ 4.50 % 5.25 % ​ 05/11/2028 1,952 ​ 1,951 ​ ​ ​ ​ ​ ​ ​ ​ 5,888 ​ ​ 5,360 Beverage, Food & Tobacco ​ ​ ​ CBC Restaurant Corp. ​ n/a 5.00 % PIK (f) ​ 12/30/2022 1,116 ​ 1,072 SW Ingredients Holdings, LLC L+ 4.75 % 5.75 % ​ 07/3/2025 3,619 ​ 3,619 ​ ​ ​ ​ ​ ​ ​ ​ 4,735 ​ ​ 4,691 Capital Equipment ​ ​ ​ Analogic Corporation L+ 5.25 % 6.25 % ​ 06/24/2024 4,752 ​ 4,702 DS Parent, Inc. (e) L+ 5.75 % 6.50 % ​ 12/8/2028 3,000 ​ 2,970 ​ ​ ​ ​ ​ ​ ​ ​ 7,752 ​ ​ 7,672 Chemicals, Plastics & Rubber ​ ​ ​ Polymer Solutions Group L+ 7.00 % 8.00 % ​ 01/3/2023 1,178 ​ 1,169 ​ ​ ​ ​ ​ ​ ​ ​ 1,178 ​ ​ 1,169 Construction & Building ​ ​ ​ The Cook & Boardman Group LLC L+ 5.75 % 6.75 % ​ 10/20/2025 2,910 ​ 2,838 ​ ​ ​ ​ ​ ​ ​ ​ 2,910 ​ ​ 2,838 Consumer Goods: Durable ​ ​ ​ International Textile Group, Inc. L+ 5.00 % 5.13 % ​ 05/1/2024 1,711 ​ 1,590 Runner Buyer Inc. (e) L+ 5.50 % 6.25 % ​ 10/23/2028 3,000 ​ 2,970 ​ ​ ​ ​ ​ ​ ​ ​ 4,711 ​ ​ 4,560 Consumer Goods: Non-Durable ​ ​ ​ PH Beauty Holdings III, INC. L+ 5.00 % 5.18 % ​ 09/26/2025 2,418 ​ 2,284 ​ ​ ​ ​ ​ ​ ​ ​ 2,418 ​ ​ 2,284 Containers, Packaging & Glass ​ ​ ​ Liqui-Box Holdings, Inc. L+ 4.50 % 5.50 % ​ 02/26/2027 4,268 ​ 3,991 Polychem Acquisition, LLC L+ 5.00 % 5.50 % ​ 03/17/2025 2,918 ​ 2,917 ​ ​ ​ ​ ​ 5.75 % Cash/ ​ ​ ​ ​ ​ ​ ​ Port Townsend Holdings Company, Inc. and Crown Corrugated Company L+ 6.75 % 2.00 % PIK ​ 04/3/2024 4,751 ​ 4,238 PVHC Holding Corp L+ 4.75 % 5.75 % ​ 08/5/2024 3,217 ​ 2,976 ​ ​ ​ ​ ​ ​ ​ ​ 15,154 ​ ​ 14,122 Energy: Oil & Gas ​ ​ ​ Drilling Info Holdings, Inc. L+ 4.25 % 4.35 % ​ 07/30/2025 4,516 ​ 4,471 Offen, Inc. L+ 5.00 % 5.10 % ​ 06/22/2026 2,388 ​ 2,387 Offen, Inc. L+ 5.00 % 5.10 % ​ 06/22/2026 876 ​ 876 ​ ​ ​ ​ ​ ​ ​ ​ 7,780 ​ ​ 7,734 FIRE: Finance ​ ​ ​ Harbour Benefit Holdings, Inc. L+ 5.25 % 6.25 % ​ 12/13/2024 2,948 ​ 2,932 Harbour Benefit Holdings, Inc. L+ 5.25 % 6.25 % ​ 12/13/2024 66 ​ 65 Minotaur Acquisition, Inc. (e) L+ 4.75 % 4.85 % ​ 3/27/2026 4,912 ​ 4,894 ​ ​ ​ ​ ​ ​ ​ ​ 7,926 ​ ​ 7,891 FIRE: Real Estate ​ ​ ​ Avison Young (USA) Inc. (c) L+ 5.75 % 5.97 % ​ 1/30/2026 4,850 ​ 4,824 ​ ​ ​ ​ ​ ​ ​ ​ 4,850 ​ ​ 4,824 Healthcare & Pharmaceuticals ​ ​ ​ Cano Health, LLC (e) ​ SF+ 4.00 % 4.51 % ​ 11/23/2027 ​ 1,995 ​ ​ 1,997 LSCS Holdings, Inc. (e) L+ 4.50 % 5.00 % ​ 12/15/2028 1,846 ​ 1,849 Radiology Partners, Inc. L+ 4.25 % 4.35 % ​ 07/9/2025 4,760 ​ 4,700 TEAM Public Choices, LLC (e) L+ 5.00 % 6.00 % ​ 12/17/2027 2,992 ​ 2,985 ​ ​ ​ ​ ​ ​ ​ ​ 11,593 ​ ​ 11,531 ​ ​ MRCC SENIOR LOAN FUND I, LLC CONSOLIDATED SCHEDULE OF INVESTMENTS - (continued) December 31, 2021 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Spread Above ​ ​ ​ ​ ​ ​ Portfolio Company (a) Index (b) Interest Rate (b) ​ Maturity Principal Fair Value High Tech Industries ​ ​ ​ ​ ​ ​ ​ ​ ​ Corel Inc. (c) L+ 5.00 % 5.18 % ​ 7/2/2026 3,800 ​ $ 3,797 Lightbox Intermediate, L.P. L+ 5.00 % 5.13 % ​ 5/11/2026 4,875 ​ 4,814 LW Buyer, LLC L+ 5.00 % 5.14 % ​ 12/30/2024 4,875 ​ 4,863 TGG TS Acquisition Company L+ 6.50 % 6.60 % ​ 12/12/2025 3,435 ​ 3,446 ​ ​ ​ ​ ​ ​ ​ ​ 16,985 ​ ​ 16,920 Hotels, Gaming & Leisure ​ ​ ​ Excel Fitness Holdings, Inc. L+ 5.25 % 6.25 % ​ 10/7/2025 4,165 ​ 4,155 North Haven Spartan US Holdco, LLC L+ 5.00 % 6.00 % ​ 6/6/2025 2,297 ​ 2,037 Tait LLC L+ 5.00 % 5.14 % ​ 3/28/2025 4,125 ​ 3,785 Tait LLC (Revolver) P+ 4.00 % 7.25 % ​ 3/28/2025 769 ​ 728 ​ ​ ​ ​ ​ ​ ​ ​ 11,356 ​ ​ 10,705 Media: Advertising, Printing & Publishing ​ ​ ​ Cadent, LLC L+ 5.00 % 6.00 % ​ 9/11/2023 4,339 ​ 4,296 Cadent, LLC (Revolver) (d) L+ 5.00 % 6.00 % ​ 9/11/2023 167 ​ — ​ ​ ​ ​ ​ ​ ​ ​ 4,506 ​ ​ 4,296 Media: Diversified & Production ​ ​ ​ Research Now Group, Inc. and Survey Sampling International, LLC L+ 5.50 % 6.50 % ​ 12/20/2024 6,720 ​ 6,645 STATS Intermediate Holdings, LLC L+ 5.25 % 5.41 % ​ 7/10/2026 4,900 ​ 4,897 The Octave Music Group, Inc. L+ 6.00 % 7.00 % ​ 5/29/2025 3,866 ​ 3,871 ​ ​ ​ ​ ​ ​ ​ ​ 15,486 ​ ​ 15,413 Services: Business ​ ​ ​ AQ Carver Buyer, Inc. L+ 5.00 % 6.00 % ​ 9/23/2025 4,888 ​ 4,900 CHA Holdings, Inc L+ 4.50 % 5.50 % ​ 4/10/2025 1,980 ​ 1,901 CHA Holdings, Inc L+ 4.50 % 5.50 % ​ 4/10/2025 418 ​ 401 Eliassen Group LLC L+ 4.25 % 4.35 % ​ 11/5/2024 3,956 ​ 3,956 ​ ​ ​ ​ ​ 7.00 % Cash/ ​ ​ ​ ​ ​ ​ ​ Engage2Excel, Inc. L+ 8.00 % 2.00 % PIK ​ 3/7/2023 4,326 ​ 4,329 ​ ​ ​ ​ ​ 7.00 % Cash/ ​ ​ ​ ​ ​ ​ ​ Engage2Excel, Inc. L+ 8.00 % 2.00 % PIK ​ 3/7/2023 781 ​ 781 ​ ​ ​ ​ ​ 7.00 % Cash/ ​ ​ ​ ​ ​ ​ ​ Engage2Excel, Inc. (Revolver) (d) L+ 8.00 % 2.00 % PIK ​ 3/7/2023 555 ​ 541 Orbit Purchaser LLC L+ 4.50 % 5.50 % ​ 10/21/2024 2,431 ​ 2,425 Orbit Purchaser LLC L+ 4.50 % 5.50 % ​ 10/21/2024 1,877 ​ 1,873 Orbit Purchaser LLC L+ 4.50 % 5.50 % ​ 10/21/2024 549 ​ 548 Output Services Group, Inc. L+ 4.50 % 5.50 % ​ 3/27/2024 4,815 ​ 4,145 Secretariat Advisors LLC (e) L+ 4.75 % 5.50 % ​ 12/29/2028 1,710 ​ 1,693 Secretariat Advisors LLC (d) (e) L+ 4.75 % 5.50 % ​ 12/29/2028 270 ​ — SIRVA Worldwide Inc. L+ 5.50 % 5.60 % ​ 8/4/2025 1,850 ​ 1,683 Teneo Holdings LLC L+ 5.25 % 6.25 % ​ 7/11/2025 4,888 ​ 4,908 The Kleinfelder Group, Inc. L+ 5.25 % 6.25 % ​ 11/29/2024 2,387 ​ 2,387 ​ ​ ​ ​ ​ ​ ​ ​ 37,681 ​ ​ 36,471 Services: Consumer ​ ​ ​ 360Holdco, Inc. L+ 4.75 % 5.75 % ​ 8/2/2025 2,168 ​ 2,161 360Holdco, Inc. (Delayed Draw) (d) L+ 4.75 % 5.75 % ​ 8/2/2025 827 ​ — Laseraway Intermediate Holdings II, LLC L+ 5.75 % 6.50 % ​ 10/14/2027 2,222 ​ 2,214 ​ ​ ​ ​ ​ ​ ​ ​ 5,217 ​ ​ 4,375 Telecommunications ​ ​ ​ Intermedia Holdings, Inc. L+ 6.00 % 7.00 % ​ 7/21/2025 1,778 ​ 1,770 Mavenir Systems, Inc. L+ 4.75 % 5.25 % ​ 8/18/2028 1,667 ​ 1,669 Sandvine Corporation L+ 4.50 % 4.60 % ​ 10/31/2025 2,000 ​ 1,999 ​ ​ ​ ​ ​ ​ ​ ​ 5,445 ​ ​ 5,438 Transportation: Cargo ​ ​ ​ Keystone Purchaser, LLC (e) L+ 6.25 % 7.25 % ​ 5/7/2027 3,000 ​ 2,947 ​ ​ ​ ​ ​ ​ ​ ​ 3,000 ​ ​ 2,947 Utilities: Oil & Gas ​ ​ ​ NGS US Finco, LLC L+ 4.25 % 5.25 % ​ 10/1/2025 1,695 ​ 1,644 NGS US Finco, LLC L+ 5.25 % 6.25 % ​ 10/1/2025 248 ​ 244 ​ ​ ​ ​ ​ ​ ​ ​ 1,943 ​ ​ 1,888 Wholesale ​ ​ ​ BMC Acquisition, Inc. L+ 5.25 % 6.25 % ​ 12/30/2024 4,486 ​ 4,469 HALO Buyer, Inc. L+ 4.50 % 5.50 % ​ 6/30/2025 4,824 ​ 4,547 ​ ​ ​ ​ ​ ​ ​ ​ 9,310 ​ ​ 9,016 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ TOTAL INVESTMENTS ​ ​ ​ ​ ​ $ 189,109 (a) All investments are U.S. companies unless otherwise noted. (b) The majority of investments bear interest at a rate that may be determined by reference to the London Interbank Offered Rate (“LIBOR” or “L”), Secured Overnight Financing Rate (“SOFR” or “SF”) or Prime (“P”) which reset daily, monthly, quarterly or semiannually. The Company has provided the spread over LIBOR, SOFR or Prime and the current contractual rate of interest in effect at December 31, 2021. Certain investments may be subject to an interest rate floor or cap. (c) This is an international company. (d) All or a portion of this commitment was unfunded as of December 31, 2021. As such, interest is earned only on the funded portion of this commitment. Principal reflects the commitment outstanding. (e) Investment position or portion thereof unsettled at December 31, 2021. (f) This position was on non-accrual status as of December 31, 2021, meaning that the Company has ceased accruing interest income on the position. ​ Below is certain summarized financial information for SLF as of December 31, 2022 and 2021 and for the years ended December 31, 2022, 2021 and 2020: ​ ​ ​ ​ ​ ​ ​ ​ December 31, 2022 December 31, 2021 Assets ​ ​ Investments, at fair value ​ $ 183,150 ​ $ 189,109 Cash ​ 1,608 ​ 40 Restricted cash ​ 6,454 ​ 4,862 Interest receivable ​ 1,613 ​ 600 Other assets ​ 5 ​ 12 Total assets ​ ​ 192,830 ​ ​ 194,623 Liabilities ​ ​ ​ ​ Revolving credit facility ​ ​ 122,215 ​ ​ 94,765 Less: Unamortized deferred financing costs ​ (1,518) ​ (2,319) Total debt, less unamortized deferred financing costs ​ 120,697 ​ 92,446 Payable for open trades ​ — ​ 19,367 Interest payable ​ 769 ​ 242 Accounts payable and accrued expenses ​ 346 ​ 318 Total liabilities ​ 121,812 ​ 112,373 Members’ capital ​ 71,018 ​ 82,250 Total liabilities and members’ capital ​ $ 192,830 ​ $ 194,623 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ For the years ended December 31, ​ 2022 2021 ​ 2020 Investment income: ​ ​ ​ ​ ​ Interest income ​ $ 15,400 ​ $ 13,164 ​ $ 15,578 Total investment income ​ 15,400 ​ 13,164 ​ ​ 15,578 Expenses: ​ ​ ​ ​ ​ ​ ​ Interest and other debt financing expenses ​ 6,009 ​ 3,918 ​ ​ 5,227 Professional fees ​ 814 ​ 647 ​ ​ 666 Total expenses ​ 6,823 ​ 4,565 ​ ​ 5,893 Net investment income ​ 8,577 ​ 8,599 ​ ​ 9,685 Net gain (loss): ​ ​ ​ ​ ​ ​ ​ Net realized gain (loss) ​ ​ (3,089) ​ ​ — ​ ​ (1,713) Net change in unrealized gain (loss) ​ (10,520) ​ 3,734 ​ ​ (5,429) Net gain (loss) ​ (13,609) ​ 3,734 ​ ​ (7,142) Net increase (decrease) in members’ capital ​ $ (5,032) ​ $ 12,333 ​ $ 2,543 ​

Fair Value Measurements

Fair Value Measurements	12 Months Ended
	Dec. 31, 2022
Fair Value Measurements
Fair Value Measurements	Note 4. Fair Value Measurements Investments The Company values all investments in accordance with ASC Topic 820. ASC Topic 820 requires enhanced disclosures about assets and liabilities that are measured and reported at fair value. As defined in ASC Topic 820, fair value is the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date. Where available, fair value is based on observable market prices or parameters, or derived from such prices or parameters. Where observable prices or inputs are not available, valuation models are applied. These valuation models involve some level of management estimation and judgment, the degree of which is dependent on the price transparency for the assets or liabilities or market and the assets’ or liabilities’ complexity. ASC Topic 820 establishes a hierarchal disclosure framework which prioritizes and ranks the level of market price observability of inputs used in measuring investments at fair value. Market price observability is affected by a number of factors, including the type of investment and the characteristics specific to the investment. Investments with readily available active quoted prices or for which fair value can be measured from actively quoted prices generally will have a higher degree of market price observability and a lesser degree of judgment used in measuring fair value. Based on the observability of the inputs used in the valuation techniques, the Company is required to provide disclosures on fair value measurements according to the fair value hierarchy. The fair value hierarchy ranks the observability of the inputs used to determine fair values. Investments carried at fair value are classified and disclosed in one of the following three categories: ● Level 1 – Valuations based on unadjusted quoted prices in active markets for identical assets or liabilities at the measurement date. ● Level 2 – Valuations based on inputs other than quoted prices in active markets, including quoted prices for similar assets or liabilities, which are either directly or indirectly observable. ● Level 3 – Valuations based on inputs that are unobservable and significant to the overall fair value measurement. This includes situations where there is little, if any, market activity for the assets or liabilities. The inputs into the determination of fair value are based upon the best information available and may require significant management judgment or estimation. In certain cases, the inputs used to measure fair value may fall into different levels of the fair value hierarchy. In such cases, an asset’s or liability’s categorization within the fair value hierarchy is based on the lowest level of input that is significant to the fair value measurement. The Company’s assessment of the significance of a particular input to the fair value measurement in its entirety requires judgment, and considers factors specific to the asset or liability. For periods prior to September 30, 2022, the Board determined the fair value of the Company’s investments. Pursuant to the new SEC Rule 2a-5 of the 1940 Act, on September 30, 2022 the Board designated MC Advisors as the Company’s valuation designee (the “Valuation Designee”). The Board is responsible for oversight of the Valuation Designee. The Valuation Designee has established a valuation committee to determine in good faith the fair value of the Company’s investments, based on input of the Valuation Designee’s management and personnel and independent valuation firms which are engaged at the direction of the valuation committee to assist in the valuation of certain portfolio investments lacking a readily available market quotation. The valuation committee determines fair values pursuant to a valuation policy approved by the Board and pursuant to a consistently applied valuation process. With respect to investments for which market quotations are not readily available, the Valuation Designee undertakes a multi-step valuation process each quarter, as described below: ● the quarterly valuation process begins with each portfolio company or investment being initially evaluated and rated by the investment professionals of Valuation Designee responsible for the credit monitoring of the portfolio investment; ● the Valuation Designee engages an independent valuation firm to conduct independent appraisals of a selection of investments for which market quotations are not readily available. The Company will consult with an independent valuation firm relative to each portfolio company at least once in every calendar year, but the independent appraisals are generally received quarterly for each investment; ● to the extent an independent valuation firm is not engaged to conduct an investment appraisal on an investment for which market quotations are not readily available, the investment will be valued by the Valuation Designee; ● preliminary valuation conclusions are then documented and discussed with the valuation committee of the Valuation Designee; ● the valuation conclusions are approved by the valuation committee of the Valuation Designee; and ● a report prepared by the Valuation Designee is presented to the Board quarterly to allow the Board to perform its oversight duties of the valuation process and the Valuation Designee. The accompanying consolidated schedules of investments held by the Company consist primarily of private debt instruments (“Level 3 debt”). The Company generally uses the income approach to determine fair value for Level 3 debt where market quotations are not readily available, as long as it is appropriate. If there is deterioration in credit quality or a debt investment is in workout status, the Company may consider other factors in determining the fair value, including the value attributable to the debt investment from the enterprise value of the portfolio company or the proceeds that would be received in a liquidation analysis. This liquidation analysis may include probability weighting of alternative outcomes. The Company generally considers its Level 3 debt to be performing if the borrower is not in default, the borrower is remitting payments in a timely manner; the loan is in covenant compliance or is otherwise not deemed to be impaired. In determining the fair value of the performing Level 3 debt, the Company considers fluctuations in current interest rates, the trends in yields of debt instruments with similar credit ratings, financial condition of the borrower, economic conditions and other relevant factors, both qualitative and quantitative. In the event that a Level 3 debt instrument is not performing, as defined above, the Company will evaluate the value of the collateral utilizing the same framework described above for a performing loan to determine the value of the Level 3 debt instrument. Under the income approach, discounted cash flow models are utilized to determine the present value of the future cash flow streams of its debt investments, based on future interest and principal payments as set forth in the associated loan agreements. In determining fair value under the income approach, the Company also considers the following factors: applicable market yields and leverage levels, credit quality, prepayment penalties, the nature and realizable value of any collateral, the portfolio company’s ability to make payments, and changes in the interest rate environment and the credit markets that generally may affect the price at which similar investments may be made. Under the market approach, the enterprise value methodology is typically utilized to determine the fair value of an investment. There is no one methodology to estimate enterprise value and, in fact, for any one portfolio company, enterprise value is generally best expressed as a range of values, from which the Company derives a single estimate of enterprise value. In estimating the enterprise value of a portfolio company, the Company analyzes various factors consistent with industry practice, including but not limited to original transaction multiples, the portfolio company’s historical and projected financial results, applicable market trading and transaction comparables, applicable market yields and leverage levels, the nature and realizable value of any collateral, the markets in which the portfolio company does business, and comparisons of financial ratios of peer companies that are public. Typically, the enterprise values of private companies are based on multiples of earnings before interest, income taxes, depreciation and amortization (“EBITDA”), cash flows, net income, revenues, or in limited cases, book value. In addition, for certain debt investments, the Company may base its valuation on indicative bid and ask prices provided by an independent third-party pricing service. Bid prices reflect the highest price that the Company and others may be willing to pay. Ask prices represent the lowest price that the Company and others may be willing to accept. The Company generally uses the midpoint of the bid/ask range as its best estimate of fair value of such investment. As of December 31, 2022, the Valuation Designee determined, in good faith, the fair value of the Company’s portfolio investments in accordance with GAAP and the Company’s valuation procedures based on the facts and circumstances known by the Company at that time, or reasonably expected to be known at that time. Foreign Currency Forward Contracts The valuation for the Company’s foreign currency forward contracts is based on the difference between the exchange rate associated with the forward contract and the exchange rate at the current period end. Foreign currency forward contracts are categorized as Level 2 in the fair value hierarchy. Fair Value Disclosures The following tables present fair value measurements of investments and foreign currency forward contracts, by major class according to the fair value hierarchy: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Fair Value Measurements December 31, 2022 ​ Level 1 ​ Level 2 ​ Level 3 ​ Total Investments: ​ ​ ​ ​ Senior secured loans ​ $ — ​ $ — ​ $ 434,023 ​ $ 434,023 Unitranche secured loans ​ — ​ — ​ 20,633 ​ 20,633 Junior secured loans ​ — ​ — ​ 22,193 ​ 22,193 Equity securities ​ 294 ​ — ​ 28,388 ​ 28,682 Investments measured at NAV (1) (2) ​ — ​ — ​ — ​ 35,509 Total investments ​ $ 294 ​ $ — ​ $ 505,237 ​ $ 541,040 Foreign currency forward contracts asset (liability) ​ $ — ​ $ 1,507 ​ $ — ​ $ 1,507 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Fair Value Measurements December 31, 2021 ​ Level 1 ​ Level 2 ​ Level 3 ​ Total Investments: ​ ​ ​ ​ Senior secured loans ​ $ — ​ $ — ​ $ 423,700 ​ $ 423,700 Unitranche secured loans ​ — ​ — ​ 51,494 ​ 51,494 Junior secured loans ​ — ​ — ​ 14,364 ​ 14,364 Equity securities ​ 1,041 ​ — ​ 29,969 ​ 31,010 Investments measured at NAV (1) (2) ​ — ​ — ​ — ​ 41,125 Total investments ​ $ 1,041 ​ $ — ​ $ 519,527 ​ $ 561,693 Foreign currency forward contracts asset (liability) ​ $ — ​ $ 781 ​ $ — ​ $ 781 (1) Certain investments that are measured at fair value using the NAV have not been categorized in the fair value hierarchy. The fair value amounts presented in this table are intended to permit reconciliation of the fair value hierarchy to the amounts presented on the consolidated statements of assets and liabilities. (2) Represents the Company’s investment in LLC equity interests in SLF. The fair value of this investment has been determined using the NAV of the Company’s ownership interest in SLF’s members’ capital. Senior secured loans, unitranche secured loans and junior secured loans are collateralized by tangible and intangible assets of the borrowers. These investments include loans to entities that have some level of challenge in obtaining financing from other, more conventional institutions, such as a bank. Interest rates on these loans are either fixed or floating, and are based on current market conditions and credit ratings of the borrower. Excluding loans on non-accrual, the contractual interest rates on the loans ranged from 8.00% to 19.50% at December 31, 2022 and 6.00% to 16.00% at December 31, 2021. The maturity dates on the loans outstanding at December 31, 2022 range between March 2023 and December 2028. The following tables provide a reconciliation of the beginning and ending balances for investments at fair value that use Level 3 inputs for the years ended December 31, 2022 and 2021: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Investments ​ ​ Senior ​ Unitranche ​ Junior ​ Equity ​ Total Level 3 ​ ​ secured loans ​ secured loans ​ secured loans ​ securities ​ investments Balance as of December 31, 2021 $ 423,700 $ 51,494 $ 14,364 $ 29,969 $ 519,527 Net realized gain (loss) on investments ​ (1,082) ​ (94) ​ (1) ​ 47 ​ (1,130) Net change in unrealized gain (loss) on investments ​ (10,140) ​ (5,238) ​ 1,003 ​ (2,544) ​ (16,919) Purchases of investments and other adjustments to cost (1) ​ 130,155 ​ 3,319 ​ 6,827 ​ 1,254 ​ 141,555 Proceeds from principal payments and sales of investments (2) ​ ​ (108,610) ​ ​ (28,848) ​ ​ — ​ ​ (338) ​ ​ (137,796) Transfers in (out) of Level 3 (3) ​ — ​ — ​ — ​ — ​ — Balance as of December 31, 2022 ​ $ 434,023 ​ $ 20,633 ​ $ 22,193 ​ $ 28,388 ​ $ 505,237 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Investments ​ ​ Senior ​ Unitranche ​ Junior ​ Equity ​ Total Level 3 ​ ​ secured loans ​ secured loans ​ secured loans ​ securities ​ investments Balance as of December 31, 2020 $ 405,224 $ 64,040 $ 14,592 $ 23,899 $ 507,755 Net realized gain (loss) on investments ​ (22,512) ​ — ​ — ​ 748 ​ (21,764) Net change in unrealized gain (loss) on investments ​ 30,041 ​ (6,054) ​ 218 ​ 8,533 ​ 32,738 Purchases of investments and other adjustments to cost (1) ​ 204,213 ​ 10,815 ​ 13,652 ​ 7,605 ​ 236,285 Proceeds from principal payments and sales of investments (2) ​ ​ (193,266) ​ ​ (17,307) ​ ​ (14,098) ​ ​ (9,775) ​ ​ (234,446) Transfers in (out) of Level 3 (3) ​ — ​ — ​ — ​ (1,041) ​ (1,041) Balance as of December 31, 2021 ​ $ 423,700 ​ $ 51,494 ​ $ 14,364 ​ $ 29,969 ​ $ 519,527 (1) Includes purchases of new investments, effects of refinancing and restructurings, premium and discount accretion and amortization and PIK interest. (2) Represents net proceeds from investments sold and principal paydowns received. (3) Represents non-cash transfers between fair value categories. The total net change in unrealized gain (loss) on investments included on the consolidated statements of operations for the year ended December 31, 2022, attributable to Level 3 investments still held at December 31, 2022 was ($15,399). The total net change in unrealized gain (loss) on investments included on the consolidated statements of operations for the year ended December 31, 2021, attributable to Level 3 investments still held at December 31, 2021 was $7,402. Reclassifications impacting Level 3 of the fair value hierarchy are reported as transfers in or out of Level 3 as of the beginning of the period in which the reclassifications occur. There were no transfers among Levels 1, 2 and 3 during the year ended December 31, 2022. During the year ended December 31, 2021 one investment transferred from Level 3 to Level 1 as a result of an acquisition. Significant Unobservable Inputs ASC Topic 820 requires disclosure of quantitative information about the significant unobservable inputs used in the valuation of assets and liabilities classified as Level 3 within the fair value hierarchy. Disclosure of this information is not required in circumstances where a valuation (unadjusted) is obtained from a third-party pricing service and the information regarding the unobservable inputs is not reasonably available to the Company and as such, the disclosures provided below exclude those investments valued in that manner. The tables below are not intended to be all-inclusive, but rather to provide information on significant unobservable inputs and valuation techniques used by the Company. The valuation techniques and significant unobservable inputs used in recurring Level 3 fair value measurements of assets as of December 31, 2022 were as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Unobservable ​ Average ​ Range ​ Fair Value Valuation Technique Input Mean Minimum Maximum Assets: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Senior secured loans ​ $ 276,433 Discounted cash flow EBITDA multiples 9.3 x 3.8 x 18.6 x ​ ​ ​ ​ ​ Market yields ​ 12.4 % 8.7 % 22.3 % Senior secured loans ​ 130,199 Discounted cash flow Revenue multiples 4.4 x 0.2 x 12.3 x ​ ​ ​ ​ ​ Market yields ​ 13.4 % 10.0 % 22.0 % Senior secured loans ​ 19,546 Enterprise value Book value multiples 1.2 x 1.2 x 1.2 x Senior secured loans ​ 5,706 Enterprise value Revenue multiples 2.5 x 2.5 x 2.5 x Senior secured loans ​ 1,488 Liquidation Probability weighting of alternative outcomes 71.3 % 29.1 % 100.0 % Senior secured loans ​ ​ 80 ​ Enterprise value ​ EBITDA multiples ​ 8.0 x 8.0 x 8.0 x Unitranche secured loans ​ 17,019 Discounted cash flow EBITDA multiples 8.8 x 8.8 x 8.8 x ​ ​ ​ ​ Market yields 11.2 % 9.1 % 13.0 % Unitranche secured loans ​ 3,614 Discounted cash flow ​ Revenue multiples ​ 8.9 x 5.8 x 12.5 x ​ ​ ​ ​ Market yields 11.9 % 11.6 % 12.1 % Junior secured loans ​ 20,311 Discounted cash flow Market yields 13.6 % 12.3 % 20.4 % Junior secured loans ​ 1,882 Liquidation Probability weighting of alternative outcomes 225.8 % 225.8 % 225.8 % Equity securities ​ 16,630 Enterprise value EBITDA multiples 9.0 x 3.8 x 16.0 x Equity securities ​ 7,502 Enterprise value Revenue multiples 2.3 x 0.2 x 12.3 x Equity securities ​ 2,173 Option pricing model Volatility 66.6 % 49.4 % 70.0 % Equity securities ​ 397 Discounted cash flow EBITDA multiples 7.0 x 7.0 x 7.0 x Total Level 3 Assets ​ $ 502,980 (1) ​ ​ ​ ​ ​ ​ (1) Excludes investments of $2,257 at fair value where valuation (unadjusted) is obtained from a third-party pricing service for which such disclosure is not required. The valuation techniques and significant unobservable inputs used in recurring Level 3 fair value measurements of assets as of December 31, 2021 were as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted ​ ​ ​ ​ ​ Fair ​ ​ ​ Unobservable ​ Average ​ Range ​ ​ Value ​ Valuation Technique ​ Input ​ Mean ​ Minimum ​ Maximum Assets: ​ ​ Senior secured loans ​ $ 305,252 Discounted cash flow EBITDA multiples 7.7 x 5.0 x 20.0 x ​ ​ Market yields 9.6 % 5.3 % 20.0 % Senior secured loans ​ 79,913 Discounted cash flow Revenue multiples 6.5 x 0.5 x 13.0 x ​ ​ ​ ​ ​ Market yields ​ 8.4 % 5.2 % 13.1 % Senior secured loans ​ 23,484 Enterprise value Book value multiples 1.5 x 1.5 x 1.5 x Senior secured loans ​ 5,771 Enterprise value Revenue multiples 2.8 x 2.8 x 2.8 x Senior secured loans ​ 5,111 Enterprise value EBITDA multiples 6.5 x 6.5 x 6.5 x Senior secured loans ​ 3,026 Liquidation Probability weighting of alternative outcomes 88.2 % 48.2 % 100.0 % Unitranche secured loans ​ 45,072 Discounted cash flow EBITDA multiples 8.4 x 5.5 x 11.0 x ​ ​ ​ ​ ​ ​ Market yields 8.5 % 7.3 % 13.3 % Unitranche secured loans ​ 4,950 Enterprise value Revenue multiples 0.6 x 0.6 x 0.6 x Unitranche secured loans ​ 1,472 Discounted cash flow Revenue multiples 14.0 x 14.0 x 14.0 x ​ ​ ​ ​ ​ ​ Market yields ​ 8.3 % 8.3 % 8.3 % Junior secured loans ​ 12,266 Discounted cash flow Market yields 15.8 % 8.0 % 25.1 % Junior secured loans ​ 1,522 Discounted cash flow Revenue multiples 15.0 x 15.0 x 15.0 x ​ ​ ​ ​ ​ ​ Market yields 2.0 % 2.0 % 2.0 % Junior secured loans ​ 576 Liquidation Probability weighting of alternative outcomes 69.1 % 69.1 % 69.1 % Equity securities ​ 15,688 Enterprise value EBITDA multiples 5.6 x 4.5 x 15.1 x Equity securities ​ 6,448 Enterprise value Revenue multiples 4.8 x 0.6 x 12.3 x Equity securities ​ 2,281 Liquidation Probability weighting of alternative outcomes 24.4 % 24.4 % 24.4 % Equity securities ​ 714 Discounted cash flow EBITDA multiples 13.3 x 13.3 x 13.3 x ​ ​ ​ ​ ​ Market yields ​ 12.3 % 12.3 % 12.3 % Equity securities ​ 455 Option pricing model Volatility 42.5 % 42.5 % 42.5 % Equity securities ​ 264 Enterprise value Tangible book value multiples 1.5 x 1.5 x 1.5 x Total Level 3 Assets ​ $ 514,265 (1) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (1) Excludes investments of $5,262 at fair value where valuation (unadjusted) is obtained from a third-party pricing service for which such disclosure is not required. The significant unobservable input used in the income approach of fair value measurement of the Company’s investments is the discount rate used to discount the estimated future cash flows expected to be received from the underlying investment, which include both future principal and interest payments. Increases (decreases) in the discount rate would result in a decrease (increase) in the fair value estimate of the investment. Included in the consideration and selection of discount rates are the following factors: risk of default, rating of the investment and comparable investments, and call provisions. The significant unobservable inputs used in the market approach of fair value measurement of the Company’s investments are the market multiples of EBITDA or revenue of the comparable guideline public companies. The Company selects a population of public companies for each investment with similar operations and attributes of the portfolio company. Using these guideline public companies’ data, a range of multiples of enterprise value to EBITDA or revenue is calculated. The Company selects percentages from the range of multiples for purposes of determining the portfolio company’s estimated enterprise value based on said multiple and generally the latest twelve months EBITDA or revenue of the portfolio company (or other meaningful measure). Increases (decreases) in the multiple will result in an increase (decrease) in enterprise value, resulting in an increase (decrease) in the fair value estimate of the investment. Other Financial Assets and Liabilities ASC Topic 820 requires disclosure of the fair value of financial instruments for which it is practical to estimate such value. The Company believes that the carrying amounts of its other financial instruments such as cash, receivables and payables approximate the fair value of such items due to the short maturity of such instruments. Fair value of the Company’s revolving credit facility is estimated by discounting remaining payments using applicable market rates or market quotes for similar instruments at the measurement date, if applicable. As of both December 31, 2022 and 2021, the Company believes that the carrying value of its revolving credit facility approximates fair value. The senior unsecured notes (“2026 Notes”) are carried at cost and with their longer maturity dates, fair value is estimated by discounting remaining payments using current market rates for similar instruments and considering such factors as the legal maturity date and the ability of market participants to prepay the notes. As of December 31, 2022, the estimated fair value of the Company’s 2026 Notes was $116,995. As of December 31, 2021, the Company believed that the carrying value of the 2026 Notes approximated fair value. SBA debentures were carried at cost and with their longer maturity dates, fair value was estimated by discounting remaining payments using current market rates for similar instruments and considering such factors as the legal maturity date and the ability of market participants to prepay the SBA debentures. As of December 31, 2022, the SBA debentures were repaid in full. As of December 31, 2021, the Company believed that the carrying value of the SBA debentures approximated fair value.

Transactions with Affiliated Co

Transactions with Affiliated Companies	12 Months Ended
	Dec. 31, 2022
Transactions with Affiliated Companies
Transactions with Affiliated Companies	Note 5. Transactions with Affiliated Companies An affiliated company is a company in which the Company has an ownership interest of 5% or more of its voting securities. A controlled affiliate company is a company in which the Company has an ownership interest of more than 25% of its voting securities. Please see the Company’s consolidated schedule of investments for the type of investment, principal amount, interest rate including the spread, and the maturity date. Transactions related to the Company’s investments with affiliates for the years ended December 31, 2022 and 2021 were as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Sales and ​ PIK ​ ​ ​ ​ ​ ​ ​ Net ​ ​ ​ ​ ​ Fair value at ​ Transfers ​ Purchases ​ paydowns ​ interest ​ Discount ​ Net realized ​ unrealized ​ Fair value at ​ ​ December 31, 2021 in (out) (cost) (cost) (cost) accretion gain (loss) gain (loss) December 31, 2022 Non-Controlled affiliate company investments: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ American Community Homes, Inc. ​ $ 10,457 ​ $ — ​ $ — ​ $ — ​ $ 789 ​ $ — ​ $ — ​ $ (2,293) ​ $ 8,953 American Community Homes, Inc. ​ 4,753 ​ — ​ ​ — ​ ​ — ​ ​ 595 ​ ​ — ​ ​ — ​ ​ (1,090) ​ ​ 4,258 American Community Homes, Inc. ​ 634 ​ — ​ ​ — ​ ​ — ​ ​ 48 ​ ​ — ​ ​ — ​ ​ (139) ​ ​ 543 American Community Homes, Inc. ​ 3,164 ​ — ​ ​ — ​ ​ — ​ ​ 176 ​ ​ — ​ ​ — ​ ​ (1,344) ​ ​ 1,996 American Community Homes, Inc. ​ 4,357 ​ — ​ ​ — ​ ​ — ​ ​ 325 ​ ​ — ​ ​ — ​ ​ (988) ​ ​ 3,694 American Community Homes, Inc. ​ 20 ​ — ​ ​ — ​ ​ — ​ ​ 2 ​ ​ — ​ ​ — ​ ​ (5) ​ ​ 17 American Community Homes, Inc. ​ 99 ​ — ​ ​ — ​ ​ — ​ ​ 7 ​ ​ — ​ ​ — ​ ​ (21) ​ ​ 85 American Community Homes, Inc. (Revolver) ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — American Community Homes, Inc. ( 4,940 shares of common stock) (1) ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — American Community Homes, Inc. (warrant to purchase up to 22.3% of the equity) (1) ​ 264 ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ (264) ​ ​ — ​ ​ 23,748 ​ — ​ ​ — ​ ​ — ​ ​ 1,942 ​ ​ — ​ ​ — ​ ​ (6,144) ​ ​ 19,546 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Ascent Midco, LLC ​ 6,392 ​ — ​ ​ — ​ ​ (174) ​ ​ — ​ ​ 25 ​ ​ — ​ ​ (26) ​ ​ 6,217 Ascent Midco, LLC (Revolver) ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — Ascent Midco, LLC ( 2,032,258 Class A units) ​ 2,554 ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ (585) ​ ​ 1,969 ​ ​ 8,946 ​ — ​ ​ — ​ ​ (174) ​ ​ — ​ ​ 25 ​ ​ — ​ ​ (611) ​ ​ 8,186 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ C Parent Holdings, LLC. (fka Curion Holdings, LLC) ​ 4,561 ​ — ​ ​ — ​ ​ (4,497) ​ ​ — ​ ​ — ​ ​ — ​ ​ 82 ​ ​ 146 C Parent Holdings, LLC. (fka Curion Holdings, LLC) (Revolver) ​ 550 ​ — ​ ​ 92 ​ ​ (620) ​ ​ — ​ ​ — ​ ​ — ​ ​ (22) ​ ​ — C Parent Holdings, LLC. (fka Curion Holdings, LLC) (Junior secured loan) ​ — ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ (1) ​ ​ 1 ​ ​ — C Parent Holdings, LLC. (fka Curion Holdings, LLC) (Junior secured loan) ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — C Parent Holdings, LLC. (fka Curion Holdings, LLC) ( 58,779 shares of common stock) (2) ​ — ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ 5,111 ​ — ​ ​ 92 ​ ​ (5,117) ​ ​ — ​ ​ — ​ ​ (1) ​ ​ 61 ​ ​ 146 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Familia Dental Group Holdings, LLC ( 1,176 Class A units) ​ 1,919 ​ — ​ ​ 245 ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ 461 ​ ​ 2,625 ​ ​ 1,919 ​ — ​ ​ 245 ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ 461 ​ ​ 2,625 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ HFZ Capital Group, LLC ​ 15,084 ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ 1,075 ​ ​ 16,159 HFZ Capital Group, LLC ​ 5,420 ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ 385 ​ ​ 5,805 MC Asset Management (Corporate), LLC ​ 7,154 ​ — ​ ​ — ​ ​ — ​ ​ 1,267 ​ ​ — ​ ​ — ​ ​ — ​ ​ 8,421 MC Asset Management (Corporate), LLC (Delayed Draw) ​ 850 ​ — ​ ​ — ​ ​ — ​ ​ 150 ​ ​ — ​ ​ — ​ ​ — ​ ​ 1,000 MC Asset Management (Corporate), LLC ( 15.9% interest) ​ 644 ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ 647 ​ ​ 1,291 ​ ​ 29,152 ​ — ​ ​ — ​ ​ — ​ ​ 1,417 ​ ​ — ​ ​ — ​ ​ 2,107 ​ ​ 32,676 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Mnine Holdings, Inc. ​ 5,771 ​ — ​ ​ — ​ ​ (22) ​ ​ 320 ​ ​ 14 ​ ​ — ​ ​ (591) ​ ​ 5,492 Mnine Holdings, Inc. (Revolver) ​ ​ — ​ ​ — ​ ​ 587 ​ ​ (374) ​ ​ 1 ​ ​ — ​ ​ — ​ ​ — ​ ​ 214 Mnine Holdings, Inc. ( 6,400 Class B units) ​ — ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ 5,771 ​ — ​ ​ 587 ​ ​ (396) ​ ​ 321 ​ ​ 14 ​ ​ — ​ ​ (591) ​ ​ 5,706 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ NECB Collections, LLC (Revolver) ​ 632 ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ (250) ​ ​ 382 NECB Collections, LLC, LLC ( 20.8% of units) ​ — ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ 632 ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ (250) ​ ​ 382 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Second Avenue SFR Holdings II LLC (Revolver) (3) ​ 2,104 ​ — ​ ​ 2,681 ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ (30) ​ ​ 4,755 ​ ​ 2,104 ​ — ​ ​ 2,681 ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ (30) ​ ​ 4,755 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ SFR Holdings, LLC (Junior secured loan) ​ 5,850 ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ 5,850 SFR Holding, LLC ( 24.4% of interests) ​ 3,900 ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ 3,900 ​ ​ 9,750 ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ 9,750 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ TJ Management HoldCo, LLC (Revolver) ​ — ​ — ​ ​ 80 ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ 80 TJ Management HoldCo, LLC ( 16 shares of common stock) ​ 3,148 ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ (382) ​ ​ 2,766 ​ ​ 3,148 ​ — ​ ​ 80 ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ (382) ​ ​ 2,846 Total non-controlled affiliate company investments ​ $ 90,281 ​ $ — ​ $ 3,685 ​ $ (5,687) ​ $ 3,680 ​ $ 39 ​ $ (1) ​ $ (5,379) ​ $ 86,618 Controlled affiliate company investments: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ MRCC Senior Loan Fund I, LLC ​ $ 41,125 ​ $ — ​ $ 500 ​ $ — ​ $ — ​ $ — ​ $ — ​ $ (6,116) ​ $ 35,509 ​ ​ 41,125 ​ — ​ 500 ​ — ​ — ​ — ​ — ​ (6,116) ​ ​ 35,509 Total Controlled affiliate company investments ​ $ 41,125 ​ $ — ​ $ 500 ​ $ — ​ $ — ​ $ — ​ $ — ​ $ (6,116) ​ $ 35,509 (1) On December 29, 2022, the Company exercised the American Community Homes, Inc. (“ACH”) warrants held by the Company. The Company acquired 4,940 shares of ACH’s common stock, or 22.3% of the equity, in exchange for a nominal exercise price in accordance with the terms of the warrant. (2) During the year ended December 31, 2022, Curion Holdings, LLC (“Curion”) sold the underlying operating company and repaid the Company’s debt investment. The remaining fair value at December 31, 2022 represents the remaining expected escrow proceeds associated with the sale. The Company continues to hold an equity investment in Curion that is valued at zero at December 31, 2022. (3) Second Avenue SFR Holdings II LLC is a related entity to SFR Holdco, LLC and is being presented as a non-controlled affiliate for that reason. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Fair value at ​ ​ ​ ​ Sales and PIK ​ ​ Net Net Fair value at ​ ​ December 31, ​ Transfers ​ Purchases ​ paydowns ​ interest ​ Discount ​ realized ​ unrealized ​ December ​ ​ 2020 ​ in (out) ​ (cost) ​ (cost) ​ (cost) ​ accretion ​ gain (loss) ​ gain (loss) ​ 31, 2021 Non-Controlled affiliate company investments: ​ ​ ​ ​ ​ ​ ​ ​ ​ American Community Homes, Inc. ​ $ 9,401 ​ $ — ​ $ — ​ $ (90) ​ $ 1,146 ​ $ — ​ $ — ​ $ — ​ $ 10,457 American Community Homes, Inc. ​ 6,239 ​ — ​ — ​ (2,229) ​ 743 ​ — ​ — ​ — ​ 4,753 American Community Homes, Inc. ​ 825 ​ — ​ — ​ (838) ​ 13 ​ — ​ — ​ — ​ — American Community Homes, Inc. ​ 570 ​ — ​ — ​ (5) ​ 69 ​ — ​ — ​ — ​ 634 American Community Homes, Inc. ​ 335 ​ — ​ — ​ (341) ​ 6 ​ — ​ — ​ — ​ — American Community Homes, Inc. ​ 2,915 ​ — ​ — ​ (20) ​ 256 ​ — ​ — ​ 13 ​ 3,164 American Community Homes, Inc. ​ 3,879 ​ — ​ — ​ (37) ​ 473 ​ — ​ — ​ 42 ​ 4,357 American Community Homes, Inc. ​ 18 ​ — ​ — ​ — ​ 2 ​ — ​ — ​ — ​ 20 American Community Homes, Inc. ​ 89 ​ — ​ — ​ (1) ​ 11 ​ — ​ — ​ — ​ 99 American Community Homes, Inc. (warrant to purchase up to 22.3% of the equity) ​ — ​ — ​ — ​ — ​ — ​ — ​ — ​ 264 ​ 264 ​ ​ 24,271 ​ — ​ — ​ (3,561) ​ 2,719 ​ — ​ — ​ 319 ​ 23,748 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Ascent Midco, LLC ​ 6,997 ​ — ​ — ​ (531) ​ — ​ 25 ​ — ​ (99) ​ 6,392 Ascent Midco, LLC (Delayed Draw) ​ — ​ — ​ — ​ — ​ — ​ — ​ — ​ — ​ — Ascent Midco, LLC (Revolver) ​ — ​ — ​ — ​ — ​ — ​ — ​ — ​ — ​ — Ascent Midco, LLC (2,032,258 Class A units) ​ 3,016 ​ — ​ — ​ — ​ — ​ — ​ — ​ (462) ​ 2,554 ​ ​ 10,013 ​ — ​ — ​ (531) ​ — ​ 25 ​ — ​ (561) ​ 8,946 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Curion Holdings, LLC ​ 3,159 ​ — ​ 308 ​ — ​ — ​ — ​ — ​ 1,094 ​ 4,561 Curion Holdings, LLC (Revolver) ​ 820 ​ — ​ — ​ (308) ​ — ​ — ​ — ​ 38 ​ 550 Curion Holdings, LLC (Junior secured loan) ​ — ​ — ​ — ​ — ​ — ​ — ​ — ​ — ​ — Curion Holdings, LLC (Junior secured loan) ​ — ​ — ​ — ​ — ​ — ​ — ​ — ​ — ​ — Curion Holdings, LLC (58,779 shares of common stock) ​ — ​ — ​ — ​ — ​ — ​ — ​ — ​ — ​ — ​ ​ 3,979 ​ — ​ 308 ​ (308) ​ — ​ — ​ — ​ 1,132 ​ 5,111 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Familia Dental Group Holdings, LLC (1,105 Class A units) ​ 3,118 ​ — ​ 183 ​ — ​ — ​ — ​ — ​ (1,382) ​ 1,919 ​ ​ 3,118 ​ — ​ 183 ​ — ​ — ​ — ​ — ​ (1,382) ​ 1,919 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ HFZ Capital Group, LLC ​ 13,106 ​ — ​ — ​ — ​ — ​ — ​ — ​ 1,978 ​ 15,084 HFZ Capital Group, LLC ​ 4,709 ​ — ​ — ​ — ​ — ​ — ​ — ​ 711 ​ 5,420 MC Asset Management (Corporate), LLC ​ — ​ — ​ 6,423 ​ — ​ 731 ​ — ​ — ​ — ​ 7,154 MC Asset Management (Corporate), LLC (Delayed Draw) ​ — ​ — ​ 793 ​ — ​ 57 ​ — ​ — ​ — ​ 850 MC Asset Management (Corporate), LLC (15.9% interest) ​ 785 ​ — ​ — ​ — ​ — ​ — ​ — ​ (141) ​ 644 MC Asset Management (Industrial), LLC ​ 11,579 ​ — ​ — ​ (12,119) ​ 1,423 ​ 1 ​ — ​ (884) ​ — ​ ​ 30,179 ​ — ​ 7,216 ​ (12,119) ​ 2,211 ​ 1 ​ — ​ 1,664 ​ 29,152 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Incipio, LLC (1) ​ 1,764 ​ — ​ — ​ — ​ — ​ — ​ — ​ (1,764) ​ — Incipio, LLC (1) ​ 4,227 ​ (1,562) ​ — ​ — ​ 48 ​ — ​ — ​ (2,713) ​ — Incipio, LLC (1) ​ 1,805 ​ (1,732) ​ — ​ — ​ 15 ​ — ​ — ​ (88) ​ — Incipio, LLC (1) ​ 761 ​ (730) ​ — ​ — ​ 6 ​ — ​ — ​ (37) ​ — Incipio, LLC (1) ​ 1,519 ​ (1,458) ​ — ​ — ​ 13 ​ — ​ — ​ (74) ​ — Incipio, LLC (1) ​ 1,488 ​ (1,527) ​ 108 ​ — ​ 9 ​ — ​ — ​ (78) ​ — Incipio, LLC (Junior secured loan) (1) ​ — ​ — ​ — ​ — ​ — ​ — ​ — ​ — ​ — Incipio, LLC (Junior secured loan) (1) ​ — ​ — ​ — ​ — ​ — ​ — ​ — ​ — ​ — Incipio, LLC (1,774 shares of Series C common units) (1) ​ — ​ — ​ — ​ — ​ — ​ — ​ — ​ — ​ — ​ ​ 11,564 ​ (7,009) ​ 108 ​ — ​ 91 ​ — ​ — ​ (4,754) ​ — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Luxury Optical Holdings Co. (2) ​ 1,430 ​ — ​ — ​ (1,640) ​ 159 ​ — ​ — ​ 51 ​ — Luxury Optical Holdings Co. (Delayed Draw) (2) ​ 624 ​ — ​ 1,729 ​ (2,353) ​ — ​ — ​ — ​ — ​ — Luxury Optical Holdings Co. (Revolver) (2) ​ 66 ​ — ​ — ​ (75) ​ 7 ​ — ​ — ​ 2 ​ — Luxury Optical Holdings Co. (91 preferred units) (2) ​ 2,476 ​ (78) ​ — ​ (6,132) ​ 694 ​ — ​ 1,807 ​ 1,233 ​ — Luxury Optical Holdings Co. (86 shares of common stock) (2) ​ — ​ — ​ — ​ — ​ — ​ — ​ — ​ — ​ — ​ ​ 4,596 ​ (78) ​ 1,729 ​ (10,200) ​ 860 ​ — ​ 1,807 ​ 1,286 ​ — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Mnine Holdings, Inc. ​ 12,356 ​ — ​ — ​ (7,137) ​ 603 ​ 34 ​ — ​ (85) ​ 5,771 Mnine Holdings, Inc. (6,400 Class B units) ​ — ​ — ​ — ​ — ​ — ​ — ​ — ​ — ​ — ​ ​ 12,356 ​ — ​ — ​ (7,137) ​ 603 ​ 34 ​ — ​ (85) ​ 5,771 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ NECB Collections, LLC (Revolver) ​ 834 ​ — ​ — ​ — ​ — ​ — ​ — ​ (202) ​ 632 NECB Collections, LLC, LLC (20.8% of units) ​ — ​ — ​ — ​ — ​ — ​ — ​ — ​ — ​ — ​ ​ 834 ​ — ​ — ​ — ​ — ​ — ​ — ​ (202) ​ 632 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ SHI Holdings, Inc. ​ 188 ​ — ​ — ​ — ​ — ​ — ​ (2,897) ​ 2,709 ​ — SHI Holdings, Inc. (Revolver) ​ 297 ​ — ​ — ​ (315) ​ — ​ — ​ (4,270) ​ 4,288 ​ — SHI Holdings, Inc. (24 shares of common stock) ​ — ​ — ​ — ​ — ​ — ​ — ​ (27) ​ 27 ​ — ​ ​ 485 ​ — ​ — ​ (315) ​ — ​ — ​ (7,194) ​ 7,024 ​ — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Second Avenue SFR Holdings II LLC (Revolver) ​ ​ — ​ ​ — ​ ​ 2,104 ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ 2,104 Second Avenue SFR Holdings II LLC (Delayed Draw) ​ ​ — ​ ​ — ​ ​ 5,850 ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ 5,850 Second Avenue SFR Holdings II LLC (24.4 % of interests) ​ ​ — ​ ​ — ​ ​ 3,900 ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ 3,900 ​ ​ ​ — ​ ​ — ​ ​ 11,854 ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ 11,854 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Summit Container Corporation ​ 3,204 ​ — ​ — ​ (3,019) ​ — ​ — ​ (250) ​ 65 ​ — Summit Container Corporation (Revolver) ​ 1,654 ​ — ​ 5,402 ​ (7,059) ​ — ​ — ​ — ​ 3 ​ — Summit Container Corporation (warrant to purchase up to 19.5% of the equity) ​ 139 ​ — ​ — ​ — ​ — ​ — ​ — ​ (139) ​ — ​ ​ 4,997 ​ — ​ 5,402 ​ (10,078) ​ — ​ — ​ (250) ​ (71) ​ — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ TJ Management HoldCo, LLC (Revolver) ​ — ​ — ​ — ​ — ​ — ​ — ​ — ​ — ​ — TJ Management HoldCo, LLC (16 shares of common stock) ​ 3,323 ​ — ​ — ​ (755) ​ — ​ — ​ — ​ 580 ​ 3,148 ​ ​ 3,323 ​ — ​ — ​ (755) ​ — ​ — ​ — ​ 580 ​ 3,148 Total non-controlled affiliate company investments ​ $ 109,715 ​ $ (7,087) ​ $ 26,800 ​ $ (45,004) ​ $ 6,484 ​ $ 60 ​ $ (5,637) ​ $ 4,950 ​ $ 90,281 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Controlled affiliate company investments: ​ ​ ​ ​ ​ ​ ​ ​ ​ MRCC Senior Loan Fund I, LLC ​ $ 39,284 ​ $ — ​ $ — ​ $ — ​ $ — ​ $ — ​ $ — ​ $ 1,841 ​ $ 41,125 ​ ​ 39,284 ​ — ​ — ​ — ​ — ​ — ​ — ​ 1,841 ​ 41,125 Total Controlled affiliate company investments ​ $ 39,284 ​ $ — ​ $ — ​ $ — ​ $ — ​ $ — ​ $ — ​ $ 1,841 ​ $ 41,125 (1) During the year ended December 31, 2021, Incipio, LLC (“Incipio”) underwent a restructuring whereby substantially all of the assets of Incipio were acquired by a new entity, Vinci Brands LLC (“Vinci”). The senior lenders at Incipio, including the Company, were part of the new financing at Vinci. The Company’s investments in Vinci are not categorized as affiliate company investments as the Company does not have an equity interest in Vinci. For the purpose of this schedule, transfers out represents the fair value at June 30, 2021. (2) During the year ended December 31, 2021, the Company sold its investment in Luxury Optical Holdings Co. For the purpose of this schedule, transfers out represents the fair value of the remaining escrow proceeds. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ For the years ended December 31, ​ ​ 2022 ​ 2021 ​ ​ Interest ​ Dividend ​ ​ ​ ​ Interest ​ Dividend ​ ​ ​ Portfolio Company ​ Income Income Fee Income Income Income Fee Income Non-controlled affiliate company investments: ​ ​ ​ ​ ​ ​ American Community Homes, Inc. ​ $ 1,209 ​ $ — ​ $ — ​ $ 1,148 ​ $ — ​ $ — American Community Homes, Inc. ​ 791 ​ — ​ — ​ 742 ​ — ​ — American Community Homes, Inc. ​ n/a ​ n/a ​ n/a ​ 13 ​ — ​ — American Community Homes, Inc. ​ 73 ​ — ​ — ​ 69 ​ — ​ — American Community Homes, Inc. ​ n/a ​ n/a ​ n/a ​ 5 ​ — ​ — American Community Homes, Inc. ​ 270 ​ — ​ — ​ 255 ​ — ​ — American Community Homes, Inc. ​ 499 ​ — ​ — ​ 473 ​ — ​ — American Community Homes, Inc. ​ 3 ​ — ​ — ​ 31 ​ — ​ — American Community Homes, Inc. ​ 11 ​ — ​ — ​ 12 ​ — ​ — American Community Homes, Inc. (Revolver) ​ ​ 21 ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — American Community Homes, Inc. (Common stock) ​ — ​ — ​ — ​ — ​ — ​ — American Community Homes, Inc. (Warrant) ​ — ​ — ​ — ​ — ​ — ​ — ​ ​ 2,877 ​ — ​ — ​ 2,748 ​ — ​ — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Ascent Midco, LLC ​ 516 ​ — ​ — ​ 471 ​ — ​ — Ascent Midco, LLC (Delayed Draw) ​ n/a ​ n/a ​ n/a ​ 9 ​ — ​ — Ascent Midco, LLC (Revolver) ​ 4 ​ — ​ — ​ 4 ​ — ​ — Ascent Midco, LLC (Class A units) ​ — ​ 189 ​ — ​ — ​ 174 ​ — ​ ​ 520 ​ 189 ​ — ​ 484 ​ 174 ​ — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ C Parent Holdings, LLC. (fka Curion Holdings, LLC) ​ 1,766 ​ — ​ — ​ — ​ — ​ — C Parent Holdings, LLC. (fka Curion Holdings, LLC) (Revolver) ​ 294 ​ — ​ — ​ — ​ — ​ — C Parent Holdings, LLC. (fka Curion Holdings, LLC) (Junior secured loan) ​ — ​ — ​ — ​ — ​ — ​ — C Parent Holdings, LLC. (fka Curion Holdings, LLC) (Junior secured loan) ​ — ​ — ​ — ​ — ​ — ​ — C Parent Holdings, LLC. (fka Curion Holdings, LLC) (Common stock) ​ — ​ — ​ — ​ — ​ — ​ — ​ ​ 2,060 ​ — ​ — ​ — ​ — ​ — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Familia Dental Group Holdings, LLC (Class A units) ​ — ​ — ​ — ​ — ​ — ​ — ​ ​ — ​ — ​ — ​ — ​ — ​ — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ HFZ Capital Group, LLC ​ 1,977 ​ — ​ — ​ 1,880 ​ — ​ — HFZ Capital Group, LLC ​ 710 ​ — ​ — ​ 675 ​ — ​ — MC Asset Management (Corporate), LLC ​ 1,369 ​ — ​ — ​ 1,024 ​ — ​ — MC Asset Management (Corporate), LLC (Delayed Draw) ​ 162 ​ — ​ — ​ 91 ​ — ​ — MC Asset Management (Corporate), LLC (LLC interest) ​ — ​ — ​ — ​ — ​ — ​ — MC Asset Management (Industrial), LLC ​ n/a ​ n/a ​ n/a ​ 2,136 ​ — ​ — ​ ​ 4,218 ​ — ​ — ​ 5,806 ​ — ​ — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Incipio, LLC ​ n/a ​ n/a ​ n/a ​ — ​ — ​ — Incipio, LLC ​ n/a ​ n/a ​ n/a ​ — ​ — ​ — Incipio, LLC ​ n/a ​ n/a ​ n/a ​ — ​ — ​ — Incipio, LLC ​ n/a ​ n/a ​ n/a ​ — ​ — ​ — Incipio, LLC ​ n/a ​ n/a ​ n/a ​ — ​ — ​ — Incipio, LLC ​ n/a ​ n/a ​ n/a ​ — ​ — ​ — Incipio, LLC (Junior secured loan) ​ n/a ​ n/a ​ n/a ​ — ​ — ​ — Incipio, LLC (Junior secured loan) ​ n/a ​ n/a ​ n/a ​ — ​ — ​ — Incipio, LLC (Common units) ​ n/a ​ n/a ​ n/a ​ — ​ — ​ — ​ ​ n/a ​ n/a ​ n/a ​ — ​ — ​ — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Luxury Optical Holdings Co. ​ n/a ​ n/a ​ n/a ​ 166 ​ — ​ — Luxury Optical Holdings Co. (Delayed Draw) ​ n/a ​ n/a ​ n/a ​ 219 ​ — ​ 36 Luxury Optical Holdings Co. (Revolver) ​ n/a ​ n/a ​ n/a ​ 7 ​ — ​ — Luxury Optical Holdings Co. (Preferred units) ​ n/a ​ n/a ​ n/a ​ 694 ​ 813 ​ — Luxury Optical Holdings Co. (Common stock) ​ n/a ​ n/a ​ n/a ​ — ​ — ​ — ​ ​ n/a ​ n/a ​ n/a ​ 1,086 ​ 813 ​ 36 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Mnine Holdings, Inc. ​ 787 ​ — ​ — ​ 1,301 ​ — ​ — Mnine Holdings, Inc. (Revolver) ​ ​ 9 ​ ​ — ​ ​ — ​ ​ n/a ​ ​ n/a ​ ​ n/a Mnine Holdings, Inc. (Class B units) ​ — ​ — ​ — ​ — ​ — ​ — ​ ​ 796 ​ — ​ — ​ 1,301 ​ — ​ — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ NECB Collections, LLC (Revolver) ​ — ​ — ​ — ​ — ​ — ​ — NECB Collections, LLC (LLC units) ​ — ​ — ​ — ​ — ​ — ​ — ​ ​ — ​ — ​ — ​ — ​ — ​ — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Second Avenue SFR Holdings II LLC (Delayed Draw) ​ n/a ​ n/a ​ n/a ​ 83 ​ — ​ — Second Avenue SFR Holdings II LLC (Revolver) ​ 312 ​ — ​ — ​ 22 ​ — ​ — ​ ​ ​ 312 ​ ​ — ​ ​ — ​ ​ 105 ​ ​ — ​ ​ — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ SFR Holdco, LLC (Junior secured loan) ​ 468 ​ — ​ — ​ — ​ — ​ — SFR Holdco, LLC (LLC interest) ​ — ​ — ​ — ​ — ​ — ​ — ​ ​ 468 ​ — ​ — ​ — ​ — ​ — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ SHI Holdings, Inc. ​ n/a ​ n/a ​ n/a ​ — ​ — ​ — SHI Holdings, Inc. (Revolver) ​ n/a ​ n/a ​ n/a ​ — ​ — ​ — SHI Holdings, Inc. (Common stock) ​ n/a ​ n/a ​ n/a ​ — ​ — ​ — ​ ​ n/a ​ n/a ​ n/a ​ — ​ — ​ — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Summit Container Corporation ​ n/a ​ n/a ​ n/a ​ 57 ​ — ​ — Summit Container Corporation (Revolver) ​ n/a ​ n/a ​ n/a ​ 35 ​ — ​ — Summit Container Corporation (Warrant) ​ n/a ​ n/a ​ n/a ​ — ​ — ​ — ​ ​ n/a ​ n/a ​ n/a ​ 92 ​ — ​ — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ TJ Management HoldCo, LLC (Revolver) ​ 14 ​ — ​ — ​ 12 ​ — ​ — TJ Management HoldCo, LLC (Common stock) ​ — ​ — ​ — ​ — ​ — ​ — ​ ​ 14 ​ — ​ — ​ 12 ​ — ​ — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total non-controlled affiliate company investments ​ $ 11,265 ​ $ 189 ​ $ — ​ $ 11,634 ​ $ 987 ​ $ 36 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Controlled affiliate company investments: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ MRCC Senior Loan Fund I, LLC ​ $ — ​ $ 3,600 ​ $ — ​ $ — ​ $ 4,325 ​ $ — ​ ​ — ​ 3,600 ​ — ​ — ​ 4,325 ​ — Total controlled affiliate company investments ​ $ — ​ $ 3,600 ​ $ — ​ $ — ​ $ 4,325 ​ $ — ​

Transactions with Related Parti

Transactions with Related Parties	12 Months Ended
	Dec. 31, 2022
Transactions with Related Parties
Transactions with Related Parties	Note 6. Transactions with Related Parties The Company has entered into an investment advisory agreement with MC Advisors (the “Investment Advisory Agreement”), under which MC Advisors, subject to the overall supervision of the Board, provides investment advisory services to the Company. The Company pays MC Advisors a fee for its services under the Investment Advisory Agreement consisting of two components - a base management fee and an incentive fee. The cost of both the base management fee and the incentive fee are borne by the Company’s stockholders, unless such fees are waived by MC Advisors. The base management fee is calculated initially at an annual rate equal to 1.75% of average invested assets (calculated as total assets excluding cash, which includes assets financed using leverage); provided, however, the base management fee is calculated at an annual rate equal to 1.00% of the Company’s average invested assets (calculated as total assets excluding cash, which includes assets financed using leverage) that exceeds the product of (i) 200% and (ii) the Company’s average net assets. For the avoidance of doubt, the 200% is calculated in accordance with the asset coverage limitation as defined in the 1940 Act to give effect to the Company’s exemptive relief with respect to MRCC SBIC’s SBA debentures during the period they were outstanding. This has the effect of reducing the Company’s base management fee rate on assets in excess of regulatory leverage of 1:1 debt to equity to 1.00% per annum. The base management fee is payable quarterly in arrears. Base management fees for the years ended December 31, 2022, 2021 and 2020 were $9,055, $9,514 and $9,807, respectively. MC Advisors elected to voluntarily waive $55, zero, and $430 of such base management fees for the years ended December 31, 2022, 2021, and 2020, respectively. The incentive fee consists of two parts. The first part is calculated and payable quarterly in arrears and equals 20% of “pre-incentive fee net investment income” for the immediately preceding quarter, subject to a 2% (8% annualized) preferred return, or “hurdle,” and a “catch up” feature. The foregoing incentive fee is subject to a total return requirement, which provides that no incentive fee in respect of pre-incentive fee net investment income will be payable except to the extent that 20% of the cumulative net increase in net assets resulting from operations over the then current and 11 preceding calendar quarters exceeds the cumulative incentive fees accrued and/or paid for the 11 preceding calendar quarters (the “Incentive Fee Limitation”). Therefore, any ordinary income incentive fee that is payable in a calendar quarter will be limited to the lesser of (1) 20% of the amount by which pre-incentive fee net investment income for such calendar quarter exceeds the 2% hurdle, subject to the “catch-up” provision, and (2) (x) 20% of the cumulative net increase in net assets resulting from operations for the then current and 11 preceding calendar quarters minus (y) the cumulative incentive fees accrued and/or paid for the 11 preceding calendar quarters. For the foregoing purpose, the “cumulative net increase in net assets resulting from operations” is the sum of pre-incentive fee net investment income, realized gains and losses and unrealized gains and losses for the then current and 11 preceding calendar quarters. The second part of the incentive fee is determined and payable in arrears as of the end of each fiscal year in an amount equal to 20% of realized capital gains, if any, on a cumulative basis from inception through the end of the year, computed net of all realized capital losses on a cumulative basis and unrealized depreciation, less the aggregate amount of any previously paid capital gain incentive fees. The composition of the Company’s incentive fees was as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ For the years ended December 31, ​ 2022 ​ 2021 2020 Part one incentive fees (1) ​ $ 4,127 ​ $ 3,690 ​ $ 5,724 Part two incentive fees (2) ​ — ​ — ​ — Incentive Fee Limitation ​ — ​ — ​ (5,012) Incentive fees, excluding the impact of the incentive fee waivers ​ 4,127 ​ 3,690 ​ 712 Incentive fee waivers (3) ​ (525) ​ (1,484) ​ (712) Total incentive fees, net of incentive fee waivers ​ $ 3,602 ​ $ 2,206 ​ $ — (1) Based on pre-incentive fee net investment income. (2) Based upon net realized and unrealized gains and losses, or capital gains. The Company accrues, but does not pay, a capital gains incentive fee in connection with any unrealized capital appreciation, as appropriate. If, on a cumulative basis, the sum of net realized gain (loss) plus net unrealized gain (loss) decreases during a period, the Company will reverse any excess capital gains incentive fee previously accrued such that the amount of capital gains incentive fee accrued is no more than 20% of the sum of net realized gain (loss) plus net unrealized gain (loss). (3) Represents part one incentive fees waived by MC Advisors. The Company has entered into an administration agreement with MC Management (the “Administration Agreement”), under which the Company reimburses MC Management, subject to the review and approval of the Board, for its allocable portion of overhead and other expenses, including the costs of furnishing the Company with office facilities and equipment and providing clerical, bookkeeping, record-keeping and other administrative services at such facilities, and the Company’s allocable portion of the cost of the chief financial officer and chief compliance officer and their respective staffs. To the extent that MC Management outsources any of its functions, the Company will pay the fees associated with such functions on a direct basis, without incremental profit to MC Management. For the years ended December 31, 2022, 2021 and 2020, the Company incurred $3,139, $3,442 and $3,312, respectively, in administrative expenses (included within Professional fees, Administrative service fees and General and administrative expenses on the consolidated statements of operations) under the Administration Agreement, of which $1,163, $1,357 and $1,300, respectively, was related to MC Management overhead and salary allocation and paid directly to MC Management. As of December 31, 2022 and 2021, $255 and $337, respectively, of expenses were due to MC Management under this agreement and are included in accounts payable and accrued expenses on the consolidated statements of assets and liabilities. The Company has entered into a license agreement with Monroe Capital LLC under which Monroe Capital LLC has agreed to grant the Company a non-exclusive, royalty-free license to use the name “Monroe Capital” for specified purposes in its business. Under this agreement, the Company has the right to use the “Monroe Capital” name at no cost, subject to certain conditions, for so long as MC Advisors or one of its affiliates remains its investment adviser. Other than with respect to this limited license, the Company has no legal right to the “Monroe Capital” name or logo. As of both December 31, 2022 and 2021, the Company had accounts payable to members of the Board of zero, representing accrued and unpaid fees for their services.

Borrowings

Borrowings	12 Months Ended
	Dec. 31, 2022
Borrowings
Borrowings	Note 7. Borrowings In accordance with the 1940 Act, the Company is permitted to borrow amounts such that its asset coverage ratio, as defined in the 1940 Act, is at least 150% after such borrowing. The Company has been granted exemptive relief from the SEC for permission to exclude the debt of MRCC SBIC guaranteed by the SBA, prior to its dissolution, from the asset coverage test under the 1940 Act. As of December 31, 2022 and December 31, 2021, the Company’s asset coverage ratio based on aggregate borrowings outstanding was 167% and 189%, respectively. Revolving Credit Facility On December 27, 2022, the Company amended its revolving credit facility which extended the maturity date from March 1, 2024 to December 27, 2027, increased the advance rate against certain types of assets in the Company’s portfolio, with corresponding adjustments to the concentration limits and replaced LIBOR benchmark provisions with term SOFR benchmark provisions. The other significant terms of the credit facility remained unchanged. The Company incurred expenses of $1,765 in conjunction with the amendment which have been capitalized within unamortized deferred financing costs and are amortized into interest expense over the estimated average life of the borrowings. The Company’s ability to borrow under the revolving credit facility is subject to availability under the borrowing base, which permits the Company to borrow up to 72.5% of the fair market value of its portfolio company investments depending on the type of investment the Company holds and whether the investment is quoted. The Company’s ability to borrow is also subject to certain concentration limits, and continued compliance with the representations, warranties and covenants given by the Company under the facility. The revolving credit facility contains certain financial covenants, including, but not limited to, the Company’s maintenance of: (1) minimum consolidated total net assets at least equal to $150,000 plus 65% of the net proceeds to the Company from sales of its equity securities after March 1, 2019; (2) a ratio of total assets (less total liabilities other than indebtedness) to total indebtedness of not less than 1.5 to 1; and (3) a senior debt coverage ratio of at least 2 to 1. The revolving credit facility also requires the Company to undertake customary indemnification obligations with respect to ING Capital LLC and other members of the lending group and to reimburse the lenders for expenses associated with entering into the credit facility. The revolving credit facility also has customary provisions regarding events of default, including events of default for nonpayment, change in control transactions at both Monroe Capital Corporation and MC Advisors, failure to comply with financial and negative covenants, and failure to maintain the Company’s relationship with MC Advisors. If the Company incurs an event of default under the revolving credit facility and fails to remedy such default under any applicable grace period, if any, then the entire revolving credit facility could become immediately due and payable, which would materially and adversely affect the Company’s liquidity, financial condition, results of operations and cash flows. The Company’s revolving credit facility also imposes certain conditions that may limit the amount of the Company’s distributions to stockholders. Distributions payable in the Company’s common stock under the DRIP are not limited by the revolving credit facility. Distributions in cash or property other than common stock are generally limited to 115% of the amount of distributions required to maintain the Company’s status as a RIC. As of December 31, 2022, the Company had U.S. dollar borrowings of $204,600. As of December 31, 2021, the Company had U.S. dollar borrowings of $146,400 and non-U.S. dollar borrowings denominated in Great Britain pounds of £3,433 ($4,645 in U.S. dollars) under the revolving credit facility. Any borrowings denominated in a foreign currency may be positively or negatively affected by movements in the rate of exchange between the U.S. dollar and the respective foreign currency. These movements are beyond the control of the Company and cannot be predicted. Borrowings denominated in a foreign currency are translated into U.S. dollars based on the spot rate at each balance sheet date. The impact resulting from changes in foreign currency borrowings is included in net change in unrealized gain (loss) on foreign currency and other transactions on the Company’s consolidated statements of operations and totaled $157, $660 and ($665) for the years ended December 31, 2022, 2021 and 2020, respectively. For the year ended December 31, 2022, the Company repaid borrowings denominated in Great Britain pounds of £3,433. As a result of this repayment, the Company recognized a realized gain (loss) on foreign currency and other transactions on the Company’s consolidated statements of operations of ($11) for year ended December 31, 2022. For the year ended December 31, 2021, the Company repaid borrowings denominated in Great Britain pounds of £12,667. As a result of this repayment, the Company recognized a realized gain (loss) on foreign currency and other transactions on the Company’s consolidated statements of operations of ($866) for year ended December 31, 2021. There were no repayments of foreign currency borrowings for the year ended December 31, 2020. Borrowings under the revolving credit facility bear interest, at the Company’s election, at an annual rate of SOFR (one-month or three-month at the Company’s discretion based on the term of the borrowing) plus 2.625% or at a daily rate equal to 1.625% per annum plus the greater of 1.5%, the prime interest rate, the federal funds rate plus 0.5% or SOFR plus 1.0%, with a SOFR floor of 0.5%. In addition to the stated interest rate on borrowings under the revolving credit facility, the Company is required to pay a commitment fee and certain conditional fees based on usage of the expanded borrowing base and usage of the asset coverage ratio flexibility. A commitment fee of 0.5% per annum on any unused portion of the revolving credit facility if the utilized portion of the facility is greater than 35% of the then available maximum borrowing or a commitment fee of 1.0% per annum on any unused portion of the revolving credit facility if the utilized portion of the facility is less than or equal to 35% of the then available maximum borrowing. As of December 31, 2022 and December 31, 2021, the outstanding borrowings were accruing at a weighted average interest rate of 7.0% and 3.1%, respectively. 2023 Notes: Debt – Modifications and Extinguishments 2026 Notes: SBA Debentures: As of December 31, 2022 and December 31, 2021, MRCC SBIC had zero and $57,624, respectively, in leverageable capital and the following SBA debentures outstanding: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Maturity Date Interest Rate December 31, 2022 December 31, 2021 September 2024 ​ 3.4 % $ — ​ $ 2,920 March 2025 ​ 3.3 % — ​ 14,800 March 2025 ​ 2.9 % — ​ 7,080 September 2027 ​ 3.2 % — ​ 32,100 Total ​ ​ ​ ​ $ — ​ $ 56,900 ​ Components of interest expense: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ For the years ended December 31, ​ ​ 2022 ​ 2021 2020 Interest expense - revolving credit facility ​ $ 8,442 ​ $ 4,593 ​ $ 5,594 ​ Interest expense - 2023 Notes ​ — ​ 837 ​ 6,270 ​ Interest expense - 2026 Notes ​ 6,220 ​ 5,763 ​ — ​ Interest expense - SBA debentures ​ 292 ​ 2,676 ​ 3,944 ​ Amortization of deferred financing costs ​ 2,126 ​ 2,205 ​ 2,181 ​ Total interest and other debt financing expenses ​ $ 17,080 ​ $ 16,074 ​ $ 17,989 ​ Average debt outstanding ​ ​ 314,053 ​ ​ 332,034 ​ ​ 370,904 ​ Average stated interest rate ​ 4.7 % 4.1 % 4.2 % ​

Derivative Instruments

Derivative Instruments	12 Months Ended
	Dec. 31, 2022
Derivative Instruments
Derivative Instruments	Note 8. Derivative Instruments The Company enters into foreign currency forward contracts from time to time to help mitigate the impact that an adverse change in foreign exchange rates would have on future interest cash flows from the Company’s investments denominated in foreign currencies. As of both December 31, 2022 and 2021, the counterparty to these foreign currency forward contracts was Bannockburn Global Forex, LLC. Net unrealized gain or loss on foreign currency forward contracts are included in net change in unrealized gain (loss) on foreign currency forward contracts and net realized gain or loss on forward currency forward contracts are included in net realized gain (loss) on foreign currency forward contracts on the accompanying consolidated statements of operations. Certain information related to the Company’s foreign currency forward contracts is presented below as of December 31, 2022 and December 31, 2021. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ As of December 31, 2022 ​ ​ ​ ​ ​ ​ ​ Gross ​ Gross ​ ​ ​ ​ ​ ​ ​ ​ ​ Amount of ​ Amount of ​ ​ Notional Amount Settlement Unrealized Unrealized ​ Description ​ to be Sold ​ Date ​ Gain ​ Loss Balance Sheet location of Net Amounts Foreign currency forward contract ​ AUD 153 ​ 1/18/2023 ​ $ 14 ​ $ — ​ Unrealized gain on foreign currency forward contracts Foreign currency forward contract ​ AUD 140 ​ 2/16/2023 ​ 13 ​ — ​ Unrealized gain on foreign currency forward contracts Foreign currency forward contract ​ AUD 132 ​ 3/16/2023 ​ 12 ​ — ​ Unrealized gain on foreign currency forward contracts Foreign currency forward contract ​ AUD 160 ​ 4/20/2023 ​ 14 ​ — ​ Unrealized gain on foreign currency forward contracts Foreign currency forward contract ​ AUD 121 ​ 5/16/2023 ​ 11 ​ — ​ Unrealized gain on foreign currency forward contracts Foreign currency forward contract ​ AUD 156 ​ 6/19/2023 ​ 14 ​ — ​ Unrealized gain on foreign currency forward contracts Foreign currency forward contract ​ AUD 138 ​ 7/18/2023 ​ 12 ​ — ​ Unrealized gain on foreign currency forward contracts Foreign currency forward contract ​ AUD 146 ​ 8/16/2023 ​ 13 ​ — ​ Unrealized gain on foreign currency forward contracts Foreign currency forward contract ​ AUD 146 ​ 9/18/2023 ​ 13 ​ — ​ Unrealized gain on foreign currency forward contracts Foreign currency forward contract ​ AUD 148 ​ 10/18/2023 ​ 13 ​ — ​ Unrealized gain on foreign currency forward contracts Foreign currency forward contract ​ AUD 140 ​ 11/16/2023 ​ 12 ​ — ​ Unrealized gain on foreign currency forward contracts Foreign currency forward contract ​ AUD 142 ​ 12/18/2023 ​ 12 ​ — ​ Unrealized gain on foreign currency forward contracts Foreign currency forward contract ​ AUD 150 ​ 1/17/2024 ​ 13 ​ — ​ Unrealized gain on foreign currency forward contracts Foreign currency forward contract ​ AUD 143 ​ 2/16/2024 ​ 12 ​ — ​ Unrealized gain on foreign currency forward contracts Foreign currency forward contract ​ AUD 15,410 ​ 3/18/2024 ​ 1,329 ​ — ​ Unrealized gain on foreign currency forward contracts ​ ​ ​ ​ ​ ​ ​ $ 1,507 ​ $ — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ As of December 31, 2021 ​ ​ ​ ​ ​ ​ ​ ​ Gross ​ Gross ​ ​ ​ ​ Notional ​ ​ ​ Amount of ​ Amount of ​ ​ ​ ​ Amount to be ​ Settlement ​ Unrealized ​ Unrealized ​ ​ Description ​ Sold Date Gain Loss Balance Sheet location of Net Amounts Foreign currency forward contract ​ £ 82 ​ 1/3/2022 ​ $ — ​ $ (10) ​ Unrealized gain on foreign currency forward contracts Foreign currency forward contract ​ £ ​ 79 ​ 4/4/2022 ​ ​ — ​ ​ (10) ​ Unrealized gain on foreign currency forward contracts Foreign currency forward contract ​ £ ​ 29 ​ 5/6/2022 ​ ​ — ​ ​ (3) ​ Unrealized gain on foreign currency forward contracts Foreign currency forward contract AUD 156 1/19/2022 ​ 8 ​ — Unrealized gain on foreign currency forward contracts Foreign currency forward contract AUD 136 2/16/2022 ​ 7 ​ — Unrealized gain on foreign currency forward contracts Foreign currency forward contract AUD 132 3/16/2022 ​ 6 ​ — Unrealized gain on foreign currency forward contracts Foreign currency forward contract AUD 146 4/19/2022 ​ 7 ​ — Unrealized gain on foreign currency forward contracts Foreign currency forward contract AUD 138 5/17/2022 ​ 7 ​ — Unrealized gain on foreign currency forward contracts Foreign currency forward contract AUD 153 6/17/2022 ​ 7 ​ — Unrealized gain on foreign currency forward contracts Foreign currency forward contract AUD 138 7/18/2022 ​ 7 ​ — Unrealized gain on foreign currency forward contracts Foreign currency forward contract AUD 140 8/16/2022 ​ 7 ​ — Unrealized gain on foreign currency forward contracts Foreign currency forward contract AUD 153 9/16/2022 ​ 7 ​ — Unrealized gain on foreign currency forward contracts Foreign currency forward contract AUD 152 10/19/2022 ​ 7 ​ — Unrealized gain on foreign currency forward contracts Foreign currency forward contract AUD 136 11/16/2022 ​ 6 ​ — Unrealized gain on foreign currency forward contracts Foreign currency forward contract AUD 142 12/16/2022 ​ 7 ​ — Unrealized gain on foreign currency forward contracts Foreign currency forward contract AUD 153 1/18/2023 ​ 7 ​ — Unrealized gain on foreign currency forward contracts Foreign currency forward contract AUD 140 2/16/2023 ​ 6 ​ — Unrealized gain on foreign currency forward contracts Foreign currency forward contract AUD 132 3/16/2023 ​ 6 ​ — Unrealized gain on foreign currency forward contracts Foreign currency forward contract AUD 160 4/20/2023 ​ 7 ​ — Unrealized gain on foreign currency forward contracts Foreign currency forward contract AUD 121 5/16/2023 ​ 5 ​ — Unrealized gain on foreign currency forward contracts Foreign currency forward contract AUD 156 6/19/2023 ​ 7 ​ — Unrealized gain on foreign currency forward contracts Foreign currency forward contract AUD 138 7/18/2023 ​ 6 ​ — Unrealized gain on foreign currency forward contracts Foreign currency forward contract AUD 146 8/16/2023 ​ 6 ​ — Unrealized gain on foreign currency forward contracts Foreign currency forward contract AUD 146 9/18/2023 ​ 6 ​ — Unrealized gain on foreign currency forward contracts Foreign currency forward contract AUD 148 10/18/2023 ​ 6 ​ — Unrealized gain on foreign currency forward contracts Foreign currency forward contract AUD 140 11/16/2023 ​ 6 ​ — Unrealized gain on foreign currency forward contracts Foreign currency forward contract AUD 142 12/18/2023 ​ 6 ​ — Unrealized gain on foreign currency forward contracts Foreign currency forward contract AUD 150 1/17/2024 ​ 6 ​ — Unrealized gain on foreign currency forward contracts Foreign currency forward contract AUD 143 2/16/2024 ​ 6 ​ — Unrealized gain on foreign currency forward contracts Foreign currency forward contract AUD 15,410 3/18/2024 ​ 635 ​ — Unrealized gain on foreign currency forward contracts ​ ​ ​ ​ ​ ​ ​ ​ $ 804 ​ $ (23) ​ ​ ​ For the years ended December 31, 2022, 2021 and 2020, the Company recognized net change in unrealized gain (loss) on foreign currency forward contracts of $726, $894 and ($54), respectively. For the years ended December 31, 2022, 2021 and 2020, the Company recognized net realized gain (loss) on foreign currency forward contracts of $119, ($48) and ($16), respectively.

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2022
Income Taxes
Income Taxes	Note 9. Income Taxes ​ The Company has elected to be treated as a RIC under Subchapter M of the Code. As a RIC, the Company is not taxed on any investment company taxable income or capital gains which it distributes to stockholders. The Company intends to distribute all of its investment company taxable income and capital gains annually. Accordingly, no provision for federal income tax has been made in the consolidated financial statements. Dividends from net investment income and distributions from net realized capital gains are determined in accordance with U.S. federal tax regulations, which may differ from amounts in accordance with U.S. GAAP and those differences could be material. These book-to-tax differences are either temporary or permanent in nature. Reclassifications due to permanent book-to-tax differences have no impact on net assets. The following permanent differences were reclassified for tax purposes: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ For the years ended December 31, ​ 2022 2021 2020 Increase (decrease) in capital in excess of par value ​ $ 13 ​ $ (301) ​ $ (447) Increase (decrease) in accumulated undistributed (overdistributed) earnings ​ (13) ​ 301 ​ 447 ​ Taxable income generally differs from net increase (decrease) in net assets resulting from operations for financial reporting purposes due to temporary and permanent differences in the recognition of income and expenses and generally excludes unrealized gain (loss) on investments as investment gains and losses are not included in taxable income until they are realized. Capital losses in excess of capital gains earned in a tax year may generally be carried forward and used to offset capital gains, subject to certain limitations. Under the Regulated Investment Company Modernization Act of 2010, capital losses incurred after September 30, 2011 are not subject to expiration and retain their character as either short-term or long-term capital losses. As of both December 31, 2022 and 2021, the Company had no short-term capital loss carryforwards. As of December 31, 2022 and 2021, the Company had long-term capital loss carryforwards of $41,826 and $40,696, respectively. The following table reconciles net increase in net assets resulting from operations to taxable income: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ For the years ended December 31, ​ 2022 2021 2020 Net increase (decrease) in net assets resulting from operations ​ $ (2,786) ​ $ 32,459 ​ $ 1,646 Net change in unrealized (gain) loss for book but not tax ​ 23,618 ​ (36,108) ​ 31,263 Other realized gain (loss) for tax but not book ​ — ​ — ​ (857) Other income (loss) for tax but not book ​ 84 ​ (961) ​ 217 Other deductions for book in excess of deductions for tax ​ — ​ — ​ — Expenses not currently deductible ​ 1,405 ​ 282 ​ 370 Net capital loss carryforward ​ 1,130 ​ 20,040 ​ (1,694) Total taxable income ​ $ 23,451 ​ $ 15,712 ​ $ 30,945 ​ For income tax purposes, distributions paid to stockholders are reported as ordinary income, return of capital, long term capital gains or a combination thereof. The following table provides the tax character of distributions paid: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ For the years ended December 31, ​ 2022 2021 2020 Ordinary income ​ $ 21,666 ​ $ 21,514 ​ $ 23,064 Long-term capital gains ​ — ​ — ​ — Total ​ $ 21,666 ​ $ 21,514 ​ $ 23,064 ​ The Company’s consolidated Taxable Subsidiaries are subject to U.S. federal and state income taxes. For the years ended December 31, 2022, 2021 and 2020, the Company recorded a net tax expense of approximately $1,311, $4 and $2, respectively, for these Taxable Subsidiaries. As of December 31, 2022, the estimated cost basis of investment for U.S. federal income tax purposes was $579,604, resulting in estimated net unrealized loss of $38,563, comprised of estimated gross unrealized gains and losses of $20,104 and $58,667, respectively. As of December 31, 2021, the estimated cost basis of investment for U.S. federal income tax purposes was $576,327, resulting in estimated net unrealized loss of $14,634, comprised of estimated gross unrealized gains and losses of $22,135 and $36,769, respectively.

Distributions

Distributions	12 Months Ended
	Dec. 31, 2022
Distributions
Distributions	Note 10. Distributions The Company’s distributions are recorded on the record date. The following table summarizes distributions declared during the years ended December 31, 2022, 2021 and 2020: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ DRIP Shares ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Amount ​ ​ ​ ​ DRIP ​ DRIP ​ Purchased ​ Cost of Date ​ Record ​ Payment ​ Per ​ Cash ​ Shares ​ Shares ​ in the Open ​ DRIP Shares Declared ​ Date ​ Date ​ Share ​ Distribution ​ Issued ​ Value ​ Market ​ Purchased Year ended December 31, 2022: March 2, 2022 ​ ​ March 16, 2022 ​ ​ March 31, 2022 ​ $ 0.25 ​ $ 5,417 ​ — ​ $ — ​ 25,229 ​ $ 276 June 1, 2022 ​ ​ June 15, 2022 ​ ​ June 30, 2022 ​ ​ 0.25 ​ ​ 5,416 ​ — ​ ​ — ​ 29,655 ​ ​ 280 September 1, 2022 ​ ​ September 15, 2022 ​ ​ September 30, 2022 ​ ​ 0.25 ​ ​ 5,416 ​ — ​ ​ — ​ 20,789 ​ ​ 164 December 5, 2022 ​ ​ December 15, 2022 ​ ​ December 30, 2022 ​ ​ 0.25 ​ ​ 5,417 ​ — ​ ​ — ​ 17,017 ​ ​ 149 Total distributions declared ​ ​ ​ ​ ​ ​ $ 1.00 ​ $ 21,666 — ​ $ — 92,690 $ 869 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year ended December 31, 2021: March 2, 2021 ​ ​ March 16, 2021 ​ ​ March 31, 2021 ​ $ 0.25 ​ $ 5,326 — ​ $ — 35,611 ​ $ 364 June 2, 2021 ​ ​ June 16, 2021 ​ ​ June 30, 2021 ​ ​ 0.25 ​ ​ 5,386 ​ — ​ ​ — ​ 31,277 ​ ​ 343 September 2, 2021 ​ ​ September 16, 2021 ​ ​ September 30, 2021 ​ 0.25 ​ 5,386 — ​ — 35,623 ​ 369 December 2, 2021 ​ ​ December 16, 2021 ​ ​ December 31, 2021 ​ ​ 0.25 ​ ​ 5,416 ​ — ​ ​ — ​ 27,905 ​ ​ 315 Total distributions declared ​ ​ ​ ​ ​ ​ ​ $ 1.00 ​ $ 21,514 — ​ $ — 130,416 ​ $ 1,391 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year ended December 31, 2020: March 3, 2020 ​ ​ March 16, 2020 ​ ​ March 31, 2020 ​ $ 0.35 ​ $ 7,155 — ​ $ — 55,938 ​ $ 374 May 8, 2020 ​ ​ June 15, 2020 ​ ​ June 30, 2020 ​ ​ 0.25 ​ ​ 5,257 ​ — ​ ​ — ​ 40,612 ​ ​ 283 September 4, 2020 ​ ​ September 16, 2020 ​ ​ September 30, 2020 ​ 0.25 ​ 5,326 — ​ — 44,246 ​ 305 December 4, 2020 ​ ​ December 16, 2020 ​ ​ December 31, 2020 ​ ​ 0.25 ​ ​ 5,326 ​ — ​ ​ — ​ 45,667 ​ ​ 365 Total distributions declared ​ ​ ​ ​ ​ ​ ​ $ 1.10 ​ $ 23,064 — ​ $ — 186,463 ​ $ 1,327 ​ None of the distributions declared during the years ended December 31, 2022, 2021 and 2020 represented a return of capital for tax purposes.

Stock Issuances and Repurchases

Stock Issuances and Repurchases	12 Months Ended
	Dec. 31, 2022
Stock Issuances and Repurchases
Stock Issuances and Repurchases	Note 11. Stock Issuances and Repurchases Stock Issuances:

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2022
Commitments and Contingencies.
Commitments and Contingencies	Note 12. Commitments and Contingencies Commitments Indemnifications: unknown, as these involve future claims that may be made against the Company but that have not occurred. The Company expects the risk of any future obligations under these indemnifications to be remote. Concentration of credit and counterparty risk: Market risk: Legal proceedings:

Financial Highlights

Financial Highlights	12 Months Ended
	Dec. 31, 2022
Financial Highlights
Financial Highlights	Note 13. Financial Highlights The financial highlights for the Company are as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ For the years ended December 31, ​ ​ 2022 2021 2020 2019 2018 ​ Per share data: ​ ​ ​ ​ ​ ​ ​ ​ ​ Net asset value at beginning of year ​ $ 11.51 ​ $ 11.00 ​ $ 12.20 ​ $ 12.66 ​ $ 13.77 ​ Net investment income (1) ​ 1.02 ​ 1.03 ​ 1.45 ​ 1.42 ​ 1.57 ​ Net gain (loss) (1) ​ (1.15) ​ 0.48 ​ (1.37) ​ (0.48) ​ (1.28) ​ Net increase (decrease) in net assets resulting from operations (1) ​ (0.13) ​ 1.51 ​ 0.08 ​ 0.94 ​ 0.29 ​ Stockholder distributions – income ​ (1.00) ​ (1.00) ​ (1.10) ​ (1.40) ​ (1.40) ​ Stockholder distributions – capital gains ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ Stockholder distributions – return of capital ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ Effect of share issuance above (below) NAV (2) ​ ​ — ​ ​ — ​ ​ (0.18) ​ ​ — ​ ​ — ​ Effect of share repurchases (2) ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ Other (2) ​ ​ 0.01 ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ Net asset value at end of year ​ $ 10.39 ​ $ 11.51 ​ $ 11.00 ​ $ 12.20 ​ $ 12.66 ​ Net assets at end of year ​ $ 225,019 ​ $ 249,471 ​ $ 234,434 ​ $ 249,357 ​ $ 258,767 ​ Shares outstanding at end of year ​ 21,666,340 ​ 21,666,340 ​ 21,303,540 ​ 20,444,564 ​ 20,444,564 ​ Per share market value at end of year ​ $ 8.54 ​ $ 11.22 ​ $ 8.03 ​ $ 10.86 ​ $ 9.60 ​ Total return based on market value (3) ​ (15.20) % 53.26 % (13.86) % 27.68 % (21.74) % Total return based on average net asset value (4) ​ ​ (1.18) % ​ 13.40 % ​ 0.72 % ​ 7.53 % ​ 2.17 % Ratio/Supplemental data: (5) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Ratio of net investment income to average net assets ​ ​ 9.42 % ​ 9.15 % ​ 13.32 % ​ 11.38 % ​ 11.85 % Ratio of total expenses, net of base management fee and incentive fee waivers, to average net assets ​ ​ 14.60 % ​ 13.07 % ​ 13.68 % ​ 15.35 % ​ 9.84 % Portfolio turnover ​ ​ 24.93 % ​ 41.80 % ​ 25.24 % ​ 27.18 % ​ 31.53 % ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ For the years ended December 31, ​ 2017 2016 2015 2014 2013 Per share data: ​ ​ ​ ​ ​ ​ Net asset value at beginning of year ​ $ 14.52 ​ $ 14.19 ​ $ 14.05 ​ $ 13.92 ​ $ 14.54 ​ Net investment income (1) ​ 1.40 ​ 1.55 ​ 1.60 ​ 1.57 ​ 1.13 ​ Net gain (loss) (1) ​ (0.75) ​ 0.13 ​ (0.07) ​ (0.12) ​ 0.15 ​ Net increase (decrease) in net assets from operations (1) ​ 0.65 ​ 1.68 ​ 1.53 ​ 1.45 ​ 1.28 ​ Stockholder distributions – income ​ (1.37) ​ (1.40) ​ (1.37) ​ (1.36) ​ (1.15) ​ Stockholder distributions – capital gains ​ (0.03) ​ — ​ (0.03) ​ — ​ — ​ Stockholder distributions – return of capital ​ — ​ — ​ — ​ — ​ (0.21) ​ Effect of share issuance above (below) NAV (2) ​ — ​ 0.05 ​ — ​ — ​ (0.57) ​ Effect of share repurchases (2) ​ — ​ — ​ — ​ 0.04 ​ 0.03 ​ Other (2) ​ — ​ — ​ 0.01 ​ — ​ — ​ Net asset value at end of year ​ $ 13.77 ​ $ 14.52 ​ $ 14.19 ​ $ 14.05 ​ $ 13.92 ​ Net assets at end of year ​ $ 278,699 ​ $ 240,850 ​ $ 184,535 ​ $ 133,738 ​ $ 138,092 ​ Shares outstanding at end of year ​ 20,239,957 ​ 16,581,869 ​ 13,008,007 ​ 9,517,910 ​ 9,918,269 ​ Per share market value at end of year ​ $ 13.75 ​ $ 15.38 ​ $ 13.09 ​ $ 14.46 ​ $ 12.20 ​ Total return based on market value (3) ​ (1.82) % 28.95 % (0.21) % 30.67 % (9.29) % Total return based on average net asset value (4) ​ 4.58 % 11.70 % 11.04 % 10.34 % 9.17 % Ratio/Supplemental data: (5) ​ ​ ​ ​ ​ ​ Ratio of net investment income to average net assets ​ 9.80 % 10.81 % 11.56 % 11.20 % 7.71 % Ratio of total expenses, net of base management fee and incentive fee waivers, to average net assets ​ 9.46 % 10.81 % 11.20 % 11.03 % 8.53 % Portfolio turnover ​ 39.39 % 22.41 % 30.70 % 47.03 % 39.77 % (1) Calculated using the weighted average shares outstanding during the years presented. (2) Includes the effect of share issuances above (below) net asset value and the impact of different share amounts used in calculating per share data as a result of calculating certain per share data based on weighted average shares outstanding during the period and certain per share data based on shares outstanding as of a period end or transaction date. (3) Total return based on market value is calculated assuming a purchase of common shares at the market value on the first day and a sale at the market value on the last day of the periods reported. Distributions, if any, are assumed for purposes of this calculation to be reinvested at prices obtained under the Company’s DRIP. Total return based on market value does not reflect brokerage commissions. (4) Total return based on average net asset value is calculated by dividing the net increase (decrease) in net assets resulting from operations by the average net asset value. (5) The following is a schedule of supplemental ratios for the years presented. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 2022 2021 2020 2019 2018 ​ Ratio of total investment income to average net assets 24.02 % 22.22 % 27.00 % 26.73 % 21.69 % Ratio of interest and other debt financing expenses to average net assets 7.25 % 6.63 % 7.89 % 7.95 % 4.56 % Ratio of total expenses (without base management fee waivers and incentive fees) to average net assets 13.09 % 12.16 % 13.86 % 13.61 % 9.19 % Ratio of incentive fees, net of incentive fee waivers, to average net assets (6) 1.53 % 0.91 % 0.00 % 1.74 % 0.65 % ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 2017 2016 2015 2014 2013 Ratio of total investment income to average net assets 19.26 % 21.62 % 22.76 % 22.23 % 17.10 % Ratio of interest and other debt financing expenses to average net assets 3.13 % 3.26 % 3.33 % 3.23 % 2.59 % Ratio of total expenses (without base management fee waivers and incentive fees) to average net assets 7.43 % 8.17 % 8.31 % 8.42 % 7.15 % Ratio of incentive fees, net of incentive fee waivers, to average net assets (6) 2.03 % 2.64 % 2.89 % 2.61 % 1.38 % (6) The ratio of waived incentive fees to average net assets was 0.22% , 0.61% , 0.31% , 0.46% , zero , 0.12% , 0.13% , zero , zero and zero for the years presente d.

Subsequent Events

Subsequent Events	12 Months Ended
	Dec. 31, 2022
Subsequent Events
Subsequent Events	Note 14. Subsequent Events The Company has evaluated subsequent events through March 1, 2023, the date on which the consolidated financial statements were issued. On March 1, 2023, the Board declared a quarterly distribution of $0.25 per share payable on March 31, 2023 to holders of record on March 15, 2023.

Selected Quarterly Financial Da

Selected Quarterly Financial Data (unaudited)	12 Months Ended
	Dec. 31, 2022
Selected Quarterly Financial Data (unaudited)
Selected Quarterly Financial Data (unaudited)	Note 15. Selected Quarterly Financial Data (unaudited) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ For the quarter ended ​ December 31, 2022 September 30, 2022 June 30, 2022 March 31, 2022 Total investment income ​ $ 15,164 ​ $ 15,916 ​ $ 12,995 ​ $ 12,491 Net investment income ​ $ 5,520 ​ $ 6,260 ​ $ 5,014 ​ $ 5,398 Net gain (loss) ​ $ (1,040) ​ $ (7,009) ​ $ (12,378) ​ $ (4,551) Net increase (decrease) in net assets resulting from operations ​ $ 4,480 ​ $ (749) ​ $ (7,364) ​ $ 847 Net investment income per share – basic and diluted ​ $ 0.25 ​ $ 0.29 ​ $ 0.23 ​ $ 0.25 Net increase (decrease) in net assets resulting from operations per share – basic and diluted ​ $ 0.21 ​ $ (0.03) ​ $ (0.34) ​ $ 0.04 Net asset value per share at period end ​ $ 10.39 ​ $ 10.43 ​ $ 10.71 ​ $ 11.30 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ For the quarter ended ​ December 31, 2021 September 30, 2021 June 30, 2021 March 31, 2021 Total investment income ​ $ 13,039 ​ $ 15,214 ​ $ 12,364 ​ $ 13,213 Net investment income ​ $ 5,373 ​ $ 6,312 ​ $ 5,157 ​ $ 5,326 Net gain (loss) ​ $ 1,462 ​ $ 927 ​ $ 6,173 ​ $ 1,729 Net increase (decrease) in net assets resulting from operations ​ $ 6,835 ​ $ 7,239 ​ $ 11,330 ​ $ 7,055 Net investment income per share – basic and diluted ​ $ 0.25 ​ $ 0.29 ​ $ 0.24 ​ $ 0.25 Net increase (decrease) in net assets resulting from operations per share – basic and diluted ​ $ 0.32 ​ $ 0.34 ​ $ 0.53 ​ $ 0.33 Net asset value per share at period end ​ $ 11.51 ​ $ 11.45 ​ $ 11.36 ​ $ 11.08 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ For the quarter ended ​ December 31, 2020 September 30, 2020 June 30, 2020 March 31, 2020 Total investment income ​ $ 12,552 ​ $ 13,385 ​ $ 20,642 ​ $ 15,002 Net investment income ​ $ 5,326 ​ $ 5,644 ​ $ 12,636 ​ $ 6,782 Net gain (loss) ​ $ 3,751 ​ $ 9,541 ​ $ 1,598 ​ $ (43,632) Net increase (decrease) in net assets resulting from operations ​ $ 9,077 ​ $ 15,185 ​ $ 14,234 ​ $ (36,850) Net investment income per share – basic and diluted ​ $ 0.25 ​ $ 0.26 ​ $ 0.61 ​ $ 0.33 Net increase (decrease) in net assets resulting from operations per share – basic and diluted ​ $ 0.42 ​ $ 0.71 ​ $ 0.69 ​ $ (1.81) Net asset value per share at period end ​ $ 11.00 ​ $ 10.83 ​ $ 10.37 ​ $ 10.04 ​

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2022
Summary of Significant Accounting Policies
Basis of Presentation	Basis of Presentation The accompanying consolidated financial statements of the Company have been prepared in accordance with generally accepted accounting principles in the United States of America (“GAAP”). The accompanying consolidated financial statements of the Company and related financial information have been prepared pursuant to the requirements for reporting on Form 10-K and Articles 6 and 10 of Regulation S-X. The Company has determined it meets the definition of an investment company and follows the accounting and reporting guidance in the Financial Accounting Standards Board (“FASB”) Accounting Standards Codification (“ASC”) Topic 946 – Financial Services – Investment Companies
Use of Estimates	Use of Estimates The preparation of the consolidated financial statements in conformity with GAAP requires the Company to make estimates and assumptions that affect the reported amounts of assets and liabilities and the disclosure of contingent assets and liabilities as of the date of the consolidated financial statements and the reported amounts of revenue and expenses during the reporting period. Actual results could differ from those estimates.
Consolidation	Consolidation As permitted under ASC Topic 946, the Company will generally not consolidate its investment in a portfolio company other than an investment company subsidiary or a controlled operating company whose business consists of providing services to the Company. Accordingly, the Company consolidated the results of the Company’s wholly-owned subsidiaries, including MRCC SBIC (through its dissolution date) and its wholly-owned general partner MCC SBIC GP, LLC, and the Company’s wholly-owned taxable subsidiaries (the “Taxable Subsidiaries”) in its consolidated financial statements. The purpose of the Taxable Subsidiaries is to permit the Company to hold equity investments in portfolio companies that are taxed as partnerships for U.S. federal income tax purposes while complying with the “source of income” requirements contained in the RIC tax provisions. The Taxable Subsidiaries are not consolidated with the Company for U.S. federal corporate income tax purposes, and each Taxable Subsidiary is subject to U.S. federal corporate income tax on its taxable income. All intercompany balances and transactions have been eliminated. The Company does not consolidate its non-controlling interest in MRCC Senior Loan Fund I, LLC (“SLF”). See further description of the Company’s investment in SLF in Note 3.
Fair Value of Financial Instruments	Fair Value of Financial Instruments The Company applies fair value to substantially all of its financial instruments in accordance with ASC Topic 820 — Fair Value Measurements and Disclosures ASC Topic 820 requires disclosure of the fair value of financial instruments for which it is practical to estimate such value. The Company believes that the carrying amounts of its other financial instruments such as cash, receivables and payables approximate the fair value of such items due to the short maturity of such instruments.
Revenue Recognition	Revenue Recognition The Company’s revenue recognition policies are as follows: Investments and related investment income: Dividend income on preferred equity securities is recorded as dividend income on an accrual basis to the extent that such amounts are payable by the portfolio company and are expected to be collected. Dividend income on common equity securities is recorded on the record date for private portfolio companies. Each distribution received from limited liability company (“LLC”) and limited partnership (“LP”) investments is evaluated to determine if the distribution should be recorded as dividend income or a return of capital. Generally, the Company will not record distributions from equity investments in LLCs and LPs as dividend income unless there are sufficient accumulated tax-basis earnings and profits in the LLC or LP prior to the applicable distribution. Distributions that are classified as a return of capital are recorded as a reduction in the cost basis of the investment. For the years ended December 31, 2022, 2021 and 2020, the Company received return of capital distributions from its equity investments of $290, $1,177 and zero, respectively. The Company has certain investments in its portfolio that contain a payment-in-kind (“PIK”) provision, which represents contractual interest or dividends that are added to the principal balance and recorded as income. The Company stops accruing PIK interest or PIK dividends when it is determined that PIK interest or PIK dividends are no longer collectible. To maintain RIC tax treatment, and to avoid incurring corporate U.S. federal income tax, substantially all of this income must be paid out to stockholders in the form of distributions, even though the Company has not yet collected the cash. Loan origination fees, original issue discount and market discount or premiums are capitalized, and the Company then amortizes such amounts using the effective interest method as interest income over the life of the investment. Unamortized discounts and loan origination fees totaled $4,701 and $4,370 as of December 31, 2022 and 2021, respectively. Upfront loan origination and closing fees received for the years ended December 31, 2022, 2021 and 2020 totaled $3,475, $3,752 and $1,909, respectively. Upon the prepayment of a loan or debt security, any unamortized premium or discount or loan origination fees are recorded as interest income. The components of the Company’s investment income were as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ For the years ended December 31, ​ 2022 2021 2020 Interest income ​ $ 41,449 ​ $ 35,738 ​ $ 42,640 PIK interest income ​ 6,689 ​ 8,320 ​ ​ 8,776 Dividend income (1) ​ 4,161 ​ 5,712 ​ ​ 4,557 Fee income ​ 2,380 ​ 1,267 ​ ​ 3,222 Prepayment gain (loss) ​ 803 ​ 1,691 ​ ​ 1,133 Accretion of discounts and amortization of premium ​ 1,084 ​ 1,102 ​ ​ 1,253 Total investment income ​ $ 56,566 ​ $ 53,830 ​ $ 61,581 (1) During the years ended December 31, 2022, 2021 and 2020, includes PIK dividends of $475 , $1,164 and $157 , respectively. Investment transactions are recorded on a trade-date basis. Realized gains or losses on portfolio investments are calculated based upon the difference between the net proceeds from the disposition and the amortized cost basis of the investment, without regard to unrealized gains or losses previously recognized. Realized gains and losses are recorded within net realized gain (loss) on investments on the consolidated statements of operations. Changes in the fair value of investments from the prior period, as determined through the application of the Company’s valuation policy, are included within net change in unrealized gain (loss) on investments on the consolidated statements of operations. Non-accrual:
Distributions	Distributions Distributions to common stockholders are recorded on the applicable record date. The amount, if any, to be distributed to common stockholders is determined by the Company’s board of directors (the “Board”) each quarter and is generally based upon the Company’s earnings estimated by management. Net realized capital gains, if any, are generally distributed at least annually. The determination of the tax attributes for the Company’s distributions is made annually, based upon its taxable income for the full year and distributions paid for the full year. Ordinary dividend distributions from a RIC do not qualify for the preferential tax rate on qualified dividend income from domestic corporations and qualified foreign corporations, except to the extent that the RIC received the income in the form of qualifying dividends from domestic corporations and qualified foreign corporations. The tax attributes for distributions will generally include both ordinary income and capital gains, but may also include qualified dividends or return of capital. In October 2012, the Company adopted a dividend reinvestment plan (“DRIP”) that provides for the reinvestment of dividends on behalf of its stockholders, unless a stockholder has elected to receive dividends in cash. When the Company declares a cash dividend, the Company’s stockholders who have not “opted out” of the DRIP at least three days prior to the dividend payment date will have their cash dividend automatically reinvested into additional shares of the Company’s common stock. The Company has the option to satisfy the share requirements of the DRIP through the issuance of new shares of common stock or through open market purchases of common stock by the DRIP plan administrator. Newly issued shares are valued based upon the final closing price of the Company’s common stock on a date determined by the Board. Shares purchased in the open market to satisfy the DRIP requirements will be valued based upon the average price of the applicable shares purchased by the DRIP plan administrator, before any associated brokerage or other costs. See Note 10 for additional information on the Company’s distributions.
Segments	Segments In accordance with ASC Topic 280 — Segment Reporting
Cash	Cash The Company deposits its cash in a financial institution and, at times, such balances may be in excess of the Federal Deposit Insurance Corporation insurance limits.
Restricted Cash	Restricted Cash Restricted cash included amounts held within MRCC SBIC. Cash held within an SBIC is generally restricted to the originations of new loans from the SBIC and the payment of SBA debentures and related interest expense.
Unamortized Deferred Financing Costs	Unamortized Deferred Financing Costs Deferred financing costs represent fees and other direct incremental costs incurred in connection with the Company's borrowings. As of December 31, 2022 and 2021, the Company had unamortized deferred financing costs of $4,486 and $5,794, respectively, presented as a direct reduction of the carrying amount of debt on the consolidated statements of assets and liabilities. These amounts are amortized and included in interest and other debt financing expenses on the consolidated statements of operations over the estimated average life of the borrowings. Amortization of deferred financing costs for the years ended December 31, 2022, 2021 and 2020 was $2,126, $2,205 and $2,181, respectively.
Offering Costs	Offering Costs Offering costs include, among other things, fees paid in relation to legal, accounting, regulatory and printing work completed in preparation of debt and equity offerings. Offering costs from equity offerings are charged against the proceeds from the offering within the consolidated statements of changes in net assets. Offering costs from debt offerings are reclassified to unamortized deferred financing costs on the consolidated statements of assets and liabilities as noted above. As of December 31, 2022 and 2021, other assets on the consolidated statements of assets and liabilities included $184 and $123 of deferred offering costs, respectively, which will be charged against the proceeds from future debt or equity offerings when completed.
Investments Denominated in Foreign Currency	Investments Denominated in Foreign Currency As of December 31, 2022, the Company held investments in one portfolio company that was denominated in Australian dollars. As of December 31, 2021, the Company held investments in one portfolio company that was denominated in Great Britain pounds and one portfolio company that was denominated in Australian dollars. At each balance sheet date, portfolio company investments denominated in foreign currencies are translated into U.S. dollars using the spot exchange rate on the last business day of the period. Purchases and sales of foreign portfolio company investments, and any income from such investments, are translated into U.S. dollars using the rates of exchange prevailing on the respective dates of such transactions. Although the fair values of foreign portfolio company investments and the fluctuation in such fair values are translated into U.S. dollars using the applicable foreign exchange rates described above, the Company does not isolate the portion of the change in fair value resulting from foreign currency exchange rates fluctuations from the change in fair value of the underlying investment. All fluctuations in fair value are included in net change in unrealized gain (loss) on investments on the Company’s consolidated statements of operations. Investments denominated in foreign currencies and foreign currency transactions may involve certain consideration and risks not typically associated with those of domestic origin, including unanticipated movements in the value of the foreign currency relative to the U.S. dollar.
Derivative Instruments	Derivative Instruments The Company may enter into foreign currency forward contracts to reduce the Company’s exposure to foreign currency exchange rate fluctuations. In a foreign currency forward contract, the Company agrees to receive or deliver a fixed quantity of one currency for another, at a pre-determined price at a future date. Foreign currency forward contracts are marked-to-market based on the difference between the forward rate and the exchange rate at the current period end. Unrealized gain (loss) on foreign currency forward contracts are recorded on the Company’s consolidated statements of assets and liabilities by counterparty on a net basis. The Company does not utilize hedge accounting and as such values its foreign currency forward contracts at fair value with the change in unrealized gain or loss recorded in net change in unrealized gain (loss) on foreign currency forward contracts and the realized gain or loss recorded in net realized gain (loss) on foreign currency forward contracts on the Company’s consolidated statements of operations.
Income Taxes	Income Taxes The Company has elected to be treated as a RIC under Subchapter M of the Code and operates in a manner so as to qualify for the tax treatment available to RICs. To maintain qualification as a RIC, the Company must, among other things, meet certain source-of-income and asset diversification requirements and distribute to stockholders, for each taxable year, at least 90% of the Company’s “investment company taxable income,” which is generally the Company’s net ordinary income plus the excess, if any, of realized net short-term capital gains over realized net long-term capital losses. If the Company qualifies as a RIC and satisfies the annual distribution requirement, the Company will not have to pay corporate-level federal income taxes on any income that the Company distributes to its stockholders. The Company intends to make distributions in an amount sufficient to maintain RIC status each year and to avoid any federal income taxes on income. The Company is also subject to nondeductible federal excise taxes if the Company does not distribute at least 98% of net ordinary income, 98.2% of any capital gain net income, if any, and any recognized and undistributed income from prior years for which it paid no federal income taxes. To the extent that the Company determines that its estimated current year annual taxable income may exceed estimated current year dividend distributions, the Company accrues excise tax, calculated as 4% of the estimated excess taxable income, if any, as taxable income is earned. For the years ended December 31, 2022, 2021 and 2020, the Company recorded a net expense (benefit) on the consolidated statements of operations of $94, $278, and $368, respectively, for U.S. federal excise tax. As of December 31, 2022 and 2021, the Company had payables for excise taxes of $1 and $183, respectively, which were included in accounts payable and accrued expenses on the Company’s consolidated statements of assets and liabilities. The Company’s consolidated Taxable Subsidiaries may be subject to U.S. federal and state corporate-level income taxes. For the years ended December 31, 2022, 2021 and 2020, the Company recorded a net tax expense of $1,311, $4 and $2, respectively, on the consolidated statements of operations for these subsidiaries. As of both December 31, 2022 and December 31, 2021, the Company did not have any payables for corporate-level income taxes. The Company accounts for income taxes in conformity with ASC Topic 740 — Income Taxes
Subsequent Events	Subsequent Events The Company has evaluated the need for disclosures and/or adjustments resulting from subsequent events through the date the consolidated financial statements were issued. There have been no subsequent events that occurred during such period that would require disclosure in this Form 10-K or would be required to be recognized in the consolidated financial statements as of and for the year ended December 31, 2022, except as disclosed in Note 14.
Recent Accounting Pronouncements	Recent Accounting Pronouncements In March 2020, the FASB issued ASU 2020-04, Reference Rate Reform

Summary of Significant Accoun_3

Summary of Significant Accounting Policies (Tables)	12 Months Ended
	Dec. 31, 2022
Summary of Significant Accounting Policies
Schedule of components of the Company's investment income	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ For the years ended December 31, ​ 2022 2021 2020 Interest income ​ $ 41,449 ​ $ 35,738 ​ $ 42,640 PIK interest income ​ 6,689 ​ 8,320 ​ ​ 8,776 Dividend income (1) ​ 4,161 ​ 5,712 ​ ​ 4,557 Fee income ​ 2,380 ​ 1,267 ​ ​ 3,222 Prepayment gain (loss) ​ 803 ​ 1,691 ​ ​ 1,133 Accretion of discounts and amortization of premium ​ 1,084 ​ 1,102 ​ ​ 1,253 Total investment income ​ $ 56,566 ​ $ 53,830 ​ $ 61,581 (1) During the years ended December 31, 2022, 2021 and 2020, includes PIK dividends of $475 , $1,164 and $157 , respectively.

Investments (Tables)

Investments (Tables)	12 Months Ended
	Dec. 31, 2022
Investments
Schedule of composition of the Company's investment portfolio	The following tables show the composition of the Company’s investment portfolio, at amortized cost and fair value (with corresponding percentage of total portfolio investments): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, 2022 ​ December 31, 2021 Amortized Cost: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Senior secured loans $ 436,066 75.3 % $ 415,600 72.1 % Unitranche secured loans ​ 45,352 7.8 ​ 70,977 12.3 ​ Junior secured loans ​ 21,141 3.6 ​ 14,317 2.5 ​ LLC equity interest in SLF ​ 42,650 7.4 ​ 42,150 7.3 ​ Equity securities ​ 34,098 5.9 ​ 33,134 5.8 ​ Total ​ $ 579,307 100.0 % $ 576,178 100.0 % ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, 2022 ​ December 31, 2021 Fair Value: ​ ​ ​ Senior secured loans ​ $ 434,023 80.2 % $ 423,700 75.4 % Unitranche secured loans ​ 20,633 3.8 ​ 51,494 9.2 ​ Junior secured loans ​ 22,193 4.1 ​ 14,364 2.6 ​ LLC equity interest in SLF ​ 35,509 6.6 ​ 41,125 7.3 ​ Equity securities ​ 28,682 5.3 ​ 31,010 5.5 ​ Total ​ $ 541,040 100.0 % $ 561,693 100.0 % ​ The following tables show the composition of the Company’s investment portfolio by geographic region, at amortized cost and fair value (with corresponding percentage of total portfolio investments). The geographic composition is determined by the location of the corporate headquarters of the portfolio company, which may not be indicative of the primary source of the portfolio company’s business: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, 2022 ​ December 31, 2021 Amortized Cost: ​ ​ ​ International ​ $ 11,860 2.1 % $ 11,860 2.0 % Midwest ​ 157,558 27.2 ​ 145,023 25.2 ​ Northeast ​ 100,961 17.4 ​ 107,828 18.7 ​ Southeast ​ 158,548 27.4 ​ 164,100 28.5 ​ Southwest ​ 27,348 4.7 ​ 40,121 7.0 ​ West ​ 123,032 21.2 ​ 107,246 18.6 ​ Total ​ $ 579,307 100.0 % $ 576,178 100.0 % ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, 2022 ​ December 31, 2021 Fair Value: ​ ​ ​ International ​ $ 10,405 1.9 % $ 11,093 2.0 % Midwest ​ 143,691 26.6 ​ 143,435 25.5 ​ Northeast ​ 104,157 19.2 ​ 112,175 20.0 ​ Southeast ​ 155,624 28.8 ​ 159,807 28.4 ​ Southwest ​ 28,287 5.2 ​ 44,380 7.9 ​ West ​ 98,876 18.3 ​ 90,803 16.2 ​ Total ​ $ 541,040 100.0 % $ 561,693 100.0 % ​ The following tables show the composition of the Company’s investment portfolio by industry, at amortized cost and fair value (with corresponding percentage of total portfolio investments): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, 2022 ​ December 31, 2021 Amortized Cost: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Aerospace & Defense $ 7,461 1.3 % $ 7,828 1.4 % Automotive ​ 16,775 2.9 ​ 21,162 3.7 ​ Banking ​ 17,790 3.1 ​ 5,416 1.0 ​ Beverage, Food & Tobacco ​ 15,625 2.7 ​ 21,036 3.7 ​ Capital Equipment ​ 18,615 3.2 ​ 12,656 2.2 ​ Chemicals, Plastics & Rubber ​ 2,924 0.5 ​ 9,426 1.6 ​ Construction & Building ​ 6,642 1.1 ​ 16,450 2.9 ​ Consumer Goods: Durable ​ 9,333 1.6 ​ 9,536 1.7 ​ Consumer Goods: Non-Durable ​ 28,276 4.9 ​ 28,232 4.9 ​ Environmental Industries ​ 6,164 1.1 ​ 17,103 3.0 ​ FIRE: Finance ​ 25,021 4.3 ​ 16,264 2.8 ​ FIRE: Real Estate ​ 81,922 14.1 ​ 72,826 12.6 ​ Healthcare & Pharmaceuticals ​ 59,659 10.3 ​ 52,743 9.2 ​ High Tech Industries ​ 52,385 9.0 ​ 52,710 9.1 ​ Hotels, Gaming & Leisure ​ 2,702 0.5 ​ 2,662 0.5 ​ Investment Funds & Vehicles ​ 42,650 7.4 ​ 42,150 7.3 ​ Media: Advertising, Printing & Publishing ​ 17,470 3.0 ​ 13,421 2.3 ​ Media: Broadcasting & Subscription ​ 2,747 0.5 ​ 2,472 0.4 ​ Media: Diversified & Production ​ 36,018 6.2 ​ 23,853 4.1 ​ Retail ​ 9,247 1.6 ​ 10,954 1.9 ​ Services: Business ​ 56,249 9.7 ​ 69,292 12.0 ​ Services: Consumer ​ 40,086 6.9 ​ 46,284 8.0 ​ Telecommunications ​ 7,502 1.3 ​ 5,892 1.0 ​ Wholesale ​ 16,044 2.8 ​ 15,810 2.7 ​ Total ​ $ 579,307 100.0 % $ 576,178 100.0 % ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, 2022 ​ December 31, 2021 Fair Value: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Aerospace & Defense $ 7,436 1.4 % $ 7,972 1.4 % Automotive ​ 16,637 3.1 ​ 21,556 3.8 ​ Banking ​ 19,817 3.7 ​ 6,712 1.2 ​ Beverage, Food & Tobacco ​ 12,470 2.3 ​ 19,133 3.4 ​ Capital Equipment ​ 19,012 3.5 ​ 12,839 2.3 ​ Chemicals, Plastics & Rubber ​ 4,445 0.8 ​ 10,163 1.8 ​ Construction & Building ​ 6,706 1.2 ​ 16,636 3.0 ​ Consumer Goods: Durable ​ 9,338 1.7 ​ 9,734 1.7 ​ Consumer Goods: Non-Durable ​ 3,508 0.6 ​ 8,460 1.5 ​ Environmental Industries ​ 6,558 1.2 ​ 17,693 3.2 ​ FIRE: Finance ​ 23,892 4.4 ​ 15,681 2.8 ​ FIRE: Real Estate ​ 82,498 15.2 ​ 76,698 13.6 ​ Healthcare & Pharmaceuticals ​ 59,273 11.0 ​ 53,179 9.5 ​ High Tech Industries ​ 52,891 9.8 ​ 54,085 9.6 ​ Hotels, Gaming & Leisure ​ 2,720 0.5 ​ 2,706 0.5 ​ Investment Funds & Vehicles ​ 35,509 6.6 ​ 41,125 7.3 ​ Media: Advertising, Printing & Publishing ​ 19,777 3.7 ​ 16,794 3.0 ​ Media: Broadcasting & Subscription ​ 2,691 0.5 ​ 2,477 0.5 ​ Media: Diversified & Production ​ 36,164 6.7 ​ 24,220 4.3 ​ Retail ​ 9,306 1.7 ​ 11,478 2.0 ​ Services: Business ​ 57,308 10.6 ​ 71,540 12.7 ​ Services: Consumer ​ 31,324 5.8 ​ 39,248 7.0 ​ Telecommunications ​ 7,595 1.4 ​ 5,988 1.1 ​ Wholesale ​ 14,165 2.6 ​ 15,576 2.8 ​ Total ​ $ 541,040 100.0 % $ 561,693 100.0 % ​
Summary of SLF's portfolio, followed by a listing of the individual investments in SLF's portfolio	Below is a summary of SLF’s portfolio, followed by a listing of the individual investments in SLF’s portfolio as of December 31, 2022 and 2021: ​ ​ ​ ​ ​ ​ ​ ​ As of ​ ​ December 31, 2022 ​ December 31, 2021 Senior secured loans (1) 197,867 193,062 ​ Weighted average current interest rate on senior secured loans (2) 9.7 % 5.9 % Number of portfolio company investments in SLF 60 57 ​ Largest portfolio company investment (1) 6,650 6,720 ​ Total of five largest portfolio company investments (1) 27,026 27,074 ​ (1) Represents outstanding principal amount, excluding unfunded commitments. (2) Computed as the (a) annual stated interest rate on accruing senior secured loans divided by (b) total senior secured loans at outstanding principal amount. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Portfolio Company (a) Index (b) Spread (b) Interest Rate (b) Maturity Principal Fair Value Non-Controlled/Non-Affiliate Company Investments ​ ​ Senior Secured Loans ​ ​ Aerospace & Defense ​ ​ ​ Bromford Industries Limited (c) P 5.25 % 12.75 % ​ 11/5/2025 2,744 ​ $ 2,581 Bromford Industries Limited (c) P 5.25 % 12.75 % ​ 11/5/2025 1,829 ​ 1,720 Trident Maritime Systems, Inc. L 4.75 % 9.48 % ​ 2/26/2027 2,445 ​ 2,443 Trident Maritime Systems, Inc. L 4.75 % 9.48 % ​ 2/26/2027 746 ​ 746 Trident Maritime Systems, Inc. (Revolver) (d) L 4.75 % 9.08 % ​ 2/26/2027 319 ​ 122 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 8,083 ​ 7,612 Automotive ​ ​ ​ Accelerate Auto Works Intermediate, LLC L 4.50 % 9.23 % ​ 12/1/2027 1,391 ​ 1,386 Accelerate Auto Works Intermediate, LLC (Delayed Draw) (d) L 4.50 % 9.23 % ​ 12/1/2027 388 ​ — Accelerate Auto Works Intermediate, LLC (Revolver) (d) L 4.50 % 9.23 % ​ 12/1/2027 132 ​ — Truck-Lite Co., LLC SF 6.25 % 11.14 % ​ 12/14/2026 1,691 ​ 1,690 Truck-Lite Co., LLC SF 6.25 % 11.14 % ​ 12/14/2026 251 ​ 250 Truck-Lite Co., LLC SF 6.25 % 11.14 % ​ 12/14/2026 43 ​ 43 Wheel Pros, Inc. L 4.50 % 8.82 % ​ 5/11/2028 1,932 ​ 1,321 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 5,828 ​ 4,690 Beverage, Food & Tobacco ​ ​ ​ CBC Restaurant Corp. n/a n/a 5.00 % PIK (e) n/a (f) 1,066 ​ 415 SW Ingredients Holdings, LLC L 4.75 % 9.13 % ​ 7/3/2025 3,581 ​ 3,581 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 4,647 ​ 3,996 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Portfolio Company (a) Index (b) Spread (b) Interest Rate (b) Maturity Principal Fair Value Capital Equipment ​ Analogic Corporation L 5.25 % 9.66 % 6/24/2024 4,703 ​ $ 4,433 DS Parent, Inc. L 5.75 % 9.92 % 12/8/2028 2,850 ​ 2,725 MacQueen Equipment, LLC L 5.25 % 9.98 % 1/7/2028 2,096 ​ 2,096 MacQueen Equipment, LLC (Delayed Draw) (d) L 5.25 % 9.98 % 1/7/2028 592 ​ 69 MacQueen Equipment, LLC (Revolver) (d) L 5.25 % 9.98 % 1/7/2028 296 ​ — ​ ​ ​ ​ ​ ​ ​ ​ ​ 10,537 ​ 9,323 Chemicals, Plastics & Rubber ​ ​ Phoenix Chemical Holding Company LLC (fka Polymer Solutions Group) L 7.00 % 11.39 % 6/15/2023 1,139 ​ 1,132 TJC Spartech Acquisition Corp. L 4.75 % 8.53 % 5/5/2028 4,253 ​ 4,131 ​ ​ ​ ​ ​ ​ ​ ​ ​ 5,392 ​ 5,263 Construction & Building ​ ​ The Cook & Boardman Group LLC SF 5.75 % 9.99 % 10/20/2025 2,879 ​ 2,458 ​ ​ ​ ​ ​ ​ ​ ​ ​ 2,879 ​ 2,458 Consumer Goods: Durable ​ ​ International Textile Group, Inc. L 5.00 % 9.21 % 5/1/2024 1,664 ​ 1,166 Runner Buyer INC. L 5.50 % 10.23 % 10/23/2028 2,978 ​ 2,114 ​ ​ ​ ​ ​ ​ ​ ​ ​ 4,642 ​ 3,280 Consumer Goods: Non-Durable ​ ​ PH Beauty Holdings III, INC. L 5.00 % 9.73 % 9/26/2025 2,393 ​ 1,950 ​ ​ ​ ​ ​ ​ ​ ​ ​ 2,393 ​ 1,950 Containers, Packaging & Glass ​ ​ Liqui-Box Holdings, Inc. L 4.50 % 9.23 % 2/26/2027 4,225 ​ 4,186 Polychem Acquisition, LLC L 5.00 % 9.38 % 3/17/2025 2,888 ​ 2,888 PVHC Holding Corp L 4.75 % 9.48 % 8/5/2024 3,184 ​ 3,072 ​ ​ ​ ​ ​ ​ ​ ​ ​ 10,297 ​ 10,146 Energy: Oil & Gas ​ ​ Drilling Info Holdings, Inc. L 4.25 % 8.63 % 7/30/2025 4,469 ​ 4,313 Offen, Inc. L 5.00 % 9.38 % 6/22/2026 2,249 ​ 2,249 Offen, Inc. L 5.00 % 9.38 % 6/22/2026 867 ​ 867 ​ ​ ​ ​ ​ ​ ​ ​ ​ 7,585 ​ 7,429 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Portfolio Company (a) Index (b) Spread (b) Interest Rate (b) Maturity Principal Fair Value FIRE: Finance ​ ​ Harbour Benefit Holdings, Inc. L 5.25 % 9.98 % ​ 12/13/2024 2,901 ​ $ 2,898 Harbour Benefit Holdings, Inc. L 5.25 % 9.63 % ​ 12/13/2024 61 ​ 61 Minotaur Acquisition, Inc. SF 4.75 % 9.17 % ​ 3/27/2026 4,857 ​ 4,656 TEAM Public Choices, LLC L 5.00 % 9.93 % ​ 12/17/2027 2,955 ​ 2,822 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 10,774 ​ 10,437 FIRE: Real Estate ​ ​ ​ Avison Young (USA) Inc. (c) SF 5.75 % 10.19 % ​ 1/30/2026 4,800 ​ 4,020 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 4,800 ​ 4,020 Healthcare & Pharmaceuticals ​ ​ ​ Cano Health, LLC SF 4.00 % 8.42 % ​ 11/23/2027 1,970 ​ 1,572 HAH Group Holding Company LLC SF 5.00 % 9.43 % ​ 10/29/2027 2,978 ​ 2,847 LSCS Holdings, Inc. L 4.50 % 8.88 % ​ 12/15/2028 1,828 ​ 1,751 Natus Medical Incorporated SF 5.50 % 8.68 % ​ 7/20/2029 5,000 ​ 4,650 Paragon Healthcare, Inc. SF 5.75 % 9.81 % ​ 1/19/2027 2,127 ​ 2,109 Paragon Healthcare, Inc. (Delayed Draw) (d) SF 5.75 % 10.06 % ​ 1/19/2027 366 ​ 242 Paragon Healthcare, Inc. (Revolver) (d) SF 5.75 % 10.26 % ​ 1/19/2027 490 ​ 61 Radiology Partners, Inc. L 4.25 % 8.64 % ​ 7/9/2025 4,760 ​ 4,018 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 19,519 ​ 17,250 High Tech Industries ​ ​ ​ Corel Inc. (c) L 5.00 % 9.73 % ​ 7/2/2026 3,600 ​ 3,365 Lightbox Intermediate, L.P. L 5.00 % 9.73 % ​ 5/11/2026 4,825 ​ 4,656 TGG TS Acquisition Company L 6.50 % 10.88 % ​ 12/12/2025 3,190 ​ 3,143 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 11,615 ​ 11,164 Hotels, Gaming & Leisure ​ ​ ​ Excel Fitness Holdings, Inc. SF 5.25 % 10.29 % ​ 4/27/2029 4,364 ​ 4,102 Excel Fitness Holdings, Inc. (Revolver) (d) SF 5.25 % 9.67 % ​ 4/28/2028 625 ​ 306 North Haven Spartan US Holdco, LLC SF 6.25 % 10.71 % ​ 6/6/2025 2,280 ​ 2,202 Tait LLC L 5.00 % 8.75 % ​ 3/28/2025 4,083 ​ 3,972 Tait LLC (Revolver) (d) P 4.00 % 10.25 % ​ 3/28/2025 769 ​ — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 12,121 ​ 10,582 Media: Advertising, Printing & Publishing ​ ​ ​ Cadent, LLC L 6.50 % 11.23 % ​ 9/11/2025 4,237 ​ 4,131 Cadent, LLC (Revolver) (d) L 6.50 % 11.23 % ​ 9/11/2025 167 ​ — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 4,404 ​ 4,131 Media: Diversified & Production ​ ​ ​ Research Now Group, Inc. and Survey Sampling International, LLC L 5.50 % 8.84 % ​ 12/20/2024 6,650 ​ 5,035 STATS Intermediate Holdings, LLC L 5.25 % 9.90 % ​ 7/10/2026 4,850 ​ 4,498 TA TT Buyer, LLC SF 5.00 % 8.98 % ​ 3/30/2029 3,325 ​ 3,242 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 14,825 ​ 12,775 Services: Business ​ ​ ​ AQ Carver Buyer, Inc. L 5.00 % 9.38 % ​ 9/23/2025 4,838 ​ 4,834 CHA Holdings, Inc L 4.50 % 9.23 % ​ 4/10/2025 1,960 ​ 1,886 CHA Holdings, Inc L 4.50 % 9.23 % ​ 4/10/2025 413 ​ 398 Eliassen Group, LLC SF 5.50 % 10.08 % ​ 4/14/2028 3,251 ​ 3,194 Eliassen Group, LLC (Delayed Draw) (d) SF 5.50 % 8.88 % ​ 4/14/2028 740 ​ 109 Engage2Excel, Inc. L 7.25 % 11.98 % ​ 3/7/2023 4,283 ​ 4,242 Engage2Excel, Inc. L 7.25 % 11.98 % ​ 3/7/2023 773 ​ 766 Engage2Excel, Inc. (Revolver) (d) P 6.25 % 13.75 % ​ 3/7/2023 554 ​ 509 Orbit Purchaser LLC L 4.50 % 9.23 % ​ 10/21/2024 2,406 ​ 2,190 Orbit Purchaser LLC L 4.50 % 9.23 % ​ 10/21/2024 1,858 ​ 1,691 Orbit Purchaser LLC L 4.50 % 9.23 % ​ 10/21/2024 543 ​ 494 ​ ​ ​ ​ ​ 9.80 % Cash/ ​ ​ ​ ​ ​ ​ ​ Output Services Group, Inc. ​ SF 6.75 % 1.50 % PIK ​ 6/29/2026 4,807 ​ 3,275 Secretariat Advisors LLC L 4.75 % 9.48 % ​ 12/29/2028 1,693 ​ 1,634 Secretariat Advisors LLC L 4.75 % 9.48 % ​ 12/29/2028 270 ​ 260 SIRVA Worldwide Inc. L 5.50 % 10.23 % ​ 8/4/2025 1,800 ​ 1,606 Teneo Holdings LLC SF 5.25 % 9.67 % ​ 7/11/2025 4,837 ​ 4,668 The Kleinfelder Group, Inc. L 5.25 % 9.98 % ​ 11/29/2024 2,362 ​ 2,362 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 37,388 ​ 34,118 Services: Consumer ​ ​ ​ 360Holdco, Inc. SF 5.00 % 9.42 % ​ 8/2/2025 2,145 ​ 2,145 360Holdco, Inc. (Delayed Draw) (d) SF 5.00 % 9.42 % ​ 8/2/2025 827 ​ 252 Laseraway Intermediate Holdings II, LLC L 5.75 % 9.76 % ​ 10/14/2027 2,200 ​ 2,161 McKissock Investment Holdings, LLC SF 5.00 % 8.87 % ​ 3/9/2029 2,481 ​ 2,322 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 7,653 ​ 6,880 Telecommunications ​ ​ ​ Intermedia Holdings, Inc. L 6.00 % 10.38 % ​ 7/21/2025 1,760 ​ 1,360 Mavenir Systems, Inc. L 4.75 % 9.42 % ​ 8/18/2028 1,654 ​ 1,350 Sandvine Corporation L 4.50 % 8.88 % ​ 10/31/2025 2,000 ​ 1,904 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 5,414 ​ 4,614 Transportation: Cargo ​ ​ ​ Keystone Purchaser, LLC L 5.50 % 10.60 % ​ 5/7/2027 4,955 ​ 4,955 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 4,955 ​ 4,955 Utilities: Oil & Gas ​ ​ ​ Dresser Utility Solutions, LLC (fka NGS US Finco, LLC) L 4.25 % 8.63 % ​ 10/1/2025 1,678 ​ 1,619 Dresser Utility Solutions, LLC (fka NGS US Finco, LLC) L 5.25 % 9.63 % ​ 10/1/2025 245 ​ 239 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 1,923 ​ 1,858 Wholesale ​ ​ ​ HALO Buyer, Inc. L 4.50 % 8.88 % ​ 6/30/2025 4,774 ​ 4,219 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 4,774 ​ 4,219 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ TOTAL INVESTMENTS ​ ​ $ 183,150 (a) All investments are U.S. companies unless otherwise noted. (b) The majority of investments bear interest at a rate that may be determined by reference to the London Interbank Offered Rate (“LIBOR” or “L”), Secured Overnight Financing Rate (“SOFR” or “SF”) or Prime (“P”) which reset daily, monthly, quarterly or semiannually. The Company has provided the spread over LIBOR, SOFR or Prime and the current contractual rate of interest in effect at December 31, 2022. Certain investments may be subject to an interest rate floor or cap. Certain investments contain a Payment-in-Kind (“PIK”) provision. (c) This is an international company. (d) All or a portion of this commitment was unfunded as of December 31, 2022. As such, interest is earned only on the funded portion of this commitment. Principal reflects the commitment outstanding. (e) This position was on non-accrual status as of December 31, 2022, meaning that the Company has ceased accruing interest income on the position. (f) This is a demand note with no stated maturity. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Spread Above ​ ​ ​ ​ ​ ​ Portfolio Company (a) ​ Index (b) ​ Interest Rate (b) ​ ​ Maturity ​ Principal ​ Fair Value Non-Controlled/Non-Affiliate Company Investments ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Senior Secured Loans ​ ​ ​ Aerospace & Defense ​ ​ ​ Bromford Industries Limited (c) P+ 4.25 % 7.50 % ​ 11/5/2025 2,744 ​ $ 2,692 Bromford Industries Limited (c) P+ 4.25 % 7.50 % ​ 11/5/2025 1,829 ​ 1,794 Trident Maritime Systems, Inc. L+ 5.50 % 6.50 % ​ 02/26/2027 2,467 ​ 2,478 Trident Maritime Systems, Inc. (Revolver) (d) L+ 5.50 % 6.50 % ​ 02/26/2027 265 ​ — ​ ​ ​ ​ ​ ​ ​ ​ 7,305 ​ ​ 6,964 Automotive ​ ​ ​ Accelerate Auto Works Intermediate, LLC L+ 4.75 % 5.75 % ​ 12/1/2027 1,454 ​ 1,436 Accelerate Auto Works Intermediate, LLC (Delayed Draw) (d) L+ 4.75 % 5.75 % ​ 12/1/2027 388 ​ — Accelerate Auto Works Intermediate, LLC (Revolver) (d) L+ 4.75 % 5.75 % ​ 12/1/2027 132 ​ — Truck-Lite Co., LLC L+ 6.25 % 7.25 % ​ 12/14/2026 1,709 ​ 1,718 Truck-Lite Co., LLC L+ 6.25 % 7.25 % ​ 12/14/2026 253 ​ 255 Wheel Pros, Inc. L+ 4.50 % 5.25 % ​ 05/11/2028 1,952 ​ 1,951 ​ ​ ​ ​ ​ ​ ​ ​ 5,888 ​ ​ 5,360 Beverage, Food & Tobacco ​ ​ ​ CBC Restaurant Corp. ​ n/a 5.00 % PIK (f) ​ 12/30/2022 1,116 ​ 1,072 SW Ingredients Holdings, LLC L+ 4.75 % 5.75 % ​ 07/3/2025 3,619 ​ 3,619 ​ ​ ​ ​ ​ ​ ​ ​ 4,735 ​ ​ 4,691 Capital Equipment ​ ​ ​ Analogic Corporation L+ 5.25 % 6.25 % ​ 06/24/2024 4,752 ​ 4,702 DS Parent, Inc. (e) L+ 5.75 % 6.50 % ​ 12/8/2028 3,000 ​ 2,970 ​ ​ ​ ​ ​ ​ ​ ​ 7,752 ​ ​ 7,672 Chemicals, Plastics & Rubber ​ ​ ​ Polymer Solutions Group L+ 7.00 % 8.00 % ​ 01/3/2023 1,178 ​ 1,169 ​ ​ ​ ​ ​ ​ ​ ​ 1,178 ​ ​ 1,169 Construction & Building ​ ​ ​ The Cook & Boardman Group LLC L+ 5.75 % 6.75 % ​ 10/20/2025 2,910 ​ 2,838 ​ ​ ​ ​ ​ ​ ​ ​ 2,910 ​ ​ 2,838 Consumer Goods: Durable ​ ​ ​ International Textile Group, Inc. L+ 5.00 % 5.13 % ​ 05/1/2024 1,711 ​ 1,590 Runner Buyer Inc. (e) L+ 5.50 % 6.25 % ​ 10/23/2028 3,000 ​ 2,970 ​ ​ ​ ​ ​ ​ ​ ​ 4,711 ​ ​ 4,560 Consumer Goods: Non-Durable ​ ​ ​ PH Beauty Holdings III, INC. L+ 5.00 % 5.18 % ​ 09/26/2025 2,418 ​ 2,284 ​ ​ ​ ​ ​ ​ ​ ​ 2,418 ​ ​ 2,284 Containers, Packaging & Glass ​ ​ ​ Liqui-Box Holdings, Inc. L+ 4.50 % 5.50 % ​ 02/26/2027 4,268 ​ 3,991 Polychem Acquisition, LLC L+ 5.00 % 5.50 % ​ 03/17/2025 2,918 ​ 2,917 ​ ​ ​ ​ ​ 5.75 % Cash/ ​ ​ ​ ​ ​ ​ ​ Port Townsend Holdings Company, Inc. and Crown Corrugated Company L+ 6.75 % 2.00 % PIK ​ 04/3/2024 4,751 ​ 4,238 PVHC Holding Corp L+ 4.75 % 5.75 % ​ 08/5/2024 3,217 ​ 2,976 ​ ​ ​ ​ ​ ​ ​ ​ 15,154 ​ ​ 14,122 Energy: Oil & Gas ​ ​ ​ Drilling Info Holdings, Inc. L+ 4.25 % 4.35 % ​ 07/30/2025 4,516 ​ 4,471 Offen, Inc. L+ 5.00 % 5.10 % ​ 06/22/2026 2,388 ​ 2,387 Offen, Inc. L+ 5.00 % 5.10 % ​ 06/22/2026 876 ​ 876 ​ ​ ​ ​ ​ ​ ​ ​ 7,780 ​ ​ 7,734 FIRE: Finance ​ ​ ​ Harbour Benefit Holdings, Inc. L+ 5.25 % 6.25 % ​ 12/13/2024 2,948 ​ 2,932 Harbour Benefit Holdings, Inc. L+ 5.25 % 6.25 % ​ 12/13/2024 66 ​ 65 Minotaur Acquisition, Inc. (e) L+ 4.75 % 4.85 % ​ 3/27/2026 4,912 ​ 4,894 ​ ​ ​ ​ ​ ​ ​ ​ 7,926 ​ ​ 7,891 FIRE: Real Estate ​ ​ ​ Avison Young (USA) Inc. (c) L+ 5.75 % 5.97 % ​ 1/30/2026 4,850 ​ 4,824 ​ ​ ​ ​ ​ ​ ​ ​ 4,850 ​ ​ 4,824 Healthcare & Pharmaceuticals ​ ​ ​ Cano Health, LLC (e) ​ SF+ 4.00 % 4.51 % ​ 11/23/2027 ​ 1,995 ​ ​ 1,997 LSCS Holdings, Inc. (e) L+ 4.50 % 5.00 % ​ 12/15/2028 1,846 ​ 1,849 Radiology Partners, Inc. L+ 4.25 % 4.35 % ​ 07/9/2025 4,760 ​ 4,700 TEAM Public Choices, LLC (e) L+ 5.00 % 6.00 % ​ 12/17/2027 2,992 ​ 2,985 ​ ​ ​ ​ ​ ​ ​ ​ 11,593 ​ ​ 11,531 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Spread Above ​ ​ ​ ​ ​ ​ Portfolio Company (a) Index (b) Interest Rate (b) ​ Maturity Principal Fair Value High Tech Industries ​ ​ ​ ​ ​ ​ ​ ​ ​ Corel Inc. (c) L+ 5.00 % 5.18 % ​ 7/2/2026 3,800 ​ $ 3,797 Lightbox Intermediate, L.P. L+ 5.00 % 5.13 % ​ 5/11/2026 4,875 ​ 4,814 LW Buyer, LLC L+ 5.00 % 5.14 % ​ 12/30/2024 4,875 ​ 4,863 TGG TS Acquisition Company L+ 6.50 % 6.60 % ​ 12/12/2025 3,435 ​ 3,446 ​ ​ ​ ​ ​ ​ ​ ​ 16,985 ​ ​ 16,920 Hotels, Gaming & Leisure ​ ​ ​ Excel Fitness Holdings, Inc. L+ 5.25 % 6.25 % ​ 10/7/2025 4,165 ​ 4,155 North Haven Spartan US Holdco, LLC L+ 5.00 % 6.00 % ​ 6/6/2025 2,297 ​ 2,037 Tait LLC L+ 5.00 % 5.14 % ​ 3/28/2025 4,125 ​ 3,785 Tait LLC (Revolver) P+ 4.00 % 7.25 % ​ 3/28/2025 769 ​ 728 ​ ​ ​ ​ ​ ​ ​ ​ 11,356 ​ ​ 10,705 Media: Advertising, Printing & Publishing ​ ​ ​ Cadent, LLC L+ 5.00 % 6.00 % ​ 9/11/2023 4,339 ​ 4,296 Cadent, LLC (Revolver) (d) L+ 5.00 % 6.00 % ​ 9/11/2023 167 ​ — ​ ​ ​ ​ ​ ​ ​ ​ 4,506 ​ ​ 4,296 Media: Diversified & Production ​ ​ ​ Research Now Group, Inc. and Survey Sampling International, LLC L+ 5.50 % 6.50 % ​ 12/20/2024 6,720 ​ 6,645 STATS Intermediate Holdings, LLC L+ 5.25 % 5.41 % ​ 7/10/2026 4,900 ​ 4,897 The Octave Music Group, Inc. L+ 6.00 % 7.00 % ​ 5/29/2025 3,866 ​ 3,871 ​ ​ ​ ​ ​ ​ ​ ​ 15,486 ​ ​ 15,413 Services: Business ​ ​ ​ AQ Carver Buyer, Inc. L+ 5.00 % 6.00 % ​ 9/23/2025 4,888 ​ 4,900 CHA Holdings, Inc L+ 4.50 % 5.50 % ​ 4/10/2025 1,980 ​ 1,901 CHA Holdings, Inc L+ 4.50 % 5.50 % ​ 4/10/2025 418 ​ 401 Eliassen Group LLC L+ 4.25 % 4.35 % ​ 11/5/2024 3,956 ​ 3,956 ​ ​ ​ ​ ​ 7.00 % Cash/ ​ ​ ​ ​ ​ ​ ​ Engage2Excel, Inc. L+ 8.00 % 2.00 % PIK ​ 3/7/2023 4,326 ​ 4,329 ​ ​ ​ ​ ​ 7.00 % Cash/ ​ ​ ​ ​ ​ ​ ​ Engage2Excel, Inc. L+ 8.00 % 2.00 % PIK ​ 3/7/2023 781 ​ 781 ​ ​ ​ ​ ​ 7.00 % Cash/ ​ ​ ​ ​ ​ ​ ​ Engage2Excel, Inc. (Revolver) (d) L+ 8.00 % 2.00 % PIK ​ 3/7/2023 555 ​ 541 Orbit Purchaser LLC L+ 4.50 % 5.50 % ​ 10/21/2024 2,431 ​ 2,425 Orbit Purchaser LLC L+ 4.50 % 5.50 % ​ 10/21/2024 1,877 ​ 1,873 Orbit Purchaser LLC L+ 4.50 % 5.50 % ​ 10/21/2024 549 ​ 548 Output Services Group, Inc. L+ 4.50 % 5.50 % ​ 3/27/2024 4,815 ​ 4,145 Secretariat Advisors LLC (e) L+ 4.75 % 5.50 % ​ 12/29/2028 1,710 ​ 1,693 Secretariat Advisors LLC (d) (e) L+ 4.75 % 5.50 % ​ 12/29/2028 270 ​ — SIRVA Worldwide Inc. L+ 5.50 % 5.60 % ​ 8/4/2025 1,850 ​ 1,683 Teneo Holdings LLC L+ 5.25 % 6.25 % ​ 7/11/2025 4,888 ​ 4,908 The Kleinfelder Group, Inc. L+ 5.25 % 6.25 % ​ 11/29/2024 2,387 ​ 2,387 ​ ​ ​ ​ ​ ​ ​ ​ 37,681 ​ ​ 36,471 Services: Consumer ​ ​ ​ 360Holdco, Inc. L+ 4.75 % 5.75 % ​ 8/2/2025 2,168 ​ 2,161 360Holdco, Inc. (Delayed Draw) (d) L+ 4.75 % 5.75 % ​ 8/2/2025 827 ​ — Laseraway Intermediate Holdings II, LLC L+ 5.75 % 6.50 % ​ 10/14/2027 2,222 ​ 2,214 ​ ​ ​ ​ ​ ​ ​ ​ 5,217 ​ ​ 4,375 Telecommunications ​ ​ ​ Intermedia Holdings, Inc. L+ 6.00 % 7.00 % ​ 7/21/2025 1,778 ​ 1,770 Mavenir Systems, Inc. L+ 4.75 % 5.25 % ​ 8/18/2028 1,667 ​ 1,669 Sandvine Corporation L+ 4.50 % 4.60 % ​ 10/31/2025 2,000 ​ 1,999 ​ ​ ​ ​ ​ ​ ​ ​ 5,445 ​ ​ 5,438 Transportation: Cargo ​ ​ ​ Keystone Purchaser, LLC (e) L+ 6.25 % 7.25 % ​ 5/7/2027 3,000 ​ 2,947 ​ ​ ​ ​ ​ ​ ​ ​ 3,000 ​ ​ 2,947 Utilities: Oil & Gas ​ ​ ​ NGS US Finco, LLC L+ 4.25 % 5.25 % ​ 10/1/2025 1,695 ​ 1,644 NGS US Finco, LLC L+ 5.25 % 6.25 % ​ 10/1/2025 248 ​ 244 ​ ​ ​ ​ ​ ​ ​ ​ 1,943 ​ ​ 1,888 Wholesale ​ ​ ​ BMC Acquisition, Inc. L+ 5.25 % 6.25 % ​ 12/30/2024 4,486 ​ 4,469 HALO Buyer, Inc. L+ 4.50 % 5.50 % ​ 6/30/2025 4,824 ​ 4,547 ​ ​ ​ ​ ​ ​ ​ ​ 9,310 ​ ​ 9,016 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ TOTAL INVESTMENTS ​ ​ ​ ​ ​ $ 189,109 (a) All investments are U.S. companies unless otherwise noted. (b) The majority of investments bear interest at a rate that may be determined by reference to the London Interbank Offered Rate (“LIBOR” or “L”), Secured Overnight Financing Rate (“SOFR” or “SF”) or Prime (“P”) which reset daily, monthly, quarterly or semiannually. The Company has provided the spread over LIBOR, SOFR or Prime and the current contractual rate of interest in effect at December 31, 2021. Certain investments may be subject to an interest rate floor or cap. (c) This is an international company. (d) All or a portion of this commitment was unfunded as of December 31, 2021. As such, interest is earned only on the funded portion of this commitment. Principal reflects the commitment outstanding. (e) Investment position or portion thereof unsettled at December 31, 2021. (f) This position was on non-accrual status as of December 31, 2021, meaning that the Company has ceased accruing interest income on the position.
Schedule of summarized financial information for SLF	Below is certain summarized financial information for SLF as of December 31, 2022 and 2021 and for the years ended December 31, 2022, 2021 and 2020: ​ ​ ​ ​ ​ ​ ​ ​ December 31, 2022 December 31, 2021 Assets ​ ​ Investments, at fair value ​ $ 183,150 ​ $ 189,109 Cash ​ 1,608 ​ 40 Restricted cash ​ 6,454 ​ 4,862 Interest receivable ​ 1,613 ​ 600 Other assets ​ 5 ​ 12 Total assets ​ ​ 192,830 ​ ​ 194,623 Liabilities ​ ​ ​ ​ Revolving credit facility ​ ​ 122,215 ​ ​ 94,765 Less: Unamortized deferred financing costs ​ (1,518) ​ (2,319) Total debt, less unamortized deferred financing costs ​ 120,697 ​ 92,446 Payable for open trades ​ — ​ 19,367 Interest payable ​ 769 ​ 242 Accounts payable and accrued expenses ​ 346 ​ 318 Total liabilities ​ 121,812 ​ 112,373 Members’ capital ​ 71,018 ​ 82,250 Total liabilities and members’ capital ​ $ 192,830 ​ $ 194,623 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ For the years ended December 31, ​ 2022 2021 ​ 2020 Investment income: ​ ​ ​ ​ ​ Interest income ​ $ 15,400 ​ $ 13,164 ​ $ 15,578 Total investment income ​ 15,400 ​ 13,164 ​ ​ 15,578 Expenses: ​ ​ ​ ​ ​ ​ ​ Interest and other debt financing expenses ​ 6,009 ​ 3,918 ​ ​ 5,227 Professional fees ​ 814 ​ 647 ​ ​ 666 Total expenses ​ 6,823 ​ 4,565 ​ ​ 5,893 Net investment income ​ 8,577 ​ 8,599 ​ ​ 9,685 Net gain (loss): ​ ​ ​ ​ ​ ​ ​ Net realized gain (loss) ​ ​ (3,089) ​ ​ — ​ ​ (1,713) Net change in unrealized gain (loss) ​ (10,520) ​ 3,734 ​ ​ (5,429) Net gain (loss) ​ (13,609) ​ 3,734 ​ ​ (7,142) Net increase (decrease) in members’ capital ​ $ (5,032) ​ $ 12,333 ​ $ 2,543

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	12 Months Ended
	Dec. 31, 2022
Fair Value Measurements
Schedule of fair value measurements of investments and foreign currency forward contracts, by major class according to the fair value hierarchy	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Fair Value Measurements December 31, 2022 ​ Level 1 ​ Level 2 ​ Level 3 ​ Total Investments: ​ ​ ​ ​ Senior secured loans ​ $ — ​ $ — ​ $ 434,023 ​ $ 434,023 Unitranche secured loans ​ — ​ — ​ 20,633 ​ 20,633 Junior secured loans ​ — ​ — ​ 22,193 ​ 22,193 Equity securities ​ 294 ​ — ​ 28,388 ​ 28,682 Investments measured at NAV (1) (2) ​ — ​ — ​ — ​ 35,509 Total investments ​ $ 294 ​ $ — ​ $ 505,237 ​ $ 541,040 Foreign currency forward contracts asset (liability) ​ $ — ​ $ 1,507 ​ $ — ​ $ 1,507 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Fair Value Measurements December 31, 2021 ​ Level 1 ​ Level 2 ​ Level 3 ​ Total Investments: ​ ​ ​ ​ Senior secured loans ​ $ — ​ $ — ​ $ 423,700 ​ $ 423,700 Unitranche secured loans ​ — ​ — ​ 51,494 ​ 51,494 Junior secured loans ​ — ​ — ​ 14,364 ​ 14,364 Equity securities ​ 1,041 ​ — ​ 29,969 ​ 31,010 Investments measured at NAV (1) (2) ​ — ​ — ​ — ​ 41,125 Total investments ​ $ 1,041 ​ $ — ​ $ 519,527 ​ $ 561,693 Foreign currency forward contracts asset (liability) ​ $ — ​ $ 781 ​ $ — ​ $ 781 (1) Certain investments that are measured at fair value using the NAV have not been categorized in the fair value hierarchy. The fair value amounts presented in this table are intended to permit reconciliation of the fair value hierarchy to the amounts presented on the consolidated statements of assets and liabilities. (2) Represents the Company’s investment in LLC equity interests in SLF. The fair value of this investment has been determined using the NAV of the Company’s ownership interest in SLF’s members’ capital.
Schedule of reconciliation of the beginning and ending balances for investments at fair value that use Level 3 inputs	The following tables provide a reconciliation of the beginning and ending balances for investments at fair value that use Level 3 inputs for the years ended December 31, 2022 and 2021: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Investments ​ ​ Senior ​ Unitranche ​ Junior ​ Equity ​ Total Level 3 ​ ​ secured loans ​ secured loans ​ secured loans ​ securities ​ investments Balance as of December 31, 2021 $ 423,700 $ 51,494 $ 14,364 $ 29,969 $ 519,527 Net realized gain (loss) on investments ​ (1,082) ​ (94) ​ (1) ​ 47 ​ (1,130) Net change in unrealized gain (loss) on investments ​ (10,140) ​ (5,238) ​ 1,003 ​ (2,544) ​ (16,919) Purchases of investments and other adjustments to cost (1) ​ 130,155 ​ 3,319 ​ 6,827 ​ 1,254 ​ 141,555 Proceeds from principal payments and sales of investments (2) ​ ​ (108,610) ​ ​ (28,848) ​ ​ — ​ ​ (338) ​ ​ (137,796) Transfers in (out) of Level 3 (3) ​ — ​ — ​ — ​ — ​ — Balance as of December 31, 2022 ​ $ 434,023 ​ $ 20,633 ​ $ 22,193 ​ $ 28,388 ​ $ 505,237 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Investments ​ ​ Senior ​ Unitranche ​ Junior ​ Equity ​ Total Level 3 ​ ​ secured loans ​ secured loans ​ secured loans ​ securities ​ investments Balance as of December 31, 2020 $ 405,224 $ 64,040 $ 14,592 $ 23,899 $ 507,755 Net realized gain (loss) on investments ​ (22,512) ​ — ​ — ​ 748 ​ (21,764) Net change in unrealized gain (loss) on investments ​ 30,041 ​ (6,054) ​ 218 ​ 8,533 ​ 32,738 Purchases of investments and other adjustments to cost (1) ​ 204,213 ​ 10,815 ​ 13,652 ​ 7,605 ​ 236,285 Proceeds from principal payments and sales of investments (2) ​ ​ (193,266) ​ ​ (17,307) ​ ​ (14,098) ​ ​ (9,775) ​ ​ (234,446) Transfers in (out) of Level 3 (3) ​ — ​ — ​ — ​ (1,041) ​ (1,041) Balance as of December 31, 2021 ​ $ 423,700 ​ $ 51,494 ​ $ 14,364 ​ $ 29,969 ​ $ 519,527 (1) Includes purchases of new investments, effects of refinancing and restructurings, premium and discount accretion and amortization and PIK interest. (2) Represents net proceeds from investments sold and principal paydowns received. (3) Represents non-cash transfers between fair value categories.
Schedule of valuation techniques and significant unobservable inputs used in recurring Level 3 fair value measurements of assets	The valuation techniques and significant unobservable inputs used in recurring Level 3 fair value measurements of assets as of December 31, 2022 were as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Unobservable ​ Average ​ Range ​ Fair Value Valuation Technique Input Mean Minimum Maximum Assets: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Senior secured loans ​ $ 276,433 Discounted cash flow EBITDA multiples 9.3 x 3.8 x 18.6 x ​ ​ ​ ​ ​ Market yields ​ 12.4 % 8.7 % 22.3 % Senior secured loans ​ 130,199 Discounted cash flow Revenue multiples 4.4 x 0.2 x 12.3 x ​ ​ ​ ​ ​ Market yields ​ 13.4 % 10.0 % 22.0 % Senior secured loans ​ 19,546 Enterprise value Book value multiples 1.2 x 1.2 x 1.2 x Senior secured loans ​ 5,706 Enterprise value Revenue multiples 2.5 x 2.5 x 2.5 x Senior secured loans ​ 1,488 Liquidation Probability weighting of alternative outcomes 71.3 % 29.1 % 100.0 % Senior secured loans ​ ​ 80 ​ Enterprise value ​ EBITDA multiples ​ 8.0 x 8.0 x 8.0 x Unitranche secured loans ​ 17,019 Discounted cash flow EBITDA multiples 8.8 x 8.8 x 8.8 x ​ ​ ​ ​ Market yields 11.2 % 9.1 % 13.0 % Unitranche secured loans ​ 3,614 Discounted cash flow ​ Revenue multiples ​ 8.9 x 5.8 x 12.5 x ​ ​ ​ ​ Market yields 11.9 % 11.6 % 12.1 % Junior secured loans ​ 20,311 Discounted cash flow Market yields 13.6 % 12.3 % 20.4 % Junior secured loans ​ 1,882 Liquidation Probability weighting of alternative outcomes 225.8 % 225.8 % 225.8 % Equity securities ​ 16,630 Enterprise value EBITDA multiples 9.0 x 3.8 x 16.0 x Equity securities ​ 7,502 Enterprise value Revenue multiples 2.3 x 0.2 x 12.3 x Equity securities ​ 2,173 Option pricing model Volatility 66.6 % 49.4 % 70.0 % Equity securities ​ 397 Discounted cash flow EBITDA multiples 7.0 x 7.0 x 7.0 x Total Level 3 Assets ​ $ 502,980 (1) ​ ​ ​ ​ ​ ​ (1) Excludes investments of $2,257 at fair value where valuation (unadjusted) is obtained from a third-party pricing service for which such disclosure is not required. The valuation techniques and significant unobservable inputs used in recurring Level 3 fair value measurements of assets as of December 31, 2021 were as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted ​ ​ ​ ​ ​ Fair ​ ​ ​ Unobservable ​ Average ​ Range ​ ​ Value ​ Valuation Technique ​ Input ​ Mean ​ Minimum ​ Maximum Assets: ​ ​ Senior secured loans ​ $ 305,252 Discounted cash flow EBITDA multiples 7.7 x 5.0 x 20.0 x ​ ​ Market yields 9.6 % 5.3 % 20.0 % Senior secured loans ​ 79,913 Discounted cash flow Revenue multiples 6.5 x 0.5 x 13.0 x ​ ​ ​ ​ ​ Market yields ​ 8.4 % 5.2 % 13.1 % Senior secured loans ​ 23,484 Enterprise value Book value multiples 1.5 x 1.5 x 1.5 x Senior secured loans ​ 5,771 Enterprise value Revenue multiples 2.8 x 2.8 x 2.8 x Senior secured loans ​ 5,111 Enterprise value EBITDA multiples 6.5 x 6.5 x 6.5 x Senior secured loans ​ 3,026 Liquidation Probability weighting of alternative outcomes 88.2 % 48.2 % 100.0 % Unitranche secured loans ​ 45,072 Discounted cash flow EBITDA multiples 8.4 x 5.5 x 11.0 x ​ ​ ​ ​ ​ ​ Market yields 8.5 % 7.3 % 13.3 % Unitranche secured loans ​ 4,950 Enterprise value Revenue multiples 0.6 x 0.6 x 0.6 x Unitranche secured loans ​ 1,472 Discounted cash flow Revenue multiples 14.0 x 14.0 x 14.0 x ​ ​ ​ ​ ​ ​ Market yields ​ 8.3 % 8.3 % 8.3 % Junior secured loans ​ 12,266 Discounted cash flow Market yields 15.8 % 8.0 % 25.1 % Junior secured loans ​ 1,522 Discounted cash flow Revenue multiples 15.0 x 15.0 x 15.0 x ​ ​ ​ ​ ​ ​ Market yields 2.0 % 2.0 % 2.0 % Junior secured loans ​ 576 Liquidation Probability weighting of alternative outcomes 69.1 % 69.1 % 69.1 % Equity securities ​ 15,688 Enterprise value EBITDA multiples 5.6 x 4.5 x 15.1 x Equity securities ​ 6,448 Enterprise value Revenue multiples 4.8 x 0.6 x 12.3 x Equity securities ​ 2,281 Liquidation Probability weighting of alternative outcomes 24.4 % 24.4 % 24.4 % Equity securities ​ 714 Discounted cash flow EBITDA multiples 13.3 x 13.3 x 13.3 x ​ ​ ​ ​ ​ Market yields ​ 12.3 % 12.3 % 12.3 % Equity securities ​ 455 Option pricing model Volatility 42.5 % 42.5 % 42.5 % Equity securities ​ 264 Enterprise value Tangible book value multiples 1.5 x 1.5 x 1.5 x Total Level 3 Assets ​ $ 514,265 (1) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (1) Excludes investments of $5,262 at fair value where valuation (unadjusted) is obtained from a third-party pricing service for which such disclosure is not required.

Transactions with Affiliated _2

Transactions with Affiliated Companies (Tables)	12 Months Ended
	Dec. 31, 2022
Transactions with Affiliated Companies
Schedule of transactions with affiliated companies	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Sales and ​ PIK ​ ​ ​ ​ ​ ​ ​ Net ​ ​ ​ ​ ​ Fair value at ​ Transfers ​ Purchases ​ paydowns ​ interest ​ Discount ​ Net realized ​ unrealized ​ Fair value at ​ ​ December 31, 2021 in (out) (cost) (cost) (cost) accretion gain (loss) gain (loss) December 31, 2022 Non-Controlled affiliate company investments: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ American Community Homes, Inc. ​ $ 10,457 ​ $ — ​ $ — ​ $ — ​ $ 789 ​ $ — ​ $ — ​ $ (2,293) ​ $ 8,953 American Community Homes, Inc. ​ 4,753 ​ — ​ ​ — ​ ​ — ​ ​ 595 ​ ​ — ​ ​ — ​ ​ (1,090) ​ ​ 4,258 American Community Homes, Inc. ​ 634 ​ — ​ ​ — ​ ​ — ​ ​ 48 ​ ​ — ​ ​ — ​ ​ (139) ​ ​ 543 American Community Homes, Inc. ​ 3,164 ​ — ​ ​ — ​ ​ — ​ ​ 176 ​ ​ — ​ ​ — ​ ​ (1,344) ​ ​ 1,996 American Community Homes, Inc. ​ 4,357 ​ — ​ ​ — ​ ​ — ​ ​ 325 ​ ​ — ​ ​ — ​ ​ (988) ​ ​ 3,694 American Community Homes, Inc. ​ 20 ​ — ​ ​ — ​ ​ — ​ ​ 2 ​ ​ — ​ ​ — ​ ​ (5) ​ ​ 17 American Community Homes, Inc. ​ 99 ​ — ​ ​ — ​ ​ — ​ ​ 7 ​ ​ — ​ ​ — ​ ​ (21) ​ ​ 85 American Community Homes, Inc. (Revolver) ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — American Community Homes, Inc. ( 4,940 shares of common stock) (1) ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — American Community Homes, Inc. (warrant to purchase up to 22.3% of the equity) (1) ​ 264 ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ (264) ​ ​ — ​ ​ 23,748 ​ — ​ ​ — ​ ​ — ​ ​ 1,942 ​ ​ — ​ ​ — ​ ​ (6,144) ​ ​ 19,546 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Ascent Midco, LLC ​ 6,392 ​ — ​ ​ — ​ ​ (174) ​ ​ — ​ ​ 25 ​ ​ — ​ ​ (26) ​ ​ 6,217 Ascent Midco, LLC (Revolver) ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — Ascent Midco, LLC ( 2,032,258 Class A units) ​ 2,554 ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ (585) ​ ​ 1,969 ​ ​ 8,946 ​ — ​ ​ — ​ ​ (174) ​ ​ — ​ ​ 25 ​ ​ — ​ ​ (611) ​ ​ 8,186 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ C Parent Holdings, LLC. (fka Curion Holdings, LLC) ​ 4,561 ​ — ​ ​ — ​ ​ (4,497) ​ ​ — ​ ​ — ​ ​ — ​ ​ 82 ​ ​ 146 C Parent Holdings, LLC. (fka Curion Holdings, LLC) (Revolver) ​ 550 ​ — ​ ​ 92 ​ ​ (620) ​ ​ — ​ ​ — ​ ​ — ​ ​ (22) ​ ​ — C Parent Holdings, LLC. (fka Curion Holdings, LLC) (Junior secured loan) ​ — ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ (1) ​ ​ 1 ​ ​ — C Parent Holdings, LLC. (fka Curion Holdings, LLC) (Junior secured loan) ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — C Parent Holdings, LLC. (fka Curion Holdings, LLC) ( 58,779 shares of common stock) (2) ​ — ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ 5,111 ​ — ​ ​ 92 ​ ​ (5,117) ​ ​ — ​ ​ — ​ ​ (1) ​ ​ 61 ​ ​ 146 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Familia Dental Group Holdings, LLC ( 1,176 Class A units) ​ 1,919 ​ — ​ ​ 245 ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ 461 ​ ​ 2,625 ​ ​ 1,919 ​ — ​ ​ 245 ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ 461 ​ ​ 2,625 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ HFZ Capital Group, LLC ​ 15,084 ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ 1,075 ​ ​ 16,159 HFZ Capital Group, LLC ​ 5,420 ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ 385 ​ ​ 5,805 MC Asset Management (Corporate), LLC ​ 7,154 ​ — ​ ​ — ​ ​ — ​ ​ 1,267 ​ ​ — ​ ​ — ​ ​ — ​ ​ 8,421 MC Asset Management (Corporate), LLC (Delayed Draw) ​ 850 ​ — ​ ​ — ​ ​ — ​ ​ 150 ​ ​ — ​ ​ — ​ ​ — ​ ​ 1,000 MC Asset Management (Corporate), LLC ( 15.9% interest) ​ 644 ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ 647 ​ ​ 1,291 ​ ​ 29,152 ​ — ​ ​ — ​ ​ — ​ ​ 1,417 ​ ​ — ​ ​ — ​ ​ 2,107 ​ ​ 32,676 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Mnine Holdings, Inc. ​ 5,771 ​ — ​ ​ — ​ ​ (22) ​ ​ 320 ​ ​ 14 ​ ​ — ​ ​ (591) ​ ​ 5,492 Mnine Holdings, Inc. (Revolver) ​ ​ — ​ ​ — ​ ​ 587 ​ ​ (374) ​ ​ 1 ​ ​ — ​ ​ — ​ ​ — ​ ​ 214 Mnine Holdings, Inc. ( 6,400 Class B units) ​ — ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ 5,771 ​ — ​ ​ 587 ​ ​ (396) ​ ​ 321 ​ ​ 14 ​ ​ — ​ ​ (591) ​ ​ 5,706 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ NECB Collections, LLC (Revolver) ​ 632 ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ (250) ​ ​ 382 NECB Collections, LLC, LLC ( 20.8% of units) ​ — ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ 632 ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ (250) ​ ​ 382 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Second Avenue SFR Holdings II LLC (Revolver) (3) ​ 2,104 ​ — ​ ​ 2,681 ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ (30) ​ ​ 4,755 ​ ​ 2,104 ​ — ​ ​ 2,681 ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ (30) ​ ​ 4,755 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ SFR Holdings, LLC (Junior secured loan) ​ 5,850 ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ 5,850 SFR Holding, LLC ( 24.4% of interests) ​ 3,900 ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ 3,900 ​ ​ 9,750 ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ 9,750 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ TJ Management HoldCo, LLC (Revolver) ​ — ​ — ​ ​ 80 ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ 80 TJ Management HoldCo, LLC ( 16 shares of common stock) ​ 3,148 ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ (382) ​ ​ 2,766 ​ ​ 3,148 ​ — ​ ​ 80 ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ (382) ​ ​ 2,846 Total non-controlled affiliate company investments ​ $ 90,281 ​ $ — ​ $ 3,685 ​ $ (5,687) ​ $ 3,680 ​ $ 39 ​ $ (1) ​ $ (5,379) ​ $ 86,618 Controlled affiliate company investments: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ MRCC Senior Loan Fund I, LLC ​ $ 41,125 ​ $ — ​ $ 500 ​ $ — ​ $ — ​ $ — ​ $ — ​ $ (6,116) ​ $ 35,509 ​ ​ 41,125 ​ — ​ 500 ​ — ​ — ​ — ​ — ​ (6,116) ​ ​ 35,509 Total Controlled affiliate company investments ​ $ 41,125 ​ $ — ​ $ 500 ​ $ — ​ $ — ​ $ — ​ $ — ​ $ (6,116) ​ $ 35,509 (1) On December 29, 2022, the Company exercised the American Community Homes, Inc. (“ACH”) warrants held by the Company. The Company acquired 4,940 shares of ACH’s common stock, or 22.3% of the equity, in exchange for a nominal exercise price in accordance with the terms of the warrant. (2) During the year ended December 31, 2022, Curion Holdings, LLC (“Curion”) sold the underlying operating company and repaid the Company’s debt investment. The remaining fair value at December 31, 2022 represents the remaining expected escrow proceeds associated with the sale. The Company continues to hold an equity investment in Curion that is valued at zero at December 31, 2022. (3) Second Avenue SFR Holdings II LLC is a related entity to SFR Holdco, LLC and is being presented as a non-controlled affiliate for that reason. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Fair value at ​ ​ ​ ​ Sales and PIK ​ ​ Net Net Fair value at ​ ​ December 31, ​ Transfers ​ Purchases ​ paydowns ​ interest ​ Discount ​ realized ​ unrealized ​ December ​ ​ 2020 ​ in (out) ​ (cost) ​ (cost) ​ (cost) ​ accretion ​ gain (loss) ​ gain (loss) ​ 31, 2021 Non-Controlled affiliate company investments: ​ ​ ​ ​ ​ ​ ​ ​ ​ American Community Homes, Inc. ​ $ 9,401 ​ $ — ​ $ — ​ $ (90) ​ $ 1,146 ​ $ — ​ $ — ​ $ — ​ $ 10,457 American Community Homes, Inc. ​ 6,239 ​ — ​ — ​ (2,229) ​ 743 ​ — ​ — ​ — ​ 4,753 American Community Homes, Inc. ​ 825 ​ — ​ — ​ (838) ​ 13 ​ — ​ — ​ — ​ — American Community Homes, Inc. ​ 570 ​ — ​ — ​ (5) ​ 69 ​ — ​ — ​ — ​ 634 American Community Homes, Inc. ​ 335 ​ — ​ — ​ (341) ​ 6 ​ — ​ — ​ — ​ — American Community Homes, Inc. ​ 2,915 ​ — ​ — ​ (20) ​ 256 ​ — ​ — ​ 13 ​ 3,164 American Community Homes, Inc. ​ 3,879 ​ — ​ — ​ (37) ​ 473 ​ — ​ — ​ 42 ​ 4,357 American Community Homes, Inc. ​ 18 ​ — ​ — ​ — ​ 2 ​ — ​ — ​ — ​ 20 American Community Homes, Inc. ​ 89 ​ — ​ — ​ (1) ​ 11 ​ — ​ — ​ — ​ 99 American Community Homes, Inc. (warrant to purchase up to 22.3% of the equity) ​ — ​ — ​ — ​ — ​ — ​ — ​ — ​ 264 ​ 264 ​ ​ 24,271 ​ — ​ — ​ (3,561) ​ 2,719 ​ — ​ — ​ 319 ​ 23,748 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Ascent Midco, LLC ​ 6,997 ​ — ​ — ​ (531) ​ — ​ 25 ​ — ​ (99) ​ 6,392 Ascent Midco, LLC (Delayed Draw) ​ — ​ — ​ — ​ — ​ — ​ — ​ — ​ — ​ — Ascent Midco, LLC (Revolver) ​ — ​ — ​ — ​ — ​ — ​ — ​ — ​ — ​ — Ascent Midco, LLC (2,032,258 Class A units) ​ 3,016 ​ — ​ — ​ — ​ — ​ — ​ — ​ (462) ​ 2,554 ​ ​ 10,013 ​ — ​ — ​ (531) ​ — ​ 25 ​ — ​ (561) ​ 8,946 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Curion Holdings, LLC ​ 3,159 ​ — ​ 308 ​ — ​ — ​ — ​ — ​ 1,094 ​ 4,561 Curion Holdings, LLC (Revolver) ​ 820 ​ — ​ — ​ (308) ​ — ​ — ​ — ​ 38 ​ 550 Curion Holdings, LLC (Junior secured loan) ​ — ​ — ​ — ​ — ​ — ​ — ​ — ​ — ​ — Curion Holdings, LLC (Junior secured loan) ​ — ​ — ​ — ​ — ​ — ​ — ​ — ​ — ​ — Curion Holdings, LLC (58,779 shares of common stock) ​ — ​ — ​ — ​ — ​ — ​ — ​ — ​ — ​ — ​ ​ 3,979 ​ — ​ 308 ​ (308) ​ — ​ — ​ — ​ 1,132 ​ 5,111 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Familia Dental Group Holdings, LLC (1,105 Class A units) ​ 3,118 ​ — ​ 183 ​ — ​ — ​ — ​ — ​ (1,382) ​ 1,919 ​ ​ 3,118 ​ — ​ 183 ​ — ​ — ​ — ​ — ​ (1,382) ​ 1,919 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ HFZ Capital Group, LLC ​ 13,106 ​ — ​ — ​ — ​ — ​ — ​ — ​ 1,978 ​ 15,084 HFZ Capital Group, LLC ​ 4,709 ​ — ​ — ​ — ​ — ​ — ​ — ​ 711 ​ 5,420 MC Asset Management (Corporate), LLC ​ — ​ — ​ 6,423 ​ — ​ 731 ​ — ​ — ​ — ​ 7,154 MC Asset Management (Corporate), LLC (Delayed Draw) ​ — ​ — ​ 793 ​ — ​ 57 ​ — ​ — ​ — ​ 850 MC Asset Management (Corporate), LLC (15.9% interest) ​ 785 ​ — ​ — ​ — ​ — ​ — ​ — ​ (141) ​ 644 MC Asset Management (Industrial), LLC ​ 11,579 ​ — ​ — ​ (12,119) ​ 1,423 ​ 1 ​ — ​ (884) ​ — ​ ​ 30,179 ​ — ​ 7,216 ​ (12,119) ​ 2,211 ​ 1 ​ — ​ 1,664 ​ 29,152 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Incipio, LLC (1) ​ 1,764 ​ — ​ — ​ — ​ — ​ — ​ — ​ (1,764) ​ — Incipio, LLC (1) ​ 4,227 ​ (1,562) ​ — ​ — ​ 48 ​ — ​ — ​ (2,713) ​ — Incipio, LLC (1) ​ 1,805 ​ (1,732) ​ — ​ — ​ 15 ​ — ​ — ​ (88) ​ — Incipio, LLC (1) ​ 761 ​ (730) ​ — ​ — ​ 6 ​ — ​ — ​ (37) ​ — Incipio, LLC (1) ​ 1,519 ​ (1,458) ​ — ​ — ​ 13 ​ — ​ — ​ (74) ​ — Incipio, LLC (1) ​ 1,488 ​ (1,527) ​ 108 ​ — ​ 9 ​ — ​ — ​ (78) ​ — Incipio, LLC (Junior secured loan) (1) ​ — ​ — ​ — ​ — ​ — ​ — ​ — ​ — ​ — Incipio, LLC (Junior secured loan) (1) ​ — ​ — ​ — ​ — ​ — ​ — ​ — ​ — ​ — Incipio, LLC (1,774 shares of Series C common units) (1) ​ — ​ — ​ — ​ — ​ — ​ — ​ — ​ — ​ — ​ ​ 11,564 ​ (7,009) ​ 108 ​ — ​ 91 ​ — ​ — ​ (4,754) ​ — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Luxury Optical Holdings Co. (2) ​ 1,430 ​ — ​ — ​ (1,640) ​ 159 ​ — ​ — ​ 51 ​ — Luxury Optical Holdings Co. (Delayed Draw) (2) ​ 624 ​ — ​ 1,729 ​ (2,353) ​ — ​ — ​ — ​ — ​ — Luxury Optical Holdings Co. (Revolver) (2) ​ 66 ​ — ​ — ​ (75) ​ 7 ​ — ​ — ​ 2 ​ — Luxury Optical Holdings Co. (91 preferred units) (2) ​ 2,476 ​ (78) ​ — ​ (6,132) ​ 694 ​ — ​ 1,807 ​ 1,233 ​ — Luxury Optical Holdings Co. (86 shares of common stock) (2) ​ — ​ — ​ — ​ — ​ — ​ — ​ — ​ — ​ — ​ ​ 4,596 ​ (78) ​ 1,729 ​ (10,200) ​ 860 ​ — ​ 1,807 ​ 1,286 ​ — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Mnine Holdings, Inc. ​ 12,356 ​ — ​ — ​ (7,137) ​ 603 ​ 34 ​ — ​ (85) ​ 5,771 Mnine Holdings, Inc. (6,400 Class B units) ​ — ​ — ​ — ​ — ​ — ​ — ​ — ​ — ​ — ​ ​ 12,356 ​ — ​ — ​ (7,137) ​ 603 ​ 34 ​ — ​ (85) ​ 5,771 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ NECB Collections, LLC (Revolver) ​ 834 ​ — ​ — ​ — ​ — ​ — ​ — ​ (202) ​ 632 NECB Collections, LLC, LLC (20.8% of units) ​ — ​ — ​ — ​ — ​ — ​ — ​ — ​ — ​ — ​ ​ 834 ​ — ​ — ​ — ​ — ​ — ​ — ​ (202) ​ 632 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ SHI Holdings, Inc. ​ 188 ​ — ​ — ​ — ​ — ​ — ​ (2,897) ​ 2,709 ​ — SHI Holdings, Inc. (Revolver) ​ 297 ​ — ​ — ​ (315) ​ — ​ — ​ (4,270) ​ 4,288 ​ — SHI Holdings, Inc. (24 shares of common stock) ​ — ​ — ​ — ​ — ​ — ​ — ​ (27) ​ 27 ​ — ​ ​ 485 ​ — ​ — ​ (315) ​ — ​ — ​ (7,194) ​ 7,024 ​ — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Second Avenue SFR Holdings II LLC (Revolver) ​ ​ — ​ ​ — ​ ​ 2,104 ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ 2,104 Second Avenue SFR Holdings II LLC (Delayed Draw) ​ ​ — ​ ​ — ​ ​ 5,850 ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ 5,850 Second Avenue SFR Holdings II LLC (24.4 % of interests) ​ ​ — ​ ​ — ​ ​ 3,900 ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ 3,900 ​ ​ ​ — ​ ​ — ​ ​ 11,854 ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ 11,854 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Summit Container Corporation ​ 3,204 ​ — ​ — ​ (3,019) ​ — ​ — ​ (250) ​ 65 ​ — Summit Container Corporation (Revolver) ​ 1,654 ​ — ​ 5,402 ​ (7,059) ​ — ​ — ​ — ​ 3 ​ — Summit Container Corporation (warrant to purchase up to 19.5% of the equity) ​ 139 ​ — ​ — ​ — ​ — ​ — ​ — ​ (139) ​ — ​ ​ 4,997 ​ — ​ 5,402 ​ (10,078) ​ — ​ — ​ (250) ​ (71) ​ — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ TJ Management HoldCo, LLC (Revolver) ​ — ​ — ​ — ​ — ​ — ​ — ​ — ​ — ​ — TJ Management HoldCo, LLC (16 shares of common stock) ​ 3,323 ​ — ​ — ​ (755) ​ — ​ — ​ — ​ 580 ​ 3,148 ​ ​ 3,323 ​ — ​ — ​ (755) ​ — ​ — ​ — ​ 580 ​ 3,148 Total non-controlled affiliate company investments ​ $ 109,715 ​ $ (7,087) ​ $ 26,800 ​ $ (45,004) ​ $ 6,484 ​ $ 60 ​ $ (5,637) ​ $ 4,950 ​ $ 90,281 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Controlled affiliate company investments: ​ ​ ​ ​ ​ ​ ​ ​ ​ MRCC Senior Loan Fund I, LLC ​ $ 39,284 ​ $ — ​ $ — ​ $ — ​ $ — ​ $ — ​ $ — ​ $ 1,841 ​ $ 41,125 ​ ​ 39,284 ​ — ​ — ​ — ​ — ​ — ​ — ​ 1,841 ​ 41,125 Total Controlled affiliate company investments ​ $ 39,284 ​ $ — ​ $ — ​ $ — ​ $ — ​ $ — ​ $ — ​ $ 1,841 ​ $ 41,125 (1) During the year ended December 31, 2021, Incipio, LLC (“Incipio”) underwent a restructuring whereby substantially all of the assets of Incipio were acquired by a new entity, Vinci Brands LLC (“Vinci”). The senior lenders at Incipio, including the Company, were part of the new financing at Vinci. The Company’s investments in Vinci are not categorized as affiliate company investments as the Company does not have an equity interest in Vinci. For the purpose of this schedule, transfers out represents the fair value at June 30, 2021. (2) During the year ended December 31, 2021, the Company sold its investment in Luxury Optical Holdings Co. For the purpose of this schedule, transfers out represents the fair value of the remaining escrow proceeds. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ For the years ended December 31, ​ ​ 2022 ​ 2021 ​ ​ Interest ​ Dividend ​ ​ ​ ​ Interest ​ Dividend ​ ​ ​ Portfolio Company ​ Income Income Fee Income Income Income Fee Income Non-controlled affiliate company investments: ​ ​ ​ ​ ​ ​ American Community Homes, Inc. ​ $ 1,209 ​ $ — ​ $ — ​ $ 1,148 ​ $ — ​ $ — American Community Homes, Inc. ​ 791 ​ — ​ — ​ 742 ​ — ​ — American Community Homes, Inc. ​ n/a ​ n/a ​ n/a ​ 13 ​ — ​ — American Community Homes, Inc. ​ 73 ​ — ​ — ​ 69 ​ — ​ — American Community Homes, Inc. ​ n/a ​ n/a ​ n/a ​ 5 ​ — ​ — American Community Homes, Inc. ​ 270 ​ — ​ — ​ 255 ​ — ​ — American Community Homes, Inc. ​ 499 ​ — ​ — ​ 473 ​ — ​ — American Community Homes, Inc. ​ 3 ​ — ​ — ​ 31 ​ — ​ — American Community Homes, Inc. ​ 11 ​ — ​ — ​ 12 ​ — ​ — American Community Homes, Inc. (Revolver) ​ ​ 21 ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — American Community Homes, Inc. (Common stock) ​ — ​ — ​ — ​ — ​ — ​ — American Community Homes, Inc. (Warrant) ​ — ​ — ​ — ​ — ​ — ​ — ​ ​ 2,877 ​ — ​ — ​ 2,748 ​ — ​ — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Ascent Midco, LLC ​ 516 ​ — ​ — ​ 471 ​ — ​ — Ascent Midco, LLC (Delayed Draw) ​ n/a ​ n/a ​ n/a ​ 9 ​ — ​ — Ascent Midco, LLC (Revolver) ​ 4 ​ — ​ — ​ 4 ​ — ​ — Ascent Midco, LLC (Class A units) ​ — ​ 189 ​ — ​ — ​ 174 ​ — ​ ​ 520 ​ 189 ​ — ​ 484 ​ 174 ​ — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ C Parent Holdings, LLC. (fka Curion Holdings, LLC) ​ 1,766 ​ — ​ — ​ — ​ — ​ — C Parent Holdings, LLC. (fka Curion Holdings, LLC) (Revolver) ​ 294 ​ — ​ — ​ — ​ — ​ — C Parent Holdings, LLC. (fka Curion Holdings, LLC) (Junior secured loan) ​ — ​ — ​ — ​ — ​ — ​ — C Parent Holdings, LLC. (fka Curion Holdings, LLC) (Junior secured loan) ​ — ​ — ​ — ​ — ​ — ​ — C Parent Holdings, LLC. (fka Curion Holdings, LLC) (Common stock) ​ — ​ — ​ — ​ — ​ — ​ — ​ ​ 2,060 ​ — ​ — ​ — ​ — ​ — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Familia Dental Group Holdings, LLC (Class A units) ​ — ​ — ​ — ​ — ​ — ​ — ​ ​ — ​ — ​ — ​ — ​ — ​ — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ HFZ Capital Group, LLC ​ 1,977 ​ — ​ — ​ 1,880 ​ — ​ — HFZ Capital Group, LLC ​ 710 ​ — ​ — ​ 675 ​ — ​ — MC Asset Management (Corporate), LLC ​ 1,369 ​ — ​ — ​ 1,024 ​ — ​ — MC Asset Management (Corporate), LLC (Delayed Draw) ​ 162 ​ — ​ — ​ 91 ​ — ​ — MC Asset Management (Corporate), LLC (LLC interest) ​ — ​ — ​ — ​ — ​ — ​ — MC Asset Management (Industrial), LLC ​ n/a ​ n/a ​ n/a ​ 2,136 ​ — ​ — ​ ​ 4,218 ​ — ​ — ​ 5,806 ​ — ​ — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Incipio, LLC ​ n/a ​ n/a ​ n/a ​ — ​ — ​ — Incipio, LLC ​ n/a ​ n/a ​ n/a ​ — ​ — ​ — Incipio, LLC ​ n/a ​ n/a ​ n/a ​ — ​ — ​ — Incipio, LLC ​ n/a ​ n/a ​ n/a ​ — ​ — ​ — Incipio, LLC ​ n/a ​ n/a ​ n/a ​ — ​ — ​ — Incipio, LLC ​ n/a ​ n/a ​ n/a ​ — ​ — ​ — Incipio, LLC (Junior secured loan) ​ n/a ​ n/a ​ n/a ​ — ​ — ​ — Incipio, LLC (Junior secured loan) ​ n/a ​ n/a ​ n/a ​ — ​ — ​ — Incipio, LLC (Common units) ​ n/a ​ n/a ​ n/a ​ — ​ — ​ — ​ ​ n/a ​ n/a ​ n/a ​ — ​ — ​ — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Luxury Optical Holdings Co. ​ n/a ​ n/a ​ n/a ​ 166 ​ — ​ — Luxury Optical Holdings Co. (Delayed Draw) ​ n/a ​ n/a ​ n/a ​ 219 ​ — ​ 36 Luxury Optical Holdings Co. (Revolver) ​ n/a ​ n/a ​ n/a ​ 7 ​ — ​ — Luxury Optical Holdings Co. (Preferred units) ​ n/a ​ n/a ​ n/a ​ 694 ​ 813 ​ — Luxury Optical Holdings Co. (Common stock) ​ n/a ​ n/a ​ n/a ​ — ​ — ​ — ​ ​ n/a ​ n/a ​ n/a ​ 1,086 ​ 813 ​ 36 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Mnine Holdings, Inc. ​ 787 ​ — ​ — ​ 1,301 ​ — ​ — Mnine Holdings, Inc. (Revolver) ​ ​ 9 ​ ​ — ​ ​ — ​ ​ n/a ​ ​ n/a ​ ​ n/a Mnine Holdings, Inc. (Class B units) ​ — ​ — ​ — ​ — ​ — ​ — ​ ​ 796 ​ — ​ — ​ 1,301 ​ — ​ — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ NECB Collections, LLC (Revolver) ​ — ​ — ​ — ​ — ​ — ​ — NECB Collections, LLC (LLC units) ​ — ​ — ​ — ​ — ​ — ​ — ​ ​ — ​ — ​ — ​ — ​ — ​ — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Second Avenue SFR Holdings II LLC (Delayed Draw) ​ n/a ​ n/a ​ n/a ​ 83 ​ — ​ — Second Avenue SFR Holdings II LLC (Revolver) ​ 312 ​ — ​ — ​ 22 ​ — ​ — ​ ​ ​ 312 ​ ​ — ​ ​ — ​ ​ 105 ​ ​ — ​ ​ — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ SFR Holdco, LLC (Junior secured loan) ​ 468 ​ — ​ — ​ — ​ — ​ — SFR Holdco, LLC (LLC interest) ​ — ​ — ​ — ​ — ​ — ​ — ​ ​ 468 ​ — ​ — ​ — ​ — ​ — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ SHI Holdings, Inc. ​ n/a ​ n/a ​ n/a ​ — ​ — ​ — SHI Holdings, Inc. (Revolver) ​ n/a ​ n/a ​ n/a ​ — ​ — ​ — SHI Holdings, Inc. (Common stock) ​ n/a ​ n/a ​ n/a ​ — ​ — ​ — ​ ​ n/a ​ n/a ​ n/a ​ — ​ — ​ — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Summit Container Corporation ​ n/a ​ n/a ​ n/a ​ 57 ​ — ​ — Summit Container Corporation (Revolver) ​ n/a ​ n/a ​ n/a ​ 35 ​ — ​ — Summit Container Corporation (Warrant) ​ n/a ​ n/a ​ n/a ​ — ​ — ​ — ​ ​ n/a ​ n/a ​ n/a ​ 92 ​ — ​ — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ TJ Management HoldCo, LLC (Revolver) ​ 14 ​ — ​ — ​ 12 ​ — ​ — TJ Management HoldCo, LLC (Common stock) ​ — ​ — ​ — ​ — ​ — ​ — ​ ​ 14 ​ — ​ — ​ 12 ​ — ​ — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total non-controlled affiliate company investments ​ $ 11,265 ​ $ 189 ​ $ — ​ $ 11,634 ​ $ 987 ​ $ 36 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Controlled affiliate company investments: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ MRCC Senior Loan Fund I, LLC ​ $ — ​ $ 3,600 ​ $ — ​ $ — ​ $ 4,325 ​ $ — ​ ​ — ​ 3,600 ​ — ​ — ​ 4,325 ​ — Total controlled affiliate company investments ​ $ — ​ $ 3,600 ​ $ — ​ $ — ​ $ 4,325 ​ $ —

Transactions with Related Par_2

Transactions with Related Parties (Tables)	12 Months Ended
	Dec. 31, 2022
Transactions with Related Parties
Schedule of composition of the Company's incentive fees	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ For the years ended December 31, ​ 2022 ​ 2021 2020 Part one incentive fees (1) ​ $ 4,127 ​ $ 3,690 ​ $ 5,724 Part two incentive fees (2) ​ — ​ — ​ — Incentive Fee Limitation ​ — ​ — ​ (5,012) Incentive fees, excluding the impact of the incentive fee waivers ​ 4,127 ​ 3,690 ​ 712 Incentive fee waivers (3) ​ (525) ​ (1,484) ​ (712) Total incentive fees, net of incentive fee waivers ​ $ 3,602 ​ $ 2,206 ​ $ — (1) Based on pre-incentive fee net investment income. (2) Based upon net realized and unrealized gains and losses, or capital gains. The Company accrues, but does not pay, a capital gains incentive fee in connection with any unrealized capital appreciation, as appropriate. If, on a cumulative basis, the sum of net realized gain (loss) plus net unrealized gain (loss) decreases during a period, the Company will reverse any excess capital gains incentive fee previously accrued such that the amount of capital gains incentive fee accrued is no more than 20% of the sum of net realized gain (loss) plus net unrealized gain (loss). (3) Represents part one incentive fees waived by MC Advisors.

Borrowings (Tables)

Borrowings (Tables)	12 Months Ended
	Dec. 31, 2022
Borrowings
Schedule of SBA debentures outstanding	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Maturity Date Interest Rate December 31, 2022 December 31, 2021 September 2024 ​ 3.4 % $ — ​ $ 2,920 March 2025 ​ 3.3 % — ​ 14,800 March 2025 ​ 2.9 % — ​ 7,080 September 2027 ​ 3.2 % — ​ 32,100 Total ​ ​ ​ ​ $ — ​ $ 56,900 ​
Schedule of components of the Company's interest expense and other debt financing expenses, average debt outstanding balances and average stated interest rates	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ For the years ended December 31, ​ ​ 2022 ​ 2021 2020 Interest expense - revolving credit facility ​ $ 8,442 ​ $ 4,593 ​ $ 5,594 ​ Interest expense - 2023 Notes ​ — ​ 837 ​ 6,270 ​ Interest expense - 2026 Notes ​ 6,220 ​ 5,763 ​ — ​ Interest expense - SBA debentures ​ 292 ​ 2,676 ​ 3,944 ​ Amortization of deferred financing costs ​ 2,126 ​ 2,205 ​ 2,181 ​ Total interest and other debt financing expenses ​ $ 17,080 ​ $ 16,074 ​ $ 17,989 ​ Average debt outstanding ​ ​ 314,053 ​ ​ 332,034 ​ ​ 370,904 ​ Average stated interest rate ​ 4.7 % 4.1 % 4.2 %

Derivative Instruments (Tables)

Derivative Instruments (Tables)	12 Months Ended
	Dec. 31, 2022
Derivative Instruments
Schedule of information related to foreign currency forward contracts	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ As of December 31, 2022 ​ ​ ​ ​ ​ ​ ​ Gross ​ Gross ​ ​ ​ ​ ​ ​ ​ ​ ​ Amount of ​ Amount of ​ ​ Notional Amount Settlement Unrealized Unrealized ​ Description ​ to be Sold ​ Date ​ Gain ​ Loss Balance Sheet location of Net Amounts Foreign currency forward contract ​ AUD 153 ​ 1/18/2023 ​ $ 14 ​ $ — ​ Unrealized gain on foreign currency forward contracts Foreign currency forward contract ​ AUD 140 ​ 2/16/2023 ​ 13 ​ — ​ Unrealized gain on foreign currency forward contracts Foreign currency forward contract ​ AUD 132 ​ 3/16/2023 ​ 12 ​ — ​ Unrealized gain on foreign currency forward contracts Foreign currency forward contract ​ AUD 160 ​ 4/20/2023 ​ 14 ​ — ​ Unrealized gain on foreign currency forward contracts Foreign currency forward contract ​ AUD 121 ​ 5/16/2023 ​ 11 ​ — ​ Unrealized gain on foreign currency forward contracts Foreign currency forward contract ​ AUD 156 ​ 6/19/2023 ​ 14 ​ — ​ Unrealized gain on foreign currency forward contracts Foreign currency forward contract ​ AUD 138 ​ 7/18/2023 ​ 12 ​ — ​ Unrealized gain on foreign currency forward contracts Foreign currency forward contract ​ AUD 146 ​ 8/16/2023 ​ 13 ​ — ​ Unrealized gain on foreign currency forward contracts Foreign currency forward contract ​ AUD 146 ​ 9/18/2023 ​ 13 ​ — ​ Unrealized gain on foreign currency forward contracts Foreign currency forward contract ​ AUD 148 ​ 10/18/2023 ​ 13 ​ — ​ Unrealized gain on foreign currency forward contracts Foreign currency forward contract ​ AUD 140 ​ 11/16/2023 ​ 12 ​ — ​ Unrealized gain on foreign currency forward contracts Foreign currency forward contract ​ AUD 142 ​ 12/18/2023 ​ 12 ​ — ​ Unrealized gain on foreign currency forward contracts Foreign currency forward contract ​ AUD 150 ​ 1/17/2024 ​ 13 ​ — ​ Unrealized gain on foreign currency forward contracts Foreign currency forward contract ​ AUD 143 ​ 2/16/2024 ​ 12 ​ — ​ Unrealized gain on foreign currency forward contracts Foreign currency forward contract ​ AUD 15,410 ​ 3/18/2024 ​ 1,329 ​ — ​ Unrealized gain on foreign currency forward contracts ​ ​ ​ ​ ​ ​ ​ $ 1,507 ​ $ — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ As of December 31, 2021 ​ ​ ​ ​ ​ ​ ​ ​ Gross ​ Gross ​ ​ ​ ​ Notional ​ ​ ​ Amount of ​ Amount of ​ ​ ​ ​ Amount to be ​ Settlement ​ Unrealized ​ Unrealized ​ ​ Description ​ Sold Date Gain Loss Balance Sheet location of Net Amounts Foreign currency forward contract ​ £ 82 ​ 1/3/2022 ​ $ — ​ $ (10) ​ Unrealized gain on foreign currency forward contracts Foreign currency forward contract ​ £ ​ 79 ​ 4/4/2022 ​ ​ — ​ ​ (10) ​ Unrealized gain on foreign currency forward contracts Foreign currency forward contract ​ £ ​ 29 ​ 5/6/2022 ​ ​ — ​ ​ (3) ​ Unrealized gain on foreign currency forward contracts Foreign currency forward contract AUD 156 1/19/2022 ​ 8 ​ — Unrealized gain on foreign currency forward contracts Foreign currency forward contract AUD 136 2/16/2022 ​ 7 ​ — Unrealized gain on foreign currency forward contracts Foreign currency forward contract AUD 132 3/16/2022 ​ 6 ​ — Unrealized gain on foreign currency forward contracts Foreign currency forward contract AUD 146 4/19/2022 ​ 7 ​ — Unrealized gain on foreign currency forward contracts Foreign currency forward contract AUD 138 5/17/2022 ​ 7 ​ — Unrealized gain on foreign currency forward contracts Foreign currency forward contract AUD 153 6/17/2022 ​ 7 ​ — Unrealized gain on foreign currency forward contracts Foreign currency forward contract AUD 138 7/18/2022 ​ 7 ​ — Unrealized gain on foreign currency forward contracts Foreign currency forward contract AUD 140 8/16/2022 ​ 7 ​ — Unrealized gain on foreign currency forward contracts Foreign currency forward contract AUD 153 9/16/2022 ​ 7 ​ — Unrealized gain on foreign currency forward contracts Foreign currency forward contract AUD 152 10/19/2022 ​ 7 ​ — Unrealized gain on foreign currency forward contracts Foreign currency forward contract AUD 136 11/16/2022 ​ 6 ​ — Unrealized gain on foreign currency forward contracts Foreign currency forward contract AUD 142 12/16/2022 ​ 7 ​ — Unrealized gain on foreign currency forward contracts Foreign currency forward contract AUD 153 1/18/2023 ​ 7 ​ — Unrealized gain on foreign currency forward contracts Foreign currency forward contract AUD 140 2/16/2023 ​ 6 ​ — Unrealized gain on foreign currency forward contracts Foreign currency forward contract AUD 132 3/16/2023 ​ 6 ​ — Unrealized gain on foreign currency forward contracts Foreign currency forward contract AUD 160 4/20/2023 ​ 7 ​ — Unrealized gain on foreign currency forward contracts Foreign currency forward contract AUD 121 5/16/2023 ​ 5 ​ — Unrealized gain on foreign currency forward contracts Foreign currency forward contract AUD 156 6/19/2023 ​ 7 ​ — Unrealized gain on foreign currency forward contracts Foreign currency forward contract AUD 138 7/18/2023 ​ 6 ​ — Unrealized gain on foreign currency forward contracts Foreign currency forward contract AUD 146 8/16/2023 ​ 6 ​ — Unrealized gain on foreign currency forward contracts Foreign currency forward contract AUD 146 9/18/2023 ​ 6 ​ — Unrealized gain on foreign currency forward contracts Foreign currency forward contract AUD 148 10/18/2023 ​ 6 ​ — Unrealized gain on foreign currency forward contracts Foreign currency forward contract AUD 140 11/16/2023 ​ 6 ​ — Unrealized gain on foreign currency forward contracts Foreign currency forward contract AUD 142 12/18/2023 ​ 6 ​ — Unrealized gain on foreign currency forward contracts Foreign currency forward contract AUD 150 1/17/2024 ​ 6 ​ — Unrealized gain on foreign currency forward contracts Foreign currency forward contract AUD 143 2/16/2024 ​ 6 ​ — Unrealized gain on foreign currency forward contracts Foreign currency forward contract AUD 15,410 3/18/2024 ​ 635 ​ — Unrealized gain on foreign currency forward contracts ​ ​ ​ ​ ​ ​ ​ ​ $ 804 ​ $ (23) ​ ​ ​

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2022
Income Taxes
Schedule of permanent differences were reclassified for tax purposes	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ For the years ended December 31, ​ 2022 2021 2020 Increase (decrease) in capital in excess of par value ​ $ 13 ​ $ (301) ​ $ (447) Increase (decrease) in accumulated undistributed (overdistributed) earnings ​ (13) ​ 301 ​ 447 ​
Schedule of reconciliation of net increase in net assets resulting from operations to taxable income	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ For the years ended December 31, ​ 2022 2021 2020 Net increase (decrease) in net assets resulting from operations ​ $ (2,786) ​ $ 32,459 ​ $ 1,646 Net change in unrealized (gain) loss for book but not tax ​ 23,618 ​ (36,108) ​ 31,263 Other realized gain (loss) for tax but not book ​ — ​ — ​ (857) Other income (loss) for tax but not book ​ 84 ​ (961) ​ 217 Other deductions for book in excess of deductions for tax ​ — ​ — ​ — Expenses not currently deductible ​ 1,405 ​ 282 ​ 370 Net capital loss carryforward ​ 1,130 ​ 20,040 ​ (1,694) Total taxable income ​ $ 23,451 ​ $ 15,712 ​ $ 30,945 ​
Schedule of tax character of distributions paid	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ For the years ended December 31, ​ 2022 2021 2020 Ordinary income ​ $ 21,666 ​ $ 21,514 ​ $ 23,064 Long-term capital gains ​ — ​ — ​ — Total ​ $ 21,666 ​ $ 21,514 ​ $ 23,064 ​

Distributions (Tables)

Distributions (Tables)	12 Months Ended
	Dec. 31, 2022
Distributions
Schedule of distributions declared	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ DRIP Shares ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Amount ​ ​ ​ ​ DRIP ​ DRIP ​ Purchased ​ Cost of Date ​ Record ​ Payment ​ Per ​ Cash ​ Shares ​ Shares ​ in the Open ​ DRIP Shares Declared ​ Date ​ Date ​ Share ​ Distribution ​ Issued ​ Value ​ Market ​ Purchased Year ended December 31, 2022: March 2, 2022 ​ ​ March 16, 2022 ​ ​ March 31, 2022 ​ $ 0.25 ​ $ 5,417 ​ — ​ $ — ​ 25,229 ​ $ 276 June 1, 2022 ​ ​ June 15, 2022 ​ ​ June 30, 2022 ​ ​ 0.25 ​ ​ 5,416 ​ — ​ ​ — ​ 29,655 ​ ​ 280 September 1, 2022 ​ ​ September 15, 2022 ​ ​ September 30, 2022 ​ ​ 0.25 ​ ​ 5,416 ​ — ​ ​ — ​ 20,789 ​ ​ 164 December 5, 2022 ​ ​ December 15, 2022 ​ ​ December 30, 2022 ​ ​ 0.25 ​ ​ 5,417 ​ — ​ ​ — ​ 17,017 ​ ​ 149 Total distributions declared ​ ​ ​ ​ ​ ​ $ 1.00 ​ $ 21,666 — ​ $ — 92,690 $ 869 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year ended December 31, 2021: March 2, 2021 ​ ​ March 16, 2021 ​ ​ March 31, 2021 ​ $ 0.25 ​ $ 5,326 — ​ $ — 35,611 ​ $ 364 June 2, 2021 ​ ​ June 16, 2021 ​ ​ June 30, 2021 ​ ​ 0.25 ​ ​ 5,386 ​ — ​ ​ — ​ 31,277 ​ ​ 343 September 2, 2021 ​ ​ September 16, 2021 ​ ​ September 30, 2021 ​ 0.25 ​ 5,386 — ​ — 35,623 ​ 369 December 2, 2021 ​ ​ December 16, 2021 ​ ​ December 31, 2021 ​ ​ 0.25 ​ ​ 5,416 ​ — ​ ​ — ​ 27,905 ​ ​ 315 Total distributions declared ​ ​ ​ ​ ​ ​ ​ $ 1.00 ​ $ 21,514 — ​ $ — 130,416 ​ $ 1,391 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year ended December 31, 2020: March 3, 2020 ​ ​ March 16, 2020 ​ ​ March 31, 2020 ​ $ 0.35 ​ $ 7,155 — ​ $ — 55,938 ​ $ 374 May 8, 2020 ​ ​ June 15, 2020 ​ ​ June 30, 2020 ​ ​ 0.25 ​ ​ 5,257 ​ — ​ ​ — ​ 40,612 ​ ​ 283 September 4, 2020 ​ ​ September 16, 2020 ​ ​ September 30, 2020 ​ 0.25 ​ 5,326 — ​ — 44,246 ​ 305 December 4, 2020 ​ ​ December 16, 2020 ​ ​ December 31, 2020 ​ ​ 0.25 ​ ​ 5,326 ​ — ​ ​ — ​ 45,667 ​ ​ 365 Total distributions declared ​ ​ ​ ​ ​ ​ ​ $ 1.10 ​ $ 23,064 — ​ $ — 186,463 ​ $ 1,327 ​

Financial Highlights (Tables)

Financial Highlights (Tables)	12 Months Ended
	Dec. 31, 2022
Financial Highlights
Schedule of financial highlights and supplemental ratios	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ For the years ended December 31, ​ ​ 2022 2021 2020 2019 2018 ​ Per share data: ​ ​ ​ ​ ​ ​ ​ ​ ​ Net asset value at beginning of year ​ $ 11.51 ​ $ 11.00 ​ $ 12.20 ​ $ 12.66 ​ $ 13.77 ​ Net investment income (1) ​ 1.02 ​ 1.03 ​ 1.45 ​ 1.42 ​ 1.57 ​ Net gain (loss) (1) ​ (1.15) ​ 0.48 ​ (1.37) ​ (0.48) ​ (1.28) ​ Net increase (decrease) in net assets resulting from operations (1) ​ (0.13) ​ 1.51 ​ 0.08 ​ 0.94 ​ 0.29 ​ Stockholder distributions – income ​ (1.00) ​ (1.00) ​ (1.10) ​ (1.40) ​ (1.40) ​ Stockholder distributions – capital gains ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ Stockholder distributions – return of capital ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ Effect of share issuance above (below) NAV (2) ​ ​ — ​ ​ — ​ ​ (0.18) ​ ​ — ​ ​ — ​ Effect of share repurchases (2) ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ Other (2) ​ ​ 0.01 ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ Net asset value at end of year ​ $ 10.39 ​ $ 11.51 ​ $ 11.00 ​ $ 12.20 ​ $ 12.66 ​ Net assets at end of year ​ $ 225,019 ​ $ 249,471 ​ $ 234,434 ​ $ 249,357 ​ $ 258,767 ​ Shares outstanding at end of year ​ 21,666,340 ​ 21,666,340 ​ 21,303,540 ​ 20,444,564 ​ 20,444,564 ​ Per share market value at end of year ​ $ 8.54 ​ $ 11.22 ​ $ 8.03 ​ $ 10.86 ​ $ 9.60 ​ Total return based on market value (3) ​ (15.20) % 53.26 % (13.86) % 27.68 % (21.74) % Total return based on average net asset value (4) ​ ​ (1.18) % ​ 13.40 % ​ 0.72 % ​ 7.53 % ​ 2.17 % Ratio/Supplemental data: (5) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Ratio of net investment income to average net assets ​ ​ 9.42 % ​ 9.15 % ​ 13.32 % ​ 11.38 % ​ 11.85 % Ratio of total expenses, net of base management fee and incentive fee waivers, to average net assets ​ ​ 14.60 % ​ 13.07 % ​ 13.68 % ​ 15.35 % ​ 9.84 % Portfolio turnover ​ ​ 24.93 % ​ 41.80 % ​ 25.24 % ​ 27.18 % ​ 31.53 % ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ For the years ended December 31, ​ 2017 2016 2015 2014 2013 Per share data: ​ ​ ​ ​ ​ ​ Net asset value at beginning of year ​ $ 14.52 ​ $ 14.19 ​ $ 14.05 ​ $ 13.92 ​ $ 14.54 ​ Net investment income (1) ​ 1.40 ​ 1.55 ​ 1.60 ​ 1.57 ​ 1.13 ​ Net gain (loss) (1) ​ (0.75) ​ 0.13 ​ (0.07) ​ (0.12) ​ 0.15 ​ Net increase (decrease) in net assets from operations (1) ​ 0.65 ​ 1.68 ​ 1.53 ​ 1.45 ​ 1.28 ​ Stockholder distributions – income ​ (1.37) ​ (1.40) ​ (1.37) ​ (1.36) ​ (1.15) ​ Stockholder distributions – capital gains ​ (0.03) ​ — ​ (0.03) ​ — ​ — ​ Stockholder distributions – return of capital ​ — ​ — ​ — ​ — ​ (0.21) ​ Effect of share issuance above (below) NAV (2) ​ — ​ 0.05 ​ — ​ — ​ (0.57) ​ Effect of share repurchases (2) ​ — ​ — ​ — ​ 0.04 ​ 0.03 ​ Other (2) ​ — ​ — ​ 0.01 ​ — ​ — ​ Net asset value at end of year ​ $ 13.77 ​ $ 14.52 ​ $ 14.19 ​ $ 14.05 ​ $ 13.92 ​ Net assets at end of year ​ $ 278,699 ​ $ 240,850 ​ $ 184,535 ​ $ 133,738 ​ $ 138,092 ​ Shares outstanding at end of year ​ 20,239,957 ​ 16,581,869 ​ 13,008,007 ​ 9,517,910 ​ 9,918,269 ​ Per share market value at end of year ​ $ 13.75 ​ $ 15.38 ​ $ 13.09 ​ $ 14.46 ​ $ 12.20 ​ Total return based on market value (3) ​ (1.82) % 28.95 % (0.21) % 30.67 % (9.29) % Total return based on average net asset value (4) ​ 4.58 % 11.70 % 11.04 % 10.34 % 9.17 % Ratio/Supplemental data: (5) ​ ​ ​ ​ ​ ​ Ratio of net investment income to average net assets ​ 9.80 % 10.81 % 11.56 % 11.20 % 7.71 % Ratio of total expenses, net of base management fee and incentive fee waivers, to average net assets ​ 9.46 % 10.81 % 11.20 % 11.03 % 8.53 % Portfolio turnover ​ 39.39 % 22.41 % 30.70 % 47.03 % 39.77 % (1) Calculated using the weighted average shares outstanding during the years presented. (2) Includes the effect of share issuances above (below) net asset value and the impact of different share amounts used in calculating per share data as a result of calculating certain per share data based on weighted average shares outstanding during the period and certain per share data based on shares outstanding as of a period end or transaction date. (3) Total return based on market value is calculated assuming a purchase of common shares at the market value on the first day and a sale at the market value on the last day of the periods reported. Distributions, if any, are assumed for purposes of this calculation to be reinvested at prices obtained under the Company’s DRIP. Total return based on market value does not reflect brokerage commissions. (4) Total return based on average net asset value is calculated by dividing the net increase (decrease) in net assets resulting from operations by the average net asset value. (5) The following is a schedule of supplemental ratios for the years presented. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 2022 2021 2020 2019 2018 ​ Ratio of total investment income to average net assets 24.02 % 22.22 % 27.00 % 26.73 % 21.69 % Ratio of interest and other debt financing expenses to average net assets 7.25 % 6.63 % 7.89 % 7.95 % 4.56 % Ratio of total expenses (without base management fee waivers and incentive fees) to average net assets 13.09 % 12.16 % 13.86 % 13.61 % 9.19 % Ratio of incentive fees, net of incentive fee waivers, to average net assets (6) 1.53 % 0.91 % 0.00 % 1.74 % 0.65 % ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 2017 2016 2015 2014 2013 Ratio of total investment income to average net assets 19.26 % 21.62 % 22.76 % 22.23 % 17.10 % Ratio of interest and other debt financing expenses to average net assets 3.13 % 3.26 % 3.33 % 3.23 % 2.59 % Ratio of total expenses (without base management fee waivers and incentive fees) to average net assets 7.43 % 8.17 % 8.31 % 8.42 % 7.15 % Ratio of incentive fees, net of incentive fee waivers, to average net assets (6) 2.03 % 2.64 % 2.89 % 2.61 % 1.38 % (6) The ratio of waived incentive fees to average net assets was 0.22% , 0.61% , 0.31% , 0.46% , zero , 0.12% , 0.13% , zero , zero and zero for the years presente d.

Selected Quarterly Financial _2

Selected Quarterly Financial Data (unaudited) (Tables)	12 Months Ended
	Dec. 31, 2022
Selected Quarterly Financial Data (unaudited)
Schedule of quarterly financial data	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ For the quarter ended ​ December 31, 2022 September 30, 2022 June 30, 2022 March 31, 2022 Total investment income ​ $ 15,164 ​ $ 15,916 ​ $ 12,995 ​ $ 12,491 Net investment income ​ $ 5,520 ​ $ 6,260 ​ $ 5,014 ​ $ 5,398 Net gain (loss) ​ $ (1,040) ​ $ (7,009) ​ $ (12,378) ​ $ (4,551) Net increase (decrease) in net assets resulting from operations ​ $ 4,480 ​ $ (749) ​ $ (7,364) ​ $ 847 Net investment income per share – basic and diluted ​ $ 0.25 ​ $ 0.29 ​ $ 0.23 ​ $ 0.25 Net increase (decrease) in net assets resulting from operations per share – basic and diluted ​ $ 0.21 ​ $ (0.03) ​ $ (0.34) ​ $ 0.04 Net asset value per share at period end ​ $ 10.39 ​ $ 10.43 ​ $ 10.71 ​ $ 11.30 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ For the quarter ended ​ December 31, 2021 September 30, 2021 June 30, 2021 March 31, 2021 Total investment income ​ $ 13,039 ​ $ 15,214 ​ $ 12,364 ​ $ 13,213 Net investment income ​ $ 5,373 ​ $ 6,312 ​ $ 5,157 ​ $ 5,326 Net gain (loss) ​ $ 1,462 ​ $ 927 ​ $ 6,173 ​ $ 1,729 Net increase (decrease) in net assets resulting from operations ​ $ 6,835 ​ $ 7,239 ​ $ 11,330 ​ $ 7,055 Net investment income per share – basic and diluted ​ $ 0.25 ​ $ 0.29 ​ $ 0.24 ​ $ 0.25 Net increase (decrease) in net assets resulting from operations per share – basic and diluted ​ $ 0.32 ​ $ 0.34 ​ $ 0.53 ​ $ 0.33 Net asset value per share at period end ​ $ 11.51 ​ $ 11.45 ​ $ 11.36 ​ $ 11.08 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ For the quarter ended ​ December 31, 2020 September 30, 2020 June 30, 2020 March 31, 2020 Total investment income ​ $ 12,552 ​ $ 13,385 ​ $ 20,642 ​ $ 15,002 Net investment income ​ $ 5,326 ​ $ 5,644 ​ $ 12,636 ​ $ 6,782 Net gain (loss) ​ $ 3,751 ​ $ 9,541 ​ $ 1,598 ​ $ (43,632) Net increase (decrease) in net assets resulting from operations ​ $ 9,077 ​ $ 15,185 ​ $ 14,234 ​ $ (36,850) Net investment income per share – basic and diluted ​ $ 0.25 ​ $ 0.26 ​ $ 0.61 ​ $ 0.33 Net increase (decrease) in net assets resulting from operations per share – basic and diluted ​ $ 0.42 ​ $ 0.71 ​ $ 0.69 ​ $ (1.81) Net asset value per share at period end ​ $ 11.00 ​ $ 10.83 ​ $ 10.37 ​ $ 10.04

Summary of Significant Accoun_4

Summary of Significant Accounting Policies - Revenue Recognition (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Revenue Recognition
Unamortized discounts and loan origination fees	$ 4,701	$ 4,370
Upfront loan origination and closing fees received	3,475	3,752	$ 1,909
Investment in LLC equity interest in SLF
Revenue Recognition
Return of capital distributions	$ 290	$ 1,177	$ 0

Summary of Significant Accoun_5

Summary of Significant Accounting Policies - Components of the Company's investment income (Details) - USD ($) $ in Thousands	3 Months Ended												12 Months Ended
	Dec. 31, 2022	Sep. 30, 2022	Jun. 30, 2022	Mar. 31, 2022	Dec. 31, 2021	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Summary of Significant Accounting Policies
Interest income													$ 41,449	$ 35,738	$ 42,640
PIK interest income													6,689	8,320	8,776
Dividend income													4,161	5,712	4,557
Fee income													2,380	1,267	3,222
Prepayment gain (loss)													803	1,691	1,133
Accretion of discounts and amortization of premium													1,084	1,102	1,253
Total investment income	$ 15,164	$ 15,916	$ 12,995	$ 12,491	$ 13,039	$ 15,214	$ 12,364	$ 13,213	$ 12,552	$ 13,385	$ 20,642	$ 15,002	56,566	53,830	61,581
PIK dividends													475	1,164	$ 157
Fair value of the Company's investments on non-accrual status	$ 2,835				$ 14,693								$ 2,835	$ 14,693

Summary of Significant Accoun_6

Summary of Significant Accounting Policies - Additional Information (Details) $ in Thousands	1 Months Ended	12 Months Ended
	Oct. 31, 2012 D	Dec. 31, 2022 USD ($) $ / $	Dec. 31, 2021 USD ($) $ / $ $ / £	Dec. 31, 2020 USD ($)
Summary of Significant Accounting Policies
Threshold minimum number of days for cash dividend to get automatically reinvested | D	3
Unamortized deferred financing costs		$ 4,486	$ 5,794
Amortization of deferred financing costs		2,126	2,205	$ 2,181
Deferred offering costs		$ 184	$ 123
Number of investments held in portfolio company that was denominated in Australian dollars | $ / $		1	1
Number of investments held in portfolio company that was denominated in Great Britain pounds | $ / £			1
Excise tax accrued (in percent)		4%
Net expense (benefit) for U.S. federal excise tax		$ 94	$ 278	368
Payables for excise taxes		1	183
U.S. federal and state corporate-level income taxes, Net tax expense		1,311	4	$ 2
U.S. federal and state corporate-level income taxes, Payables		$ 0	$ 0

Investments - Composition of th

Investments - Composition of the Company's investment portfolio, at amortized cost and fair value (with corresponding percentage of total portfolio investments) (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Investments
Amortized Cost	$ 579,307	$ 576,178
Fair Value	$ 541,040	$ 561,693
Amortized Cost, Percentage of total portfolio investments	100%	100%
Fair Value, Percentage of total portfolio investments	100%	100%
Senior secured loans
Investments
Amortized Cost	$ 436,066	$ 415,600
Fair Value	$ 434,023	$ 423,700
Amortized Cost, Percentage of total portfolio investments	75.30%	72.10%
Fair Value, Percentage of total portfolio investments	80.20%	75.40%
Unitranche secured loans
Investments
Amortized Cost	$ 45,352	$ 70,977
Fair Value	$ 20,633	$ 51,494
Amortized Cost, Percentage of total portfolio investments	7.80%	12.30%
Fair Value, Percentage of total portfolio investments	3.80%	9.20%
Junior secured loans
Investments
Amortized Cost	$ 21,141	$ 14,317
Fair Value	$ 22,193	$ 14,364
Amortized Cost, Percentage of total portfolio investments	3.60%	2.50%
Fair Value, Percentage of total portfolio investments	4.10%	2.60%
LLC equity interest in SLF
Investments
Amortized Cost	$ 42,650	$ 42,150
Fair Value	$ 35,509	$ 41,125
Amortized Cost, Percentage of total portfolio investments	7.40%	7.30%
Fair Value, Percentage of total portfolio investments	6.60%	7.30%
Equity securities
Investments
Amortized Cost	$ 34,098	$ 33,134
Fair Value	$ 28,682	$ 31,010
Amortized Cost, Percentage of total portfolio investments	5.90%	5.80%
Fair Value, Percentage of total portfolio investments	5.30%	5.50%

Investments - Composition of _2

Investments - Composition of the Company's investment portfolio by geographic region, at amortized cost and fair value (with corresponding percentage of total portfolio investments) (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Investments
Amortized Cost	$ 579,307	$ 576,178
Fair Value	$ 541,040	$ 561,693
Amortized Cost, Percentage of total portfolio investments	100%	100%
Fair Value, Percentage of total portfolio investments	100%	100%
International
Investments
Amortized Cost	$ 11,860	$ 11,860
Fair Value	$ 10,405	$ 11,093
Amortized Cost, Percentage of total portfolio investments	2.10%	2%
Fair Value, Percentage of total portfolio investments	1.90%	2%
Midwest
Investments
Amortized Cost	$ 157,558	$ 145,023
Fair Value	$ 143,691	$ 143,435
Amortized Cost, Percentage of total portfolio investments	27.20%	25.20%
Fair Value, Percentage of total portfolio investments	26.60%	25.50%
Northeast
Investments
Amortized Cost	$ 100,961	$ 107,828
Fair Value	$ 104,157	$ 112,175
Amortized Cost, Percentage of total portfolio investments	17.40%	18.70%
Fair Value, Percentage of total portfolio investments	19.20%	20%
Southeast
Investments
Amortized Cost	$ 158,548	$ 164,100
Fair Value	$ 155,624	$ 159,807
Amortized Cost, Percentage of total portfolio investments	27.40%	28.50%
Fair Value, Percentage of total portfolio investments	28.80%	28.40%
Southwest
Investments
Amortized Cost	$ 27,348	$ 40,121
Fair Value	$ 28,287	$ 44,380
Amortized Cost, Percentage of total portfolio investments	4.70%	7%
Fair Value, Percentage of total portfolio investments	5.20%	7.90%
West
Investments
Amortized Cost	$ 123,032	$ 107,246
Fair Value	$ 98,876	$ 90,803
Amortized Cost, Percentage of total portfolio investments	21.20%	18.60%
Fair Value, Percentage of total portfolio investments	18.30%	16.20%

Investments - Composition of _3

Investments - Composition of the Company's investment portfolio by industry, at amortized cost and fair value (with corresponding percentage of total portfolio investments) (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Investments
Amortized Cost	$ 579,307	$ 576,178
Fair Value	$ 541,040	$ 561,693
Amortized Cost, Percentage of total portfolio investments	100%	100%
Fair Value, Percentage of total portfolio investments	100%	100%
Aerospace & Defense
Investments
Amortized Cost	$ 7,461	$ 7,828
Fair Value	$ 7,436	$ 7,972
Amortized Cost, Percentage of total portfolio investments	1.30%	1.40%
Fair Value, Percentage of total portfolio investments	1.40%	1.40%
Automotive
Investments
Amortized Cost	$ 16,775	$ 21,162
Fair Value	$ 16,637	$ 21,556
Amortized Cost, Percentage of total portfolio investments	2.90%	3.70%
Fair Value, Percentage of total portfolio investments	3.10%	3.80%
Banking
Investments
Amortized Cost	$ 17,790	$ 5,416
Fair Value	$ 19,817	$ 6,712
Amortized Cost, Percentage of total portfolio investments	3.10%	1%
Fair Value, Percentage of total portfolio investments	3.70%	1.20%
Beverage, Food & Tobacco
Investments
Amortized Cost	$ 15,625	$ 21,036
Fair Value	$ 12,470	$ 19,133
Amortized Cost, Percentage of total portfolio investments	2.70%	3.70%
Fair Value, Percentage of total portfolio investments	2.30%	3.40%
Capital Equipment
Investments
Amortized Cost	$ 18,615	$ 12,656
Fair Value	$ 19,012	$ 12,839
Amortized Cost, Percentage of total portfolio investments	3.20%	2.20%
Fair Value, Percentage of total portfolio investments	3.50%	2.30%
Chemicals, Plastics & Rubber
Investments
Amortized Cost	$ 2,924	$ 9,426
Fair Value	$ 4,445	$ 10,163
Amortized Cost, Percentage of total portfolio investments	0.50%	1.60%
Fair Value, Percentage of total portfolio investments	0.80%	1.80%
Construction & Building
Investments
Amortized Cost	$ 6,642	$ 16,450
Fair Value	$ 6,706	$ 16,636
Amortized Cost, Percentage of total portfolio investments	1.10%	2.90%
Fair Value, Percentage of total portfolio investments	1.20%	3%
Consumer Goods: Durable
Investments
Amortized Cost	$ 9,333	$ 9,536
Fair Value	$ 9,338	$ 9,734
Amortized Cost, Percentage of total portfolio investments	1.60%	1.70%
Fair Value, Percentage of total portfolio investments	1.70%	1.70%
Consumer Goods: Non-Durable
Investments
Amortized Cost	$ 28,276	$ 28,232
Fair Value	$ 3,508	$ 8,460
Amortized Cost, Percentage of total portfolio investments	4.90%	4.90%
Fair Value, Percentage of total portfolio investments	0.60%	1.50%
Environmental Industries
Investments
Amortized Cost	$ 6,164	$ 17,103
Fair Value	$ 6,558	$ 17,693
Amortized Cost, Percentage of total portfolio investments	1.10%	3%
Fair Value, Percentage of total portfolio investments	1.20%	3.20%
FIRE: Finance
Investments
Amortized Cost	$ 25,021	$ 16,264
Fair Value	$ 23,892	$ 15,681
Amortized Cost, Percentage of total portfolio investments	4.30%	2.80%
Fair Value, Percentage of total portfolio investments	4.40%	2.80%
FIRE: Real Estate
Investments
Amortized Cost	$ 81,922	$ 72,826
Fair Value	$ 82,498	$ 76,698
Amortized Cost, Percentage of total portfolio investments	14.10%	12.60%
Fair Value, Percentage of total portfolio investments	15.20%	13.60%
Healthcare & Pharmaceuticals
Investments
Amortized Cost	$ 59,659	$ 52,743
Fair Value	$ 59,273	$ 53,179
Amortized Cost, Percentage of total portfolio investments	10.30%	9.20%
Fair Value, Percentage of total portfolio investments	11%	9.50%
High Tech Industries
Investments
Amortized Cost	$ 52,385	$ 52,710
Fair Value	$ 52,891	$ 54,085
Amortized Cost, Percentage of total portfolio investments	9%	9.10%
Fair Value, Percentage of total portfolio investments	9.80%	9.60%
Hotels, Gaming & Leisure
Investments
Amortized Cost	$ 2,702	$ 2,662
Fair Value	$ 2,720	$ 2,706
Amortized Cost, Percentage of total portfolio investments	0.50%	0.50%
Fair Value, Percentage of total portfolio investments	0.50%	0.50%
Investment Funds & Vehicles
Investments
Amortized Cost	$ 42,650	$ 42,150
Fair Value	$ 35,509	$ 41,125
Amortized Cost, Percentage of total portfolio investments	7.40%	7.30%
Fair Value, Percentage of total portfolio investments	6.60%	7.30%
Media: Advertising, Printing & Publishing
Investments
Amortized Cost	$ 17,470	$ 13,421
Fair Value	$ 19,777	$ 16,794
Amortized Cost, Percentage of total portfolio investments	3%	2.30%
Fair Value, Percentage of total portfolio investments	3.70%	3%
Media: Broadcasting & Subscription
Investments
Amortized Cost	$ 2,747	$ 2,472
Fair Value	$ 2,691	$ 2,477
Amortized Cost, Percentage of total portfolio investments	0.50%	0.40%
Fair Value, Percentage of total portfolio investments	0.50%	0.50%
Media: Diversified & Production
Investments
Amortized Cost	$ 36,018	$ 23,853
Fair Value	$ 36,164	$ 24,220
Amortized Cost, Percentage of total portfolio investments	6.20%	4.10%
Fair Value, Percentage of total portfolio investments	6.70%	4.30%
Retail
Investments
Amortized Cost	$ 9,247	$ 10,954
Fair Value	$ 9,306	$ 11,478
Amortized Cost, Percentage of total portfolio investments	1.60%	1.90%
Fair Value, Percentage of total portfolio investments	1.70%	2%
Services: Business
Investments
Amortized Cost	$ 56,249	$ 69,292
Fair Value	$ 57,308	$ 71,540
Amortized Cost, Percentage of total portfolio investments	9.70%	12%
Fair Value, Percentage of total portfolio investments	10.60%	12.70%
Services: Consumer
Investments
Amortized Cost	$ 40,086	$ 46,284
Fair Value	$ 31,324	$ 39,248
Amortized Cost, Percentage of total portfolio investments	6.90%	8%
Fair Value, Percentage of total portfolio investments	5.80%	7%
Telecommunications
Investments
Amortized Cost	$ 7,502	$ 5,892
Fair Value	$ 7,595	$ 5,988
Amortized Cost, Percentage of total portfolio investments	1.30%	1%
Fair Value, Percentage of total portfolio investments	1.40%	1.10%
Wholesale
Investments
Amortized Cost	$ 16,044	$ 15,810
Fair Value	$ 14,165	$ 15,576
Amortized Cost, Percentage of total portfolio investments	2.80%	2.70%
Fair Value, Percentage of total portfolio investments	2.60%	2.80%

Investments - MRCC Senior Loan

Investments - MRCC Senior Loan Fund I, LLC (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2022 USD ($) item	Dec. 31, 2021 USD ($) item	Dec. 31, 2020 USD ($)
Investments
Outstanding commitments to fund investments under undrawn revolvers and delayed draw commitments	$ 63,450	$ 55,483
SLF
Investments
Percentage of equity interest	50%	50%
Funded amount	$ 42,650	$ 42,150
Dividend income	3,600	4,325	$ 4,400
Senior secured loans	$ 197,867	$ 193,062
Weighted average interest rate	9.70%	5.90%
Number of portfolio company investments in SLF	60,000	57
Largest portfolio company investment	$ 6,650	$ 6,720
Total of five largest portfolio company investments	27,026	27,074
SLF
Investments
Equity commitments	100,000
Funded amount	85,300	84,300
Total assets at fair value	$ 192,830	$ 194,623
Number of portfolio company investments on non-accrual status | item	1	1
Investments on non-accrual status with a fair value	$ 415	$ 1,072
Outstanding commitments to fund investments under undrawn revolvers and delayed draw commitments	50,000	50,000
Outstanding commitments to fund investments under undrawn revolvers and delayed draw commitments	4,579	2,061
SLF | Administrative arrangement with MC Management
Investments
Allocable expenses	237	$ 211	$ 209
SLF | SLF Credit Facility
Investments
Maximum borrowing capacity	$ 175,000
SLF | SLF Credit Facility | LIBOR
Investments
Interest rate, basis spread	2.10%

Investments - Schedule of Inves

Investments - Schedule of Investments (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Type [Extensible Enumeration]		Equity Securities [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Interest Rate, Paid in Cash	10.92%
Investment Owned, at Fair Value	$ 541,040	$ 561,693
Investment, Identifier [Axis]: 360 Holdco, Inc. ( Delayed Draw), Senior Secured Loans, due 8/2/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:ThreeSixty360HoldcoIncMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Services: Consumer
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Basis Spread, Variable Rate	5%
Investment Interest Rate	9.42%
Investment Maturity Date	Aug. 02, 2025
Investment Owned, Balance, Principal Amount	$ 827
Investment Owned, at Fair Value	$ 252
Investment, Identifier [Axis]: 360 Holdco, Inc., Senior Secured Loans, due 8/2/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:ThreeSixty360HoldcoIncMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Services: Consumer
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Basis Spread, Variable Rate	5%
Investment Interest Rate	9.42%
Investment Maturity Date	Aug. 02, 2025
Investment Owned, Balance, Principal Amount	$ 2,145
Investment Owned, at Fair Value	$ 2,145
Investment, Identifier [Axis]: A P C O Worldwide, Inc, Equity Securities, Class A voting common stock
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:APCOWorldwideIncMember	mrcc:APCOWorldwideIncMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Equity Securities [Member]
Investment, Industry Sector [Extensible Enumeration]	Services: Business	Services: Business
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Acquisition Date	Nov. 01, 2017	Nov. 01, 2017
Investment Owned, at Fair Value	$ 921	$ 737
Investment, Identifier [Axis]: A Q Carver Buyer, Inc., Senior Secured Loans, due 9/23/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:AQCarverBuyerIncMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Services: Business
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Basis Spread, Variable Rate	5%
Investment Interest Rate	9.38%
Investment Maturity Date	Sep. 23, 2025
Investment Owned, Balance, Principal Amount	$ 4,838
Investment Owned, at Fair Value	$ 4,834
Investment, Identifier [Axis]: A S G I I, L L C ( Delayed Draw), Unitranche Secured Loans, 5/25/2028
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:ASGIILLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Services: Business
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Basis Spread, Variable Rate	6.25%
Investment Interest Rate	10.67%
Investment, Acquisition Date	May 25, 2022
Investment Maturity Date	May 25, 2028
Investment Owned, Balance, Principal Amount	$ 285
Investment Owned, at Fair Value	$ 51
Investment, Identifier [Axis]: A S G I I, L L C, Unitranche Secured Loans, due 5/25/2028
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:ASGIILLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Services: Business
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Basis Spread, Variable Rate	6.25%
Investment Interest Rate	10.67%
Investment, Acquisition Date	May 25, 2022
Investment Maturity Date	May 25, 2028
Investment Owned, Balance, Principal Amount	$ 1,900
Investment Owned, at Fair Value	$ 1,900
Investment, Identifier [Axis]: Accelerate Auto Works Intermediate, L L C ( Delayed Draw), Senior Secured Loans, due 12/1/2027
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:AccelerateAutoWorksIntermediateLLCMember	mrcc:AccelerateAutoWorksIntermediateLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Automotive	Automotive
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR	LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Basis Spread, Variable Rate	4.50%	4.75%
Investment Interest Rate	9.23%	5.75%
Investment Maturity Date	Dec. 01, 2027	Dec. 01, 2027
Investment Owned, Balance, Principal Amount	$ 388	$ 388
Investment, Identifier [Axis]: Accelerate Auto Works Intermediate, L L C ( Revolver), Senior Secured Loans, due 12/1/2027
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:AccelerateAutoWorksIntermediateLLCMember	mrcc:AccelerateAutoWorksIntermediateLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Automotive	Automotive
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR	LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Basis Spread, Variable Rate	4.50%	4.75%
Investment Interest Rate	9.23%	5.75%
Investment Maturity Date	Dec. 01, 2027	Dec. 01, 2027
Investment Owned, Balance, Principal Amount	$ 132	$ 132
Investment, Identifier [Axis]: Accelerate Auto Works Intermediate, L L C, Senior Secured Loans, due 12/1/2027
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:AccelerateAutoWorksIntermediateLLCMember	mrcc:AccelerateAutoWorksIntermediateLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Automotive	Automotive
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR	LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Basis Spread, Variable Rate	4.50%	4.75%
Investment Interest Rate	9.23%	5.75%
Investment Maturity Date	Dec. 01, 2027	Dec. 01, 2027
Investment Owned, Balance, Principal Amount	$ 1,391	$ 1,454
Investment Owned, at Fair Value	$ 1,386	$ 1,436
Investment, Identifier [Axis]: Ad Theorent Holding Company, Inc. Equity Securities, common stock
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:AdTheorentHoldingCompanyIncMember	mrcc:AdTheorentHoldingCompanyIncMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Equity Securities [Member]
Investment, Industry Sector [Extensible Enumeration]	Media: Advertising, Printing & Publishing	Media: Advertising, Printing & Publishing
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Acquisition Date	Dec. 22, 2016	Dec. 22, 2016
Investment Owned, at Fair Value	$ 294	$ 1,041
Investment, Identifier [Axis]: Amelia Holding II, LLC (Delayed Draw), Due 12/21/2027
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:AmeliaHoldingIiLlcDelayedDrawMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	High Tech Industries Sector [Member]
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Basis Spread, Variable Rate	10.26%
Investment, Interest Rate, Paid in Cash	13.77%
Investment, Interest Rate, Paid in Kind	1%
Investment, Acquisition Date	Dec. 21, 2022
Investment Maturity Date	Dec. 21, 2027
Investment Owned, Balance, Principal Amount	$ 667
Investment, Identifier [Axis]: Amelia Holding II, LLC (Revolver), Due 12/21/2027
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:AmeliaHoldingIiLlcRevolverMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	High Tech Industries Sector [Member]
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Basis Spread, Variable Rate	10.26%
Investment, Interest Rate, Paid in Cash	13.77%
Investment, Interest Rate, Paid in Kind	1%
Investment, Acquisition Date	Dec. 21, 2022
Investment Maturity Date	Dec. 21, 2027
Investment Owned, Balance, Principal Amount	$ 133
Investment, Identifier [Axis]: Amelia Holding II, LLC, Due 12/21/2027
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:AmeliaHoldingIiLlcMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	High Tech Industries Sector [Member]
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Basis Spread, Variable Rate	10.26%
Investment, Interest Rate, Paid in Cash	13.77%
Investment, Interest Rate, Paid in Kind	1%
Investment, Acquisition Date	Dec. 21, 2022
Investment Maturity Date	Dec. 21, 2027
Investment Owned, Balance, Principal Amount	$ 2,000
Investment Owned, at Fair Value	$ 1,940
Investment, Identifier [Axis]: Amelia Holding II, LLC, Equity Securities
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:AmeliaHoldingIiLlcMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	High Tech Industries Sector [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Acquisition Date	Dec. 21, 2022
Investment Maturity Date	Dec. 21, 2027
Investment, Identifier [Axis]: American Broadband and Telecommunications Company L L C ( Delayed Draw), Senior Secured Loans, due 6/10/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:AmericanBroadbandandTelecommunicationsCompanyLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Telecommunications
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Prime Rate [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Basis Spread, Variable Rate	12%
Investment, Interest Rate, Paid in Cash	17.50%
Investment, Interest Rate, Paid in Kind	2%
Investment, Acquisition Date	Jun. 10, 2022
Investment Maturity Date	Jun. 10, 2025
Investment Owned, Balance, Principal Amount	$ 1,689
Investment Owned, at Fair Value	$ 1,539
Investment, Identifier [Axis]: American Broadband and Telecommunications Company L L C ( Revolver), Senior Secured Loans, due 6/10/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:AmericanBroadbandandTelecommunicationsCompanyLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Telecommunications
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Prime Rate [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Basis Spread, Variable Rate	12%
Investment, Interest Rate, Paid in Cash	17.50%
Investment, Interest Rate, Paid in Kind	2%
Investment, Acquisition Date	Jun. 10, 2022
Investment Maturity Date	Jun. 10, 2025
Investment Owned, Balance, Principal Amount	$ 500
Investment Owned, at Fair Value	$ 118
Investment, Identifier [Axis]: American Broadband and Telecommunications Company L L C, Equity Securities, Warrants
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:AmericanBroadbandandTelecommunicationsCompanyLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Telecommunications
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Acquisition Date	Jun. 10, 2022
Investment Maturity Date	Jun. 10, 2032
Investment Owned, at Fair Value	$ 69
Investment, Identifier [Axis]: American Community Homes, Inc, Senior Secured Loans (Common stock)
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	American Community Homes, Inc. [ Member]
Investment, Identifier [Axis]: American Community Homes, Inc. ( Revolver), Senior Secured Loans Due 12/31/2026
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	American Community Homes, Inc. [ Member]	American Community Homes, Inc. [ Member]
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	FIRE: Real Estate
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Basis Spread, Variable Rate	8.11%
Investment, Interest Rate, Paid in Kind	12.44%
Investment, Acquisition Date	Mar. 30, 2020
Investment Maturity Date	Dec. 31, 2026
Investment Owned, Balance, Principal Amount	$ 2,500
Investment, Identifier [Axis]: American Community Homes, Inc., Equity Securities Due 12/18/2024, Warrants
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	American Community Homes, Inc. [ Member]	American Community Homes, Inc. [ Member]
Investment, Type [Extensible Enumeration]		Equity Securities [Member]
Investment, Industry Sector [Extensible Enumeration]		FIRE: Real Estate
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Acquisition Date		Oct. 09, 2014
Investment Maturity Date		Dec. 18, 2024
Investment Owned, at Fair Value		$ 264
Investment, Identifier [Axis]: American Community Homes, Inc., Equity Securities, Common Stock
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	American Community Homes, Inc. [ Member]
Investment, Type [Extensible Enumeration]	Equity Securities [Member]
Investment, Industry Sector [Extensible Enumeration]	FIRE: Real Estate
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Acquisition Date	Dec. 29, 2022
Investment, Identifier [Axis]: American Community Homes, Inc., Loan Five
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	American Community Homes, Inc. [ Member]	American Community Homes, Inc. [ Member]
Investment Owned, at Fair Value			$ 335
Investment, Identifier [Axis]: American Community Homes, Inc., Loan Three
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	American Community Homes, Inc. [ Member]	American Community Homes, Inc. [ Member]
Investment Owned, at Fair Value			825
Investment, Identifier [Axis]: American Community Homes, Inc., Senior Secured Loans, Eight, Acquisition Date 9/30/2019
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	American Community Homes, Inc. [ Member]	American Community Homes, Inc. [ Member]
Investment Owned, at Fair Value	$ 17	$ 20	18
Investment, Identifier [Axis]: American Community Homes, Inc., Senior Secured Loans, Five, Due 12/31/2026
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	American Community Homes, Inc. [ Member]
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	FIRE: Real Estate
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Basis Spread, Variable Rate	8.11%
Investment, Interest Rate, Paid in Kind	12.44%
Investment, Acquisition Date	Mar. 29, 2019
Investment Maturity Date	Dec. 31, 2026
Investment Owned, Balance, Principal Amount	$ 4,640
Investment Owned, at Fair Value	$ 3,694
Investment, Identifier [Axis]: American Community Homes, Inc., Senior Secured Loans, Five, Due 3/31/2022
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		American Community Homes, Inc. [ Member]
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		FIRE: Real Estate
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Basis Spread, Variable Rate		10%
Investment, Interest Rate, Paid in Kind		11.50%
Investment, Acquisition Date		Mar. 29, 2019
Investment Maturity Date		Mar. 31, 2022
Investment Owned, Balance, Principal Amount		$ 4,315
Investment Owned, at Fair Value		$ 4,357
Investment, Identifier [Axis]: American Community Homes, Inc., Senior Secured Loans, Four, Acquisition Date 5/24/2017
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	American Community Homes, Inc. [ Member]	American Community Homes, Inc. [ Member]
Investment Owned, at Fair Value	$ 543	$ 634	570
Investment, Identifier [Axis]: American Community Homes, Inc., Senior Secured Loans, Four, Due 12/31/2026
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	American Community Homes, Inc. [ Member]
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	FIRE: Real Estate
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Basis Spread, Variable Rate	8.11%
Investment, Interest Rate, Paid in Kind	12.44%
Investment, Acquisition Date	Aug. 10, 2018
Investment Maturity Date	Dec. 31, 2026
Investment Owned, Balance, Principal Amount	$ 2,507
Investment Owned, at Fair Value	$ 1,996
Investment, Identifier [Axis]: American Community Homes, Inc., Senior Secured Loans, Four, Due 3/31/2022
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		American Community Homes, Inc. [ Member]
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		FIRE: Real Estate
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Basis Spread, Variable Rate		10%
Investment, Interest Rate, Paid in Kind		11.50%
Investment, Acquisition Date		Aug. 10, 2018
Investment Maturity Date		Mar. 31, 2022
Investment Owned, Balance, Principal Amount		$ 2,331
Investment Owned, at Fair Value		$ 3,164
Investment, Identifier [Axis]: American Community Homes, Inc., Senior Secured Loans, Nine, Acquisition Date 12/30/2019
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	American Community Homes, Inc. [ Member]	American Community Homes, Inc. [ Member]
Investment Owned, at Fair Value	$ 85	$ 99	89
Investment, Identifier [Axis]: American Community Homes, Inc., Senior Secured Loans, One, Acquisition Date 7/22/2014
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	American Community Homes, Inc. [ Member]	American Community Homes, Inc. [ Member]
Investment Owned, at Fair Value	$ 8,953	$ 10,457	9,401
Investment, Identifier [Axis]: American Community Homes, Inc., Senior Secured Loans, One, Due 12/31/2026
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	American Community Homes, Inc. [ Member]
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	FIRE: Real Estate
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Basis Spread, Variable Rate	8.11%
Investment, Interest Rate, Paid in Kind	12.44%
Investment, Acquisition Date	Jul. 22, 2014
Investment Maturity Date	Dec. 31, 2026
Investment Owned, Balance, Principal Amount	$ 11,246
Investment Owned, at Fair Value	$ 8,953
Investment, Identifier [Axis]: American Community Homes, Inc., Senior Secured Loans, One, Due 3/31/2022
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		American Community Homes, Inc. [ Member]
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		FIRE: Real Estate
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Basis Spread, Variable Rate		10%
Investment Interest Rate		11.50%
Investment, Acquisition Date		Jul. 22, 2014
Investment Maturity Date		Mar. 31, 2022
Investment Owned, Balance, Principal Amount		$ 10,457
Investment Owned, at Fair Value		$ 10,457
Investment, Identifier [Axis]: American Community Homes, Inc., Senior Secured Loans, Seven, Acquisition Date 3/29/2019
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	American Community Homes, Inc. [ Member]	American Community Homes, Inc. [ Member]
Investment Owned, at Fair Value	$ 3,694	$ 4,357	3,879
Investment, Identifier [Axis]: American Community Homes, Inc., Senior Secured Loans, Seven, Due 12/31/2026
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	American Community Homes, Inc. [ Member]
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	FIRE: Real Estate
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Basis Spread, Variable Rate	8.11%
Investment, Interest Rate, Paid in Kind	12.44%
Investment, Acquisition Date	Dec. 30, 2019
Investment Maturity Date	Dec. 31, 2026
Investment Owned, Balance, Principal Amount	$ 106
Investment Owned, at Fair Value	$ 85
Investment, Identifier [Axis]: American Community Homes, Inc., Senior Secured Loans, Seven, Due 3/31/2022
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		American Community Homes, Inc. [ Member]
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		FIRE: Real Estate
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Basis Spread, Variable Rate		10%
Investment, Interest Rate, Paid in Kind		11.50%
Investment, Acquisition Date		Dec. 30, 2019
Investment Maturity Date		Mar. 31, 2022
Investment Owned, Balance, Principal Amount		$ 99
Investment Owned, at Fair Value		$ 99
Investment, Identifier [Axis]: American Community Homes, Inc., Senior Secured Loans, Six, Acquisition Date 8/10/2018
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	American Community Homes, Inc. [ Member]	American Community Homes, Inc. [ Member]
Investment Owned, at Fair Value	$ 1,996	$ 3,164	2,915
Investment, Identifier [Axis]: American Community Homes, Inc., Senior Secured Loans, Six, Due 12/31/2026
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	American Community Homes, Inc. [ Member]
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	FIRE: Real Estate
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Basis Spread, Variable Rate	8.11%
Investment, Interest Rate, Paid in Kind	12.44%
Investment, Acquisition Date	Sep. 30, 2019
Investment Maturity Date	Dec. 31, 2026
Investment Owned, Balance, Principal Amount	$ 22
Investment Owned, at Fair Value	$ 17
Investment, Identifier [Axis]: American Community Homes, Inc., Senior Secured Loans, Six, Due 3/31/2022
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		American Community Homes, Inc. [ Member]
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		FIRE: Real Estate
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Basis Spread, Variable Rate		10%
Investment, Interest Rate, Paid in Kind		11.50%
Investment, Acquisition Date		Sep. 30, 2019
Investment Maturity Date		Mar. 31, 2022
Investment Owned, Balance, Principal Amount		$ 20
Investment Owned, at Fair Value		$ 20
Investment, Identifier [Axis]: American Community Homes, Inc., Senior Secured Loans, Three, Due 12/31/2026
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	American Community Homes, Inc. [ Member]
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	FIRE: Real Estate
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Basis Spread, Variable Rate	8.11%
Investment, Interest Rate, Paid in Kind	12.44%
Investment, Acquisition Date	May 24, 2017
Investment Maturity Date	Dec. 31, 2026
Investment Owned, Balance, Principal Amount	$ 682
Investment Owned, at Fair Value	$ 543
Investment, Identifier [Axis]: American Community Homes, Inc., Senior Secured Loans, Three, Due 3/31/2022
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		American Community Homes, Inc. [ Member]
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		FIRE: Real Estate
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Basis Spread, Variable Rate		10%
Investment, Interest Rate, Paid in Kind		11.50%
Investment, Acquisition Date		May 24, 2017
Investment Maturity Date		Mar. 31, 2022
Investment Owned, Balance, Principal Amount		$ 634
Investment Owned, at Fair Value		$ 634
Investment, Identifier [Axis]: American Community Homes, Inc., Senior Secured Loans, Two, Acquisition Date 7/22/2014
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	American Community Homes, Inc. [ Member]	American Community Homes, Inc. [ Member]
Investment Owned, at Fair Value	$ 4,258	$ 4,753	6,239
Investment, Identifier [Axis]: American Community Homes, Inc., Senior Secured Loans, Two, Due 12/31/2026
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	American Community Homes, Inc. [ Member]
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	FIRE: Real Estate
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Basis Spread, Variable Rate	14.61%
Investment, Interest Rate, Paid in Kind	18.94%
Investment, Acquisition Date	Jul. 22, 2014
Investment Maturity Date	Dec. 31, 2026
Investment Owned, Balance, Principal Amount	$ 5,348
Investment Owned, at Fair Value	$ 4,258
Investment, Identifier [Axis]: American Community Homes, Inc., Senior Secured Loans, Two, Due 3/31/2022
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		American Community Homes, Inc. [ Member]
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		FIRE: Real Estate
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Basis Spread, Variable Rate		14.50%
Investment, Interest Rate, Paid in Kind		16%
Investment, Acquisition Date		Jul. 22, 2014
Investment Maturity Date		Mar. 31, 2022
Investment Owned, Balance, Principal Amount		$ 4,753
Investment Owned, at Fair Value		$ 4,753
Investment, Identifier [Axis]: Analogic Corporation, Senior Secured Loans, due 6/24/2024
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:AnalogicCorporationMember	mrcc:AnalogicCorporationMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Capital Equipment	Capital Equipment
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR	LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Basis Spread, Variable Rate		5.25%
Investment Interest Rate		6.25%
Investment Maturity Date		Jun. 24, 2024
Investment Owned, Balance, Principal Amount		$ 4,752
Investment Owned, at Fair Value		$ 4,702
Investment, Identifier [Axis]: Apotheco, L L C ( Revolver), Senior Secured Loans, due 4/8/2024
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:ApothecoLLCMember
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Healthcare & Pharmaceuticals Sector [Member]
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Basis Spread, Variable Rate		8.50%
Investment, Interest Rate, Paid in Cash		6.50%
Investment, Interest Rate, Paid in Kind		3%
Investment, Acquisition Date		Apr. 08, 2019
Investment Maturity Date		Apr. 08, 2024
Investment Owned, Balance, Principal Amount		$ 955
Investment Owned, at Fair Value		$ 910
Investment, Identifier [Axis]: Apotheco, L L C, Senior Secured Loans, due 4/8/2024
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:ApothecoLLCMember
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Healthcare & Pharmaceuticals Sector [Member]
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Basis Spread, Variable Rate		8.50%
Investment, Interest Rate, Paid in Cash		6.50%
Investment, Interest Rate, Paid in Kind		3%
Investment, Acquisition Date		Apr. 08, 2019
Investment Maturity Date		Apr. 08, 2024
Investment Owned, Balance, Principal Amount		$ 3,632
Investment Owned, at Fair Value		$ 3,462
Investment, Identifier [Axis]: Aras Corporation ( Revolver), Senior Secured Loans, due 4/13/2027
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:ArasCorporationMember	mrcc:ArasCorporationMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Services: Business	Services: Business
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR	LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Basis Spread, Variable Rate	6.50%	7%
Investment Interest Rate	9.50%
Investment, Interest Rate, Paid in Cash		4.25%
Investment, Interest Rate, Paid in Kind		3.75%
Investment, Acquisition Date	Apr. 13, 2021	Apr. 13, 2021
Investment Maturity Date	Apr. 13, 2027	Apr. 13, 2027
Investment Owned, Balance, Principal Amount	$ 150	$ 150
Investment Owned, at Fair Value	$ 50
Investment, Identifier [Axis]: Aras Corporation, Senior Secured Loans, due 4/13/2027
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:ArasCorporationMember	mrcc:ArasCorporationMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Services: Business	Services: Business
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR	LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Basis Spread, Variable Rate	7%	7%
Investment, Interest Rate, Paid in Cash	7.16%	4.25%
Investment, Interest Rate, Paid in Kind	3.75%	3.75%
Investment, Acquisition Date	Apr. 13, 2021	Apr. 13, 2021
Investment Maturity Date	Apr. 13, 2027	Apr. 13, 2027
Investment Owned, Balance, Principal Amount	$ 2,155	$ 2,079
Investment Owned, at Fair Value	$ 2,167	$ 2,103
Investment, Identifier [Axis]: Arcstor Midco, L L C, Senior Secured Loans, due 3/16/2027
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:ArcstorMidcoLLCMember	mrcc:ArcstorMidcoLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	High Tech Industries Sector [Member]	High Tech Industries Sector [Member]
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]	LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Basis Spread, Variable Rate	7.60%	7%
Investment Interest Rate		8%
Investment, Interest Rate, Paid in Cash	8.17%
Investment, Interest Rate, Paid in Kind	3.75%
Investment, Acquisition Date	Mar. 16, 2021	Mar. 16, 2021
Investment Maturity Date	Mar. 16, 2027	Mar. 16, 2027
Investment Owned, Balance, Principal Amount	$ 4,528	$ 4,466
Investment Owned, at Fair Value	$ 4,122	$ 4,433
Investment, Identifier [Axis]: Ascent Midco, L L C ( Revolver), Senior Secured Loans Due 2/5/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	Ascent Midco, L L C [ Member]	Ascent Midco, L L C [ Member]
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Healthcare & Pharmaceuticals	Healthcare & Pharmaceuticals
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR	LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Basis Spread, Variable Rate	5.75%	5.50%
Investment Interest Rate	10.14%	6.50%
Investment, Acquisition Date	Feb. 05, 2020	Feb. 05, 2020
Investment Maturity Date	Feb. 05, 2025	Feb. 05, 2025
Investment Owned, Balance, Principal Amount	$ 1,129	$ 1,129
Investment, Identifier [Axis]: Ascent Midco, L L C, ( Delayed Draw) Loan
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	Ascent Midco, L L C [ Member]	Ascent Midco, L L C [ Member]
Investment, Identifier [Axis]: Ascent Midco, L L C, Equity Securities, Class A units
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	Ascent Midco, L L C [ Member]	Ascent Midco, L L C [ Member]
Investment, Type [Extensible Enumeration]	Equity Securities [Member]	Equity Securities [Member]
Investment, Industry Sector [Extensible Enumeration]		Healthcare & Pharmaceuticals
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Interest Rate, Paid in Cash		8%
Investment, Interest Rate, Paid in Kind	8%
Investment, Acquisition Date	Feb. 05, 2020	Feb. 05, 2020
Investment Owned, at Fair Value	$ 1,969	$ 2,554	3,016
Investment, Identifier [Axis]: Ascent Midco, L L C, Senior Secured Loans Due 2/5/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	Ascent Midco, L L C [ Member]	Ascent Midco, L L C [ Member]
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Healthcare & Pharmaceuticals	Healthcare & Pharmaceuticals
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR	LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Basis Spread, Variable Rate	5.75%	5.50%
Investment Interest Rate	10.14%	6.50%
Investment, Acquisition Date	Feb. 05, 2020	Feb. 05, 2020
Investment Maturity Date	Feb. 05, 2025	Feb. 05, 2025
Investment Owned, Balance, Principal Amount	$ 6,217	$ 6,392
Investment Owned, at Fair Value	$ 6,217	$ 6,392	6,997
Investment, Identifier [Axis]: Attom Intermediate Holdco, L L C ( Revolver), Senior Secured Loans, due 1/4/2024
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:AttomIntermediateHoldcoLLCMember
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Media: Diversified & Production
Investment, Variable Interest Rate, Type [Extensible Enumeration]		us-gaap:LondonInterbankOfferedRateLiborSwapRateMember
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Basis Spread, Variable Rate		5.75%
Investment Interest Rate		6.75%
Investment, Acquisition Date		Jan. 04, 2019
Investment Maturity Date		Jan. 04, 2024
Investment Owned, Balance, Principal Amount		$ 320
Investment Owned, at Fair Value		$ 160
Investment, Identifier [Axis]: Attom Intermediate Holdco, L L C, Equity Securities, Class A units
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:AttomIntermediateHoldcoLLCMember	mrcc:AttomIntermediateHoldcoLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Equity Securities [Member]
Investment, Industry Sector [Extensible Enumeration]	Media: Diversified & Production	Media: Diversified & Production
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Acquisition Date	Jan. 04, 2019	Jan. 04, 2019
Investment Owned, at Fair Value	$ 522	$ 446
Investment, Identifier [Axis]: Attom Intermediate Holdco, L L C, Senior Secured Loans, Five, due 7/3/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:AttomIntermediateHoldcoLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Media: Diversified & Production
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Basis Spread, Variable Rate	6.25%
Investment Interest Rate	11.39%
Investment, Acquisition Date	Dec. 22, 2022
Investment Maturity Date	Jul. 03, 2025
Investment Owned, Balance, Principal Amount	$ 400
Investment Owned, at Fair Value	$ 399
Investment, Identifier [Axis]: Attom Intermediate Holdco, L L C, Senior Secured Loans, Four, due 7/3/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:AttomIntermediateHoldcoLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Media: Diversified & Production
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Basis Spread, Variable Rate	6.25%
Investment Interest Rate	10.69%
Investment, Acquisition Date	Aug. 04, 2022
Investment Maturity Date	Jul. 03, 2025
Investment Owned, Balance, Principal Amount	$ 796
Investment Owned, at Fair Value	$ 794
Investment, Identifier [Axis]: Attom Intermediate Holdco, L L C, Senior Secured Loans, One, due 1/4/2024
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:AttomIntermediateHoldcoLLCMember
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Media: Diversified & Production
Investment, Variable Interest Rate, Type [Extensible Enumeration]		us-gaap:LondonInterbankOfferedRateLiborSwapRateMember
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Basis Spread, Variable Rate		6.15%
Investment Interest Rate		7.15%
Investment, Acquisition Date		Jan. 04, 2019
Investment Maturity Date		Jan. 04, 2024
Investment Owned, Balance, Principal Amount		$ 1,940
Investment Owned, at Fair Value		$ 1,937
Investment, Identifier [Axis]: Attom Intermediate Holdco, L L C, Senior Secured Loans, One, due 7/3/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:AttomIntermediateHoldcoLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Media: Diversified & Production
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Basis Spread, Variable Rate	6.25%
Investment Interest Rate	10.69%
Investment, Acquisition Date	Jan. 04, 2019
Investment Maturity Date	Jul. 03, 2025
Investment Owned, Balance, Principal Amount	$ 1,920
Investment Owned, at Fair Value	$ 1,915
Investment, Identifier [Axis]: Attom Intermediate Holdco, L L C, Senior Secured Loans, Three, due 1/4/2024
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:AttomIntermediateHoldcoLLCMember
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Media: Diversified & Production
Investment, Variable Interest Rate, Type [Extensible Enumeration]		us-gaap:LondonInterbankOfferedRateLiborSwapRateMember
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Basis Spread, Variable Rate		6.15%
Investment Interest Rate		7.15%
Investment, Acquisition Date		Jul. 01, 2021
Investment Maturity Date		Jan. 04, 2024
Investment Owned, Balance, Principal Amount		$ 279
Investment Owned, at Fair Value		$ 278
Investment, Identifier [Axis]: Attom Intermediate Holdco, L L C, Senior Secured Loans, Three, due 7/3/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:AttomIntermediateHoldcoLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Media: Diversified & Production
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Basis Spread, Variable Rate	6.25%
Investment Interest Rate	10.69%
Investment, Acquisition Date	Jul. 01, 2021
Investment Maturity Date	Jul. 03, 2025
Investment Owned, Balance, Principal Amount	$ 276
Investment Owned, at Fair Value	$ 275
Investment, Identifier [Axis]: Attom Intermediate Holdco, L L C, Senior Secured Loans, Two, due 1/4/2024
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:AttomIntermediateHoldcoLLCMember
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Media: Diversified & Production
Investment, Variable Interest Rate, Type [Extensible Enumeration]		us-gaap:LondonInterbankOfferedRateLiborSwapRateMember
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Basis Spread, Variable Rate		6.15%
Investment Interest Rate		7.15%
Investment, Acquisition Date		Jun. 25, 2020
Investment Maturity Date		Jan. 04, 2024
Investment Owned, Balance, Principal Amount		$ 473
Investment Owned, at Fair Value		$ 472
Investment, Identifier [Axis]: Attom Intermediate Holdco, L L C, Senior Secured Loans, Two, due 7/3/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:AttomIntermediateHoldcoLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Media: Diversified & Production
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Basis Spread, Variable Rate	6.25%
Investment Interest Rate	10.69%
Investment, Acquisition Date	Jun. 25, 2020
Investment Maturity Date	Jul. 03, 2025
Investment Owned, Balance, Principal Amount	$ 468
Investment Owned, at Fair Value	$ 467
Investment, Identifier [Axis]: Attom Intermediate Holdco, LLC (Revolver), Senior Secured Loans, due 7/3/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:AttomIntermediateHoldcoLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Media: Diversified & Production
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Basis Spread, Variable Rate	6.25%
Investment Interest Rate	10.69%
Investment, Acquisition Date	Jan. 04, 2019
Investment Maturity Date	Jul. 03, 2025
Investment Owned, Balance, Principal Amount	$ 320
Investment, Identifier [Axis]: Avalara, Inc. (Revolver), Senior Secured Loans, due 10/19/2028
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:AvalaraInc.Member
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	mrcc:FireFinanceMember
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Basis Spread, Variable Rate	7.25%
Investment Interest Rate	11.83%
Investment, Acquisition Date	Oct. 19, 2022
Investment Maturity Date	Oct. 19, 2028
Investment Owned, Balance, Principal Amount	$ 400
Investment, Identifier [Axis]: Avalara, Inc. Senior Secured Loans, due 10/19/2028
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:AvalaraInc.Member
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	mrcc:FireFinanceMember
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Basis Spread, Variable Rate	7.25%
Investment Interest Rate	11.83%
Investment, Acquisition Date	Oct. 19, 2022
Investment Maturity Date	Oct. 19, 2028
Investment Owned, Balance, Principal Amount	$ 4,000
Investment Owned, at Fair Value	$ 3,900
Investment, Identifier [Axis]: Avison Young ( U S A) Inc., Senior Secured Loans, due 1/30/2026
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:AvisonYoungUSAIncMember	mrcc:AvisonYoungUSAIncMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	FIRE Real Estate Sector [Member]	FIRE Real Estate Sector [Member]
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]	us-gaap:LondonInterbankOfferedRateLiborSwapRateMember
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Basis Spread, Variable Rate	5.75%	5.75%
Investment Interest Rate	10.19%	5.97%
Investment Maturity Date	Jan. 30, 2026	Jan. 30, 2026
Investment Owned, Balance, Principal Amount	$ 4,800	$ 4,850
Investment Owned, at Fair Value	$ 4,020	$ 4,824
Investment, Identifier [Axis]: B L S T Operating Company, L L C, Equity Securities, Class A units
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:BLSTOperatingCompanyLLCMember	mrcc:BLSTOperatingCompanyLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Equity Securities [Member]
Investment, Industry Sector [Extensible Enumeration]	Retail	Retail
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Acquisition Date	Aug. 28, 2020	Aug. 28, 2020
Investment Owned, at Fair Value	$ 420	$ 420
Investment, Identifier [Axis]: B L S T Operating Company, L L C, Senior Secured Loans, due 8/28/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:BLSTOperatingCompanyLLCMember
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Retail
Investment, Variable Interest Rate, Type [Extensible Enumeration]		us-gaap:LondonInterbankOfferedRateLiborSwapRateMember
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Basis Spread, Variable Rate		8.50%
Investment, Interest Rate, Paid in Cash		1%
Investment, Interest Rate, Paid in Kind		9%
Investment, Acquisition Date		Aug. 28, 2020
Investment Maturity Date		Aug. 28, 2025
Investment Owned, Balance, Principal Amount		$ 1,147
Investment Owned, at Fair Value		$ 1,143
Investment, Identifier [Axis]: BLST Operating Company, LLC, Due 8/28/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:BLSTOperatingCompanyLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Retail
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Basis Spread, Variable Rate	8.50%
Investment Interest Rate	12.62%
Investment, Acquisition Date	Aug. 28, 2020
Investment Maturity Date	Aug. 28, 2025
Investment Owned, Balance, Principal Amount	$ 588
Investment Owned, at Fair Value	$ 571
Investment, Identifier [Axis]: Bonterra, L L C (fka Cybergrants Holdings) ( Delayed Draw) , Senior Secured Loans, due 9/8/2027
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:BonterraLLCfkaCybergrantsHoldingsMember	mrcc:BonterraLLCfkaCybergrantsHoldingsMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Media: Diversified & Production	Media: Diversified & Production
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR	us-gaap:LondonInterbankOfferedRateLiborSwapRateMember
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Basis Spread, Variable Rate	6.25%	6.50%
Investment Interest Rate	10.98%	7.25%
Investment, Acquisition Date	Sep. 08, 2021	Sep. 08, 2021
Investment Maturity Date	Sep. 08, 2027	Sep. 08, 2027
Investment Owned, Balance, Principal Amount	$ 1,906	$ 1,069
Investment, Identifier [Axis]: Bonterra, L L C (fka Cybergrants Holdings) ( Revolver), Senior Secured Loans, due 9/8/2027
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:BonterraLLCfkaCybergrantsHoldingsMember	mrcc:BonterraLLCfkaCybergrantsHoldingsMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Media: Diversified & Production	Media: Diversified & Production
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR	us-gaap:LondonInterbankOfferedRateLiborSwapRateMember
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Basis Spread, Variable Rate	6.25%	6.50%
Investment Interest Rate	10.98%	7.25%
Investment, Acquisition Date	Sep. 08, 2021	Sep. 08, 2021
Investment Maturity Date	Sep. 08, 2027	Sep. 08, 2027
Investment Owned, Balance, Principal Amount	$ 1,069	$ 1,069
Investment Owned, at Fair Value	$ 389
Investment, Identifier [Axis]: Bonterra, L L C (fka Cybergrants Holdings), Senior Secured Loans, due 9/8/2027
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:BonterraLLCfkaCybergrantsHoldingsMember	mrcc:BonterraLLCfkaCybergrantsHoldingsMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Media: Diversified & Production	Media: Diversified & Production
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR	us-gaap:LondonInterbankOfferedRateLiborSwapRateMember
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Basis Spread, Variable Rate	6.25%	6.50%
Investment Interest Rate	10.98%	7.25%
Investment, Acquisition Date	Sep. 08, 2021	Sep. 08, 2021
Investment Maturity Date	Sep. 08, 2027	Sep. 08, 2027
Investment Owned, Balance, Principal Amount	$ 13,195	$ 10,900
Investment Owned, at Fair Value	$ 12,898	$ 10,900
Investment, Identifier [Axis]: Born To Run, L L C ( Delayed Draw) Senior Secured Loans, due 4/1/2027
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:BornToRunLLCMember	mrcc:BornToRunLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Automotive	Automotive
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR	LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Basis Spread, Variable Rate	6%	6%
Investment Interest Rate	10.73%	7%
Investment, Acquisition Date	Apr. 01, 2021	Apr. 01, 2021
Investment Maturity Date	Apr. 01, 2027	Apr. 01, 2027
Investment Owned, Balance, Principal Amount	$ 470	$ 569
Investment Owned, at Fair Value	$ 452	$ 34
Investment, Identifier [Axis]: Born To Run, L L C, Equity Securities, Class A units
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:BornToRunLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Automotive
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Basis Spread, Variable Rate	0%
Investment Interest Rate	0%
Investment, Acquisition Date	Apr. 01, 2021	Apr. 01, 2021
Investment Owned, Balance, Principal Amount	$ 0
Investment Owned, at Fair Value	$ 233	$ 293
Investment, Identifier [Axis]: Born To Run, L L C, Senior Secured Loans, due 4/1/2027
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:BornToRunLLCMember	mrcc:BornToRunLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Automotive	Automotive
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR	LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Basis Spread, Variable Rate	6%	6%
Investment Interest Rate	10.73%	7%
Investment, Acquisition Date	Apr. 01, 2021	Apr. 01, 2021
Investment Maturity Date	Apr. 01, 2027	Apr. 01, 2027
Investment Owned, Balance, Principal Amount	$ 3,448	$ 3,483
Investment Owned, at Fair Value	$ 3,318	$ 3,544
Investment, Identifier [Axis]: Brickell Bay Acquisition Corp, Senior Secured Loans, due 2/12/2026
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:BrickellBayAcquisitionCorpMember	mrcc:BrickellBayAcquisitionCorpMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Healthcare & Pharmaceuticals Sector [Member]	Healthcare & Pharmaceuticals Sector [Member]
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR	LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Basis Spread, Variable Rate	6.50%	6.50%
Investment Interest Rate	10.24%	7.50%
Investment, Acquisition Date	Feb. 12, 2021	Feb. 12, 2021
Investment Maturity Date	Feb. 12, 2026	Feb. 12, 2026
Investment Owned, Balance, Principal Amount	$ 1,880	$ 1,899
Investment Owned, at Fair Value	$ 1,847	$ 1,889
Investment, Identifier [Axis]: Brickell Bay Acquisition Corp. ( Delayed Draw), Senior Secured Loans, due 2/12/2026
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:BrickellBayAcquisitionCorpMember
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Healthcare & Pharmaceuticals Sector [Member]
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Basis Spread, Variable Rate		6.50%
Investment Interest Rate		7.50%
Investment, Acquisition Date		Feb. 12, 2021
Investment Maturity Date		Feb. 12, 2026
Investment Owned, Balance, Principal Amount		$ 382
Investment, Identifier [Axis]: Brickell Bay Acquisition Corp., Senior Secured Loans, due 6/30/2027
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:BrickellBayAcquisitionCorpMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Healthcare & Pharmaceuticals Sector [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Interest Rate, Paid in Cash	8.97%
Investment, Acquisition Date	Jun. 30, 2021
Investment Maturity Date	Jun. 30, 2027
Investment Owned, Balance, Principal Amount	$ 5,016
Investment Owned, at Fair Value	$ 4,630
Investment, Identifier [Axis]: Brightly Software Holdings, Inc. (fka Dude Solutions Holdings, Inc.), Senior Secured Loans, ( Revolver), due 6/13/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:BrightlySoftwareHoldingsInc.fkaDudeSolutionsHoldingsInc.Member
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Construction & Building
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Basis Spread, Variable Rate		6.25%
Investment Interest Rate		7.25%
Investment, Acquisition Date		Jun. 14, 2019
Investment Maturity Date		Jun. 13, 2025
Investment Owned, Balance, Principal Amount		$ 1,304
Investment, Identifier [Axis]: Brightly Software Holdings, Inc. (fka Dude Solutions Holdings, Inc.), Senior Secured Loans, due 6/13/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:BrightlySoftwareHoldingsInc.fkaDudeSolutionsHoldingsInc.Member
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Construction & Building
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Basis Spread, Variable Rate		6.25%
Investment Interest Rate		7.25%
Investment, Acquisition Date		Jun. 14, 2019
Investment Maturity Date		Jun. 13, 2025
Investment Owned, Balance, Principal Amount		$ 9,900
Investment Owned, at Fair Value		$ 9,870
Investment, Identifier [Axis]: Bromford Industries Limited, Senior Secured Loans, One, due 11/5/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:BromfordIndustriesLimitedMember	mrcc:BromfordIndustriesLimitedMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Aerospace & Defense	Aerospace & Defense
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Prime Rate [Member]	Prime Rate [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	Non-US [Member]
Investment, Basis Spread, Variable Rate	5.25%	4.25%
Investment Interest Rate	12.75%	7.50%
Investment Maturity Date	Nov. 05, 2025	Nov. 05, 2025
Investment Owned, Balance, Principal Amount	$ 2,744	$ 2,744
Investment Owned, at Fair Value	$ 2,581	$ 2,692
Investment, Identifier [Axis]: Bromford Industries Limited, Senior Secured Loans, Two, due 11/5/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:BromfordIndustriesLimitedMember	mrcc:BromfordIndustriesLimitedMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Aerospace & Defense	Aerospace & Defense
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Prime Rate [Member]	Prime Rate [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	Non-US [Member]
Investment, Basis Spread, Variable Rate	5.25%	4.25%
Investment Interest Rate	12.75%	7.50%
Investment Maturity Date	Nov. 05, 2025	Nov. 05, 2025
Investment Owned, Balance, Principal Amount	$ 1,829	$ 1,829
Investment Owned, at Fair Value	$ 1,720	$ 1,794
Investment, Identifier [Axis]: Burroughs, Inc. ( Revolver), Senior Secured Loans, due 12/22/2022
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:BurroughsInc.Member
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Services: Business
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Basis Spread, Variable Rate		6.50%
Investment Interest Rate		7.50%
Investment, Acquisition Date		Dec. 22, 2017
Investment Maturity Date		Dec. 22, 2022
Investment Owned, Balance, Principal Amount		$ 1,220
Investment, Identifier [Axis]: Burroughs, Inc. ( Revolver), Senior Secured Loans, due 12/22/2023
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:BurroughsInc.Member
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Services: Business
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Basis Spread, Variable Rate	6.50%
Investment Interest Rate	10.72%
Investment, Acquisition Date	Dec. 22, 2017
Investment Maturity Date	Dec. 22, 2023
Investment Owned, Balance, Principal Amount	$ 1,215
Investment, Identifier [Axis]: Burroughs, Inc., Senior Secured Loans, due 12/22/2022
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:BurroughsInc.Member
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Services: Business
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Basis Spread, Variable Rate		6.50%
Investment Interest Rate		7.50%
Investment, Acquisition Date		Dec. 22, 2017
Investment Maturity Date		Dec. 22, 2022
Investment Owned, Balance, Principal Amount		$ 5,501
Investment Owned, at Fair Value		$ 5,480
Investment, Identifier [Axis]: Burroughs, Inc., Senior Secured Loans, due 12/22/2023
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:BurroughsInc.Member
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Services: Business
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Basis Spread, Variable Rate	6.50%
Investment Interest Rate	10.72%
Investment, Acquisition Date	Dec. 22, 2017
Investment Maturity Date	Dec. 22, 2023
Investment Owned, Balance, Principal Amount	$ 5,201
Investment Owned, at Fair Value	$ 5,201
Investment, Identifier [Axis]: C B C Restaurant Corp., Senior Secured Loans, due 12/30/2022
Schedule of Investments [Line Items]
Investment, Issuer Name [Extensible Enumeration]		mrcc:CBCRestaurantCorpMember
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		mrcc:BeverageFoodAndTobaccoSectorMember
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment Interest Rate	5%
Investment, Interest Rate, Paid in Kind		5%
Investment Maturity Date		Dec. 30, 2022
Investment Owned, Balance, Principal Amount	$ 1,066	$ 1,116
Investment Owned, at Fair Value	$ 415	$ 1,072
Investment, Identifier [Axis]: C H A Holdings, Inc, Senior Secured Loans, One, due 4/10/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:CHAHoldingsIncMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Services: Business
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Basis Spread, Variable Rate	4.50%
Investment Interest Rate	9.23%
Investment Maturity Date	Apr. 10, 2025
Investment Owned, Balance, Principal Amount	$ 1,960
Investment Owned, at Fair Value	$ 1,886
Investment, Identifier [Axis]: C H A Holdings, Inc, Senior Secured Loans, Two, due 4/10/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:CHAHoldingsIncMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Services: Business
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Basis Spread, Variable Rate	4.50%
Investment Interest Rate	9.23%
Investment Maturity Date	Apr. 10, 2025
Investment Owned, Balance, Principal Amount	$ 413
Investment Owned, at Fair Value	$ 398
Investment, Identifier [Axis]: C Parent Holdings, LLC. (fka Curion Holdings, LLC), Equity Securities, Common Stock
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:CParentHoldingsLlc.Member
Investment, Type [Extensible Enumeration]	Equity Securities [Member]
Investment, Industry Sector [Extensible Enumeration]	Services: Business
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Acquisition Date	Aug. 17, 2018
Investment, Identifier [Axis]: C Parent Holdings, LLC. (fka Curion Holdings, LLC), Senior Secured Loan
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:CParentHoldingsLlc.Member
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Services: Business
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Acquisition Date	May 02, 2017
Investment Owned, at Fair Value	$ 146
Investment, Identifier [Axis]: CGI Automated Manufacturing, LLC, Senior Secured Loans, One, due 12/17/2026
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:CgiAutomatedManufacturingLlcMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Capital Equipment
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Basis Spread, Variable Rate	6.50%
Investment Interest Rate	11.34%
Investment, Acquisition Date	Sep. 09, 2022
Investment Maturity Date	Dec. 17, 2026
Investment Owned, Balance, Principal Amount	$ 3,975
Investment Owned, at Fair Value	$ 3,975
Investment, Identifier [Axis]: CGI Automated Manufacturing, LLC, Senior Secured Loans, Two, due 12/17/2026
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:CgiAutomatedManufacturingLlcMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Capital Equipment
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Basis Spread, Variable Rate	6.50%
Investment Interest Rate	11.34%
Investment, Acquisition Date	Sep. 30, 2022
Investment Maturity Date	Dec. 17, 2026
Investment Owned, Balance, Principal Amount	$ 1,141
Investment Owned, at Fair Value	$ 1,141
Investment, Identifier [Axis]: Cadent, L L C ( Revolver), Senior Secured Loans, due 9/11/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:CadentLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Media: Advertising, Printing & Publishing
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Basis Spread, Variable Rate	6.50%
Investment Interest Rate	11.23%
Investment Maturity Date	Sep. 11, 2025
Investment Owned, Balance, Principal Amount	$ 167
Investment, Identifier [Axis]: Cadent, L L C, Senior Secured Loans, due 9/11/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:CadentLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Media: Advertising, Printing & Publishing
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Basis Spread, Variable Rate	6.50%
Investment Interest Rate	11.23%
Investment Maturity Date	Sep. 11, 2025
Investment Owned, Balance, Principal Amount	$ 4,237
Investment Owned, at Fair Value	$ 4,131
Investment, Identifier [Axis]: Calabrio, Inc. ( Revolver), Senior Secured Loans, due 4/16/2027
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:CalabrioIncMember	mrcc:CalabrioIncMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Telecommunications	Telecommunications
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR	LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Basis Spread, Variable Rate	7%	7%
Investment Interest Rate	11.75%	8%
Investment, Acquisition Date	Apr. 16, 2021	Apr. 16, 2021
Investment Maturity Date	Apr. 16, 2027	Apr. 16, 2027
Investment Owned, Balance, Principal Amount	$ 409	$ 409
Investment Owned, at Fair Value	$ 233
Investment, Identifier [Axis]: Calabrio, Inc., Senior Secured Loans, due 4/16/2027
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:CalabrioIncMember	mrcc:CalabrioIncMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Telecommunications	Telecommunications
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR	LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Basis Spread, Variable Rate	7%	7%
Investment Interest Rate	11.73%	8%
Investment, Acquisition Date	Apr. 16, 2021	Apr. 16, 2021
Investment Maturity Date	Apr. 16, 2027	Apr. 16, 2027
Investment Owned, Balance, Principal Amount	$ 3,400	$ 3,400
Investment Owned, at Fair Value	$ 3,379	$ 3,400
Investment, Identifier [Axis]: California Pizza Kitchen, Inc., Equity Securities, Common units
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:CaliforniaPizzaKitchenInc.Member	mrcc:CaliforniaPizzaKitchenInc.Member
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Equity Securities [Member]
Investment, Industry Sector [Extensible Enumeration]	mrcc:BeverageFoodAndTobaccoSectorMember	Beverage, Food & Tobacco
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Acquisition Date	Aug. 19, 2016	Aug. 19, 2016
Investment Owned, at Fair Value	$ 1,266	$ 3,699
Investment, Identifier [Axis]: Cano Health, L L C, Senior Secured Loans, due 11/23/2027
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:CanoHealthLLMember	mrcc:CanoHealthLLMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Healthcare & Pharmaceuticals Sector [Member]	Healthcare & Pharmaceuticals Sector [Member]
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Basis Spread, Variable Rate	4%	4%
Investment Interest Rate	8.42%	4.51%
Investment Maturity Date	Nov. 23, 2027	Nov. 23, 2027
Investment Owned, Balance, Principal Amount	$ 1,970	$ 1,995
Investment Owned, at Fair Value	$ 1,572	$ 1,997
Investment, Identifier [Axis]: Caravel Autism Health, L L C ( Delayed Draw), Senior Secured Loans, due 6/30/2027
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:CaravelAutismHealthLLCMember	mrcc:CaravelAutismHealthLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Healthcare & Pharmaceuticals Sector [Member]	Healthcare & Pharmaceuticals Sector [Member]
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]	LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Basis Spread, Variable Rate	8.75%	5.75%
Investment Interest Rate		6.75%
Investment, Interest Rate, Paid in Cash	8.97%
Investment, Interest Rate, Paid in Kind	3%
Investment, Acquisition Date	Jun. 30, 2021	Jun. 30, 2021
Investment Maturity Date	Jun. 30, 2027	Jun. 30, 2027
Investment Owned, Balance, Principal Amount	$ 3,750	$ 3,750
Investment Owned, at Fair Value	$ 173	$ 176
Investment, Identifier [Axis]: Caravel Autism Health, L L C ( Revolver), Senior Secured Loans, due 6/30/2027
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:CaravelAutismHealthLLCMember	mrcc:CaravelAutismHealthLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Healthcare & Pharmaceuticals Sector [Member]	Healthcare & Pharmaceuticals Sector [Member]
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]	LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Basis Spread, Variable Rate	8.75%	5.75%
Investment Interest Rate		6.75%
Investment, Interest Rate, Paid in Kind	3%
Investment, Acquisition Date	Jun. 30, 2021	Jun. 30, 2021
Investment Maturity Date	Jun. 30, 2027	Jun. 30, 2027
Investment Owned, Balance, Principal Amount	$ 1,260	$ 1,250
Investment Owned, at Fair Value	$ 1,048	$ 587
Investment, Identifier [Axis]: Caravel Autism Health, L L C, Senior Secured Loans, due 6/30/2027
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:CaravelAutismHealthLLCMember	mrcc:CaravelAutismHealthLLCMember
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Healthcare & Pharmaceuticals Sector [Member]
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]	LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Basis Spread, Variable Rate	8.75%	5.75%
Investment Interest Rate		6.75%
Investment, Interest Rate, Paid in Cash	8.97%
Investment, Interest Rate, Paid in Kind	3%
Investment, Acquisition Date		Jun. 30, 2021
Investment Maturity Date		Jun. 30, 2027
Investment Owned, Balance, Principal Amount		$ 5,000
Investment Owned, at Fair Value		$ 4,699
Investment, Identifier [Axis]: Cassavant Holdings, L L C, Unitranche Secured Loans, due 9/8/2026
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:CassavantHoldingsLLCMember	mrcc:CassavantHoldingsLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Unitranche Debt [Member]
Investment, Industry Sector [Extensible Enumeration]	Aerospace & Defense	Aerospace & Defense
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR	LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Basis Spread, Variable Rate	6.50%	6.50%
Investment Interest Rate	10.62%	7.50%
Investment, Acquisition Date	Sep. 08, 2021	Sep. 08, 2021
Investment Maturity Date	Sep. 08, 2026	Sep. 08, 2026
Investment Owned, Balance, Principal Amount	$ 7,580	$ 7,980
Investment Owned, at Fair Value	$ 7,436	$ 7,972
Investment, Identifier [Axis]: Centaur ( Palm Beach) Owner L L C and Panther National Golf Club L L C ( Delayed Draw), Senior Secured Loans, due 4/30/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:CentaurPalmBeachOwnerLLCandPantherNationalGolfClubLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	FIRE Real Estate Sector [Member]
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Basis Spread, Variable Rate	8.25%
Investment Interest Rate	12.43%
Investment, Acquisition Date	May 03, 2022
Investment Maturity Date	Apr. 30, 2025
Investment Owned, Balance, Principal Amount	$ 337
Investment Owned, at Fair Value	$ 337
Investment, Identifier [Axis]: Centaur ( Palm Beach) Owner L L C and Panther National Golf Club L L C ( Revolver), Senior Secured Loans, due 4/30/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:CentaurPalmBeachOwnerLLCandPantherNationalGolfClubLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	FIRE Real Estate Sector [Member]
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Basis Spread, Variable Rate	8.25%
Investment Interest Rate	12.43%
Investment, Acquisition Date	May 03, 2022
Investment Maturity Date	Apr. 30, 2025
Investment Owned, Balance, Principal Amount	$ 1,653
Investment Owned, at Fair Value	$ 719
Investment, Identifier [Axis]: Centaur ( Palm Beach) Owner L L C and Panther National Golf Club L L C, Senior Secured Loans, due 4/30/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:CentaurPalmBeachOwnerLLCandPantherNationalGolfClubLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	FIRE Real Estate Sector [Member]
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Basis Spread, Variable Rate	8.25%
Investment Interest Rate	12.43%
Investment, Acquisition Date	May 03, 2022
Investment Maturity Date	Apr. 30, 2025
Investment Owned, Balance, Principal Amount	$ 3,300
Investment Owned, at Fair Value	$ 3,296
Investment, Identifier [Axis]: Certify, Inc, Senior Secured Loans, One, due 2/28/2024
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:CertifyIncMember
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Services: Business
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Basis Spread, Variable Rate		5.50%
Investment Interest Rate		6.50%
Investment, Acquisition Date		Feb. 28, 2019
Investment Maturity Date		Feb. 28, 2024
Investment Owned, Balance, Principal Amount		$ 9,000
Investment Owned, at Fair Value		$ 9,000
Investment, Identifier [Axis]: Certify, Inc, Senior Secured Loans, Two, due 2/28/2024
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:CertifyIncMember
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Services: Business
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Basis Spread, Variable Rate		5.50%
Investment Interest Rate		6.50%
Investment, Acquisition Date		Feb. 28, 2019
Investment Maturity Date		Feb. 28, 2024
Investment Owned, Balance, Principal Amount		$ 1,227
Investment Owned, at Fair Value		$ 1,227
Investment, Identifier [Axis]: Certify, Inc. (Revolver), Senior Secured Loans, due 2/28/2024
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:CertifyIncMember
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Services: Business
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Basis Spread, Variable Rate		5.50%
Investment Interest Rate		6.50%
Investment, Acquisition Date		Feb. 28, 2019
Investment Maturity Date		Feb. 28, 2024
Investment Owned, Balance, Principal Amount		$ 409
Investment Owned, at Fair Value		$ 102
Investment, Identifier [Axis]: Chess.com, L L C ( Revolver), Senior Secured Loans, due 12/31/2027
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:Chess.comLLCMember	mrcc:Chess.comLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Media: Diversified & Production	Media: Diversified & Production
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR	us-gaap:LondonInterbankOfferedRateLiborSwapRateMember
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Basis Spread, Variable Rate	6.50%	6.50%
Investment Interest Rate	11.23%	7.50%
Investment, Acquisition Date	Dec. 31, 2021	Dec. 31, 2021
Investment Maturity Date	Dec. 31, 2027	Dec. 31, 2027
Investment Owned, Balance, Principal Amount	$ 652	$ 652
Investment, Identifier [Axis]: Chess.com, L L C, Equity Securities, Class A units
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:Chess.comLLCMember	mrcc:Chess.comLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Equity Securities [Member]
Investment, Industry Sector [Extensible Enumeration]	Media: Diversified & Production	Media: Diversified & Production
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Acquisition Date	Dec. 31, 2021	Dec. 31, 2021
Investment Owned, at Fair Value	$ 50	$ 87
Investment, Identifier [Axis]: Chess.com, L L C, Senior Secured Loans, due 12/31/2027
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:Chess.comLLCMember	mrcc:Chess.comLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Media: Diversified & Production	Media: Diversified & Production
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR	us-gaap:LondonInterbankOfferedRateLiborSwapRateMember
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Basis Spread, Variable Rate	6.50%	6.50%
Investment Interest Rate	11.23%	7.50%
Investment, Acquisition Date	Dec. 31, 2021	Dec. 31, 2021
Investment Maturity Date	Dec. 31, 2027	Dec. 31, 2027
Investment Owned, Balance, Principal Amount	$ 5,955	$ 6,000
Investment Owned, at Fair Value	$ 5,866	$ 5,880
Investment, Identifier [Axis]: Corel Inc. (c), Senior Secured Loans, due 7/2/2026
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:CorelIncMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	High Tech Industries Sector [Member]
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Basis Spread, Variable Rate	5%
Investment Interest Rate	9.73%
Investment Maturity Date	Jul. 02, 2026
Investment Owned, Balance, Principal Amount	$ 3,600
Investment Owned, at Fair Value	$ 3,365
Investment, Identifier [Axis]: Crownpeak Technology Inc. (Revolver) Senior Secured Loans, Due 2/28/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:CrownpeakTechnologyIncMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Media: Diversified & Production
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Basis Spread, Variable Rate	7.25%
Investment Interest Rate	11.47%
Investment, Acquisition Date	Feb. 28, 2019
Investment Maturity Date	Feb. 28, 2025
Investment Owned, Balance, Principal Amount	$ 500
Investment, Identifier [Axis]: Crownpeak Technology Inc. Senior Secured Loans Four, Due 2/28/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:CrownpeakTechnologyIncMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Media: Diversified & Production
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Basis Spread, Variable Rate	7.25%
Investment Interest Rate	11.41%
Investment, Acquisition Date	Sep. 27, 2022
Investment Maturity Date	Feb. 28, 2025
Investment Owned, Balance, Principal Amount	$ 3,333
Investment Owned, at Fair Value	$ 3,333
Investment, Identifier [Axis]: Crownpeak Technology Inc. Senior Secured Loans One, Due 2/28/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:CrownpeakTechnologyIncMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Media: Diversified & Production
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Basis Spread, Variable Rate	7.25%
Investment Interest Rate	11.47%
Investment, Acquisition Date	Feb. 28, 2019
Investment Maturity Date	Feb. 28, 2025
Investment Owned, Balance, Principal Amount	$ 4,000
Investment Owned, at Fair Value	$ 4,000
Investment, Identifier [Axis]: Crownpeak Technology Inc. Senior Secured Loans Three, Due 2/28/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:CrownpeakTechnologyIncMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Media: Diversified & Production
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Basis Spread, Variable Rate	7.25%
Investment Interest Rate	11.47%
Investment, Acquisition Date	Feb. 28, 2019
Investment Maturity Date	Feb. 28, 2025
Investment Owned, Balance, Principal Amount	$ 60
Investment Owned, at Fair Value	$ 60
Investment, Identifier [Axis]: Crownpeak Technology Inc. Senior Secured Loans Two, Due 2/28/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:CrownpeakTechnologyIncMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Media: Diversified & Production
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Basis Spread, Variable Rate	7.25%
Investment Interest Rate	11.47%
Investment, Acquisition Date	Sep. 27, 2022
Investment Maturity Date	Feb. 28, 2025
Investment Owned, Balance, Principal Amount	$ 1,273
Investment Owned, at Fair Value	$ 1,273
Investment, Identifier [Axis]: Crownpeak Technology, Inc. ( Revolver), Senior Secured Loans, due 2/28/2024
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:CrownpeakTechnologyIncMember
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Media: Diversified & Production
Investment, Variable Interest Rate, Type [Extensible Enumeration]		us-gaap:LondonInterbankOfferedRateLiborSwapRateMember
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Basis Spread, Variable Rate		5.75%
Investment Interest Rate		6.75%
Investment, Acquisition Date		Feb. 28, 2019
Investment Maturity Date		Feb. 28, 2024
Investment Owned, Balance, Principal Amount		$ 167
Investment, Identifier [Axis]: Crownpeak Technology, Inc., Senior Secured Loans, One, due 2/28/2024
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:CrownpeakTechnologyIncMember
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Media: Diversified & Production
Investment, Variable Interest Rate, Type [Extensible Enumeration]		us-gaap:LondonInterbankOfferedRateLiborSwapRateMember
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Basis Spread, Variable Rate		5.75%
Investment Interest Rate		6.75%
Investment, Acquisition Date		Feb. 28, 2019
Investment Maturity Date		Feb. 28, 2024
Investment Owned, Balance, Principal Amount		$ 4,000
Investment Owned, at Fair Value		$ 4,000
Investment, Identifier [Axis]: Crownpeak Technology, Inc., Senior Secured Loans, Two, due 2/28/2024
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:CrownpeakTechnologyIncMember
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Media: Diversified & Production
Investment, Variable Interest Rate, Type [Extensible Enumeration]		us-gaap:LondonInterbankOfferedRateLiborSwapRateMember
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Basis Spread, Variable Rate		5.75%
Investment Interest Rate		6.75%
Investment, Acquisition Date		Feb. 28, 2019
Investment Maturity Date		Feb. 28, 2024
Investment Owned, Balance, Principal Amount		$ 60
Investment Owned, at Fair Value		$ 60
Investment, Identifier [Axis]: Curion Holdings, L L C ( Revolver), Senior Secured Loans, Due 8/31/2022
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		Curion Holdings, L L C [ Member]
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Services: Business
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Interest Rate, Paid in Kind		14%
Investment, Acquisition Date		May 02, 2017
Investment Maturity Date		Aug. 31, 2022
Investment Owned, Balance, Principal Amount		$ 871
Investment Owned, at Fair Value		$ 550
Investment, Identifier [Axis]: Curion Holdings, L L C, Equity Securities, Common stock
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	Curion Holdings, L L C [ Member]	Curion Holdings, L L C [ Member]
Investment, Type [Extensible Enumeration]		Equity Securities [Member]
Investment, Industry Sector [Extensible Enumeration]		Services: Business
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Acquisition Date		Aug. 17, 2018
Investment, Identifier [Axis]: Curion Holdings, L L C, Junior Secured Loans, One, Due 1/2/2023
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	Curion Holdings, L L C [ Member]	Curion Holdings, L L C [ Member]
Investment, Type [Extensible Enumeration]		Junior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Services: Business
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Interest Rate, Paid in Kind		15%
Investment, Acquisition Date		Aug. 17, 2018
Investment Maturity Date		Jan. 02, 2023
Investment Owned, Balance, Principal Amount		$ 1,720
Investment, Identifier [Axis]: Curion Holdings, L L C, Junior Secured Loans, Two, Due 1/2/2023
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	Curion Holdings, L L C [ Member]	Curion Holdings, L L C [ Member]
Investment, Type [Extensible Enumeration]		Junior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Services: Business
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Interest Rate, Paid in Kind		15%
Investment, Acquisition Date		Aug. 17, 2018
Investment Maturity Date		Jan. 02, 2023
Investment Owned, Balance, Principal Amount		$ 44
Investment, Identifier [Axis]: Curion Holdings, L L C, Senior Secured Loans, Due 8/31/2022
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		Curion Holdings, L L C [ Member]
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Services: Business
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Interest Rate, Paid in Kind		14%
Investment, Acquisition Date		May 02, 2017
Investment Maturity Date		Aug. 31, 2022
Investment Owned, Balance, Principal Amount		$ 4,533
Investment Owned, at Fair Value		$ 4,561
Investment, Identifier [Axis]: Curion Holdings, L L C, Senior Secured Loans, One, Acquisition Date 5/2/2017
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	Curion Holdings, L L C [ Member]	Curion Holdings, L L C [ Member]
Investment Owned, at Fair Value	$ 146	$ 4,561	3,159
Investment, Identifier [Axis]: Curion Holdings, LLC (Revolver), Senior Secured Loans, Two, Acquisition Date 5/2/2017
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	Curion Holdings, L L C [ Member]	Curion Holdings, L L C [ Member]
Investment Owned, at Fair Value		$ 550	820
Investment, Identifier [Axis]: D S Parent, Inc., Senior Secured Loans, due 12/8/2028
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:DSParentIncMember	mrcc:DSParentIncMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Capital Equipment	Capital Equipment
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR	LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Basis Spread, Variable Rate		5.75%
Investment Interest Rate		6.50%
Investment Maturity Date		Dec. 08, 2028
Investment Owned, Balance, Principal Amount		$ 3,000
Investment Owned, at Fair Value		$ 2,970
Investment, Identifier [Axis]: Destination Media, Inc (Revolver), Senior Secured Loans, due 4/7/2023
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:DestinationMediaIncMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Media: Advertising, Printing & Publishing
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Basis Spread, Variable Rate	5.50%
Investment Interest Rate	9.94%
Investment, Acquisition Date	Apr. 07, 2017
Investment Maturity Date	Apr. 07, 2023
Investment Owned, Balance, Principal Amount	$ 542
Investment, Identifier [Axis]: Destination Media, Inc, Senior Secured Loans, due 4/7/2023
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:DestinationMediaIncMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Media: Advertising, Printing & Publishing
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Basis Spread, Variable Rate	5.50%
Investment Interest Rate	9.94%
Investment, Acquisition Date	Apr. 07, 2017
Investment Maturity Date	Apr. 07, 2023
Investment Owned, Balance, Principal Amount	$ 377
Investment Owned, at Fair Value	$ 377
Investment, Identifier [Axis]: Destination Media, Inc. ( Revolver), Senior Secured Loans, due 4/7/2022
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:DestinationMediaIncMember
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Media: Advertising, Printing & Publishing
Investment, Variable Interest Rate, Type [Extensible Enumeration]		us-gaap:LondonInterbankOfferedRateLiborSwapRateMember
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Basis Spread, Variable Rate		5.50%
Investment Interest Rate		6.50%
Investment, Acquisition Date		Apr. 07, 2017
Investment Maturity Date		Apr. 07, 2022
Investment Owned, Balance, Principal Amount		$ 542
Investment, Identifier [Axis]: Destination Media, Inc., Senior Secured Loans, due 4/7/2022
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:DestinationMediaIncMember
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Media: Advertising, Printing & Publishing
Investment, Variable Interest Rate, Type [Extensible Enumeration]		us-gaap:LondonInterbankOfferedRateLiborSwapRateMember
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Basis Spread, Variable Rate		5.50%
Investment Interest Rate		6.50%
Investment, Acquisition Date		Apr. 07, 2017
Investment Maturity Date		Apr. 07, 2022
Investment Owned, Balance, Principal Amount		$ 1,738
Investment Owned, at Fair Value		$ 1,738
Investment, Identifier [Axis]: Dorado Acquisition, Inc, Equity Securities, One, Class A-1 units
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:DoradoAcquisitionIncMember	mrcc:DoradoAcquisitionIncMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Equity Securities [Member]
Investment, Industry Sector [Extensible Enumeration]	Healthcare & Pharmaceuticals Sector [Member]	Healthcare & Pharmaceuticals
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Acquisition Date	Jun. 30, 2021	Jun. 30, 2021
Investment Owned, at Fair Value	$ 215	$ 179
Investment, Identifier [Axis]: Dorado Acquisition, Inc, Equity Securities, Two, Class A-2 units
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:DoradoAcquisitionIncMember	mrcc:DoradoAcquisitionIncMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Equity Securities [Member]
Investment, Industry Sector [Extensible Enumeration]	Healthcare & Pharmaceuticals Sector [Member]	Healthcare & Pharmaceuticals
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Acquisition Date	Jun. 30, 2021	Jun. 30, 2021
Investment Owned, at Fair Value	$ 224	$ 9
Investment, Identifier [Axis]: Dorado Acquisition, Inc. ( Delayed Draw) , Senior Secured Loans, due 6/30/2026
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:DoradoAcquisitionInc.Member	mrcc:DoradoAcquisitionInc.Member
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Healthcare & Pharmaceuticals Sector [Member]	Healthcare & Pharmaceuticals Sector [Member]
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]	LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Basis Spread, Variable Rate	6.50%	6.75%
Investment Interest Rate	10.72%	7.75%
Investment, Acquisition Date	Jun. 30, 2021	Jun. 30, 2021
Investment Maturity Date	Jun. 30, 2026	Jun. 30, 2026
Investment Owned, Balance, Principal Amount	$ 216	$ 216
Investment, Identifier [Axis]: Dorado Acquisition, Inc. ( Revolver) , Senior Secured Loans, due 6/30/2026
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:DoradoAcquisitionInc.Member	mrcc:DoradoAcquisitionInc.Member
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Healthcare & Pharmaceuticals Sector [Member]	Healthcare & Pharmaceuticals Sector [Member]
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]	LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Basis Spread, Variable Rate	6.50%	6.75%
Investment Interest Rate	10.92%	7.75%
Investment, Interest Rate, Paid in Cash	8.08%
Investment, Acquisition Date	Jun. 30, 2021	Jun. 30, 2021
Investment Maturity Date	Jun. 30, 2026	Jun. 30, 2026
Investment Owned, Balance, Principal Amount	$ 596	$ 596
Investment Owned, at Fair Value	$ 596
Investment, Identifier [Axis]: Dorado Acquisition, Inc., Senior Secured Loans, One, due 6/30/2026
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:DoradoAcquisitionInc.Member
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Healthcare & Pharmaceuticals Sector [Member]
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Basis Spread, Variable Rate	6.76%
Investment Interest Rate	11.34%
Investment, Acquisition Date	Nov. 27, 2022
Investment Maturity Date	Jun. 30, 2026
Investment Owned, Balance, Principal Amount	$ 4,082
Investment Owned, at Fair Value	$ 4,074
Investment, Identifier [Axis]: Dorado Acquisition, Inc., Senior Secured Loans, due 6/30/2026
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:DoradoAcquisitionInc.Member	mrcc:DoradoAcquisitionInc.Member
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Healthcare & Pharmaceuticals Sector [Member]	Healthcare & Pharmaceuticals Sector [Member]
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]	LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Basis Spread, Variable Rate	6.50%	6.75%
Investment Interest Rate	10.72%	7.75%
Investment, Acquisition Date	Jun. 30, 2021	Jun. 30, 2021
Investment Maturity Date	Jun. 30, 2026	Jun. 30, 2026
Investment Owned, Balance, Principal Amount	$ 4,938	$ 4,988
Investment Owned, at Fair Value	$ 4,928	$ 4,983
Investment, Identifier [Axis]: Drawbridge Partners, LLC (Delayed Draw), Senior Secured Loans, due 9/1/2028
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:DrawbridgePartnersLlcMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	High Tech Industries Sector [Member]
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Basis Spread, Variable Rate	7%
Investment, Interest Rate, Paid in Kind	11.56%
Investment, Acquisition Date	Sep. 01, 2022
Investment Maturity Date	Sep. 01, 2028
Investment Owned, Balance, Principal Amount	$ 330
Investment Owned, at Fair Value	$ 102
Investment, Identifier [Axis]: Drawbridge Partners, LLC (Revolver), Senior Secured Loans, due 9/1/2028
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:DrawbridgePartnersLlcMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	High Tech Industries Sector [Member]
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Basis Spread, Variable Rate	7%
Investment Interest Rate	11.56%
Investment, Acquisition Date	Sep. 01, 2022
Investment Maturity Date	Sep. 01, 2028
Investment Owned, Balance, Principal Amount	$ 522
Investment, Identifier [Axis]: Drawbridge Partners, LLC, Equity Securities, Class A Units
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:DrawbridgePartnersLlcMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	High Tech Industries Sector [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Acquisition Date	Sep. 01, 2022
Investment Owned, at Fair Value	$ 126
Investment, Identifier [Axis]: Drawbridge Partners, LLC, Senior Secured Loans, due 9/1/2028
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:DrawbridgePartnersLlcMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	High Tech Industries Sector [Member]
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Basis Spread, Variable Rate	7%
Investment, Interest Rate, Paid in Kind	11.56%
Investment, Acquisition Date	Sep. 01, 2022
Investment Maturity Date	Sep. 01, 2028
Investment Owned, Balance, Principal Amount	$ 3,000
Investment Owned, at Fair Value	$ 2,971
Investment, Identifier [Axis]: Dresser Utility Solutions, L L C (fka N G S U S Finco, L L C), Senior Secured Loans, One, due 10/1/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:DresserUtilitySolutionsLLCfkaNGSUSFincoLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Utilities, Oil & Gas Sector [Member]
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Basis Spread, Variable Rate	4.25%
Investment Interest Rate	8.63%
Investment Maturity Date	Oct. 01, 2025
Investment Owned, Balance, Principal Amount	$ 1,678
Investment Owned, at Fair Value	$ 1,619
Investment, Identifier [Axis]: Dresser Utility Solutions, L L C (fka N G S U S Finco, L L C), Senior Secured Loans, Two, due 10/1/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:DresserUtilitySolutionsLLCfkaNGSUSFincoLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Utilities, Oil & Gas Sector [Member]
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Basis Spread, Variable Rate	5.25%
Investment Interest Rate	9.63%
Investment Maturity Date	Oct. 01, 2025
Investment Owned, Balance, Principal Amount	$ 245
Investment Owned, at Fair Value	$ 239
Investment, Identifier [Axis]: Drilling Info Holdings, Inc., Senior Secured Loans, due 7/30/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:DrillingInfoHoldingsIncMember	mrcc:DrillingInfoHoldingsIncMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	us-gaap-supplement:EnergySectorMember	Utilities, Oil & Gas Sector [Member]
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR	LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Basis Spread, Variable Rate		4.25%
Investment Interest Rate		4.35%
Investment Maturity Date		Jul. 30, 2025
Investment Owned, Balance, Principal Amount		$ 4,516
Investment Owned, at Fair Value		$ 4,471
Investment, Identifier [Axis]: Education Corporation of America, Equity Securities, Series G Preferred Stock
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:EducationCorporationofAmericaMember	mrcc:EducationCorporationofAmericaMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Equity Securities [Member]
Investment, Industry Sector [Extensible Enumeration]	Services: Consumer	Services: Consumer
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Interest Rate, Paid in Kind	12%	12%
Investment, Acquisition Date	Sep. 03, 2015	Sep. 03, 2015
Investment Owned, at Fair Value		$ 2,281
Investment, Identifier [Axis]: Education Corporation of America, Junior Secured Loans
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:EducationCorporationofAmericaMember	mrcc:EducationCorporationofAmericaMember
Investment, Type [Extensible Enumeration]	Junior Loans [Member]	Junior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Services: Consumer	Services: Consumer
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR	LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Basis Spread, Variable Rate	11%	11%
Investment, Interest Rate, Paid in Cash		5.72%
Investment, Interest Rate, Paid in Kind	5.50%	5.50%
Investment, Acquisition Date	Sep. 03, 2015	Sep. 03, 2015
Investment Owned, Balance, Principal Amount	$ 833	$ 833
Investment Owned, at Fair Value	$ 1,882	$ 576
Investment, Identifier [Axis]: Eliassen Group, L L C ( Delayed Draw), Senior Secured Loans, due 4/14/2028
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:EliassenGroupLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Services: Business
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Basis Spread, Variable Rate	5.50%
Investment Interest Rate	8.88%
Investment Maturity Date	Apr. 14, 2028
Investment Owned, Balance, Principal Amount	$ 740
Investment Owned, at Fair Value	$ 109
Investment, Identifier [Axis]: Eliassen Group, L L C, Senior Secured Loans, due 4/14/2028
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:EliassenGroupLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Services: Business
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Basis Spread, Variable Rate	5.50%
Investment Interest Rate	10.08%
Investment Maturity Date	Apr. 14, 2028
Investment Owned, Balance, Principal Amount	$ 3,251
Investment Owned, at Fair Value	$ 3,194
Investment, Identifier [Axis]: Energy Services Group, L L C, Unitranche Secured Loans, One, Due 5/4/2022
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:EnergyServicesGroupLLCMember
Investment, Type [Extensible Enumeration]		Unitranche Debt [Member]
Investment, Industry Sector [Extensible Enumeration]		High Tech Industries
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Basis Spread, Variable Rate		8.42%
Investment Interest Rate		9.42%
Investment, Acquisition Date		May 04, 2017
Investment Maturity Date		May 04, 2022
Investment Owned, Balance, Principal Amount		$ 3,725
Investment Owned, at Fair Value		$ 3,725
Investment, Identifier [Axis]: Energy Services Group, L L C, Unitranche Secured Loans, Three, Due 5/4/2022
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:EnergyServicesGroupLLCMember
Investment, Type [Extensible Enumeration]		Unitranche Debt [Member]
Investment, Industry Sector [Extensible Enumeration]		High Tech Industries
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Basis Spread, Variable Rate		8.42%
Investment Interest Rate		9.42%
Investment, Acquisition Date		May 04, 2017
Investment Maturity Date		May 04, 2022
Investment Owned, Balance, Principal Amount		$ 1,060
Investment Owned, at Fair Value		$ 1,060
Investment, Identifier [Axis]: Energy Services Group, L L C, Unitranche Secured Loans, Two, Due 5/4/2022
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:EnergyServicesGroupLLCMember
Investment, Type [Extensible Enumeration]		Unitranche Debt [Member]
Investment, Industry Sector [Extensible Enumeration]		High Tech Industries
Investment, Variable Interest Rate, Type [Extensible Enumeration]		Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Basis Spread, Variable Rate		8.42%
Investment Interest Rate		9.42%
Investment, Acquisition Date		May 04, 2017
Investment Maturity Date		May 04, 2022
Investment Owned, Balance, Principal Amount		$ 4,541
Investment Owned, at Fair Value		$ 4,541
Investment, Identifier [Axis]: Engage2 Excel, Inc. ( Revolver), Senior Secured Loans, due 3/7/2023
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:Engage2ExcelIncMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Services: Business
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Basis Spread, Variable Rate	6.25%
Investment Interest Rate	13.75%
Investment Maturity Date	Mar. 07, 2023
Investment Owned, Balance, Principal Amount	$ 554
Investment Owned, at Fair Value	$ 509
Investment, Identifier [Axis]: Engage2 Excel, Inc., Senior Secured Loans, One, due 3/7/2023
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:Engage2ExcelIncMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Services: Business
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Basis Spread, Variable Rate	7.25%
Investment Interest Rate	11.98%
Investment Maturity Date	Mar. 07, 2023
Investment Owned, Balance, Principal Amount	$ 4,283
Investment Owned, at Fair Value	$ 4,242
Investment, Identifier [Axis]: Engage2 Excel, Inc., Senior Secured Loans, Two,due 3/7/2023
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:Engage2ExcelIncMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Services: Business
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Basis Spread, Variable Rate	7.25%
Investment Interest Rate	11.98%
Investment Maturity Date	Mar. 07, 2023
Investment Owned, Balance, Principal Amount	$ 773
Investment Owned, at Fair Value	$ 766
Investment, Identifier [Axis]: Equine Network, L L C ( Delayed Draw), Senior Secured Loans, due 12/13/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:EquineNetworkLLCMember
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Hotels, Gaming & Leisure
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Investment, Basis Spread, Variable Rate		8%
Investment Interest Rate		9%
Investment, Acquisition Date		Dec. 31, 2020
Investment Maturity Date		Dec. 31, 2025
Investment Owned, Balance, Principal Amount		$ 427
Investment, Identifier [Axis]: Equine Network, L L C ( Revolver) , Senior Secured Loans, due 12/13/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:EquineNetworkLLCMember
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Hotels, Gaming & Leisure
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Investment, Basis Spread, Variable Rate		8%
Investment Interest Rate		9%
Investment, Acquisition Date		Dec. 31, 2020
Investment Maturity Date		Dec. 31, 2025
Investment Owned, Balance, Principal Amount		$ 171
Investment Owned, at Fair Value		$ 85
Investment, Identifier [Axis]: Equine Network, L L C, (Delayed Draw), Senior Secured Loans, due 12/31/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:EquineNetworkLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Hotels, Gaming & Leisure
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Basis Spread, Variable Rate	6%
Investment Interest Rate	10.24%
Investment, Acquisition Date	Dec. 31, 2020
Investment Maturity Date	Dec. 31, 2025
Investment Owned, Balance, Principal Amount	$ 427
Investment, Identifier [Axis]: Equine Network, L L C, (Revolver), Senior Secured Loans, due 12/31/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:EquineNetworkLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Hotels, Gaming & Leisure
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Basis Spread, Variable Rate	6%
Investment Interest Rate	10.30%
Investment, Acquisition Date	Dec. 31, 2020
Investment Maturity Date	Dec. 31, 2025
Investment Owned, Balance, Principal Amount	$ 171
Investment Owned, at Fair Value	$ 127
Investment, Identifier [Axis]: Equine Network, L L C, Equity Securities, Class A units
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:EquineNetworkLLCMember	mrcc:EquineNetworkLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Equity Securities [Member]
Investment, Industry Sector [Extensible Enumeration]	Hotels, Gaming & Leisure	Hotels, Gaming & Leisure
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Acquisition Date	Dec. 31, 2020	Dec. 31, 2020
Investment Owned, at Fair Value	$ 109	$ 102
Investment, Identifier [Axis]: Equine Network, L L C, Senior Secured Loans, One, due 12/13/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:EquineNetworkLLCMember
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Hotels, Gaming & Leisure
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Investment, Basis Spread, Variable Rate		8%
Investment Interest Rate		9%
Investment, Acquisition Date		Dec. 31, 2020
Investment Maturity Date		Dec. 31, 2025
Investment Owned, Balance, Principal Amount		$ 1,737
Investment Owned, at Fair Value		$ 1,733
Investment, Identifier [Axis]: Equine Network, L L C, Senior Secured Loans, One, due 12/31/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:EquineNetworkLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Hotels, Gaming & Leisure
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Basis Spread, Variable Rate	6%
Investment Interest Rate	10.24%
Investment, Acquisition Date	Dec. 31, 2020
Investment Maturity Date	Dec. 31, 2025
Investment Owned, Balance, Principal Amount	$ 1,719
Investment Owned, at Fair Value	$ 1,709
Investment, Identifier [Axis]: Equine Network, L L C, Senior Secured Loans, Two, due 12/13/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:EquineNetworkLLCMember
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Hotels, Gaming & Leisure
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Investment, Basis Spread, Variable Rate		8%
Investment Interest Rate		9%
Investment, Acquisition Date		Jan. 29, 2021
Investment Maturity Date		Dec. 31, 2025
Investment Owned, Balance, Principal Amount		$ 788
Investment Owned, at Fair Value		$ 786
Investment, Identifier [Axis]: Equine Network, L L C, Senior Secured Loans, Two, due 12/31/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:EquineNetworkLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Hotels, Gaming & Leisure
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Basis Spread, Variable Rate	6%
Investment Interest Rate	10.24%
Investment, Acquisition Date	Jan. 29, 2021
Investment Maturity Date	Dec. 31, 2025
Investment Owned, Balance, Principal Amount	$ 780
Investment Owned, at Fair Value	$ 775
Investment, Identifier [Axis]: Excel Fitness Holdings, Inc. ( Revolver), Senior Secured Loans, due 4/28/2028
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:ExcelFitnessHoldingsIncMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Hotels, Gaming & Leisure
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Basis Spread, Variable Rate	5.25%
Investment Interest Rate	9.67%
Investment Maturity Date	Apr. 28, 2028
Investment Owned, Balance, Principal Amount	$ 625
Investment Owned, at Fair Value	$ 306
Investment, Identifier [Axis]: Excel Fitness Holdings, Inc., Senior Secured Loans, due 4/27/2029
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:ExcelFitnessHoldingsIncMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Hotels, Gaming & Leisure
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Basis Spread, Variable Rate	5.25%
Investment Interest Rate	10.29%
Investment Maturity Date	Apr. 27, 2029
Investment Owned, Balance, Principal Amount	$ 4,364
Investment Owned, at Fair Value	$ 4,102
Investment, Identifier [Axis]: Express Wash Acquisition Company, L L C ( Delayed Draw), Senior Secured Loans, Four, due 12/26/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:ExpressWashAcquisitionCompanyLLCMember
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Services: Consumer
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Basis Spread, Variable Rate		6.50%
Investment Interest Rate		7.50%
Investment, Acquisition Date		Sep. 03, 2021
Investment Maturity Date		Dec. 26, 2025
Investment Owned, Balance, Principal Amount		$ 2,500
Investment Owned, at Fair Value		$ 925
Investment, Identifier [Axis]: Express Wash Acquisition Company, L L C ( Revolver), Senior Secured Loans, due 12/26/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:ExpressWashAcquisitionCompanyLLCMember
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Services: Consumer
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Basis Spread, Variable Rate		6.50%
Investment Interest Rate		7.50%
Investment, Acquisition Date		Dec. 28, 2020
Investment Maturity Date		Dec. 26, 2025
Investment Owned, Balance, Principal Amount		$ 750
Investment Owned, at Fair Value		$ 400
Investment, Identifier [Axis]: Express Wash Acquisition Company, L L C, Equity Securities, Class A units
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:ExpressWashAcquisitionCompanyLLCMember	mrcc:ExpressWashAcquisitionCompanyLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Equity Securities [Member]
Investment, Industry Sector [Extensible Enumeration]	Services: Consumer	Services: Consumer
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Interest Rate, Paid in Kind	8%	8%
Investment, Acquisition Date	Dec. 28, 2020	Dec. 28, 2020
Investment Owned, at Fair Value	$ 118	$ 208
Investment, Identifier [Axis]: Express Wash Acquisition Company, L L C, Senior Secured Loans, One, due 12/26/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:ExpressWashAcquisitionCompanyLLCMember
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Services: Consumer
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Basis Spread, Variable Rate		6.50%
Investment Interest Rate		7.50%
Investment, Acquisition Date		Dec. 28, 2020
Investment Maturity Date		Dec. 26, 2025
Investment Owned, Balance, Principal Amount		$ 3,203
Investment Owned, at Fair Value		$ 3,203
Investment, Identifier [Axis]: Express Wash Acquisition Company, L L C, Senior Secured Loans, Three, due 12/26/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:ExpressWashAcquisitionCompanyLLCMember
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Services: Consumer
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Basis Spread, Variable Rate		6.50%
Investment Interest Rate		7.50%
Investment, Acquisition Date		Sep. 03, 2021
Investment Maturity Date		Dec. 26, 2025
Investment Owned, Balance, Principal Amount		$ 3,500
Investment Owned, at Fair Value		$ 3,500
Investment, Identifier [Axis]: Express Wash Acquisition Company, L L C, Senior Secured Loans, Two, due 12/26/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:ExpressWashAcquisitionCompanyLLCMember
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Services: Consumer
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Basis Spread, Variable Rate		6.50%
Investment Interest Rate		7.50%
Investment, Acquisition Date		Sep. 03, 2021
Investment Maturity Date		Dec. 26, 2025
Investment Owned, Balance, Principal Amount		$ 7,275
Investment Owned, at Fair Value		$ 7,275
Investment, Identifier [Axis]: Express Wash Acquisition Company, LLC (Revolver), Senior Secured Loans, due 7/14/2028
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:ExpressWashAcquisitionCompanyLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Services: Consumer
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Basis Spread, Variable Rate	6.50%
Investment Interest Rate	10.83%
Investment, Acquisition Date	Jul. 14, 2022
Investment Maturity Date	Jul. 14, 2028
Investment Owned, Balance, Principal Amount	$ 379
Investment Owned, at Fair Value	$ 208
Investment, Identifier [Axis]: Express Wash Acquisition Company, LLC, Senior Secured Loans, One, Due 7/14/2028
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:ExpressWashAcquisitionCompanyLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Services: Consumer
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Basis Spread, Variable Rate	6.50%
Investment Interest Rate	10.32%
Investment, Acquisition Date	Jul. 14, 2022
Investment Maturity Date	Jul. 14, 2028
Investment Owned, Balance, Principal Amount	$ 8,160
Investment Owned, at Fair Value	$ 8,119
Investment, Identifier [Axis]: Express Wash Acquisition Company, LLC, Senior Secured Loans, Two, Due 7/14/2028
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:ExpressWashAcquisitionCompanyLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Services: Consumer
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Basis Spread, Variable Rate	6.50%
Investment Interest Rate	10.43%
Investment, Acquisition Date	Jul. 14, 2022
Investment Maturity Date	Jul. 14, 2028
Investment Owned, Balance, Principal Amount	$ 1,528
Investment Owned, at Fair Value	$ 1,521
Investment, Identifier [Axis]: Familia Dental Group Holdings, L L C, Equity Securities, Class A units
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	Familia Dental Group Holdings, L L C [ Member]	Familia Dental Group Holdings, L L C [ Member]
Investment, Type [Extensible Enumeration]	Equity Securities [Member]	Equity Securities [Member]
Investment, Industry Sector [Extensible Enumeration]	Healthcare & Pharmaceuticals	Healthcare & Pharmaceuticals
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Acquisition Date	Apr. 08, 2016	Apr. 08, 2016
Investment Owned, at Fair Value	$ 2,625	$ 1,919	3,118
Investment, Identifier [Axis]: Florida East Coast Industries, L L C, Junior Secured Loans, due 6/28/2024
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:FloridaEastCoastIndustriesLLCMember
Investment, Type [Extensible Enumeration]	Junior Loans [Member]	Junior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	FIRE: Real Estate	FIRE: Real Estate
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Interest Rate, Paid in Cash	8%
Investment, Interest Rate, Paid in Kind	16%	16%
Investment, Acquisition Date	Aug. 09, 2021	Aug. 09, 2021
Investment Maturity Date	Jun. 28, 2024	Jun. 28, 2024
Investment Owned, Balance, Principal Amount	$ 1,778	$ 1,520
Investment Owned, at Fair Value	$ 1,784	$ 1,530
Investment, Identifier [Axis]: Florida East Coast Industries, L L C, Senior Secured Loans, due 6/28/2024
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:FloridaEastCoastIndustriesLLCMember
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		FIRE Real Estate Sector [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment Interest Rate	10.50%	10.50%
Investment, Acquisition Date	Aug. 09, 2021	Aug. 09, 2021
Investment Maturity Date	Jun. 28, 2024	Jun. 28, 2024
Investment Owned, Balance, Principal Amount	$ 617	$ 3,572
Investment Owned, at Fair Value	$ 619	$ 3,571
Investment, Identifier [Axis]: Forman Mills, Inc, Equity Securities, Warrants
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:FormanMillsIncMember	mrcc:FormanMillsInc.Member
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Equity Securities [Member]
Investment, Industry Sector [Extensible Enumeration]	Retail	Retail
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Acquisition Date	Jan. 14, 2020	Jan. 14, 2020
Investment Maturity Date	Jan. 14, 2029	Jan. 14, 2029
Investment Owned, at Fair Value	$ 155	$ 702
Investment, Identifier [Axis]: Forman Mills, Inc, Senior Secured Loans, One, due 4/30/2024
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:FormanMillsIncMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Retail
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Basis Spread, Variable Rate	9.50%
Investment, Interest Rate, Paid in Cash	11.94%
Investment, Interest Rate, Paid in Kind	2%
Investment, Acquisition Date	Jan. 14, 2020
Investment Maturity Date	Apr. 30, 2024
Investment Owned, Balance, Principal Amount	$ 1,275
Investment Owned, at Fair Value	$ 1,253
Investment, Identifier [Axis]: Forman Mills, Inc, Senior Secured Loans, Two, due 4/30/2024
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:FormanMillsIncMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Retail
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Basis Spread, Variable Rate	9.50%
Investment, Interest Rate, Paid in Cash	11.94%
Investment, Interest Rate, Paid in Kind	2%
Investment, Acquisition Date	Apr. 10, 2016
Investment Maturity Date	Apr. 30, 2024
Investment Owned, Balance, Principal Amount	$ 6,909
Investment Owned, at Fair Value	$ 6,698
Investment, Identifier [Axis]: Forman Mills, Inc., Senior Secured Loans, One, due 12/30/2022
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:FormanMillsInc.Member
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Retail
Investment, Variable Interest Rate, Type [Extensible Enumeration]		us-gaap:LondonInterbankOfferedRateLiborSwapRateMember
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Basis Spread, Variable Rate		9.50%
Investment, Interest Rate, Paid in Cash		8.50%
Investment, Interest Rate, Paid in Kind		2%
Investment, Acquisition Date		Jan. 14, 2020
Investment Maturity Date		Dec. 30, 2022
Investment Owned, Balance, Principal Amount		$ 1,336
Investment Owned, at Fair Value		$ 1,330
Investment, Identifier [Axis]: Forman Mills, Inc., Senior Secured Loans, Three, due 12/30/2022
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:FormanMillsInc.Member
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Retail
Investment, Variable Interest Rate, Type [Extensible Enumeration]		us-gaap:LondonInterbankOfferedRateLiborSwapRateMember
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Basis Spread, Variable Rate		9.50%
Investment, Interest Rate, Paid in Cash		8.50%
Investment, Interest Rate, Paid in Kind		2%
Investment, Acquisition Date		Oct. 04, 2016
Investment Maturity Date		Dec. 30, 2022
Investment Owned, Balance, Principal Amount		$ 7,623
Investment Owned, at Fair Value		$ 7,524
Investment, Identifier [Axis]: Forman Mills, Inc., Senior Secured Loans, Two, due 12/30/2022
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:FormanMillsInc.Member
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Retail
Investment, Variable Interest Rate, Type [Extensible Enumeration]		us-gaap:LondonInterbankOfferedRateLiborSwapRateMember
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Basis Spread, Variable Rate		9.50%
Investment, Interest Rate, Paid in Cash		8.50%
Investment, Interest Rate, Paid in Kind		2%
Investment, Acquisition Date		Oct. 04, 2016
Investment Maturity Date		Dec. 30, 2022
Investment Owned, Balance, Principal Amount		$ 282
Investment Owned, at Fair Value		$ 281
Investment, Identifier [Axis]: GC Champion Acquisition LLC (Delayed Draw), Senior Notes, Due 8/18/2028
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:GCChampionAcquisitionLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	mrcc:FireFinanceMember
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Basis Spread, Variable Rate	6.75%
Investment Interest Rate	11.15%
Investment, Acquisition Date	Aug. 19, 2022
Investment Maturity Date	Aug. 18, 2028
Investment Owned, Balance, Principal Amount	$ 704
Investment, Identifier [Axis]: GC Champion Acquisition LLC, Senior Notes, Due 8/18/2028
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:GCChampionAcquisitionLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	mrcc:FireFinanceMember
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Basis Spread, Variable Rate	6.75%
Investment Interest Rate	11.15%
Investment, Acquisition Date	Aug. 19, 2022
Investment Maturity Date	Aug. 18, 2028
Investment Owned, Balance, Principal Amount	$ 2,528
Investment Owned, at Fair Value	$ 2,503
Investment, Identifier [Axis]: H A H Group Holding Company L L C, Senior Secured Loans, due 10/29/2027
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:HAHGroupHoldingCompanyLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Healthcare & Pharmaceuticals Sector [Member]
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Basis Spread, Variable Rate	5%
Investment Interest Rate	9.43%
Investment Maturity Date	Oct. 29, 2027
Investment Owned, Balance, Principal Amount	$ 2,978
Investment Owned, at Fair Value	$ 2,847
Investment, Identifier [Axis]: H A L O Buyer, Inc., Senior Secured Loans, due 6/30/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:HALOBuyerIncMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Basis Spread, Variable Rate	4.50%
Investment Interest Rate	8.88%
Investment Maturity Date	Jun. 30, 2025
Investment Owned, Balance, Principal Amount	$ 4,774
Investment Owned, at Fair Value	$ 4,219
Investment, Identifier [Axis]: H F Z Capital Group L L C, Senior Secured Loans , Two
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:HFZCapitalGroupLLCMember	mrcc:HFZCapitalGroupLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	FIRE: Real Estate	FIRE: Real Estate
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR	LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Basis Spread, Variable Rate	12.50%	12.50%
Investment, Interest Rate, Paid in Kind	16.62%	14%
Investment, Acquisition Date	Oct. 20, 2017	Oct. 20, 2017
Investment Owned, Balance, Principal Amount	$ 4,758	$ 4,758
Investment Owned, at Fair Value	$ 5,805	$ 5,420	4,709
Investment, Identifier [Axis]: H F Z Capital Group L L C, Senior Secured Loans, One
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:HFZCapitalGroupLLCMember	mrcc:HFZCapitalGroupLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	FIRE: Real Estate	FIRE: Real Estate
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR	LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Basis Spread, Variable Rate	12.50%	12.50%
Investment, Interest Rate, Paid in Kind	16.62%	14%
Investment, Acquisition Date	Oct. 20, 2017	Oct. 20, 2017
Investment Owned, Balance, Principal Amount	$ 13,242	$ 13,242
Investment Owned, at Fair Value	$ 16,159	$ 15,084	13,106
Investment, Identifier [Axis]: H S4 Acquisitionco, Inc. ( Revolver), Senior Secured Loans, due 7/9/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:HS4AcquisitioncoIncMember	mrcc:HS4AcquisitioncoIncMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Services: Business	Services: Business
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR	LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Basis Spread, Variable Rate	6.75%	6.75%
Investment Interest Rate	11.14%	7.75%
Investment, Acquisition Date	Jul. 09, 2019	Jul. 09, 2019
Investment Maturity Date	Jul. 09, 2025	Jul. 09, 2025
Investment Owned, Balance, Principal Amount	$ 817	$ 817
Investment Owned, at Fair Value	$ 407
Investment, Identifier [Axis]: H S4 Acquisitionco, Inc., Senior Secured Loans, due 7/9/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:HS4AcquisitioncoIncMember	mrcc:HS4AcquisitioncoIncMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Services: Business	Services: Business
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR	LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Basis Spread, Variable Rate	6.75%	6.75%
Investment Interest Rate	11.14%	7.75%
Investment, Acquisition Date	Jul. 09, 2019	Jul. 09, 2019
Investment Maturity Date	Jul. 09, 2025	Jul. 09, 2025
Investment Owned, Balance, Principal Amount	$ 9,899	$ 10,000
Investment Owned, at Fair Value	$ 9,855	$ 9,910
Investment, Identifier [Axis]: Harbour Benefit Holdings, Inc., Senior Secured Loans, One, due 12/13/2024
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:HarbourBenefitHoldingsIncMember	mrcc:HarbourBenefitHoldingsIncMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	mrcc:FireFinanceMember	mrcc:FireFinanceMember
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR	us-gaap:LondonInterbankOfferedRateLiborSwapRateMember
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Basis Spread, Variable Rate	5.25%	5.25%
Investment Interest Rate	9.98%	6.25%
Investment Maturity Date	Dec. 13, 2024	Dec. 13, 2024
Investment Owned, Balance, Principal Amount	$ 2,901	$ 2,948
Investment Owned, at Fair Value	$ 2,898	$ 2,932
Investment, Identifier [Axis]: Harbour Benefit Holdings, Inc., Senior Secured Loans, Two, due 12/13/2024
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:HarbourBenefitHoldingsIncMember	mrcc:HarbourBenefitHoldingsIncMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	mrcc:FireFinanceMember	mrcc:FireFinanceMember
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR	us-gaap:LondonInterbankOfferedRateLiborSwapRateMember
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Basis Spread, Variable Rate	5.25%	5.25%
Investment Interest Rate	9.63%	6.25%
Investment Maturity Date	Dec. 13, 2024	Dec. 13, 2024
Investment Owned, Balance, Principal Amount	$ 61	$ 66
Investment Owned, at Fair Value	$ 61	$ 65
Investment, Identifier [Axis]: Hastings Manufacturing Company, Senior Secured Loans, due 4/24/2023
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:HastingsManufacturingCompanyMember	mrcc:HastingsManufacturingCompanyMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Automotive	Automotive
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR	LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Basis Spread, Variable Rate	7.25%	7.25%
Investment Interest Rate	11.64%	8.25%
Investment, Acquisition Date	Apr. 24, 2018	Apr. 24, 2018
Investment Maturity Date	Apr. 24, 2023	Apr. 24, 2023
Investment Owned, Balance, Principal Amount	$ 2,026	$ 2,524
Investment Owned, at Fair Value	$ 2,026	$ 2,524
Investment, Identifier [Axis]: I D I G Parent, L L C ( Revolver), Senior Secured Loans, due 12/15/2026
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		I D I G Parent, L L C [ Member]
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Services: Consumer
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Basis Spread, Variable Rate		6%
Investment Interest Rate		7%
Investment, Acquisition Date		Dec. 15, 2020
Investment Maturity Date		Dec. 15, 2026
Investment Owned, Balance, Principal Amount		$ 429
Investment, Identifier [Axis]: I D I G Parent, L L C, Equity Securities, Common stock
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	I D I G Parent, L L C [ Member]	I D I G Parent, L L C [ Member]
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Equity Securities [Member]
Investment, Industry Sector [Extensible Enumeration]	Services: Consumer	Services: Consumer
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Acquisition Date	Jan. 04, 2021	Jan. 04, 2021
Investment Owned, at Fair Value	$ 324	$ 428
Investment, Identifier [Axis]: I D I G Parent, L L C, Senior Secured Loans, One, due 12/15/2026
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		I D I G Parent, L L C [ Member]
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Services: Consumer
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Basis Spread, Variable Rate		6%
Investment Interest Rate		7%
Investment, Acquisition Date		Dec. 15, 2020
Investment Maturity Date		Dec. 15, 2026
Investment Owned, Balance, Principal Amount		$ 5,517
Investment Owned, at Fair Value		$ 5,530
Investment, Identifier [Axis]: I D I G Parent, L L C, Senior Secured Loans, Two, due 12/15/2026
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		I D I G Parent, L L C [ Member]
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Services: Consumer
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Basis Spread, Variable Rate		6%
Investment Interest Rate		7%
Investment, Acquisition Date		Dec. 15, 2020
Investment Maturity Date		Dec. 15, 2026
Investment Owned, Balance, Principal Amount		$ 918
Investment Owned, at Fair Value		$ 920
Investment, Identifier [Axis]: I N H Buyer, Inc., Senior Secured Loans, due 6/28/2028
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:INHBuyerInc.Member	mrcc:INHBuyerInc.Member
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Healthcare & Pharmaceuticals Sector [Member]	Healthcare & Pharmaceuticals Sector [Member]
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]	LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Basis Spread, Variable Rate	7%	6%
Investment Interest Rate		7%
Investment, Interest Rate, Paid in Kind	3.50%
Investment, Acquisition Date	Jun. 30, 2021	Jun. 30, 2021
Investment Maturity Date	Jun. 28, 2028	Jun. 28, 2028
Investment Owned, Balance, Principal Amount	$ 2,950	$ 2,939
Investment Owned, at Fair Value	$ 2,832	$ 2,857
Investment, Identifier [Axis]: I T Global Holding L L C ( Revolver), Senior Secured Loans, due 11/10/2023
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:ITGlobalHoldingLLCMember
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Services: Business
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Basis Spread, Variable Rate		9%
Investment Interest Rate		10%
Investment, Acquisition Date		Nov. 15, 2018
Investment Maturity Date		Nov. 10, 2023
Investment Owned, Balance, Principal Amount		$ 875
Investment Owned, at Fair Value		$ 1,060
Investment, Identifier [Axis]: I T Global Holding L L C, Senior Secured Loans, One, due 11/10/2023
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:ITGlobalHoldingLLCMember
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Services: Business
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Basis Spread, Variable Rate		9%
Investment Interest Rate		10%
Investment, Acquisition Date		Nov. 15, 2018
Investment Maturity Date		Nov. 10, 2023
Investment Owned, Balance, Principal Amount		$ 3,405
Investment Owned, at Fair Value		$ 4,411
Investment, Identifier [Axis]: I T Global Holding L L C, Senior Secured Loans, Two, due 11/10/2023
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:ITGlobalHoldingLLCMember
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Services: Business
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Basis Spread, Variable Rate		9%
Investment Interest Rate		10%
Investment, Acquisition Date		Jul. 19, 2019
Investment Maturity Date		Nov. 10, 2023
Investment Owned, Balance, Principal Amount		$ 1,270
Investment Owned, at Fair Value		$ 1,645
Investment, Identifier [Axis]: In Mobi Pte, Ltd, Media: Equity Securities, due 9/18/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:InMobiPteLtdMember	mrcc:InMobiPteLtdMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Equity Securities [Member]
Investment, Industry Sector [Extensible Enumeration]	Media: Advertising, Printing & Publishing	Media: Advertising, Printing & Publishing
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	Non-US [Member]
Investment, Acquisition Date	Sep. 18, 2015	Sep. 18, 2015
Investment Maturity Date	Sep. 18, 2025	Sep. 18, 2025
Investment Owned, at Fair Value	$ 1,816	$ 2,204
Investment, Identifier [Axis]: Independence Buyer, Inc, Senior Secured Loans, due 8/3/2026
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:IndependenceBuyerInc.Member	mrcc:IndependenceBuyerInc.Member
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Consumer Goods: Durable	Consumer Goods: Durable
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]	LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Basis Spread, Variable Rate	5.50%	5.75%
Investment Interest Rate	9.74%	6.75%
Investment, Acquisition Date	Aug. 03, 2021	Aug. 03, 2021
Investment Maturity Date	Aug. 03, 2026	Aug. 03, 2026
Investment Owned, Balance, Principal Amount	$ 5,940	$ 6,000
Investment Owned, at Fair Value	$ 5,866	$ 6,000
Investment, Identifier [Axis]: Independence Buyer, Inc. ( Revolver), Senior Secured Loans, due 8/3/2026
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:IndependenceBuyerInc.Member	mrcc:IndependenceBuyerInc.Member
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Consumer Goods: Durable	Consumer Goods: Durable
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR	LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Basis Spread, Variable Rate	5.50%	5.75%
Investment Interest Rate	9.74%	6.75%
Investment, Acquisition Date	Aug. 03, 2021	Aug. 03, 2021
Investment Maturity Date	Aug. 03, 2026	Aug. 03, 2026
Investment Owned, Balance, Principal Amount	$ 1,423	$ 1,423
Investment, Identifier [Axis]: Independence Buyer, Inc., Equity Securities, Class A units
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:IndependenceBuyerInc.Member	mrcc:IndependenceBuyerInc.Member
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Equity Securities [Member]
Investment, Industry Sector [Extensible Enumeration]	Consumer Goods: Durable	Consumer Goods: Durable
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Acquisition Date	Aug. 03, 2021	Aug. 03, 2021
Investment Owned, at Fair Value	$ 102	$ 101
Investment, Identifier [Axis]: Intermedia Holdings, Inc., Senior Secured Loans, due 7/21/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:IntermediaHoldingsIncMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Telecommunications
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Basis Spread, Variable Rate	6%
Investment Interest Rate	10.38%
Investment Maturity Date	Jul. 21, 2025
Investment Owned, Balance, Principal Amount	$ 1,760
Investment Owned, at Fair Value	$ 1,360
Investment, Identifier [Axis]: International Textile Group, Inc., Senior Secured Loans, due 5/1/2024
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:InternationalTextileGroupIncMember	mrcc:InternationalTextileGroupIncMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Consumer Goods: Durable	Consumer Goods: Durable
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR	LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Basis Spread, Variable Rate		5%
Investment Interest Rate		5.13%
Investment Maturity Date		May 01, 2024
Investment Owned, Balance, Principal Amount		$ 1,711
Investment Owned, at Fair Value		$ 1,590
Investment, Identifier [Axis]: J2 B W A Funding L L C ( Delayed Draw), Senior Secured Loans, due 12/24/2026
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:J2BWAFundingLLCMember
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		mrcc:FireFinanceMember
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment Interest Rate		9%
Investment, Acquisition Date		Dec. 24, 2020
Investment Maturity Date		Dec. 24, 2026
Investment Owned, Balance, Principal Amount		$ 2,710
Investment Owned, at Fair Value		$ 677
Investment, Identifier [Axis]: J2 B W A Funding L L C, Equity Securities
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:J2BWAFundingLLCMember	mrcc:J2BWAFundingLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Equity Securities [Member]
Investment, Industry Sector [Extensible Enumeration]	FIRE: Finance	FIRE: Finance
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Acquisition Date	Dec. 24, 2020	Dec. 24, 2020
Investment, Identifier [Axis]: J2 BWA Funding LLC (Delayed Draw), Senior Notes, Due 12/24/2026
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:J2BWAFundingLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	mrcc:FireFinanceMember
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment Interest Rate	9%
Investment, Acquisition Date	Dec. 24, 2020
Investment Maturity Date	Dec. 24, 2026
Investment Owned, Balance, Principal Amount	$ 2,750
Investment Owned, at Fair Value	$ 1,298
Investment, Identifier [Axis]: Kar Wash Holdings, L L C ( Delayed Draw), Senior Secured Loans, due 2/26/2027
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:KarWashHoldingsLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Services: Consumer
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Basis Spread, Variable Rate	6%
Investment Interest Rate	10.77%
Investment, Acquisition Date	Aug. 03, 2022
Investment Maturity Date	Feb. 26, 2027
Investment Owned, Balance, Principal Amount	$ 2,667
Investment Owned, at Fair Value	$ 1,782
Investment, Identifier [Axis]: Kar Wash Holdings, L L C ( Revolver), Senior Secured Loans, due 2/26/2027
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:KarWashHoldingsLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Services: Consumer
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Basis Spread, Variable Rate	6%
Investment Interest Rate	10.77%
Investment, Acquisition Date	Feb. 28, 2022
Investment Maturity Date	Feb. 26, 2027
Investment Owned, Balance, Principal Amount	$ 572
Investment Owned, at Fair Value	$ 303
Investment, Identifier [Axis]: Kar Wash Holdings, L L C, Equity Securities, Class A units
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:KarWashHoldingsLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Services: Consumer
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Acquisition Date	Feb. 28, 2022
Investment Owned, at Fair Value	$ 111
Investment, Identifier [Axis]: Kar Wash Holdings, LLC, Senior Secured Loans, One, due 2/26/2027
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:KarWashHoldingsLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Services: Consumer
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Basis Spread, Variable Rate	6%
Investment Interest Rate	9.82%
Investment, Acquisition Date	Feb. 28, 2022
Investment Maturity Date	Feb. 26, 2027
Investment Owned, Balance, Principal Amount	$ 1,592
Investment Owned, at Fair Value	$ 1,585
Investment, Identifier [Axis]: Kar Wash Holdings, LLC, Senior Secured Loans, Two, due 2/26/2027
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:KarWashHoldingsLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Services: Consumer
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Basis Spread, Variable Rate	6%
Investment Interest Rate	10.35%
Investment, Acquisition Date	Feb. 28, 2022
Investment Maturity Date	Feb. 26, 2027
Investment Owned, Balance, Principal Amount	$ 1,140
Investment Owned, at Fair Value	$ 1,135
Investment, Identifier [Axis]: Keystone Purchaser, L L C, Senior Secured Loans, due 5/7/2027
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:KeystonePurchaserLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Transportation Sector [Member]
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Basis Spread, Variable Rate	5.50%
Investment Interest Rate	10.60%
Investment Maturity Date	May 07, 2027
Investment Owned, Balance, Principal Amount	$ 4,955
Investment Owned, at Fair Value	$ 4,955
Investment, Identifier [Axis]: Kingsley Gate Partners, LLC (Delayed Draw), One, Due 12/11/2028
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:KingsleyGatePartnersLlcMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Services: Business
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Basis Spread, Variable Rate	6.65%
Investment Interest Rate	11.12%
Investment, Acquisition Date	Dec. 09, 2022
Investment Maturity Date	Dec. 11, 2028
Investment Owned, Balance, Principal Amount	$ 720
Investment, Identifier [Axis]: Kingsley Gate Partners, LLC (Delayed Draw), Two, Due 12/11/2028
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:KingsleyGatePartnersLlcMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Services: Business
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Basis Spread, Variable Rate	6.65%
Investment Interest Rate	11.12%
Investment, Acquisition Date	Dec. 09, 2022
Investment Maturity Date	Dec. 11, 2028
Investment Owned, Balance, Principal Amount	$ 600
Investment, Identifier [Axis]: Kingsley Gate Partners, LLC (Revolver), Due 12/11/2028
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:KingsleyGatePartnersLlcMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Services: Business
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Basis Spread, Variable Rate	6.65%
Investment Interest Rate	11.12%
Investment, Acquisition Date	Dec. 09, 2022
Investment Maturity Date	Dec. 11, 2028
Investment Owned, Balance, Principal Amount	$ 240
Investment, Identifier [Axis]: Kingsley Gate Partners, LLC, Due 12/11/2028
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:KingsleyGatePartnersLlcMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Services: Business
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Basis Spread, Variable Rate	6.65%
Investment Interest Rate	11.12%
Investment, Acquisition Date	Dec. 09, 2022
Investment Maturity Date	Dec. 11, 2028
Investment Owned, Balance, Principal Amount	$ 600
Investment Owned, at Fair Value	$ 588
Investment, Identifier [Axis]: L S C S Holdings, Inc., Senior Secured Loans, due 12/15/2028
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:LSCSHoldingsIncMember	mrcc:LSCSHoldingsIncMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Healthcare & Pharmaceuticals Sector [Member]	Healthcare & Pharmaceuticals Sector [Member]
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR	LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Basis Spread, Variable Rate	4.50%	4.50%
Investment Interest Rate	8.88%	5%
Investment Maturity Date	Dec. 15, 2028	Dec. 15, 2028
Investment Owned, Balance, Principal Amount	$ 1,828	$ 1,846
Investment Owned, at Fair Value	$ 1,751	$ 1,849
Investment, Identifier [Axis]: L V F Holdings, Inc. ( Revolver), Senior Secured Loans, due 6/10/2027
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:LVFHoldingsIncMember	mrcc:LVFHoldingsIncMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	mrcc:BeverageFoodAndTobaccoSectorMember	Beverage, Food & Tobacco
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR	LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Basis Spread, Variable Rate	6.25%	6.25%
Investment Interest Rate	10.98%	7.25%
Investment, Acquisition Date	Jun. 10, 2021	Oct. 06, 2021
Investment Maturity Date	Jun. 10, 2027	Jun. 10, 2027
Investment Owned, Balance, Principal Amount	$ 238	$ 238
Investment Owned, at Fair Value	$ 152	$ 119
Investment, Identifier [Axis]: L V F Holdings, Inc., Senior Secured Loans, ( Delayed Draw) due 6/10/2027
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:LVFHoldingsIncMember	mrcc:LVFHoldingsIncMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	mrcc:BeverageFoodAndTobaccoSectorMember	Beverage, Food & Tobacco
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR	LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Basis Spread, Variable Rate	6.25%	6.25%
Investment Interest Rate	8.45%	7.25%
Investment, Acquisition Date	Jun. 10, 2021	Oct. 06, 2021
Investment Maturity Date	Jun. 10, 2027	Jun. 10, 2027
Investment Owned, Balance, Principal Amount	$ 344	$ 344
Investment, Identifier [Axis]: L V F Holdings, Inc., Senior Secured Loans, One, due 6/10/2027
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:LVFHoldingsIncMember	mrcc:LVFHoldingsIncMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	mrcc:BeverageFoodAndTobaccoSectorMember	Beverage, Food & Tobacco
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR	LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Basis Spread, Variable Rate	6.25%	6.25%
Investment Interest Rate	8.45%	7.25%
Investment, Acquisition Date	Jun. 10, 2021	Jun. 10, 2021
Investment Maturity Date	Jun. 10, 2027	Jun. 10, 2027
Investment Owned, Balance, Principal Amount	$ 1,481	$ 1,496
Investment Owned, at Fair Value	$ 1,437	$ 1,496
Investment, Identifier [Axis]: L V F Holdings, Inc., Senior Secured Loans, Two, due 6/10/2027
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:LVFHoldingsIncMember	mrcc:LVFHoldingsIncMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	mrcc:BeverageFoodAndTobaccoSectorMember	Beverage, Food & Tobacco
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR	LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Basis Spread, Variable Rate	6.25%	6.25%
Investment Interest Rate	8.45%	7.25%
Investment, Acquisition Date	Jun. 10, 2021	Jun. 10, 2021
Investment Maturity Date	Jun. 10, 2027	Jun. 10, 2027
Investment Owned, Balance, Principal Amount	$ 1,418	$ 1,432
Investment Owned, at Fair Value	$ 1,375	$ 1,432
Investment, Identifier [Axis]: L X/ J T Intermediate Holdings, Inc. ( Revolver), Senior Secured Loans, due 3/11/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:LXJTIntermediateHoldingsIncMember	mrcc:LXJTIntermediateHoldingsIncMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	mrcc:BeverageFoodAndTobaccoSectorMember	Beverage, Food & Tobacco
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]	LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Basis Spread, Variable Rate	6%	6%
Investment Interest Rate	10.42%	7.50%
Investment, Acquisition Date	Mar. 11, 2020	Mar. 11, 2020
Investment Maturity Date	Mar. 11, 2025	Mar. 11, 2025
Investment Owned, Balance, Principal Amount	$ 833	$ 833
Investment, Identifier [Axis]: L X/ J T Intermediate Holdings, Inc., Senior Secured Loans, due 3/11/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:LXJTIntermediateHoldingsIncMember	mrcc:LXJTIntermediateHoldingsIncMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	mrcc:BeverageFoodAndTobaccoSectorMember	Beverage, Food & Tobacco
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]	LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Basis Spread, Variable Rate	6%	6%
Investment Interest Rate	10.42%	7.50%
Investment, Acquisition Date	Mar. 11, 2020	Nov. 03, 2020
Investment Maturity Date	Mar. 11, 2025	Mar. 11, 2025
Investment Owned, Balance, Principal Amount	$ 5,468	$ 9,375
Investment Owned, at Fair Value	$ 5,394	$ 9,239
Investment, Identifier [Axis]: Laseraway Intermediate Holdings I I, L L C, Senior Secured Loans, due 10/14/2027
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:LaserawayIntermediateHoldingsIILLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Services: Consumer
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Basis Spread, Variable Rate	5.75%
Investment Interest Rate	9.76%
Investment Maturity Date	Oct. 14, 2027
Investment Owned, Balance, Principal Amount	$ 2,200
Investment Owned, at Fair Value	$ 2,161
Investment, Identifier [Axis]: Lifted Trucks Holdings, L L C ( Delayed Draw), Senior Secured Loans, due 8/2/2027
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:LiftedTrucksHoldingsLLCMember	mrcc:LiftedTrucksHoldingsLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Automotive	Automotive
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR	LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Basis Spread, Variable Rate	5.75%	5.75%
Investment Interest Rate	9.49%	6.75%
Investment, Acquisition Date	Aug. 02, 2021	Aug. 02, 2021
Investment Maturity Date	Aug. 02, 2027	Aug. 02, 2027
Investment Owned, Balance, Principal Amount	$ 1,400	$ 1,400
Investment, Identifier [Axis]: Lifted Trucks Holdings, L L C ( Revolver), Senior Secured Loans, due 8/2/2027
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:LiftedTrucksHoldingsLLCMember	mrcc:LiftedTrucksHoldingsLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Automotive	Automotive
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR	LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Basis Spread, Variable Rate	5.75%	5.75%
Investment Interest Rate	9.49%	6.75%
Investment, Acquisition Date	Aug. 02, 2021	Aug. 02, 2021
Investment Maturity Date	Aug. 02, 2027	Aug. 02, 2027
Investment Owned, Balance, Principal Amount	$ 1,667	$ 1,667
Investment Owned, at Fair Value		$ 443
Investment, Identifier [Axis]: Lifted Trucks Holdings, L L C, Equity Securities, Class A units
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:LiftedTrucksHoldingsLLCMember	mrcc:LiftedTrucksHoldingsLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Automotive	Automotive
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Basis Spread, Variable Rate	0%
Investment Interest Rate	0%
Investment, Acquisition Date	Aug. 02, 2021	Aug. 02, 2021
Investment Owned, Balance, Principal Amount	$ 0
Investment Owned, at Fair Value	$ 78	$ 109
Investment, Identifier [Axis]: Lifted Trucks Holdings, L L C, Senior Secured Loans, due 8/2/2027
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:LiftedTrucksHoldingsLLCMember	mrcc:LiftedTrucksHoldingsLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Automotive	Automotive
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR	LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Basis Spread, Variable Rate	5.75%	5.75%
Investment Interest Rate	9.49%	6.75%
Investment, Acquisition Date	Aug. 02, 2021	Aug. 02, 2021
Investment Maturity Date	Aug. 02, 2027	Aug. 02, 2027
Investment Owned, Balance, Principal Amount	$ 6,930	$ 7,000
Investment Owned, at Fair Value	$ 6,840	$ 6,979
Investment, Identifier [Axis]: Liftforward S P V I I, L L C, Senior Secured Loans, due 9/30/2022
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:LiftforwardSPVIILLCMember
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		mrcc:FireFinanceMember
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Basis Spread, Variable Rate		10.75%
Investment Interest Rate		11.25%
Investment, Acquisition Date		Nov. 10, 2016
Investment Maturity Date		Sep. 30, 2022
Investment Owned, Balance, Principal Amount		$ 744
Investment Owned, at Fair Value		$ 713
Investment, Identifier [Axis]: Liftforward SPV II, LLC, Senior Secured Loans, due 3/31/2023
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:LiftforwardSPVIILLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	mrcc:FireFinanceMember
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Basis Spread, Variable Rate	10.75%
Investment Interest Rate	15.14%
Investment, Acquisition Date	Nov. 10, 2016
Investment Maturity Date	Mar. 31, 2023
Investment Owned, Balance, Principal Amount	$ 413
Investment Owned, at Fair Value	$ 403
Investment, Identifier [Axis]: Lightbox Intermediate, L. P., Senior Secured Loans, due 5/11/2026
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:LightboxIntermediateL.PMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	High Tech Industries Sector [Member]
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Basis Spread, Variable Rate	5%
Investment Interest Rate	9.73%
Investment Maturity Date	May 11, 2026
Investment Owned, Balance, Principal Amount	$ 4,825
Investment Owned, at Fair Value	$ 4,656
Investment, Identifier [Axis]: Liqui- Box Holdings, Inc., Senior Secured Loans, due 2/26/2027
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:Liqui-BoxHoldingsIncMember	mrcc:Liqui-BoxHoldingsIncMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Container and Packaging Sector [Member]	Container and Packaging Sector [Member]
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR	LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Basis Spread, Variable Rate		4.50%
Investment Interest Rate		5.50%
Investment Maturity Date		Feb. 26, 2027
Investment Owned, Balance, Principal Amount		$ 4,268
Investment Owned, at Fair Value		$ 3,991
Investment, Identifier [Axis]: Luxury Optical Holdings Co. ( Delayed Draw)
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	Luxury Optical Holdings Co [ Member]	Luxury Optical Holdings Co [ Member]
Investment Owned, at Fair Value			624
Investment, Identifier [Axis]: Luxury Optical Holdings Co. Investment, One
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	Luxury Optical Holdings Co [ Member]	Luxury Optical Holdings Co [ Member]
Investment Owned, at Fair Value			1,430
Investment, Identifier [Axis]: Luxury Optical Holdings Co.( Revolver)
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	Luxury Optical Holdings Co [ Member]	Luxury Optical Holdings Co [ Member]
Investment Owned, at Fair Value			66
Investment, Identifier [Axis]: Luxury Optical Holdings Co., Equity Securities
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	Luxury Optical Holdings Co [ Member]	mrcc:LuxuryOpticalHoldingsCo.Member
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Equity Securities [Member]
Investment, Industry Sector [Extensible Enumeration]	Retail	Retail
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Acquisition Date	Sep. 12, 2014	Sep. 12, 2014
Investment Owned, at Fair Value	$ 209	$ 78
Investment, Identifier [Axis]: Luxury Optical Holdings Co., Equity Securities, Common Stock
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	Luxury Optical Holdings Co [ Member]	Luxury Optical Holdings Co [ Member]
Investment, Identifier [Axis]: Luxury Optical Holdings Co., Equity Securities, Preferred Units
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	Luxury Optical Holdings Co [ Member]	Luxury Optical Holdings Co [ Member]
Investment Owned, at Fair Value			2,476
Investment, Identifier [Axis]: M C Asset Management ( Corporate), L L C ( Delayed Draw), Senior Secured Loans Due 1/26/2024
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:MCAssetManagementCorporateLLCMember	mrcc:MCAssetManagementCorporateLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	FIRE: Real Estate	FIRE: Real Estate
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR	LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Basis Spread, Variable Rate	15%	15%
Investment, Interest Rate, Paid in Kind	18.74%	16%
Investment, Acquisition Date	Apr. 26, 2021	Apr. 26, 2021
Investment Maturity Date	Jan. 26, 2024	Jan. 26, 2024
Investment Owned, Balance, Principal Amount	$ 1,793	$ 1,643
Investment Owned, at Fair Value	$ 1,000	$ 850
Investment, Identifier [Axis]: M C Asset Management ( Corporate), L L C, Equity Securites
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:MCAssetManagementCorporateLLCMember	mrcc:MCAssetManagementCorporateLLCMember
Investment, Type [Extensible Enumeration]	Equity Securities [Member]	Equity Securities [Member]
Investment, Industry Sector [Extensible Enumeration]	FIRE: Real Estate	FIRE: Real Estate
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Acquisition Date	Jun. 11, 2019	Jun. 11, 2019
Investment Owned, at Fair Value	$ 1,291	$ 644
Investment, Identifier [Axis]: M C Asset Management ( Corporate), L L C, Equity Securities
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:MCAssetManagementCorporateLLCMember	mrcc:MCAssetManagementCorporateLLCMember
Investment Owned, at Fair Value	$ 1,291	$ 644	785
Investment, Identifier [Axis]: M C Asset Management ( Corporate), L L C, Senior Secured Loans Due 1/26/2024
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:MCAssetManagementCorporateLLCMember	mrcc:MCAssetManagementCorporateLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	FIRE: Real Estate	FIRE: Real Estate
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR	LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Basis Spread, Variable Rate	15%	15%
Investment, Interest Rate, Paid in Kind	18.74%	16%
Investment, Acquisition Date	Jan. 26, 2021	Jan. 26, 2021
Investment Maturity Date	Jan. 26, 2024	Jan. 26, 2024
Investment Owned, Balance, Principal Amount	$ 8,421	$ 7,154
Investment Owned, at Fair Value	$ 8,421	$ 7,154
Investment, Identifier [Axis]: M C Asset Management ( Industrial), L L C Promissory Note
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:MCAssetManagementIndustrialLLCMember	mrcc:MCAssetManagementIndustrialLLCMember
Investment Owned, at Fair Value			11,579
Investment, Identifier [Axis]: M C P Shaw Acquisitionco, L L C ( Delayed Draw), Senior Secured Loans, due 11/28/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:MCPShawAcquisitioncoLLCMember	mrcc:MCPShawAcquisitioncoLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Capital Equipment	Capital Equipment
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Basis Spread, Variable Rate	6.50%	6.50%
Investment Interest Rate	11.06%	7.50%
Investment, Acquisition Date	Dec. 29, 2021	Dec. 29, 2021
Investment Maturity Date	Nov. 28, 2025	Nov. 28, 2025
Investment Owned, Balance, Principal Amount	$ 978	$ 983
Investment Owned, at Fair Value	$ 979
Investment, Identifier [Axis]: M C P Shaw Acquisitionco, L L C ( Revolver), Senior Secured Loans, due 11/28/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:MCPShawAcquisitioncoLLCMember	mrcc:MCPShawAcquisitioncoLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Capital Equipment	Capital Equipment
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Basis Spread, Variable Rate	6.50%	6.50%
Investment Interest Rate	11.06%	7.50%
Investment, Acquisition Date	Feb. 28, 2020	Feb. 28, 2020
Investment Maturity Date	Nov. 28, 2025	Nov. 28, 2025
Investment Owned, Balance, Principal Amount	$ 1,784	$ 1,784
Investment, Identifier [Axis]: M C P Shaw Acquisitionco, L L C , Equity Securities, Class A-2 units
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:MCPShawAcquisitioncoLLCMember	mrcc:MCPShawAcquisitioncoLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Equity Securities [Member]
Investment, Industry Sector [Extensible Enumeration]	Capital Equipment	Capital Equipment
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Acquisition Date	Feb. 28, 2020	Feb. 28, 2020
Investment Owned, at Fair Value	$ 204	$ 148
Investment, Identifier [Axis]: M C P Shaw Acquisitionco, L L C, Senior Secured Loans, One, due 11/28/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:MCPShawAcquisitioncoLLCMember	mrcc:MCPShawAcquisitioncoLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Capital Equipment	Capital Equipment
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Basis Spread, Variable Rate	6.50%	6.50%
Investment Interest Rate	11.06%	7.50%
Investment, Acquisition Date	Feb. 28, 2020	Feb. 28, 2020
Investment Maturity Date	Nov. 28, 2025	Nov. 28, 2025
Investment Owned, Balance, Principal Amount	$ 9,722	$ 9,733
Investment Owned, at Fair Value	$ 9,736	$ 9,699
Investment, Identifier [Axis]: M C P Shaw Acquisitionco, L L C, Senior Secured Loans, Two, due 11/28/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:MCPShawAcquisitioncoLLCMember	mrcc:MCPShawAcquisitioncoLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Capital Equipment	Capital Equipment
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Basis Spread, Variable Rate	6.50%	6.50%
Investment Interest Rate	11.06%	7.50%
Investment, Acquisition Date	Dec. 29, 2021	Dec. 29, 2021
Investment Maturity Date	Nov. 28, 2025	Nov. 28, 2025
Investment Owned, Balance, Principal Amount	$ 2,972	$ 3,002
Investment Owned, at Fair Value	$ 2,977	$ 2,992
Investment, Identifier [Axis]: M F G Chemical, L L C, Unitranche Secured Loans, One, Due 6/23/2022
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:MFGChemicalLLCMember
Investment, Type [Extensible Enumeration]		Unitranche Debt [Member]
Investment, Industry Sector [Extensible Enumeration]		Chemicals, Plastics & Rubber
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Basis Spread, Variable Rate		8%
Investment Interest Rate		9%
Investment, Acquisition Date		Jun. 23, 2017
Investment Maturity Date		Jun. 23, 2022
Investment Owned, Balance, Principal Amount		$ 5,555
Investment Owned, at Fair Value		$ 5,555
Investment, Identifier [Axis]: M F G Chemical, L L C, Unitranche Secured Loans, Two, Due 6/23/2022
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:MFGChemicalLLCMember
Investment, Type [Extensible Enumeration]		Unitranche Debt [Member]
Investment, Industry Sector [Extensible Enumeration]		Chemicals, Plastics & Rubber
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Basis Spread, Variable Rate		8%
Investment Interest Rate		9%
Investment, Acquisition Date		Mar. 15, 2018
Investment Maturity Date		Jun. 23, 2022
Investment Owned, Balance, Principal Amount		$ 543
Investment Owned, at Fair Value		$ 543
Investment, Identifier [Axis]: M R C C Senior Loan Fund I, L L C, Equity Securities
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Controlled affiliate company investments	Controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	MRCC Senior Loan Fund I, LLC	MRCC Senior Loan Fund I, LLC
Investment, Type [Extensible Enumeration]	Equity Securities [Member]	Equity Securities [Member]
Investment, Industry Sector [Extensible Enumeration]	mrcc:InvestmentFundsVehiclesMember	mrcc:InvestmentFundsVehiclesMember
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Acquisition Date	Oct. 31, 2017	Oct. 31, 2017
Investment Owned, at Fair Value	$ 35,509	$ 41,125	39,284
Investment, Identifier [Axis]: M V Receivables I I, L L C ( Delayed Draw), Senior Secured Loans, due 7/29/2026
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:MVReceivablesIILLCMember	mrcc:MVReceivablesIILLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Banking	Banking
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR	LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Basis Spread, Variable Rate	9.75%	9.75%
Investment Interest Rate	13.87%	11.25%
Investment, Acquisition Date	Jul. 29, 2021	Jul. 29, 2021
Investment Maturity Date	Jul. 29, 2026	Jul. 29, 2026
Investment Owned, Balance, Principal Amount	$ 8,115	$ 8,000
Investment Owned, at Fair Value	$ 7,968	$ 1,289
Investment, Identifier [Axis]: M V Receivables I I, L L C, Equity Securities, Common units
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:MVReceivablesIILLCMember	mrcc:MVReceivablesIILLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Banking	Banking
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Acquisition Date	Jul. 29, 2021	Jul. 29, 2021
Investment Owned, at Fair Value	$ 1,154	$ 558
Investment, Identifier [Axis]: M V Receivables I I, L L C, Equity Securities, Due 7/28/2031, Warrants
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:MVReceivablesIILLCMember	mrcc:MVReceivablesIILLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Banking	Banking
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Acquisition Date	Jul. 28, 2021	Jul. 28, 2021
Investment Maturity Date	Jul. 28, 2031	Jul. 28, 2031
Investment Owned, at Fair Value	$ 1,655	$ 1,007
Investment, Identifier [Axis]: MC Asset Management (Corporate), LLC (Delayed Draw)
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:MCAssetManagementCorporateLLCMember
Investment Owned, at Fair Value	$ 1,000	$ 850
Investment, Identifier [Axis]: Mac Queen Equipment, L L C ( Delayed Draw), Senior Secured Loans, due 1/7/2028
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:MacQueenEquipmentLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Capital Equipment
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Identifier [Axis]: Mac Queen Equipment, L L C ( Revolver), Senior Secured Loans, due 1/7/2028
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:MacQueenEquipmentLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Capital Equipment
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Identifier [Axis]: Mac Queen Equipment, L L C, Senior Secured Loans, due 1/7/2028
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:MacQueenEquipmentLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Capital Equipment
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Identifier [Axis]: Magneto & Diesel Acquisition, Inc, Senior Secured Loans, One, due 12/18/2023
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:MagnetoDieselAcquisitionInc.Member
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Automotive
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Basis Spread, Variable Rate		5.50%
Investment Interest Rate		6.50%
Investment, Acquisition Date		Dec. 18, 2018
Investment Maturity Date		Dec. 18, 2023
Investment Owned, Balance, Principal Amount		$ 4,850
Investment Owned, at Fair Value		$ 4,850
Investment, Identifier [Axis]: Magneto & Diesel Acquisition, Inc, Senior Secured Loans, Three, due 12/8/2023
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:MagnetoDieselAcquisitionInc.Member
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Automotive
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Basis Spread, Variable Rate		5.50%
Investment Interest Rate		6.50%
Investment, Acquisition Date		Aug. 04, 2021
Investment Maturity Date		Dec. 18, 2023
Investment Owned, Balance, Principal Amount		$ 829
Investment Owned, at Fair Value		$ 842
Investment, Identifier [Axis]: Magneto & Diesel Acquisition, Inc, Senior Secured Loans, Two, due 12/8/2023
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:MagnetoDieselAcquisitionInc.Member
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Automotive
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Basis Spread, Variable Rate		5.50%
Investment Interest Rate		6.50%
Investment, Acquisition Date		Jul. 06, 2020
Investment Maturity Date		Dec. 18, 2023
Investment Owned, Balance, Principal Amount		$ 1,908
Investment Owned, at Fair Value		$ 1,938
Investment, Identifier [Axis]: Magneto & Diesel Acquisition, Inc. ( Revolver), Senior Secured Loans, due 12/8/2023
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:MagnetoDieselAcquisitionInc.Member
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Automotive
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Basis Spread, Variable Rate		5.50%
Investment Interest Rate		6.50%
Investment, Acquisition Date		Dec. 18, 2018
Investment Maturity Date		Dec. 18, 2023
Investment Owned, Balance, Principal Amount		$ 500
Investment, Identifier [Axis]: Mammoth Holdings, L L C ( Delayed Draw), Senior Secured Loans, due 10/16/2023
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:MammothHoldingsLLCMember
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Services: Consumer
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Basis Spread, Variable Rate		6%
Investment Interest Rate		7%
Investment, Acquisition Date		Jun. 15, 2021
Investment Maturity Date		Oct. 16, 2023
Investment Owned, Balance, Principal Amount		$ 1,646
Investment Owned, at Fair Value		$ 989
Investment, Identifier [Axis]: Mammoth Holdings, L L C ( Revolver), Senior Secured Loans, due 10/16/2023
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:MammothHoldingsLLCMember
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Services: Consumer
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Basis Spread, Variable Rate		6%
Investment Interest Rate		7%
Investment, Acquisition Date		Oct. 16, 2018
Investment Maturity Date		Oct. 16, 2023
Investment Owned, Balance, Principal Amount		$ 657
Investment, Identifier [Axis]: Mammoth Holdings, L L C, Senior Secured Loans, One, due 10/16/2023
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:MammothHoldingsLLCMember
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Services: Consumer
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Basis Spread, Variable Rate		6%
Investment Interest Rate		7%
Investment, Acquisition Date		Oct. 16, 2018
Investment Maturity Date		Oct. 16, 2023
Investment Owned, Balance, Principal Amount		$ 1,940
Investment Owned, at Fair Value		$ 1,940
Investment, Identifier [Axis]: Mammoth Holdings, L L C, Senior Secured Loans, Three, due 10/16/2023
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:MammothHoldingsLLCMember
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Services: Consumer
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Basis Spread, Variable Rate		6%
Investment Interest Rate		7%
Investment, Acquisition Date		Mar. 12, 2021
Investment Maturity Date		Oct. 16, 2023
Investment Owned, Balance, Principal Amount		$ 6,355
Investment Owned, at Fair Value		$ 6,368
Investment, Identifier [Axis]: Mammoth Holdings, L L C, Senior Secured Loans, Two, due 10/16/2023
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:MammothHoldingsLLCMember
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Services: Consumer
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Basis Spread, Variable Rate		6%
Investment Interest Rate		7%
Investment, Acquisition Date		Oct. 16, 2018
Investment Maturity Date		Oct. 16, 2023
Investment Owned, Balance, Principal Amount		$ 4,073
Investment Owned, at Fair Value		$ 4,073
Investment, Identifier [Axis]: Mammoth Holdings, LLC (Revolver), Senior Secured Loans, Due, 10/16/2024
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:MammothHoldingsLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Services: Consumer
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Basis Spread, Variable Rate	6%
Investment Interest Rate	9.82%
Investment, Acquisition Date	Oct. 16, 2018
Investment Maturity Date	Oct. 16, 2024
Investment Owned, Balance, Principal Amount	$ 657
Investment, Identifier [Axis]: Mammoth Holdings, LLC, Senior Secured Loans, Four, due 10/16/2024
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:MammothHoldingsLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Services: Consumer
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Basis Spread, Variable Rate	6%
Investment Interest Rate	9.82%
Investment, Acquisition Date	Jun. 15, 2021
Investment Maturity Date	Oct. 16, 2024
Investment Owned, Balance, Principal Amount	$ 1,633
Investment Owned, at Fair Value	$ 1,630
Investment, Identifier [Axis]: Mammoth Holdings, LLC, Senior Secured Loans, One, due 10/16/2024
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:MammothHoldingsLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Services: Consumer
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Basis Spread, Variable Rate	6%
Investment Interest Rate	9.82%
Investment, Acquisition Date	Oct. 16, 2018
Investment Maturity Date	Oct. 16, 2024
Investment Owned, Balance, Principal Amount	$ 1,920
Investment Owned, at Fair Value	$ 1,917
Investment, Identifier [Axis]: Mammoth Holdings, LLC, Senior Secured Loans, Three, due 10/16/2024
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:MammothHoldingsLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Services: Consumer
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Basis Spread, Variable Rate	6%
Investment Interest Rate	9.82%
Investment, Acquisition Date	Mar. 12, 2021
Investment Maturity Date	Oct. 16, 2024
Investment Owned, Balance, Principal Amount	$ 6,291
Investment Owned, at Fair Value	$ 6,282
Investment, Identifier [Axis]: Mammoth Holdings, LLC, Senior Secured Loans, Two, due 10/16/2024
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:MammothHoldingsLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Services: Consumer
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Basis Spread, Variable Rate	6%
Investment Interest Rate	9.82%
Investment, Acquisition Date	Oct. 16, 2018
Investment Maturity Date	Oct. 16, 2024
Investment Owned, Balance, Principal Amount	$ 4,031
Investment Owned, at Fair Value	$ 4,025
Investment, Identifier [Axis]: Mark Logic Corporation ( Revolver), Senior Secured Loans, due 10/20/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:MarkLogicCorporationMember	mrcc:MarkLogicCorporationMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	High Tech Industries Sector [Member]	High Tech Industries Sector [Member]
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]	LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Basis Spread, Variable Rate	6.50%	6%
Investment Interest Rate	10.85%	7%
Investment, Acquisition Date	Oct. 20, 2020	Oct. 20, 2020
Investment Maturity Date	Oct. 20, 2025	Oct. 20, 2025
Investment Owned, Balance, Principal Amount	$ 269	$ 269
Investment, Identifier [Axis]: Mark Logic Corporation, Equity Securities, Class A units
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:MarkLogicCorporationMember	mrcc:MarkLogicCorporationMember
Investment, Type [Extensible Enumeration]	Equity Securities [Member]	Equity Securities [Member]
Investment, Industry Sector [Extensible Enumeration]	High Tech Industries Sector [Member]	High Tech Industries Sector [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Acquisition Date	Oct. 20, 2020	Oct. 20, 2020
Investment Owned, at Fair Value	$ 426	$ 423
Investment, Identifier [Axis]: Mark Logic Corporation, Senior Secured Loans, Four, due 10/20/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:MarkLogicCorporationMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	High Tech Industries Sector [Member]
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Basis Spread, Variable Rate	6.50%
Investment Interest Rate	10.85%
Investment, Acquisition Date	Nov. 23, 2021
Investment Maturity Date	Oct. 20, 2025
Investment Owned, Balance, Principal Amount	$ 214
Investment Owned, at Fair Value	$ 213
Investment, Identifier [Axis]: Mark Logic Corporation, Senior Secured Loans, One, due 10/20/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:MarkLogicCorporationMember	mrcc:MarkLogicCorporationMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	High Tech Industries Sector [Member]	High Tech Industries Sector [Member]
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]	LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Basis Spread, Variable Rate	6.50%	6%
Investment Interest Rate	10.85%	7%
Investment, Acquisition Date	Oct. 20, 2020	Oct. 20, 2020
Investment Maturity Date	Oct. 20, 2025	Oct. 20, 2025
Investment Owned, Balance, Principal Amount	$ 3,430	$ 3,465
Investment Owned, at Fair Value	$ 3,414	$ 3,517
Investment, Identifier [Axis]: Mark Logic Corporation, Senior Secured Loans, Three, due 10/20/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:MarkLogicCorporationMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	High Tech Industries Sector [Member]
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Basis Spread, Variable Rate	6.50%
Investment Interest Rate	10.85%
Investment, Acquisition Date	May 10, 2022
Investment Maturity Date	Oct. 20, 2025
Investment Owned, Balance, Principal Amount	$ 2,669
Investment Owned, at Fair Value	$ 2,656
Investment, Identifier [Axis]: Mark Logic Corporation, Senior Secured Loans, Two, due 10/20/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:MarkLogicCorporationMember	mrcc:MarkLogicCorporationMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	High Tech Industries Sector [Member]	High Tech Industries Sector [Member]
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]	LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Basis Spread, Variable Rate	6.50%	6%
Investment Interest Rate	10.85%	7%
Investment, Acquisition Date	Nov. 23, 2021	Nov. 23, 2021
Investment Maturity Date	Oct. 20, 2025	Oct. 20, 2025
Investment Owned, Balance, Principal Amount	$ 320	$ 323
Investment Owned, at Fair Value	$ 318	$ 330
Investment, Identifier [Axis]: MarkLogic Corporation (Delayed Draw), Senior Secured Loans 10/20/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:MarkLogicCorporationMember
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		High Tech Industries Sector [Member]
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Basis Spread, Variable Rate		6%
Investment Interest Rate		7%
Investment, Acquisition Date		Nov. 23, 2021
Investment Maturity Date		Oct. 20, 2025
Investment Owned, Balance, Principal Amount		$ 215
Investment, Identifier [Axis]: Mavenir Systems, Inc., Senior Secured Loans, due 8/18/2028
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:MavenirSystemsIncMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Telecommunications
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Basis Spread, Variable Rate	4.75%
Investment Interest Rate	9.42%
Investment Maturity Date	Aug. 18, 2028
Investment Owned, Balance, Principal Amount	$ 1,654
Investment Owned, at Fair Value	$ 1,350
Investment, Identifier [Axis]: Mc Kissock Investment Holdings, L L C, Senior Secured Loans, due 3/9/2029
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:McKissockInvestmentHoldingsLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Services: Consumer
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Basis Spread, Variable Rate	5%
Investment Interest Rate	8.87%
Investment Maturity Date	Mar. 09, 2029
Investment Owned, Balance, Principal Amount	$ 2,481
Investment Owned, at Fair Value	$ 2,322
Investment, Identifier [Axis]: Medallia, Inc, Senior Secured Loans, due 10/27/2028
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:MedalliaIncMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	High Tech Industries Sector [Member]
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Basis Spread, Variable Rate	6.50%
Investment, Interest Rate, Paid in Kind	10.88%
Investment, Acquisition Date	Aug. 15, 2022
Investment Maturity Date	Oct. 27, 2028
Investment Owned, Balance, Principal Amount	$ 2,049
Investment Owned, at Fair Value	$ 2,041
Investment, Identifier [Axis]: Mindbody, Inc. ( Revolver) (f), Senior Secured Loans, due 2/14/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:MindbodyIncMember	mrcc:MindbodyIncMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	High Tech Industries Sector [Member]	High Tech Industries Sector [Member]
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR	LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Basis Spread, Variable Rate	7%	8%
Investment Interest Rate	11.73%	9%
Investment, Acquisition Date	Feb. 15, 2019	Feb. 15, 2019
Investment Maturity Date	Feb. 14, 2025	Feb. 14, 2025
Investment Owned, Balance, Principal Amount	$ 667	$ 667
Investment, Identifier [Axis]: Mindbody, Inc., Senior Secured Loans, One, due 2/14/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:MindbodyIncMember	mrcc:MindbodyIncMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	High Tech Industries Sector [Member]	High Tech Industries Sector [Member]
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR	LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Basis Spread, Variable Rate	7%	8.50%
Investment Interest Rate	11.73%
Investment, Interest Rate, Paid in Cash		8%
Investment, Interest Rate, Paid in Kind		1.50%
Investment, Acquisition Date	Feb. 15, 2019	Feb. 15, 2019
Investment Maturity Date	Feb. 14, 2025	Feb. 14, 2025
Investment Owned, Balance, Principal Amount	$ 6,536	$ 6,487
Investment Owned, at Fair Value	$ 6,526	$ 6,438
Investment, Identifier [Axis]: Mindbody, Inc., Senior Secured Loans, Two, due 2/14/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:MindbodyIncMember	mrcc:MindbodyIncMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	High Tech Industries Sector [Member]	High Tech Industries Sector [Member]
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR	LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Basis Spread, Variable Rate	7%	8.50%
Investment Interest Rate	11.73%
Investment, Interest Rate, Paid in Cash		8%
Investment, Interest Rate, Paid in Kind		1.50%
Investment, Acquisition Date	Sep. 22, 2021	Sep. 22, 2021
Investment Maturity Date	Feb. 14, 2025	Feb. 14, 2025
Investment Owned, Balance, Principal Amount	$ 674	$ 669
Investment Owned, at Fair Value	$ 673	$ 664
Investment, Identifier [Axis]: Minotaur Acquisition, Inc., Senior Secured Loans, due 3/27/2026
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:MinotaurAcquisitionIncMember	mrcc:MinotaurAcquisitionIncMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	mrcc:FireFinanceMember	mrcc:FireFinanceMember
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]	us-gaap:LondonInterbankOfferedRateLiborSwapRateMember
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Basis Spread, Variable Rate	4.75%	4.75%
Investment Interest Rate	9.17%	4.85%
Investment Maturity Date	Mar. 27, 2026	Mar. 27, 2026
Investment Owned, Balance, Principal Amount	$ 4,857	$ 4,912
Investment Owned, at Fair Value	$ 4,656	$ 4,894
Investment, Identifier [Axis]: Mnine Holdings Inc. (Revolver)
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	Mnine Holdings, Inc [ Member]
Investment Owned, at Fair Value	$ 214
Investment, Identifier [Axis]: Mnine Holdings, Inc. (Revolver), Senior Secured Loans
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	Mnine Holdings, Inc [ Member]	Mnine Holdings, Inc [ Member]
Investment, Identifier [Axis]: Mnine Holdings, Inc. (Revolver), Senior Secured Loans, due 12/30/2023
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	Mnine Holdings, Inc [ Member]
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	High Tech Industries Sector [Member]
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Basis Spread, Variable Rate	8%
Investment, Interest Rate, Paid in Cash	7.84%
Investment, Interest Rate, Paid in Kind	5%
Investment, Acquisition Date	Aug. 09, 2022
Investment Maturity Date	Dec. 30, 2023
Investment Owned, Balance, Principal Amount	$ 533
Investment Owned, at Fair Value	$ 214
Investment, Identifier [Axis]: Mnine Holdings, Inc., Equity Securities, Class B units
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	Mnine Holdings, Inc [ Member]	Mnine Holdings, Inc [ Member]
Investment, Type [Extensible Enumeration]	Equity Securities [Member]	Equity Securities [Member]
Investment, Industry Sector [Extensible Enumeration]	High Tech Industries	High Tech Industries
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Acquisition Date	Jun. 30, 2020	Jun. 30, 2020
Investment, Identifier [Axis]: Mnine Holdings, Inc., Senior Secured Loans Due 12/30/2022
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	Mnine Holdings, Inc [ Member]	Mnine Holdings, Inc [ Member]
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	High Tech Industries Sector [Member]	High Tech Industries
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]	LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Basis Spread, Variable Rate	8%	8%
Investment, Interest Rate, Paid in Cash	7.84%	4%
Investment, Interest Rate, Paid in Kind	5%	5%
Investment, Acquisition Date	Nov. 02, 2018	Nov. 02, 2018
Investment Maturity Date	Dec. 30, 2022	Dec. 30, 2022
Investment Owned, Balance, Principal Amount	$ 5,492	$ 5,193
Investment Owned, at Fair Value	$ 5,492	$ 5,771	12,356
Investment, Identifier [Axis]: Money Lion, Inc. ( Delayed Draw), Junior Secured Loans, due 3/24/2026
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:MoneyLionIncMember
Investment, Type [Extensible Enumeration]	Junior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Banking
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Basis Spread, Variable Rate	9.25%
Investment Interest Rate	14.07%
Investment, Acquisition Date	Mar. 25, 2022
Investment Maturity Date	Mar. 24, 2026
Investment Owned, Balance, Principal Amount	$ 1,500
Investment, Identifier [Axis]: Money Lion, Inc., Junior Secured Loans, due 3/24/2026
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:MoneyLionIncMember
Investment, Type [Extensible Enumeration]	Junior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Banking
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Basis Spread, Variable Rate	9.25%
Investment Interest Rate	14.07%
Investment, Acquisition Date	Mar. 25, 2022
Investment Maturity Date	Mar. 24, 2026
Investment Owned, Balance, Principal Amount	$ 5,250
Investment Owned, at Fair Value	$ 5,165
Investment, Identifier [Axis]: Money Lion, Inc., Junior Secured Loans, due 5/1/2023
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:MoneyLionIncMember	mrcc:MoneyLionIncMember
Investment, Type [Extensible Enumeration]	Junior Loans [Member]	Junior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Banking	Banking
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Prime Rate [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Basis Spread, Variable Rate	5.75%
Investment Interest Rate	13.25%	12%
Investment, Acquisition Date	Aug. 27, 2021	Aug. 27, 2021
Investment Maturity Date	May 01, 2023	May 01, 2023
Investment Owned, Balance, Principal Amount	$ 1,500	$ 1,500
Investment Owned, at Fair Value	$ 1,498	$ 1,522
Investment, Identifier [Axis]: N C B P Property, L L C, Senior Secured Loans, due 12/16/2022
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:NCBPPropertyLLCMember	mrcc:NCBPPropertyLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	FIRE Real Estate Sector [Member]	FIRE Real Estate Sector [Member]
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR	LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Basis Spread, Variable Rate	9.50%	9.50%
Investment Interest Rate	13.62%	10.50%
Investment, Acquisition Date	Dec. 18, 2020	Dec. 18, 2020
Investment Maturity Date	Jun. 16, 2023	Dec. 16, 2022
Investment Owned, Balance, Principal Amount	$ 1,950	$ 1,950
Investment Owned, at Fair Value	$ 1,955	$ 1,955
Investment, Identifier [Axis]: N E C B Collections, L L C ( Revolver), Senior Secured Loans
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	N E C B Collections, L L C [ Member]	N E C B Collections, L L C [ Member]
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Services: Consumer	Services: Consumer
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR	LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Basis Spread, Variable Rate	11%	11%
Investment, Interest Rate, Paid in Kind	14.61%	12%
Investment, Acquisition Date	Jun. 25, 2019	Jun. 25, 2019
Investment Owned, Balance, Principal Amount	$ 1,356	$ 1,356
Investment Owned, at Fair Value	$ 382	$ 632	834
Investment, Identifier [Axis]: N E C B Collections, L L C, Equity Securities
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	N E C B Collections, L L C [ Member]	N E C B Collections, L L C [ Member]
Investment, Type [Extensible Enumeration]		Equity Securities [Member]
Investment, Industry Sector [Extensible Enumeration]		Services: Consumer
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Acquisition Date		Jun. 21, 2019
Investment, Identifier [Axis]: N E C B Collections, L L C, Equity Securities, Common stock
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	N E C B Collections, L L C [ Member]
Investment, Type [Extensible Enumeration]	Equity Securities [Member]
Investment, Industry Sector [Extensible Enumeration]	Services: Consumer
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Acquisition Date	Jun. 21, 2019
Investment, Identifier [Axis]: NQ PE Project Colosseum Midco Inc. (Delayed Draw), Senior Secured Loans, Due 10/4/2028
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:NqPeProjectColosseumMidcoInc.Member
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Healthcare & Pharmaceuticals Sector [Member]
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Basis Spread, Variable Rate	6%
Investment Interest Rate	10.59%
Investment, Acquisition Date	Oct. 04, 2022
Investment Maturity Date	Oct. 04, 2028
Investment Owned, Balance, Principal Amount	$ 778
Investment, Identifier [Axis]: NQ PE Project Colosseum Midco Inc. (Revolver), Senior Secured Loans, Due 10/4/2028
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:NqPeProjectColosseumMidcoInc.Member
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Healthcare & Pharmaceuticals Sector [Member]
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Basis Spread, Variable Rate	6%
Investment Interest Rate	10.59%
Investment, Acquisition Date	Oct. 04, 2022
Investment Maturity Date	Oct. 04, 2028
Investment Owned, Balance, Principal Amount	$ 438
Investment, Identifier [Axis]: NQ PE Project Colosseum Midco Inc., Equity Securities, Common Units
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:NqPeProjectColosseumMidcoInc.Member
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Healthcare & Pharmaceuticals Sector [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Acquisition Date	Oct. 04, 2022
Investment Owned, at Fair Value	$ 327
Investment, Identifier [Axis]: NQ PE Project Colosseum Midco Inc., Senior Secured Loans, Due 10/4/2028
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:NqPeProjectColosseumMidcoInc.Member
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Healthcare & Pharmaceuticals Sector [Member]
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Basis Spread, Variable Rate	6%
Investment Interest Rate	10.59%
Investment, Acquisition Date	Oct. 04, 2022
Investment Maturity Date	Oct. 04, 2028
Investment Owned, Balance, Principal Amount	$ 3,500
Investment Owned, at Fair Value	$ 3,430
Investment, Identifier [Axis]: Nations Benefits L L C, Senior Secured Loans, One, Due 8/26/2027
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:NationsBenefitsLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Healthcare & Pharmaceuticals Sector [Member]
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Basis Spread, Variable Rate	7%
Investment Interest Rate	11.22%
Investment, Acquisition Date	Aug. 20, 2021
Investment Maturity Date	Aug. 26, 2027
Investment Owned, Balance, Principal Amount	$ 3,960
Investment Owned, at Fair Value	$ 4,039
Investment, Identifier [Axis]: Nations Benefits L L C, Senior Secured Loans, Two, Due 8/26/2027
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:NationsBenefitsLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Healthcare & Pharmaceuticals Sector [Member]
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Basis Spread, Variable Rate	7%
Investment Interest Rate	11.22%
Investment, Acquisition Date	Aug. 26, 2022
Investment Maturity Date	Aug. 26, 2027
Investment Owned, Balance, Principal Amount	$ 4,719
Investment Owned, at Fair Value	$ 4,813
Investment, Identifier [Axis]: Nations Benefits LLC Delayed Draw, Senior Secured Loans Due 8/26/2027
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:NationsBenefitsLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Healthcare & Pharmaceuticals Sector [Member]
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Basis Spread, Variable Rate	7%
Investment Interest Rate	11.22%
Investment, Acquisition Date	Aug. 26, 2022
Investment Maturity Date	Aug. 26, 2027
Investment Owned, Balance, Principal Amount	$ 5,089
Investment Owned, at Fair Value	$ 961
Investment, Identifier [Axis]: Nations Benefits, L L C ( Revolver), Senior Secured Loans, due 8/20/2026
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:NationsBenefitsLLCMember
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Healthcare & Pharmaceuticals Sector [Member]
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Basis Spread, Variable Rate		7%
Investment Interest Rate		8%
Investment, Acquisition Date		Aug. 20, 2021
Investment Maturity Date		Aug. 20, 2026
Investment Owned, Balance, Principal Amount		$ 445
Investment, Identifier [Axis]: Nations Benefits, L L C (Revolver), Senior Secured Loans, Due 8/26/2027
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:NationsBenefitsLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Healthcare & Pharmaceuticals Sector [Member]
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Basis Spread, Variable Rate	7%
Investment Interest Rate	11.42%
Investment, Acquisition Date	Aug. 20, 2021
Investment Maturity Date	Aug. 26, 2027
Investment Owned, Balance, Principal Amount	$ 2,222
Investment Owned, at Fair Value	$ 889
Investment, Identifier [Axis]: Nations Benefits, L L C, Equity Securities, One, Series B units
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:NationsBenefitsLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Healthcare & Pharmaceuticals Sector [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Interest Rate, Paid in Kind	5%
Investment, Acquisition Date	Aug. 20, 2021
Investment Owned, at Fair Value	$ 934
Investment, Identifier [Axis]: Nations Benefits, L L C, Equity Securities, Three, Series A units
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:NationsBenefitsLLCMember
Investment, Type [Extensible Enumeration]		Equity Securities [Member]
Investment, Industry Sector [Extensible Enumeration]		Healthcare & Pharmaceuticals
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Interest Rate, Paid in Kind		9%
Investment, Acquisition Date		Aug. 20, 2021
Investment Owned, at Fair Value		$ 714
Investment, Identifier [Axis]: Nations Benefits, L L C, Equity Securities, Two, common units
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:NationsBenefitsLLCMember	mrcc:NationsBenefitsLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Equity Securities [Member]
Investment, Industry Sector [Extensible Enumeration]	Healthcare & Pharmaceuticals Sector [Member]	Healthcare & Pharmaceuticals
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Acquisition Date	Aug. 20, 2021	Aug. 20, 2021
Investment Owned, at Fair Value	$ 66	$ 67
Investment, Identifier [Axis]: Nations Benefits, L L C, Senior Secured Loans, due 8/20/2026
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:NationsBenefitsLLCMember
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Healthcare & Pharmaceuticals Sector [Member]
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Basis Spread, Variable Rate		7%
Investment Interest Rate		8%
Investment, Acquisition Date		Aug. 20, 2021
Investment Maturity Date		Aug. 20, 2026
Investment Owned, Balance, Principal Amount		$ 4,000
Investment Owned, at Fair Value		$ 3,993
Investment, Identifier [Axis]: Natus Medical Incorporated, Senior Secured Loans, due 7/20/2029
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:NatusMedicalIncorporatedMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Healthcare & Pharmaceuticals Sector [Member]
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Basis Spread, Variable Rate	5.50%
Investment Interest Rate	8.68%
Investment Maturity Date	Jul. 20, 2029
Investment Owned, Balance, Principal Amount	$ 5,000
Investment Owned, at Fair Value	$ 4,650
Investment, Identifier [Axis]: Nearly Natural Inc. (Revolver) Senior Secured Loans due 3/31/2024
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:NearlyNaturalIncMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Wholesale
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Basis Spread, Variable Rate	11.50%
Investment, Interest Rate, Paid in Cash	12.32%
Investment, Interest Rate, Paid in Kind	4%
Investment, Acquisition Date	Dec. 15, 2017
Investment Maturity Date	Mar. 31, 2024
Investment Owned, Balance, Principal Amount	$ 2,505
Investment Owned, at Fair Value	$ 2,241
Investment, Identifier [Axis]: Nearly Natural Inc. Senior Secured Loans Four due 3/31/2024
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:NearlyNaturalIncMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Wholesale
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Basis Spread, Variable Rate	11.50%
Investment, Interest Rate, Paid in Cash	12.32%
Investment, Interest Rate, Paid in Kind	4%
Investment, Acquisition Date	Aug. 28, 2019
Investment Maturity Date	Mar. 31, 2024
Investment Owned, Balance, Principal Amount	$ 1,868
Investment Owned, at Fair Value	$ 1,672
Investment, Identifier [Axis]: Nearly Natural Inc. Senior Secured Loans One due 3/31/2024
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:NearlyNaturalIncMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Wholesale
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Basis Spread, Variable Rate	11.50%
Investment, Interest Rate, Paid in Cash	12.32%
Investment, Interest Rate, Paid in Kind	4%
Investment, Acquisition Date	Dec. 15, 2017
Investment Maturity Date	Mar. 31, 2024
Investment Owned, Balance, Principal Amount	$ 6,628
Investment Owned, at Fair Value	$ 5,931
Investment, Identifier [Axis]: Nearly Natural Inc. Senior Secured Loans Three due 3/31/2024
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:NearlyNaturalIncMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Wholesale
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Basis Spread, Variable Rate	11.50%
Investment, Interest Rate, Paid in Cash	12.32%
Investment, Interest Rate, Paid in Kind	4%
Investment, Acquisition Date	Feb. 16, 2021
Investment Maturity Date	Mar. 31, 2024
Investment Owned, Balance, Principal Amount	$ 3,115
Investment Owned, at Fair Value	$ 2,787
Investment, Identifier [Axis]: Nearly Natural Inc. Senior Secured Loans Two due 3/31/2024
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:NearlyNaturalIncMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Wholesale
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Basis Spread, Variable Rate	11.50%
Investment, Interest Rate, Paid in Cash	12.32%
Investment, Interest Rate, Paid in Kind	4%
Investment, Acquisition Date	Sep. 22, 2020
Investment Maturity Date	Mar. 31, 2024
Investment Owned, Balance, Principal Amount	$ 1,714
Investment Owned, at Fair Value	$ 1,534
Investment, Identifier [Axis]: Nearly Natural, Inc, Equity Securities, One, Class A units
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:NearlyNaturalIncMember	mrcc:NearlyNaturalInc.Member
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Equity Securities [Member]
Investment, Industry Sector [Extensible Enumeration]	Wholesale	Wholesale
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Acquisition Date	Dec. 15, 2017	Dec. 15, 2017
Investment Owned, at Fair Value		$ 69
Investment, Identifier [Axis]: Nearly Natural, Inc, Equity Securities, Two, Class A A units
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:NearlyNaturalIncMember	mrcc:NearlyNaturalInc.Member
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Equity Securities [Member]
Investment, Industry Sector [Extensible Enumeration]	Wholesale	Wholesale
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Acquisition Date	Aug. 27, 2021	Aug. 27, 2021
Investment Owned, at Fair Value		$ 5
Investment, Identifier [Axis]: Nearly Natural, Inc.( Revolver), Senior Secured loans, due 12/15/2022
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:NearlyNaturalIncMember
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Wholesale
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Basis Spread, Variable Rate		11.50%
Investment, Interest Rate, Paid in Cash		8.50%
Investment, Interest Rate, Paid in Kind		4%
Investment, Acquisition Date		Dec. 15, 2017
Investment Maturity Date		Dec. 15, 2022
Investment Owned, Balance, Principal Amount		$ 2,430
Investment Owned, at Fair Value		$ 2,400
Investment, Identifier [Axis]: Nearly Natural, Inc., Senior Secured loans, Four, due 12/15/2022
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:NearlyNaturalIncMember
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Wholesale
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Basis Spread, Variable Rate		11.50%
Investment, Interest Rate, Paid in Cash		8.50%
Investment, Interest Rate, Paid in Kind		4%
Investment, Acquisition Date		Aug. 28, 2019
Investment Maturity Date		Dec. 15, 2022
Investment Owned, Balance, Principal Amount		$ 1,859
Investment Owned, at Fair Value		$ 1,836
Investment, Identifier [Axis]: Nearly Natural, Inc., Senior Secured loans, One, due 12/15/2022
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:NearlyNaturalIncMember
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Wholesale
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Basis Spread, Variable Rate		11.50%
Investment, Interest Rate, Paid in Cash		8.50%
Investment, Interest Rate, Paid in Kind		4%
Investment, Acquisition Date		Dec. 15, 2017
Investment Maturity Date		Dec. 15, 2022
Investment Owned, Balance, Principal Amount		$ 6,601
Investment Owned, at Fair Value		$ 6,520
Investment, Identifier [Axis]: Nearly Natural, Inc., Senior Secured loans, Three, due 12/15/2022
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:NearlyNaturalIncMember
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Wholesale
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Basis Spread, Variable Rate		11.50%
Investment, Interest Rate, Paid in Cash		8.50%
Investment, Interest Rate, Paid in Kind		4%
Investment, Acquisition Date		Sep. 22, 2020
Investment Maturity Date		Dec. 15, 2022
Investment Owned, Balance, Principal Amount		$ 1,706
Investment Owned, at Fair Value		$ 1,685
Investment, Identifier [Axis]: Nearly Natural, Inc., Senior Secured loans, Two, due 12/15/2022
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:NearlyNaturalIncMember
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Wholesale
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Basis Spread, Variable Rate		11.50%
Investment, Interest Rate, Paid in Cash		8.50%
Investment, Interest Rate, Paid in Kind		4%
Investment, Acquisition Date		Feb. 16, 2021
Investment Maturity Date		Dec. 15, 2022
Investment Owned, Balance, Principal Amount		$ 3,099
Investment Owned, at Fair Value		$ 3,061
Investment, Identifier [Axis]: Newforma, Inc. ( Revolver), Senior Secured Loans, due 6/30/2022
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:NewformaIncMember
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		High Tech Industries Sector [Member]
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Basis Spread, Variable Rate		5.50%
Investment Interest Rate		6.50%
Investment, Acquisition Date		Jun. 30, 2017
Investment Maturity Date		Jun. 30, 2022
Investment Owned, Balance, Principal Amount		$ 1,250
Investment, Identifier [Axis]: Newforma, Inc. ( Revolver) (f), Senior Secured Loans, due 3/31/2023
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:NewformaIncMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	High Tech Industries Sector [Member]
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Basis Spread, Variable Rate	5.50%
Investment Interest Rate	10.23%
Investment, Acquisition Date	Jun. 30, 2017
Investment Maturity Date	Mar. 31, 2023
Investment Owned, Balance, Principal Amount	$ 1,250
Investment, Identifier [Axis]: Newforma, Inc., Senior Secured Loans, due 3/31/2023
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:NewformaIncMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	High Tech Industries Sector [Member]
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Basis Spread, Variable Rate	5.50%
Investment Interest Rate	10.23%
Investment, Acquisition Date	Jun. 30, 2017
Investment Maturity Date	Mar. 31, 2023
Investment Owned, Balance, Principal Amount	$ 938
Investment Owned, at Fair Value	$ 938
Investment, Identifier [Axis]: Newforma, Inc., Senior Secured Loans, due 6/30/2022
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:NewformaIncMember
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		High Tech Industries Sector [Member]
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Basis Spread, Variable Rate		5.50%
Investment Interest Rate		6.50%
Investment, Acquisition Date		Jun. 30, 2017
Investment Maturity Date		Jun. 30, 2022
Investment Owned, Balance, Principal Amount		$ 3,890
Investment Owned, at Fair Value		$ 3,890
Investment, Identifier [Axis]: North Haven Spartan U S Holdco, L L C, Senior Secured Loans, due 6/6/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:NorthHavenSpartanUSHoldcoLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Hotels, Gaming & Leisure
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Basis Spread, Variable Rate	6.25%
Investment Interest Rate	10.71%
Investment Maturity Date	Jun. 06, 2025
Investment Owned, Balance, Principal Amount	$ 2,280
Investment Owned, at Fair Value	$ 2,202
Investment, Identifier [Axis]: North Haven U S H C Acquisition, Inc. ( Delayed Draw), Senior Secured Loans, due, 10/30/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:NorthHavenUSHCAcquisitionIncMember	mrcc:NorthHavenUSHCAcquisitionIncMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Media: Advertising, Printing & Publishing	Media: Advertising, Printing & Publishing
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]	us-gaap:LondonInterbankOfferedRateLiborSwapRateMember
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Basis Spread, Variable Rate	6.50%	6%
Investment Interest Rate	11.18%	7%
Investment, Acquisition Date	Jul. 29, 2022	Sep. 03, 2021
Investment Maturity Date	Oct. 30, 2025	Oct. 30, 2025
Investment Owned, Balance, Principal Amount	$ 1,056	$ 1,441
Investment Owned, at Fair Value		$ 487
Investment, Identifier [Axis]: North Haven U S H C Acquisition, Inc. ( Revolver), Senior Secured Loans, due, 10/30/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:NorthHavenUSHCAcquisitionIncMember	mrcc:NorthHavenUSHCAcquisitionIncMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Media: Advertising, Printing & Publishing	Media: Advertising, Printing & Publishing
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]	us-gaap:LondonInterbankOfferedRateLiborSwapRateMember
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Basis Spread, Variable Rate	6.50%	6%
Investment Interest Rate	11.13%	7%
Investment, Acquisition Date	Oct. 30, 2020	Oct. 30, 2020
Investment Maturity Date	Oct. 30, 2025	Oct. 30, 2025
Investment Owned, Balance, Principal Amount	$ 416	$ 240
Investment Owned, at Fair Value	$ 187
Investment, Identifier [Axis]: North Haven U S H C Acquisition, Inc., Senior Secured Loans, due, One, 10/30/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:NorthHavenUSHCAcquisitionIncMember	mrcc:NorthHavenUSHCAcquisitionIncMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Media: Advertising, Printing & Publishing	Media: Advertising, Printing & Publishing
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]	us-gaap:LondonInterbankOfferedRateLiborSwapRateMember
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Basis Spread, Variable Rate	6.50%	6%
Investment Interest Rate	11.18%	7%
Investment, Acquisition Date	Oct. 30, 2020	Oct. 30, 2020
Investment Maturity Date	Oct. 30, 2025	Oct. 30, 2025
Investment Owned, Balance, Principal Amount	$ 2,450	$ 2,475
Investment Owned, at Fair Value	$ 2,448	$ 2,475
Investment, Identifier [Axis]: North Haven U S H C Acquisition, Inc., Senior Secured Loans, due, Two, 10/30/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:NorthHavenUSHCAcquisitionIncMember	mrcc:NorthHavenUSHCAcquisitionIncMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Media: Advertising, Printing & Publishing	Media: Advertising, Printing & Publishing
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]	us-gaap:LondonInterbankOfferedRateLiborSwapRateMember
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Basis Spread, Variable Rate	6.25%	6%
Investment Interest Rate	10.41%	7%
Investment, Acquisition Date	Jul. 29, 2022	Mar. 12, 2021
Investment Maturity Date	Oct. 30, 2025	Oct. 30, 2025
Investment Owned, Balance, Principal Amount	$ 2,592	$ 717
Investment Owned, at Fair Value	$ 2,575	$ 717
Investment, Identifier [Axis]: North Haven USHC Acquisition, Inc, Senior Secured Loans, Four, due 10/30/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:NorthHavenUSHCAcquisitionIncMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Media: Advertising, Printing & Publishing
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Basis Spread, Variable Rate	6.50%
Investment Interest Rate	11.18%
Investment, Acquisition Date	Sep. 03, 2021
Investment Maturity Date	Oct. 30, 2025
Investment Owned, Balance, Principal Amount	$ 1,434
Investment Owned, at Fair Value	$ 1,433
Investment, Identifier [Axis]: North Haven USHC Acquisition, Inc, Senior Secured Loans, Three, due 10/30/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:NorthHavenUSHCAcquisitionIncMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Media: Advertising, Printing & Publishing
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Basis Spread, Variable Rate	6.50%
Investment Interest Rate	11.18%
Investment, Acquisition Date	Mar. 12, 2021
Investment Maturity Date	Oct. 30, 2025
Investment Owned, Balance, Principal Amount	$ 710
Investment Owned, at Fair Value	$ 709
Investment, Identifier [Axis]: Oceana Australian Fixed Income Trust, Senior Secured Loans, One, due 6/29/2026
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:OceanaAustralianFixedIncomeTrustMember	mrcc:OceanaAustralianFixedIncomeTrustMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	mrcc:FireFinanceMember	mrcc:FireFinanceMember
Investment, Issuer Geographic Region [Extensible Enumeration]	Non-US [Member]	Non-US [Member]
Investment Interest Rate	10.75%	10.75%
Investment, Acquisition Date	Jun. 29, 2021	Jun. 29, 2021
Investment Maturity Date	Jun. 29, 2026	Jun. 29, 2026
Investment Owned, Balance, Principal Amount	$ 3,084	$ 3,288
Investment Owned, at Fair Value	$ 3,084	$ 3,288
Investment, Identifier [Axis]: Oceana Australian Fixed Income Trust, Senior Secured Loans, Two, due 2/25/2026
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:OceanaAustralianFixedIncomeTrustMember	mrcc:OceanaAustralianFixedIncomeTrustMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	mrcc:FireFinanceMember	mrcc:FireFinanceMember
Investment, Issuer Geographic Region [Extensible Enumeration]	Non-US [Member]	Non-US [Member]
Investment Interest Rate	11.50%	11.50%
Investment, Acquisition Date	Feb. 25, 2021	Feb. 25, 2021
Investment Maturity Date	Feb. 25, 2026	Feb. 25, 2026
Investment Owned, Balance, Principal Amount	$ 7,321	$ 7,805
Investment Owned, at Fair Value	$ 7,321	$ 7,805
Investment, Identifier [Axis]: Offen, Inc., Senior Secured Loans, One, due 6/22/2026
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:OffenIncMember	mrcc:OffenIncMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	us-gaap-supplement:EnergySectorMember	Utilities, Oil & Gas Sector [Member]
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR	LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Basis Spread, Variable Rate		5%
Investment Interest Rate		5.10%
Investment Maturity Date		Jun. 22, 2026
Investment Owned, Balance, Principal Amount		$ 2,388
Investment Owned, at Fair Value		$ 2,387
Investment, Identifier [Axis]: Offen, Inc., Senior Secured Loans, Two, due 6/22/2026
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:OffenIncMember	mrcc:OffenIncMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	us-gaap-supplement:EnergySectorMember	Utilities, Oil & Gas Sector [Member]
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR	LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Basis Spread, Variable Rate		5%
Investment Interest Rate		5.10%
Investment Maturity Date		Jun. 22, 2026
Investment Owned, Balance, Principal Amount		$ 876
Investment Owned, at Fair Value		$ 876
Investment, Identifier [Axis]: Onit, Inc., Unitranche Secured Loans, due 5/2/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:OnitInc.Member	mrcc:OnitInc.Member
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Unitranche Debt [Member]
Investment, Industry Sector [Extensible Enumeration]	Services: Business	Services: Business
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]	LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Basis Spread, Variable Rate	7.25%	7.25%
Investment Interest Rate	12.30%	8.25%
Investment, Acquisition Date	Dec. 20, 2021	Dec. 20, 2021
Investment Maturity Date	May 02, 2025	May 02, 2025
Investment Owned, Balance, Principal Amount	$ 1,680	$ 1,500
Investment Owned, at Fair Value	$ 1,663	$ 1,472
Investment, Identifier [Axis]: Orbit Purchaser L L C, Senior Secured Loans, One, due 10/21/2024
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:OrbitPurchaserLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Services: Business
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Basis Spread, Variable Rate	4.50%
Investment Interest Rate	9.23%
Investment Maturity Date	Oct. 21, 2024
Investment Owned, Balance, Principal Amount	$ 2,406
Investment Owned, at Fair Value	$ 2,190
Investment, Identifier [Axis]: Orbit Purchaser L L C, Senior Secured Loans, Three, due 10/21/2024
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:OrbitPurchaserLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Services: Business
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Basis Spread, Variable Rate	4.50%
Investment Interest Rate	9.23%
Investment Maturity Date	Oct. 21, 2024
Investment Owned, Balance, Principal Amount	$ 543
Investment Owned, at Fair Value	$ 494
Investment, Identifier [Axis]: Orbit Purchaser L L C, Senior Secured Loans, Two, due 10/21/2024
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:OrbitPurchaserLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Services: Business
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Basis Spread, Variable Rate	4.50%
Investment Interest Rate	9.23%
Investment Maturity Date	Oct. 21, 2024
Investment Owned, Balance, Principal Amount	$ 1,858
Investment Owned, at Fair Value	$ 1,691
Investment, Identifier [Axis]: Output Services Group Inc. Senior Secured Loans Due 6/29/2026
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:OutputServicesGroupIncMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Services: Business
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Investment, Basis Spread, Variable Rate	6.75%
Investment, Interest Rate, Paid in Kind	1.50%
Investment Maturity Date	Jun. 29, 2026
Investment Owned, Balance, Principal Amount	$ 4,807
Investment Owned, at Fair Value	$ 3,275
Investment, Identifier [Axis]: Output Services Group, Inc., Senior Secured Loans, due 3/27/2024
Schedule of Investments [Line Items]
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Services: Business
Investment, Interest Rate, Paid in Cash	9.80%
Investment, Identifier [Axis]: P H Beauty Holdings I I I, I N C., Senior Secured Loans, due 9/26/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:PHBeautyHoldingsIIIINCMember	mrcc:PHBeautyHoldingsIIIINCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Consumer Sector, Non- Durable [ Member]	Consumer Sector, Non- Durable [ Member]
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR	LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Basis Spread, Variable Rate		5%
Investment Interest Rate		5.18%
Investment Maturity Date		Sep. 26, 2025
Investment Owned, Balance, Principal Amount		$ 2,418
Investment Owned, at Fair Value		$ 2,284
Investment, Identifier [Axis]: P K S Holdings, L L C, Equity Securities, Four, Preferred units
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:PKSHoldingsLLCMember	mrcc:PKSHoldingsLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Equity Securities [Member]
Investment, Industry Sector [Extensible Enumeration]	FIRE: Finance	FIRE: Finance
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment Interest Rate	12%
Investment, Interest Rate, Paid in Kind		12%
Investment, Acquisition Date	Nov. 30, 2017	Nov. 30, 2017
Investment Owned, at Fair Value	$ 46	$ 34
Investment, Identifier [Axis]: P K S Holdings, L L C, Equity Securities, One, Preferred units
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:PKSHoldingsLLCMember	mrcc:PKSHoldingsLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Equity Securities [Member]
Investment, Industry Sector [Extensible Enumeration]	FIRE: Finance	FIRE: Finance
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment Interest Rate	12%
Investment, Interest Rate, Paid in Kind		12%
Investment, Acquisition Date	Nov. 30, 2017	Nov. 30, 2017
Investment Owned, at Fair Value	$ 298	$ 219
Investment, Identifier [Axis]: P K S Holdings, L L C, Equity Securities, Three, Preferred units
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:PKSHoldingsLLCMember	mrcc:PKSHoldingsLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Equity Securities [Member]
Investment, Industry Sector [Extensible Enumeration]	FIRE: Finance	FIRE: Finance
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment Interest Rate	12%
Investment, Interest Rate, Paid in Kind		12%
Investment, Acquisition Date	Nov. 30, 2017	Nov. 30, 2017
Investment Owned, at Fair Value	$ 7	$ 5
Investment, Identifier [Axis]: P K S Holdings, L L C, Equity Securities, Two, Preferred units
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:PKSHoldingsLLCMember	mrcc:PKSHoldingsLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Equity Securities [Member]
Investment, Industry Sector [Extensible Enumeration]	FIRE: Finance	FIRE: Finance
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment Interest Rate	12%
Investment, Interest Rate, Paid in Kind		12%
Investment, Acquisition Date	Nov. 30, 2017	Nov. 30, 2017
Investment Owned, at Fair Value	$ 46	$ 34
Investment, Identifier [Axis]: P V H C Holding Corp, Senior Secured Loans, due 8/5/2024
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:PVHCHoldingCorpMember	mrcc:PVHCHoldingCorpMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Container and Packaging Sector [Member]	Container and Packaging Sector [Member]
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR	LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Basis Spread, Variable Rate		4.75%
Investment Interest Rate		5.75%
Investment Maturity Date		Aug. 05, 2024
Investment Owned, Balance, Principal Amount		$ 3,217
Investment Owned, at Fair Value		$ 2,976
Investment, Identifier [Axis]: Panda Acquisition, LLC, Senior Secured Loans, due 10/18/2028
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:PandaAcquisitionLlcMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Automotive
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Basis Spread, Variable Rate	6.35%
Investment Interest Rate	10.28%
Investment, Acquisition Date	Dec. 20, 2022
Investment Maturity Date	Oct. 18, 2028
Investment Owned, Balance, Principal Amount	$ 4,500
Investment Owned, at Fair Value	$ 3,690
Investment, Identifier [Axis]: Paragon Healthcare Inc. Senior Secured Loan Due 1/19/2027
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:ParagonHealthcareIncMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Healthcare & Pharmaceuticals Sector [Member]
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Basis Spread, Variable Rate	5.75%
Investment Interest Rate	9.81%
Investment Maturity Date	Jan. 19, 2027
Investment Owned, Balance, Principal Amount	$ 2,127
Investment Owned, at Fair Value	$ 2,109
Investment, Identifier [Axis]: Paragon HealthcareInc. Delayed Draw Senior Secured Loans due 1/19/2027
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:ParagonHealthcareIncMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Healthcare & Pharmaceuticals Sector [Member]
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Basis Spread, Variable Rate	5.75%
Investment Interest Rate	10.06%
Investment Maturity Date	Jan. 19, 2027
Investment Owned, Balance, Principal Amount	$ 366
Investment Owned, at Fair Value	$ 242
Investment, Identifier [Axis]: Paragon HealthcareInc. Revolver Senior Secured Loan Due 1/19/2027
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:ParagonHealthcareIncMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Healthcare & Pharmaceuticals Sector [Member]
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Basis Spread, Variable Rate	5.75%
Investment Interest Rate	10.26%
Investment Maturity Date	Jan. 19, 2027
Investment Owned, Balance, Principal Amount	$ 490
Investment Owned, at Fair Value	$ 61
Investment, Identifier [Axis]: Phoenix Chemical Holding Company L L C (fka Polymer Solutions Group), Senior Secured Loans, due 1/3/2023
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:PhoenixChemicalHoldingCompanyLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Chemicals, Plastics & Rubber
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Identifier [Axis]: Planful Inc. Senior Secured Loans, One, due 12/30/2024
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:PlanfulIncMember
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		High Tech Industries Sector [Member]
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Basis Spread, Variable Rate		6.50%
Investment Interest Rate		7.50%
Investment, Acquisition Date		Dec. 28, 2018
Investment Maturity Date		Dec. 30, 2024
Investment Owned, Balance, Principal Amount		$ 9,500
Investment Owned, at Fair Value		$ 9,472
Investment, Identifier [Axis]: Planful Inc. Senior Secured Loans, Two, due 12/30/2024
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:PlanfulIncMember
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		High Tech Industries Sector [Member]
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Basis Spread, Variable Rate		6.50%
Investment Interest Rate		7.50%
Investment, Acquisition Date		Jan. 11, 2021
Investment Maturity Date		Dec. 30, 2024
Investment Owned, Balance, Principal Amount		$ 1,325
Investment Owned, at Fair Value		$ 1,322
Investment, Identifier [Axis]: Planful, Inc, Equity Securities, Class A units
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:PlanfulIncMember
Investment, Type [Extensible Enumeration]		Equity Securities [Member]
Investment, Industry Sector [Extensible Enumeration]		High Tech Industries Sector [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Interest Rate, Paid in Kind		8%
Investment, Acquisition Date		Dec. 28, 2018
Investment Owned, at Fair Value		$ 557
Investment, Identifier [Axis]: Planful, Inc, Senior Secured Loans, Four, due 12/28/2026
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:PlanfulIncMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	High Tech Industries Sector [Member]
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Basis Spread, Variable Rate	6.50%
Investment Interest Rate	10.32%
Investment, Acquisition Date	Feb. 11, 2022
Investment Maturity Date	Dec. 28, 2026
Investment Owned, Balance, Principal Amount	$ 884
Investment Owned, at Fair Value	$ 878
Investment, Identifier [Axis]: Planful, Inc, Senior Secured Loans, One, due 12/28/2026
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:PlanfulIncMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	High Tech Industries Sector [Member]
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Basis Spread, Variable Rate	6.50%
Investment Interest Rate	10.32%
Investment, Acquisition Date	Dec. 28, 2018
Investment Maturity Date	Dec. 28, 2026
Investment Owned, Balance, Principal Amount	$ 9,500
Investment Owned, at Fair Value	$ 9,443
Investment, Identifier [Axis]: Planful, Inc, Senior Secured Loans, Three, due 12/28/2026
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:PlanfulIncMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	High Tech Industries Sector [Member]
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Basis Spread, Variable Rate	6.50%
Investment Interest Rate	10.32%
Investment, Acquisition Date	Jan. 11, 2021
Investment Maturity Date	Dec. 28, 2026
Investment Owned, Balance, Principal Amount	$ 1,325
Investment Owned, at Fair Value	$ 1,318
Investment, Identifier [Axis]: Planful, Inc, Senior Secured Loans, Two, due 12/28/2026
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:PlanfulIncMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	High Tech Industries Sector [Member]
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Basis Spread, Variable Rate	6.50%
Investment Interest Rate	9.90%
Investment, Acquisition Date	Sep. 12, 2022
Investment Maturity Date	Dec. 28, 2026
Investment Owned, Balance, Principal Amount	$ 530
Investment Owned, at Fair Value	$ 527
Investment, Identifier [Axis]: Planful, Inc. ( Revolver), Senior Secured Loans, due 12/28/2026
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:PlanfulIncMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	High Tech Industries Sector [Member]
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Basis Spread, Variable Rate	6.50%
Investment Interest Rate	10.32%
Investment, Acquisition Date	Dec. 28, 2018
Investment Maturity Date	Dec. 28, 2026
Investment Owned, Balance, Principal Amount	$ 442
Investment Owned, at Fair Value	$ 439
Investment, Identifier [Axis]: Planful, Inc. ( Revolver), Senior Secured Loans, due 12/30/2024
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:PlanfulIncMember
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		High Tech Industries Sector [Member]
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Basis Spread, Variable Rate		6.50%
Investment Interest Rate		7.50%
Investment, Acquisition Date		Dec. 28, 2018
Investment Maturity Date		Dec. 30, 2024
Investment Owned, Balance, Principal Amount		$ 442
Investment Owned, at Fair Value		$ 88
Investment, Identifier [Axis]: Planful, Inc., Equity Securities, Class A Units
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:PlanfulInc.Member
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	High Tech Industries Sector [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Interest Rate, Paid in Kind	8%
Investment, Acquisition Date	Dec. 28, 2018
Investment Owned, at Fair Value	$ 563
Investment, Identifier [Axis]: Polychem Acquisition, L L C, Senior Secured Loans, due 3/17/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:PolychemAcquisitionLLCMember	mrcc:PolychemAcquisitionLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Container and Packaging Sector [Member]	Container and Packaging Sector [Member]
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR	LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Basis Spread, Variable Rate		5%
Investment Interest Rate		5.50%
Investment Maturity Date		Mar. 17, 2025
Investment Owned, Balance, Principal Amount		$ 2,918
Investment Owned, at Fair Value		$ 2,917
Investment, Identifier [Axis]: Polymer Solutions Group Senior Secured Loans Due 1/3/2023
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:PhoenixChemicalHoldingCompanyLLCMember
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Chemicals, Plastics & Rubber
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Basis Spread, Variable Rate		7%
Investment Interest Rate		8%
Investment Maturity Date		Jan. 03, 2023
Investment Owned, Balance, Principal Amount		$ 1,178
Investment Owned, at Fair Value		$ 1,169
Investment, Identifier [Axis]: Port Townsend Holdings Company, Inc. and Crown Corrugated Company, Senior Secured Loans, due 4/3/2024
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:PortTownsendHoldingsCompanyInc.andCrownCorrugatedCompanyMember
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Container and Packaging Sector [Member]
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Basis Spread, Variable Rate		6.75%
Investment, Interest Rate, Paid in Cash		5.75%
Investment, Interest Rate, Paid in Kind		2%
Investment Maturity Date		Apr. 03, 2024
Investment Owned, Balance, Principal Amount		$ 4,751
Investment Owned, at Fair Value		$ 4,238
Investment, Identifier [Axis]: Priority Ambulance, L L C, Unitranche Secured Loans, Four, due 4/12/2022
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:PriorityAmbulanceLLCMember
Investment, Type [Extensible Enumeration]		Unitranche Debt [Member]
Investment, Industry Sector [Extensible Enumeration]		Healthcare & Pharmaceuticals
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Basis Spread, Variable Rate		6.50%
Investment Interest Rate		7.50%
Investment, Acquisition Date		Oct. 22, 2020
Investment Maturity Date		Apr. 12, 2022
Investment Owned, Balance, Principal Amount		$ 990
Investment Owned, at Fair Value		$ 989
Investment, Identifier [Axis]: Priority Ambulance, L L C, Unitranche Secured Loans, One, due 4/12/2022
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:PriorityAmbulanceLLCMember
Investment, Type [Extensible Enumeration]		Unitranche Debt [Member]
Investment, Industry Sector [Extensible Enumeration]		Healthcare & Pharmaceuticals
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Basis Spread, Variable Rate		6.50%
Investment Interest Rate		7.50%
Investment, Acquisition Date		Jul. 18, 2018
Investment Maturity Date		Apr. 12, 2022
Investment Owned, Balance, Principal Amount		$ 10,015
Investment Owned, at Fair Value		$ 10,010
Investment, Identifier [Axis]: Priority Ambulance, L L C, Unitranche Secured Loans, Three, due 4/12/2022
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:PriorityAmbulanceLLCMember
Investment, Type [Extensible Enumeration]		Unitranche Debt [Member]
Investment, Industry Sector [Extensible Enumeration]		Healthcare & Pharmaceuticals
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Basis Spread, Variable Rate		6.50%
Investment Interest Rate		7.50%
Investment, Acquisition Date		Dec. 13, 2018
Investment Maturity Date		Apr. 12, 2022
Investment Owned, Balance, Principal Amount		$ 655
Investment Owned, at Fair Value		$ 655
Investment, Identifier [Axis]: Priority Ambulance, L L C, Unitranche Secured Loans, Two, due 4/12/2022
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:PriorityAmbulanceLLCMember
Investment, Type [Extensible Enumeration]		Unitranche Debt [Member]
Investment, Industry Sector [Extensible Enumeration]		Healthcare & Pharmaceuticals
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Basis Spread, Variable Rate		6.50%
Investment Interest Rate		7.50%
Investment, Acquisition Date		Apr. 12, 2017
Investment Maturity Date		Apr. 12, 2022
Investment Owned, Balance, Principal Amount		$ 1,253
Investment Owned, at Fair Value		$ 1,253
Investment, Identifier [Axis]: Prototek LLC (Delayed Draw), Due 12/8/2027
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:PrototekLlcMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Services: Business
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Basis Spread, Variable Rate	6.50%
Investment Interest Rate	10.83%
Investment, Acquisition Date	Dec. 08, 2022
Investment Maturity Date	Dec. 08, 2027
Investment Owned, Balance, Principal Amount	$ 768
Investment, Identifier [Axis]: Prototek LLC (Revolver), Due,12/8/2027
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:PrototekLlcMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Services: Business
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Basis Spread, Variable Rate	6.50%
Investment Interest Rate	10.83%
Investment, Acquisition Date	Dec. 08, 2022
Investment Maturity Date	Dec. 08, 2027
Investment Owned, Balance, Principal Amount	$ 576
Investment, Identifier [Axis]: Prototek LLC, Due 12/8/2027
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:PrototekLlcMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Services: Business
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Basis Spread, Variable Rate	6.50%
Investment Interest Rate	10.83%
Investment, Acquisition Date	Dec. 08, 2022
Investment Maturity Date	Dec. 08, 2027
Investment Owned, Balance, Principal Amount	$ 2,500
Investment Owned, at Fair Value	$ 2,425
Investment, Identifier [Axis]: Quest Resource Management Group, L L C ( Delayed Draw), Senior Secured Loans, due 10/20/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:QuestResourceManagementGroupLLCMember	mrcc:QuestResourceManagementGroupLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Environmental Industries	Environmental Industries
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR	LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Basis Spread, Variable Rate	6.50%	6.50%
Investment Interest Rate	10.62%	7.50%
Investment, Acquisition Date	Dec. 07, 2021	Dec. 07, 2021
Investment Maturity Date	Oct. 20, 2025	Oct. 20, 2025
Investment Owned, Balance, Principal Amount	$ 1,772	$ 1,778
Investment Owned, at Fair Value	$ 381
Investment, Identifier [Axis]: Quest Resource Management Group, L L C, Equity Securites, Two, Warrants
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:QuestResourceManagementGroupLLCMember	mrcc:QuestResourceManagementGroupLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Equity Securities [Member]
Investment, Industry Sector [Extensible Enumeration]	Environmental Industries	Environmental Industries
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Acquisition Date	Oct. 19, 2021	Oct. 19, 2021
Investment Maturity Date	Mar. 19, 2028	Mar. 19, 2028
Investment Owned, at Fair Value	$ 147	$ 169
Investment, Identifier [Axis]: Quest Resource Management Group, L L C, Equity Securities, One, Warrants
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:QuestResourceManagementGroupLLCMember	mrcc:QuestResourceManagementGroupLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Equity Securities [Member]
Investment, Industry Sector [Extensible Enumeration]	Environmental Industries	Environmental Industries
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Acquisition Date	Oct. 19, 2020	Oct. 19, 2020
Investment Maturity Date	Mar. 19, 2028	Mar. 19, 2028
Investment Owned, at Fair Value	$ 210	$ 286
Investment, Identifier [Axis]: Quest Resource Management Group, L L C, Senior Secured Loans, One, due 10/20/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:QuestResourceManagementGroupLLCMember	mrcc:QuestResourceManagementGroupLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Environmental Industries	Environmental Industries
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR	LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Basis Spread, Variable Rate	6.50%	6.50%
Investment Interest Rate	10.62%	7.50%
Investment, Acquisition Date	Oct. 19, 2020	Oct. 19, 2020
Investment Maturity Date	Oct. 20, 2025	Oct. 20, 2025
Investment Owned, Balance, Principal Amount	$ 972	$ 990
Investment Owned, at Fair Value	$ 972	$ 989
Investment, Identifier [Axis]: Quest Resource Management Group, L L C, Senior Secured Loans, Three, due 10/20/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:QuestResourceManagementGroupLLCMember	mrcc:QuestResourceManagementGroupLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Environmental Industries	Environmental Industries
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR	LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Basis Spread, Variable Rate	6.50%	6.50%
Investment Interest Rate	10.62%	7.50%
Investment, Acquisition Date	Dec. 07, 2021	Dec. 07, 2021
Investment Maturity Date	Oct. 20, 2025	Oct. 20, 2025
Investment Owned, Balance, Principal Amount	$ 3,796	$ 3,856
Investment Owned, at Fair Value	$ 3,781	$ 3,853
Investment, Identifier [Axis]: Quest Resource Management Group, L L C, Senior Secured Loans, Two, due 10/20/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:QuestResourceManagementGroupLLCMember	mrcc:QuestResourceManagementGroupLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Environmental Industries	Environmental Industries
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR	LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Basis Spread, Variable Rate	6.50%	6.50%
Investment Interest Rate	10.62%	7.50%
Investment, Acquisition Date	Oct. 19, 2020	Oct. 19, 2020
Investment Maturity Date	Oct. 20, 2025	Oct. 20, 2025
Investment Owned, Balance, Principal Amount	$ 1,068	$ 1,087
Investment Owned, at Fair Value	$ 1,067	$ 1,086
Investment, Identifier [Axis]: Radiology Partners, Inc., Senior Secured Loans, due 7/9/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:RadiologyPartnersIncMember	mrcc:RadiologyPartnersIncMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Healthcare & Pharmaceuticals Sector [Member]	Healthcare & Pharmaceuticals Sector [Member]
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR	LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Basis Spread, Variable Rate	4.25%	4.25%
Investment Interest Rate	8.64%	4.35%
Investment Maturity Date	Jul. 09, 2025	Jul. 09, 2025
Investment Owned, Balance, Principal Amount	$ 4,760	$ 4,760
Investment Owned, at Fair Value	$ 4,018	$ 4,700
Investment, Identifier [Axis]: Recorded Future, Inc, Equity Securities, Class A units
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	Recorded Future, Inc [ Member]	Recorded Future, Inc [ Member]
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Equity Securities [Member]
Investment, Industry Sector [Extensible Enumeration]	High Tech Industries Sector [Member]	High Tech Industries Sector [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Acquisition Date	Jul. 03, 2019	Jul. 03, 2019
Investment Owned, at Fair Value	$ 225	$ 203
Investment, Identifier [Axis]: Recycled Plastics Industries, L L C ( Revolver), Senior Secured Loans, due 8/4/2026
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:RecycledPlasticsIndustriesLLCMember	mrcc:RecycledPlasticsIndustriesLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Consumer Goods: Durable	Consumer Goods: Durable
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR	LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Basis Spread, Variable Rate	6.75%	6.75%
Investment Interest Rate	10.87%	7.75%
Investment, Acquisition Date	Aug. 04, 2021	Aug. 04, 2021
Investment Maturity Date	Aug. 04, 2026	Aug. 04, 2026
Investment Owned, Balance, Principal Amount	$ 473	$ 473
Investment Owned, at Fair Value		$ 142
Investment, Identifier [Axis]: Recycled Plastics Industries, L L C, Senior Secured Loans, due 8/4/2026
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:RecycledPlasticsIndustriesLLCMember	mrcc:RecycledPlasticsIndustriesLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Consumer Goods: Durable	Consumer Goods: Durable
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR	LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Basis Spread, Variable Rate	6.75%	6.75%
Investment Interest Rate	10.87%	7.75%
Investment, Acquisition Date	Aug. 04, 2021	Aug. 04, 2021
Investment Maturity Date	Aug. 04, 2026	Aug. 04, 2026
Investment Owned, Balance, Principal Amount	$ 3,456	$ 3,491
Investment Owned, at Fair Value	$ 3,370	$ 3,491
Investment, Identifier [Axis]: Red Zone Robotics, Inc. ( Revolver) , Senior Secured Loans, due 6/5/2023
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:RedZoneRoboticsIncMember
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Services: Business
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Basis Spread, Variable Rate		6.75%
Investment Interest Rate		7.75%
Investment, Acquisition Date		Jun. 01, 2018
Investment Maturity Date		Jun. 05, 2023
Investment Owned, Balance, Principal Amount		$ 158
Investment, Identifier [Axis]: Red Zone Robotics, Inc., Senior Secured Loans, due 6/5/2023
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:RedZoneRoboticsIncMember
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Services: Business
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Basis Spread, Variable Rate		6.75%
Investment Interest Rate		7.75%
Investment, Acquisition Date		Jun. 01, 2018
Investment Maturity Date		Jun. 05, 2023
Investment Owned, Balance, Principal Amount		$ 213
Investment Owned, at Fair Value		$ 213
Investment, Identifier [Axis]: Relativity O D A L L C ( Revolver), Senior Secured Loans, due 5/12/2027
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:RelativityODALLCMember	mrcc:RelativityODALLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Services: Business	Services: Business
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR	LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Basis Spread, Variable Rate	7.50%	7.50%
Investment, Interest Rate, Paid in Kind	11.89%	8.50%
Investment, Acquisition Date	May 12, 2021	May 12, 2021
Investment Maturity Date	May 12, 2027	May 12, 2027
Investment Owned, Balance, Principal Amount	$ 180	$ 180
Investment, Identifier [Axis]: Relativity O D A L L C, Senior Secured Loans, due 5/12/2027
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:RelativityODALLCMember	mrcc:RelativityODALLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Services: Business	Services: Business
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR	LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Basis Spread, Variable Rate	7.50%	7.50%
Investment, Interest Rate, Paid in Kind	11.89%	8.50%
Investment, Acquisition Date	May 12, 2021	May 12, 2021
Investment Maturity Date	May 12, 2027	May 12, 2027
Investment Owned, Balance, Principal Amount	$ 2,061	$ 1,896
Investment Owned, at Fair Value	$ 2,060	$ 1,894
Investment, Identifier [Axis]: Relevate Health Group, L L C ( Delayed Draw), Senior Secured Loans, due, 11/20/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:RelevateHealthGroupLLCMember	mrcc:RelevateHealthGroupLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Media: Advertising, Printing & Publishing	Media: Advertising, Printing & Publishing
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]	us-gaap:LondonInterbankOfferedRateLiborSwapRateMember
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Basis Spread, Variable Rate	5.75%	6%
Investment Interest Rate	9.97%	7%
Investment, Acquisition Date	Nov. 20, 2020	Nov. 20, 2020
Investment Maturity Date	Nov. 20, 2025	Nov. 20, 2025
Investment Owned, Balance, Principal Amount	$ 778	$ 784
Investment Owned, at Fair Value	$ 648	$ 673
Investment, Identifier [Axis]: Relevate Health Group, L L C ( Revolver), Senior Secured Loans, due, 11/20/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:RelevateHealthGroupLLCMember	mrcc:RelevateHealthGroupLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Media: Advertising, Printing & Publishing	Media: Advertising, Printing & Publishing
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]	us-gaap:LondonInterbankOfferedRateLiborSwapRateMember
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Basis Spread, Variable Rate	5.75%	6%
Investment Interest Rate	9.97%	7%
Investment, Acquisition Date	Nov. 20, 2020	Nov. 20, 2020
Investment Maturity Date	Nov. 20, 2025	Nov. 20, 2025
Investment Owned, Balance, Principal Amount	$ 316	$ 316
Investment, Identifier [Axis]: Relevate Health Group, L L C, Equity Securities, Class B common units
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:RelevateHealthGroupLLCMember	mrcc:RelevateHealthGroupLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Equity Securities [Member]
Investment, Industry Sector [Extensible Enumeration]	Media: Advertising, Printing & Publishing	Media: Advertising, Printing & Publishing
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Acquisition Date	Nov. 20, 2020	Nov. 20, 2020
Investment, Identifier [Axis]: Relevate Health Group, L L C, Equity Securities, preferred units
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:RelevateHealthGroupLLCMember	mrcc:RelevateHealthGroupLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Equity Securities [Member]
Investment, Industry Sector [Extensible Enumeration]	Media: Advertising, Printing & Publishing	Media: Advertising, Printing & Publishing
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Interest Rate, Paid in Kind	12%	12%
Investment, Acquisition Date	Nov. 20, 2020	Nov. 20, 2020
Investment Owned, at Fair Value	$ 36	$ 40
Investment, Identifier [Axis]: Relevate Health Group, L L C, Senior Secured Loans, due, 11/20/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:RelevateHealthGroupLLCMember	mrcc:RelevateHealthGroupLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Media: Advertising, Printing & Publishing	Media: Advertising, Printing & Publishing
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]	us-gaap:LondonInterbankOfferedRateLiborSwapRateMember
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Basis Spread, Variable Rate	5.75%	6%
Investment Interest Rate	9.97%	7%
Investment, Acquisition Date	Nov. 20, 2020	Nov. 20, 2020
Investment Maturity Date	Nov. 20, 2025	Nov. 20, 2025
Investment Owned, Balance, Principal Amount	$ 1,474	$ 1,489
Investment Owned, at Fair Value	$ 1,449	$ 1,504
Investment, Identifier [Axis]: Research Now Group, Inc. and Survey Sampling International, L L C, Senior Secured Loans, due 12/20/2024
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:ResearchNowGroupInc.andSurveySamplingInternationalLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Media: Diversified & Production
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Basis Spread, Variable Rate	5.50%
Investment Interest Rate	8.84%
Investment Maturity Date	Dec. 20, 2024
Investment Owned, Balance, Principal Amount	$ 6,650
Investment Owned, at Fair Value	$ 5,035
Investment, Identifier [Axis]: Rockdale Blackhawk, L L C, Senior Secured Loans, no stated maturity
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:RockdaleBlackhawkLLCMember
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Healthcare & Pharmaceuticals Sector [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Acquisition Date	Mar. 31, 2015	Mar. 31, 2015
Investment Owned, at Fair Value	$ 557	$ 1,681
Investment, Identifier [Axis]: Runner Buyer I N C., Senior Secured Loans, due 10/23/2028
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:RunnerBuyerINCMember	mrcc:RunnerBuyerINCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Consumer Goods: Durable	Consumer Goods: Durable
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR	LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Basis Spread, Variable Rate		5.50%
Investment Interest Rate		6.25%
Investment Maturity Date		Oct. 23, 2028
Investment Owned, Balance, Principal Amount		$ 3,000
Investment Owned, at Fair Value		2,970
Investment, Identifier [Axis]: S F R Holdco, L L C Equity Securities
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	S F R Holdco, L L C [ Member]
Investment, Type [Extensible Enumeration]	Equity Securities [Member]
Investment, Industry Sector [Extensible Enumeration]	FIRE: Real Estate
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Acquisition Date	Aug. 06, 2021
Investment Owned, at Fair Value	$ 3,900	3,900
Investment, Identifier [Axis]: S F R Holdco, L L C, Junior Secured Loans Due 7/28/2028
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	S F R Holdco, L L C [ Member]
Investment, Type [Extensible Enumeration]	Junior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	FIRE: Real Estate
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment Interest Rate	8%
Investment, Acquisition Date	Aug. 06, 2021
Investment Maturity Date	Jul. 28, 2028
Investment Owned, Balance, Principal Amount	$ 5,850
Investment Owned, at Fair Value	$ 5,850	$ 5,850
Investment, Identifier [Axis]: S H I Holdings, Inc. ( Common stock)
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	S H I Holdings, Inc [ Member]	S H I Holdings, Inc [ Member]
Investment, Identifier [Axis]: S H I Holdings, Inc. ( Revolver)
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	S H I Holdings, Inc [ Member]	S H I Holdings, Inc [ Member]
Investment Owned, at Fair Value			297
Investment, Identifier [Axis]: S H I Holdings, Inc., Investment One
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	S H I Holdings, Inc [ Member]	S H I Holdings, Inc [ Member]
Investment Owned, at Fair Value			188
Investment, Identifier [Axis]: S I R V A Worldwide Inc., Senior Secured Loans, due 8/4/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:SIRVAWorldwideIncMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Services: Business
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Basis Spread, Variable Rate	5.50%
Investment Interest Rate	10.23%
Investment Maturity Date	Aug. 04, 2025
Investment Owned, Balance, Principal Amount	$ 1,800
Investment Owned, at Fair Value	$ 1,606
Investment, Identifier [Axis]: S T A T S Intermediate Holdings, L L C, Senior Secured Loans, due 7/10/2026
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:STATSIntermediateHoldingsLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Media: Diversified & Production
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Basis Spread, Variable Rate	5.25%
Investment Interest Rate	9.90%
Investment Maturity Date	Oct. 07, 2026
Investment Owned, Balance, Principal Amount	$ 4,850
Investment Owned, at Fair Value	$ 4,498
Investment, Identifier [Axis]: S W Ingredients Holdings, L L C, Senior Secured Loans, due 7/3/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:SWIngredientsHoldingsLLCMember	mrcc:SWIngredientsHoldingsLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	mrcc:BeverageFoodAndTobaccoSectorMember	mrcc:BeverageFoodAndTobaccoSectorMember
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR	LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Basis Spread, Variable Rate	4.75%	4.75%
Investment Interest Rate	9.13%	5.75%
Investment Maturity Date	Jul. 03, 2025	Jul. 03, 2025
Investment Owned, Balance, Principal Amount	$ 3,581	$ 3,619
Investment Owned, at Fair Value	$ 3,581	$ 3,619
Investment, Identifier [Axis]: SFR Holdco, LLC (Junior secured loan)
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	Second Avenue S F R Holdings I I L L C [ Member]	Second Avenue S F R Holdings I I L L C [ Member]
Investment, Identifier [Axis]: SFR Holdco, LLC (LLC interest)
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	Second Avenue S F R Holdings I I L L C [ Member]	Second Avenue S F R Holdings I I L L C [ Member]
Investment, Identifier [Axis]: Sandvine Corporation, Senior Secured Loans, due 10/31/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:SandvineCorporationMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Telecommunications
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Basis Spread, Variable Rate	4.50%
Investment Interest Rate	8.88%
Investment Maturity Date	Oct. 31, 2025
Investment Owned, Balance, Principal Amount	$ 2,000
Investment Owned, at Fair Value	$ 1,904
Investment, Identifier [Axis]: Second Avenue S F R Holdings I I L L C ( Revolver), Senior Secured Loans, Due 8/9/2024
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	Second Avenue S F R Holdings I I L L C [ Member]	Second Avenue S F R Holdings I I L L C [ Member]
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	FIRE: Real Estate	FIRE: Real Estate
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR	LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Basis Spread, Variable Rate	7%	7%
Investment Interest Rate	11.12%	7.50%
Investment, Acquisition Date	Aug. 11, 2021	Aug. 11, 2021
Investment Maturity Date	Aug. 09, 2024	Aug. 09, 2024
Investment Owned, Balance, Principal Amount	$ 4,875	$ 4,875
Investment Owned, at Fair Value	$ 4,755	$ 2,104
Investment, Identifier [Axis]: Second Avenue S F R Holdings I I L L C, Equity Securities
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		Second Avenue S F R Holdings I I L L C [ Member]
Investment, Type [Extensible Enumeration]		Equity Securities [Member]
Investment, Industry Sector [Extensible Enumeration]		FIRE: Real Estate
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Acquisition Date		Aug. 06, 2021
Investment Owned, at Fair Value		$ 3,900
Investment, Identifier [Axis]: Second Avenue S F R Holdings I I L L C, Junior Secured Loans, Due 7/28/2028
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		Second Avenue S F R Holdings I I L L C [ Member]
Investment, Type [Extensible Enumeration]		Junior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		FIRE: Real Estate
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment Interest Rate		8%
Investment, Acquisition Date		Aug. 06, 2021
Investment Maturity Date		Jul. 28, 2028
Investment Owned, Balance, Principal Amount		$ 5,850
Investment Owned, at Fair Value		$ 5,850
Investment, Identifier [Axis]: Second Avenue SFR Holdings II LLC (Delayed Draw) Loan
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	Second Avenue S F R Holdings I I L L C [ Member]	Second Avenue S F R Holdings I I L L C [ Member]
Investment Owned, at Fair Value		$ 5,850
Investment, Identifier [Axis]: Secretariat Advisors L L C ( Delayed Draw), Senior Secured Loans, due 12/29/2028
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:SecretariatAdvisorsLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Services: Business
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Basis Spread, Variable Rate	4.75%
Investment Interest Rate	9.48%
Investment Maturity Date	Dec. 29, 2028
Investment Owned, Balance, Principal Amount	$ 270
Investment Owned, at Fair Value	$ 260
Investment, Identifier [Axis]: Secretariat Advisors L L C, Senior Secured Loans, due 12/29/2028
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:SecretariatAdvisorsLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Services: Business
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Basis Spread, Variable Rate	4.75%
Investment Interest Rate	9.48%
Investment Maturity Date	Dec. 29, 2028
Investment Owned, Balance, Principal Amount	$ 1,693
Investment Owned, at Fair Value	$ 1,634
Investment, Identifier [Axis]: Security Services Acquisition Sub Corp., Senior Secured Loans, Five, due 9/30/2026
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:SecurityServicesAcquisitionSubCorpMember	mrcc:SecurityServicesAcquisitionSubCorpMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Services: Business	Services: Business
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]	LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Basis Spread, Variable Rate	6%	6%
Investment Interest Rate	10.40%	7%
Investment, Acquisition Date	Feb. 15, 2019	Feb. 15, 2019
Investment Maturity Date	Sep. 30, 2026	Sep. 30, 2026
Investment Owned, Balance, Principal Amount	$ 1,535	$ 1,551
Investment Owned, at Fair Value	$ 1,532	$ 1,549
Investment, Identifier [Axis]: Security Services Acquisition Sub Corp., Senior Secured Loans, Four, due 9/30/2026
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:SecurityServicesAcquisitionSubCorpMember	mrcc:SecurityServicesAcquisitionSubCorpMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Services: Business	Services: Business
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]	LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Basis Spread, Variable Rate	6%	6%
Investment Interest Rate	10.42%	7%
Investment, Acquisition Date	Feb. 15, 2019	Feb. 15, 2019
Investment Maturity Date	Sep. 30, 2026	Sep. 30, 2026
Investment Owned, Balance, Principal Amount	$ 2,135	$ 2,157
Investment Owned, at Fair Value	$ 2,131	$ 2,154
Investment, Identifier [Axis]: Security Services Acquisition Sub Corp., Senior Secured Loans, One, due 9/30/2026
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:SecurityServicesAcquisitionSubCorpMember	mrcc:SecurityServicesAcquisitionSubCorpMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Services: Business	Services: Business
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]	LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Basis Spread, Variable Rate	6%	6%
Investment Interest Rate	10.42%	7%
Investment, Acquisition Date	Feb. 15, 2019	Sep. 30, 2021
Investment Maturity Date	Sep. 30, 2026	Sep. 30, 2026
Investment Owned, Balance, Principal Amount	$ 3,378	$ 7,980
Investment Owned, at Fair Value	$ 3,372	$ 7,972
Investment, Identifier [Axis]: Security Services Acquisition Sub Corp., Senior Secured Loans, Three, due 9/30/2026
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:SecurityServicesAcquisitionSubCorpMember	mrcc:SecurityServicesAcquisitionSubCorpMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Services: Business	Services: Business
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]	LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Basis Spread, Variable Rate	6%	6%
Investment Interest Rate	10.42%	7%
Investment, Acquisition Date	Sep. 30, 2021	Feb. 15, 2019
Investment Maturity Date	Sep. 30, 2026	Sep. 30, 2026
Investment Owned, Balance, Principal Amount	$ 7,900	$ 2,455
Investment Owned, at Fair Value	$ 7,884	$ 2,452
Investment, Identifier [Axis]: Security Services Acquisition Sub Corp., Senior Secured Loans, Two, due 9/30/2026
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:SecurityServicesAcquisitionSubCorpMember	mrcc:SecurityServicesAcquisitionSubCorpMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Services: Business	Services: Business
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]	LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Basis Spread, Variable Rate	6%	6%
Investment Interest Rate	10.42%	7%
Investment, Acquisition Date	Feb. 15, 2019	Feb. 15, 2019
Investment Maturity Date	Sep. 30, 2026	Sep. 30, 2026
Investment Owned, Balance, Principal Amount	$ 2,430	$ 3,413
Investment Owned, at Fair Value	$ 2,425	$ 3,409
Investment, Identifier [Axis]: Seran Bio Science, L L C ( Revolver), Senior Secured Loans, due 7/8/2027
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:SeranBioScienceLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Healthcare & Pharmaceuticals Sector [Member]
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Basis Spread, Variable Rate	6.25%
Investment Interest Rate	9.96%
Investment, Interest Rate, Paid in Cash	7.86%
Investment, Acquisition Date	Dec. 31, 2020
Investment Maturity Date	Jul. 08, 2027
Investment Owned, Balance, Principal Amount	$ 444
Investment, Identifier [Axis]: Seran Bio Science, L L C (Revolver), Senior Secured Loans, Due 12/31/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:SeranBioScienceLLCMember
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Healthcare & Pharmaceuticals Sector [Member]
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Basis Spread, Variable Rate		6.25%
Investment Interest Rate		7.25%
Investment, Acquisition Date		Dec. 31, 2020
Investment Maturity Date		Dec. 31, 2025
Investment Owned, Balance, Principal Amount		$ 444
Investment, Identifier [Axis]: Seran Bio Science, L L C, Equity Securities, common units
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:SeranBioScienceLLCMember
Investment, Type [Extensible Enumeration]		Equity Securities [Member]
Investment, Industry Sector [Extensible Enumeration]		Healthcare & Pharmaceuticals
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Acquisition Date		Dec. 31, 2020
Investment Owned, at Fair Value		$ 714
Investment, Identifier [Axis]: Seran Bio Science, L L C, Senior Secured Loans, Due 12/31/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:SeranBioScienceLLCMember
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Healthcare & Pharmaceuticals Sector [Member]
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Basis Spread, Variable Rate		6.25%
Investment Interest Rate		7.25%
Investment, Acquisition Date		Dec. 31, 2020
Investment Maturity Date		Dec. 31, 2025
Investment Owned, Balance, Principal Amount		$ 2,481
Investment Owned, at Fair Value		$ 2,487
Investment, Identifier [Axis]: Seran Bio Science, L L C, Senior Secured Loans, due 7/8/2027
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:SeranBioScienceLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Healthcare & Pharmaceuticals Sector [Member]
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Basis Spread, Variable Rate	6.25%
Investment Interest Rate	9.96%
Investment, Acquisition Date	Dec. 31, 2020
Investment Maturity Date	Jul. 08, 2027
Investment Owned, Balance, Principal Amount	$ 2,456
Investment Owned, at Fair Value	$ 2,435
Investment, Identifier [Axis]: Seran BioScience, LLC (Delayed Draw), Senior Secured Loans, Due 7/8/2027
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:SeranBioScienceLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Healthcare & Pharmaceuticals Sector [Member]
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Basis Spread, Variable Rate	6.25%
Investment Interest Rate	10.67%
Investment, Acquisition Date	Jul. 08, 2022
Investment Maturity Date	Jul. 08, 2027
Investment Owned, Balance, Principal Amount	$ 2,776
Investment Owned, at Fair Value	$ 1,320
Investment, Identifier [Axis]: Seran BioScience, LLC, Equity Security, Common Units
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:SeranBioScienceLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Healthcare & Pharmaceuticals Sector [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Acquisition Date	Dec. 31, 2020
Investment Owned, at Fair Value	$ 537
Investment, Identifier [Axis]: Service Max, Inc. ( Revolver) , Senior Secured Loans, due 11/1/2027
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:ServiceMaxIncMember	mrcc:ServiceMaxIncMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Services: Business	Services: Business
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR	LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Basis Spread, Variable Rate	6%	7%
Investment Interest Rate		8%
Investment, Interest Rate, Paid in Kind	10.27%
Investment, Acquisition Date	Nov. 01, 2021	Nov. 01, 2021
Investment Maturity Date	Nov. 01, 2027	Nov. 01, 2027
Investment Owned, Balance, Principal Amount	$ 350	$ 350
Investment Owned, at Fair Value	$ 175
Investment, Identifier [Axis]: Service Max, Inc., Senior Secured Loans, due 11/1/2027
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:ServiceMaxIncMember	mrcc:ServiceMaxIncMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Services: Business	Services: Business
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR	LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Basis Spread, Variable Rate	7%	7%
Investment Interest Rate		8%
Investment, Interest Rate, Paid in Kind	11.12%
Investment, Acquisition Date	Nov. 01, 2021	Nov. 01, 2021
Investment Maturity Date	Nov. 01, 2027	Nov. 01, 2027
Investment Owned, Balance, Principal Amount	$ 3,846	$ 3,500
Investment Owned, at Fair Value	$ 3,884	$ 3,500
Investment, Identifier [Axis]: Spectrum Science Communications, L L C ( Revolver), Senior Secured Loans, due 1/25/2027
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:SpectrumScienceCommunicationsLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Media: Diversified & Production
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Basis Spread, Variable Rate	6.25%
Investment Interest Rate	10.92%
Investment, Acquisition Date	Jan. 25, 2022
Investment Maturity Date	Jan. 25, 2027
Investment Owned, Balance, Principal Amount	$ 200
Investment, Identifier [Axis]: Spectrum Science Communications, L L C, Senior Secured Loans, due 1/25/2027
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:SpectrumScienceCommunicationsLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Media: Diversified & Production
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Basis Spread, Variable Rate	6.25%
Investment Interest Rate	10.92%
Investment, Acquisition Date	Jan. 25, 2022
Investment Maturity Date	Jan. 25, 2027
Investment Owned, Balance, Principal Amount	$ 995
Investment Owned, at Fair Value	$ 1,005
Investment, Identifier [Axis]: Spherix Global Inc, Equity Securities, Class A units
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:SpherixGlobalInc.Member	mrcc:SpherixGlobalInc.Member
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Equity Securities [Member]
Investment, Industry Sector [Extensible Enumeration]	Media: Advertising, Printing & Publishing	Media: Advertising, Printing & Publishing
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Acquisition Date	Dec. 22, 2021	Dec. 22, 2021
Investment Owned, at Fair Value	$ 63	$ 81
Investment, Identifier [Axis]: Spherix Global Inc. ( Revolver), Senior Secured Loans, due, 12/22/2026
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:SpherixGlobalInc.Member	mrcc:SpherixGlobalInc.Member
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Media: Advertising, Printing & Publishing	Media: Advertising, Printing & Publishing
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Basis Spread, Variable Rate	6%	6%
Investment Interest Rate	10.24%	7%
Investment, Acquisition Date	Dec. 22, 2021	Dec. 22, 2021
Investment Maturity Date	Dec. 22, 2026	Dec. 22, 2026
Investment Owned, Balance, Principal Amount	$ 122	$ 122
Investment, Identifier [Axis]: Spherix Global Inc. , Senior Secured Loans, due, 12/22/2026
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:SpherixGlobalInc.Member	mrcc:SpherixGlobalInc.Member
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Media: Advertising, Printing & Publishing	Media: Advertising, Printing & Publishing
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Basis Spread, Variable Rate	6%	6%
Investment Interest Rate	10.24%	7%
Investment, Acquisition Date	Dec. 22, 2021	Dec. 22, 2021
Investment Maturity Date	Dec. 22, 2026	Dec. 22, 2026
Investment Owned, Balance, Principal Amount	$ 1,092	$ 1,100
Investment Owned, at Fair Value	$ 1,088	$ 1,081
Investment, Identifier [Axis]: Sports Operating Holdings II, LLC (Delayed Draw), Due 11/3/2027
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:SportsOperatingHoldingsIiLlcMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Media: Diversified & Production
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Basis Spread, Variable Rate	5.75%
Investment Interest Rate	10.17%
Investment, Acquisition Date	Nov. 03, 2022
Investment Maturity Date	Nov. 03, 2027
Investment Owned, Balance, Principal Amount	$ 2,400
Investment, Identifier [Axis]: Sports Operating Holdings II, LLC (Revolver), Due, 11/3/2027
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:SportsOperatingHoldingsIiLlcMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Media: Diversified & Production
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Basis Spread, Variable Rate	5.75%
Investment Interest Rate	10.17%
Investment, Acquisition Date	Nov. 03, 2022
Investment Maturity Date	Nov. 03, 2027
Investment Owned, Balance, Principal Amount	$ 519
Investment, Identifier [Axis]: Sports Operating Holdings II, LLC, Due, 11/3/2027
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:SportsOperatingHoldingsIiLlcMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Media: Diversified & Production
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Basis Spread, Variable Rate	5.75%
Investment Interest Rate	10.17%
Investment, Acquisition Date	Nov. 03, 2022
Investment Maturity Date	Nov. 03, 2027
Investment Owned, Balance, Principal Amount	$ 2,993
Investment Owned, at Fair Value	$ 2,918
Investment, Identifier [Axis]: Star Compliance Mid Co, L L C, ( Revolver), Senior Secured Loans, due 1/12/2027
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:StarComplianceMidCoLLCMember	mrcc:StarComplianceMidCoLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Banking	Banking
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR	LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Basis Spread, Variable Rate	6.75%	6.75%
Investment Interest Rate	11.14%	7.75%
Investment, Acquisition Date	Jan. 12, 2021	Jan. 12, 2021
Investment Maturity Date	Jan. 12, 2027	Jan. 11, 2027
Investment Owned, Balance, Principal Amount	$ 322	$ 322
Investment Owned, at Fair Value	$ 79
Investment, Identifier [Axis]: Star Compliance Mid Co, L L C, Senior Secured Loans, One, due 1/12/2027
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:StarComplianceMidCoLLCMember	mrcc:StarComplianceMidCoLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Banking	Banking
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR	LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Basis Spread, Variable Rate	6.75%	6.75%
Investment Interest Rate	11.48%	7.75%
Investment, Acquisition Date	Jan. 12, 2021	Jan. 12, 2021
Investment Maturity Date	Jan. 12, 2027	Jan. 11, 2027
Investment Owned, Balance, Principal Amount	$ 2,000	$ 2,000
Investment Owned, at Fair Value	$ 1,968	$ 2,000
Investment, Identifier [Axis]: Star Compliance Mid Co, L L C, Senior Secured Loans, Two, due 1/12/2027
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:StarComplianceMidCoLLCMember	mrcc:StarComplianceMidCoLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Banking	Banking
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR	LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Basis Spread, Variable Rate	6.75%	6.75%
Investment Interest Rate	11.48%	7.75%
Investment, Acquisition Date	Oct. 12, 2021	Oct. 12, 2021
Investment Maturity Date	Jan. 12, 2027	Jan. 11, 2027
Investment Owned, Balance, Principal Amount	$ 336	$ 336
Investment Owned, at Fair Value	$ 330	$ 336
Investment, Identifier [Axis]: Storm Trap, L L C ( Revolver), Senior Secured Loans, due 12/8/2023
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:StormTrapLLCMember
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Environmental Industries
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Basis Spread, Variable Rate		5.50%
Investment Interest Rate		6.50%
Investment, Acquisition Date		Dec. 10, 2018
Investment Maturity Date		Dec. 08, 2023
Investment Owned, Balance, Principal Amount		$ 432
Investment, Identifier [Axis]: Storm Trap, L L C, Senior Secured Loans, due 12/8/2023
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:StormTrapLLCMember
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Environmental Industries
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Basis Spread, Variable Rate		5.50%
Investment Interest Rate		6.50%
Investment, Acquisition Date		Dec. 10, 2018
Investment Maturity Date		Dec. 08, 2023
Investment Owned, Balance, Principal Amount		$ 7,170
Investment Owned, at Fair Value		$ 7,170
Investment, Identifier [Axis]: Summit Container Corporation ( Revolver)
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	Summit Container Corporation [ Member]	Summit Container Corporation [ Member]
Investment Owned, at Fair Value			1,654
Investment, Identifier [Axis]: Summit Container Corporation, Equity Securities, Warrants
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	Summit Container Corporation [ Member]	Summit Container Corporation [ Member]
Investment Owned, at Fair Value			139
Investment, Identifier [Axis]: Summit Container Corporation, Investment One
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	Summit Container Corporation [ Member]	Summit Container Corporation [ Member]
Investment Owned, at Fair Value			3,204
Investment, Identifier [Axis]: Synergy Environmental Corporation ( Revolver), Senior Secured Loans, due 9/29/2023
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:SynergyEnvironmentalCorporationMember
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Environmental Industries
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Basis Spread, Variable Rate		6%
Investment Interest Rate		7%
Investment, Acquisition Date		Apr. 29, 2016
Investment Maturity Date		Sep. 29, 2023
Investment Owned, Balance, Principal Amount		$ 671
Investment, Identifier [Axis]: Synergy Environmental Corporation, Senior Secured Loans, One, due 9/29/2023
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:SynergyEnvironmentalCorporationMember
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Environmental Industries
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Basis Spread, Variable Rate		6%
Investment Interest Rate		7%
Investment, Acquisition Date		Apr. 29, 2016
Investment Maturity Date		Sep. 29, 2023
Investment Owned, Balance, Principal Amount		$ 2,853
Investment Owned, at Fair Value		$ 2,853
Investment, Identifier [Axis]: Synergy Environmental Corporation, Senior Secured Loans, Three, due 9/29/2023
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:SynergyEnvironmentalCorporationMember
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Environmental Industries
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Basis Spread, Variable Rate		6%
Investment Interest Rate		7%
Investment, Acquisition Date		Apr. 29, 2016
Investment Maturity Date		Sep. 29, 2023
Investment Owned, Balance, Principal Amount		$ 810
Investment Owned, at Fair Value		$ 810
Investment, Identifier [Axis]: Synergy Environmental Corporation, Senior Secured Loans, Two, due 9/29/2023
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:SynergyEnvironmentalCorporationMember
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Environmental Industries
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Basis Spread, Variable Rate		6%
Investment Interest Rate		7%
Investment, Acquisition Date		Apr. 29, 2016
Investment Maturity Date		Sep. 29, 2023
Investment Owned, Balance, Principal Amount		$ 477
Investment Owned, at Fair Value		$ 477
Investment, Identifier [Axis]: T A T T Buyer, L L C, Senior Secured Loans, due 3/30/2029
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:TATTBuyerLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Media: Diversified & Production
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Basis Spread, Variable Rate	5%
Investment Interest Rate	8.98%
Investment Maturity Date	Mar. 30, 2029
Investment Owned, Balance, Principal Amount	$ 3,325
Investment Owned, at Fair Value	$ 3,242
Investment, Identifier [Axis]: T C F I I I O W L Buyer L L C, Senior Secured Loans, One, due 4/17/2026
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:TCFIIIOWLBuyerLLCMember	mrcc:TCFIIIOWLBuyerLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Construction & Building	Construction & Building
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]	LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Basis Spread, Variable Rate	5.50%	6%
Investment Interest Rate	9.94%	7%
Investment, Acquisition Date	Apr. 19, 2021	Apr. 19, 2021
Investment Maturity Date	Apr. 17, 2026	Apr. 17, 2026
Investment Owned, Balance, Principal Amount	$ 2,019	$ 2,040
Investment Owned, at Fair Value	$ 2,022	$ 2,040
Investment, Identifier [Axis]: T C F I I I O W L Buyer L L C, Senior Secured Loans, Three, due 4/17/2026
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:TCFIIIOWLBuyerLLCMember	mrcc:TCFIIIOWLBuyerLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Construction & Building	Construction & Building
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]	LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Basis Spread, Variable Rate	5.50%	6%
Investment Interest Rate	9.94%	7%
Investment, Acquisition Date	Dec. 17, 2021	Dec. 17, 2021
Investment Maturity Date	Apr. 17, 2026	Apr. 17, 2026
Investment Owned, Balance, Principal Amount	$ 2,213	$ 2,235
Investment Owned, at Fair Value	$ 2,215	$ 2,235
Investment, Identifier [Axis]: T C F I I I O W L Buyer L L C, Senior Secured Loans, Two, due 4/17/2026
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:TCFIIIOWLBuyerLLCMember	mrcc:TCFIIIOWLBuyerLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Construction & Building	Construction & Building
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]	LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Basis Spread, Variable Rate	5.50%	6%
Investment Interest Rate	9.94%	7%
Investment, Acquisition Date	Apr. 19, 2021	Apr. 19, 2021
Investment Maturity Date	Apr. 17, 2026	Apr. 17, 2026
Investment Owned, Balance, Principal Amount	$ 2,466	$ 2,491
Investment Owned, at Fair Value	$ 2,469	$ 2,491
Investment, Identifier [Axis]: T E A M Public Choices, L L C, Senior Secured Loans, due 12/17/2027
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:TEAMPublicChoicesLLCMember	mrcc:TEAMPublicChoicesLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	mrcc:FireFinanceMember	Healthcare & Pharmaceuticals Sector [Member]
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR	LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Basis Spread, Variable Rate	5%	5%
Investment Interest Rate	9.93%	6%
Investment Maturity Date	Dec. 17, 2027	Dec. 17, 2027
Investment Owned, Balance, Principal Amount	$ 2,955	$ 2,992
Investment Owned, at Fair Value	$ 2,822	$ 2,985
Investment, Identifier [Axis]: T G G T S Acquisition Company, Senior Secured Loans, due 12/12/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:TGGTSAcquisitionCompanyMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	High Tech Industries Sector [Member]
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Basis Spread, Variable Rate	6.50%
Investment Interest Rate	10.88%
Investment Maturity Date	Dec. 12, 2025
Investment Owned, Balance, Principal Amount	$ 3,190
Investment Owned, at Fair Value	$ 3,143
Investment, Identifier [Axis]: T J C Spartech Acquisition Corp., Senior Secured Loans, due 5/5/2028
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:TJCSpartechAcquisitionCorpMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Chemicals, Plastics & Rubber
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Identifier [Axis]: T J Management Hold Co L L C ( Revolver), Senior Secured Loans, Due 6/28/2024
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	T J Management Hold Co L L C [ Member]	T J Management Hold Co L L C [ Member]
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Beverage, Food & Tobacco	Beverage, Food & Tobacco
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR	LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Basis Spread, Variable Rate	5.50%	5.50%
Investment Interest Rate	9.89%	6.50%
Investment, Acquisition Date	Sep. 09, 2020	Sep. 09, 2020
Investment Maturity Date	Jun. 28, 2024	Jun. 28, 2024
Investment Owned, Balance, Principal Amount	$ 477	$ 477
Investment Owned, at Fair Value	$ 80
Investment, Identifier [Axis]: T J Management Hold Co L L C, Equity Securities, Common stock
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	T J Management Hold Co L L C [ Member]	T J Management Hold Co L L C [ Member]
Investment, Type [Extensible Enumeration]	Equity Securities [Member]	Equity Securities [Member]
Investment, Industry Sector [Extensible Enumeration]	Beverage, Food & Tobacco	Beverage, Food & Tobacco
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Acquisition Date	Sep. 09, 2020	Sep. 09, 2020
Investment Owned, at Fair Value	$ 2,766	$ 3,148	3,323
Investment, Identifier [Axis]: Tait L L C ( Revolver), Senior Secured Loans, due 3/28/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:TaitLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Hotels, Gaming & Leisure
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Prime Rate [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Basis Spread, Variable Rate	4%
Investment Interest Rate	10.25%
Investment Maturity Date	Mar. 28, 2025
Investment Owned, Balance, Principal Amount	$ 769
Investment, Identifier [Axis]: Tait L L C, Senior Secured Loans, due 3/28/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:TaitLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Hotels, Gaming & Leisure
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Basis Spread, Variable Rate	5%
Investment Interest Rate	8.75%
Investment Maturity Date	Mar. 28, 2025
Investment Owned, Balance, Principal Amount	$ 4,083
Investment Owned, at Fair Value	$ 3,972
Investment, Identifier [Axis]: Teneo Holdings L L C, Senior Secured Loans, due 7/11/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:TeneoHoldingsLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Services: Business
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Basis Spread, Variable Rate	5.25%
Investment Interest Rate	9.67%
Investment Maturity Date	Jul. 11, 2025
Investment Owned, Balance, Principal Amount	$ 4,837
Investment Owned, at Fair Value	$ 4,668
Investment, Identifier [Axis]: The Cook & Boardman Group L L C, Senior Secured Loans, due 10/20/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:TheCookBoardmanGroupLLCMember	mrcc:TheCookBoardmanGroupLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Construction & Building	Construction & Building
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]	LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Basis Spread, Variable Rate		5.75%
Investment Interest Rate		6.75%
Investment Maturity Date		Oct. 20, 2025
Investment Owned, Balance, Principal Amount		$ 2,910
Investment Owned, at Fair Value		$ 2,838
Investment, Identifier [Axis]: The Kleinfelder Group, Inc., Senior Secured Loans, due 11/29/2024
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:TheKleinfelderGroupIncMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Services: Business
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Basis Spread, Variable Rate	5.25%
Investment Interest Rate	9.98%
Investment Maturity Date	Nov. 29, 2024
Investment Owned, Balance, Principal Amount	$ 2,362
Investment Owned, at Fair Value	$ 2,362
Investment, Identifier [Axis]: The Kyjen Company, L L C ( Revolver), Senior Secured Loans, due 4/3/2026
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:TheKyjenCompanyLLCMember	mrcc:TheKyjenCompanyLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Consumer Sector, Non- Durable [ Member]	Consumer Sector, Non- Durable [ Member]
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]	LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Basis Spread, Variable Rate	7.10%	6.50%
Investment Interest Rate		7.50%
Investment, Interest Rate, Paid in Kind	0.50%
Investment, Acquisition Date	May 14, 2021	May 14, 2021
Investment Maturity Date	Apr. 03, 2026	Apr. 03, 2026
Investment Owned, Balance, Principal Amount	$ 105	$ 105
Investment Owned, at Fair Value	$ 88	$ 43
Investment, Identifier [Axis]: The Kyjen Company, L L C, Senior SEcured Loans, Two, Due 4/3/2026
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:TheKyjenCompanyLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Consumer Sector, Non- Durable [ Member]
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Basis Spread, Variable Rate	7%
Investment, Interest Rate, Paid in Kind	11.42%
Investment, Acquisition Date	Sep. 13, 2022
Investment Maturity Date	Apr. 03, 2026
Investment, Identifier [Axis]: The Kyjen Company, L L C, Senior Secured Loans, due 4/3/2026
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:TheKyjenCompanyLLCMember	mrcc:TheKyjenCompanyLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Consumer Sector, Non- Durable [ Member]	Consumer Sector, Non- Durable [ Member]
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Basis Spread, Variable Rate	7.15%	6.50%
Investment Interest Rate		7.50%
Investment, Interest Rate, Paid in Cash	11.15%
Investment, Interest Rate, Paid in Kind	0.50%
Investment, Acquisition Date	May 14, 2021	May 14, 2021
Investment Maturity Date	Apr. 03, 2026	Apr. 03, 2026
Investment Owned, Balance, Principal Amount	$ 986	$ 993
Investment Owned, at Fair Value	$ 975	$ 997
Investment, Identifier [Axis]: Thrasio, L L C, Senior Secured Loans, due 12/18/2026
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:ThrasioLLCMember	mrcc:ThrasioLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Consumer Sector, Non- Durable [ Member]	Consumer Sector, Non- Durable [ Member]
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR	LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Basis Spread, Variable Rate	7%	7%
Investment Interest Rate	11.73%	8%
Investment, Acquisition Date	Dec. 18, 2020	Dec. 18, 2020
Investment Maturity Date	Dec. 18, 2026	Dec. 18, 2026
Investment Owned, Balance, Principal Amount	$ 2,445	$ 2,470
Investment Owned, at Fair Value	$ 2,445	$ 2,470
Investment, Identifier [Axis]: Tiger Connect, Inc. ( Delayed Draw), Senior Secured Loans, due 2/16/2028
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:TigerConnectIncMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Healthcare & Pharmaceuticals Sector [Member]
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Basis Spread, Variable Rate	7.25%
Investment, Interest Rate, Paid in Kind	3.63%
Investment, Acquisition Date	Feb. 16, 2022
Investment Maturity Date	Feb. 16, 2028
Investment Owned, Balance, Principal Amount	$ 124
Investment Owned, at Fair Value	$ 27
Investment, Identifier [Axis]: Tiger Connect, Inc. ( Revolver), Senior Secured Loans, due 2/16/2028
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:TigerConnectIncMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Healthcare & Pharmaceuticals Sector [Member]
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Basis Spread, Variable Rate	7.25%
Investment Interest Rate	11.49%
Investment, Acquisition Date	Feb. 16, 2022
Investment Maturity Date	Feb. 16, 2028
Investment Owned, Balance, Principal Amount	$ 429
Investment, Identifier [Axis]: Tiger Connect, Inc., Senior Secured Loans, due 2/16/2028
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:TigerConnectIncMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Healthcare & Pharmaceuticals Sector [Member]
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Basis Spread, Variable Rate	7.25%
Investment, Interest Rate, Paid in Cash	7.86%
Investment, Interest Rate, Paid in Kind	3.63%
Investment, Acquisition Date	Feb. 16, 2022
Investment Maturity Date	Feb. 16, 2028
Investment Owned, Balance, Principal Amount	$ 3,000
Investment Owned, at Fair Value	$ 2,963
Investment, Identifier [Axis]: Toojay’s Management L L C ( Revolver), Senior Secured Loans, due 10/26/2022
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:ToojaysManagementLLCMember
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Beverage, Food & Tobacco
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Acquisition Date		Oct. 26, 2018
Investment Maturity Date		Oct. 26, 2022
Investment Owned, Balance, Principal Amount		$ 66
Investment, Identifier [Axis]: Toojay’s Management L L C, Senior Secured Loans, One, due 10/26/2022
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:ToojaysManagementLLCMember
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Beverage, Food & Tobacco
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Acquisition Date		Oct. 26, 2018
Investment Maturity Date		Oct. 26, 2022
Investment Owned, Balance, Principal Amount		$ 1,448
Investment, Identifier [Axis]: Toojay’s Management L L C, Senior Secured Loans, Two, due 10/26/2022
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:ToojaysManagementLLCMember
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Beverage, Food & Tobacco
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Acquisition Date		Oct. 26, 2018
Investment Maturity Date		Oct. 26, 2022
Investment Owned, Balance, Principal Amount		$ 199
Investment, Identifier [Axis]: Trident Maritime Systems, Inc ( Revolver), Senior Secured Loans, due 2/26/2027
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:TridentMaritimeSystemsIncMember	mrcc:TridentMaritimeSystemsIncMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Aerospace & Defense	Aerospace & Defense
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR	LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Basis Spread, Variable Rate	4.75%	5.50%
Investment Interest Rate	9.08%	6.50%
Investment Maturity Date	Feb. 26, 2027	Feb. 26, 2027
Investment Owned, Balance, Principal Amount	$ 319	$ 265
Investment Owned, at Fair Value	$ 122
Investment, Identifier [Axis]: Trident Maritime Systems, Inc, Senior Secured Loans, One, due 2/26/2027
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:TridentMaritimeSystemsIncMember	mrcc:TridentMaritimeSystemsIncMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Aerospace & Defense	Aerospace & Defense
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR	LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Basis Spread, Variable Rate	4.75%	5.50%
Investment Interest Rate	9.48%	6.50%
Investment Maturity Date	Feb. 26, 2027	Feb. 26, 2027
Investment Owned, Balance, Principal Amount	$ 2,445	$ 2,467
Investment Owned, at Fair Value	$ 2,443	$ 2,478
Investment, Identifier [Axis]: Trident Maritime Systems, Inc, Senior Secured Loans, Two, due 2/26/2027
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:TridentMaritimeSystemsIncMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Aerospace & Defense
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Basis Spread, Variable Rate	4.75%
Investment Interest Rate	9.48%
Investment Maturity Date	Feb. 26, 2027
Investment Owned, Balance, Principal Amount	$ 746
Investment Owned, at Fair Value	$ 746
Investment, Identifier [Axis]: Truck- Lite Co., L L C, Senior Secured Loans, One, due 12/14/2026
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:Truck-LiteCo.LLCMember	mrcc:Truck-LiteCo.LLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Automotive	Automotive
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]	LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Basis Spread, Variable Rate	6.25%	6.25%
Investment Interest Rate	11.14%	7.25%
Investment Maturity Date	Dec. 14, 2026	Dec. 14, 2026
Investment Owned, Balance, Principal Amount	$ 1,691	$ 1,709
Investment Owned, at Fair Value	$ 1,690	$ 1,718
Investment, Identifier [Axis]: Truck- Lite Co., L L C, Senior Secured Loans, Two, due 12/14/2026
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:Truck-LiteCo.LLCMember	mrcc:Truck-LiteCo.LLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Automotive	Automotive
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]	LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Basis Spread, Variable Rate	6.25%	6.25%
Investment Interest Rate	11.14%	7.25%
Investment Maturity Date	Dec. 14, 2026	Dec. 14, 2026
Investment Owned, Balance, Principal Amount	$ 251	$ 253
Investment Owned, at Fair Value	$ 250	$ 255
Investment, Identifier [Axis]: Truck-Lite Co., LLC, Senior Secured Loans, Three, due 12/14/2026
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:Truck-LiteCo.LLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Automotive
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Basis Spread, Variable Rate	6.25%
Investment Interest Rate	11.14%
Investment Maturity Date	Dec. 14, 2026
Investment Owned, Balance, Principal Amount	$ 43
Investment Owned, at Fair Value	$ 43
Investment, Identifier [Axis]: V B E1, L L C ( Delayed Draw), Unitranche Secured Loans, due 11/18/2026
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:VBE1LLCMember
Investment, Type [Extensible Enumeration]		Unitranche Debt [Member]
Investment, Industry Sector [Extensible Enumeration]		Telecommunications
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Basis Spread, Variable Rate		7.65%
Investment Interest Rate		8.15%
Investment, Acquisition Date		Nov. 18, 2020
Investment Maturity Date		Nov. 18, 2026
Investment Owned, Balance, Principal Amount		$ 2,250
Investment Owned, at Fair Value		$ 1,118
Investment, Identifier [Axis]: V B E1, L L C, Unitranche Secured Loans, due 11/18/2026
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:VBE1LLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Telecommunications
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Basis Spread, Variable Rate	7.65%
Investment Interest Rate	12.38%
Investment, Acquisition Date	Nov. 18, 2020
Investment Maturity Date	Nov. 18, 2026
Investment Owned, Balance, Principal Amount	$ 2,250
Investment Owned, at Fair Value	$ 2,257
Investment, Identifier [Axis]: V H T Solutions ( Delayed Draw), Senior Secured Loans, due 12/21/2026
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:VHTAcquisitionsLLCMember
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Telecommunications
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Basis Spread, Variable Rate		7%
Investment, Interest Rate, Paid in Kind		8%
Investment, Acquisition Date		Dec. 21, 2021
Investment Maturity Date		Dec. 21, 2026
Investment Owned, Balance, Principal Amount		$ 120
Investment, Identifier [Axis]: V H T Solutions ( Revolver), Senior Secured Loans, due 12/21/2026
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:VHTAcquisitionsLLCMember
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Telecommunications
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Basis Spread, Variable Rate		7%
Investment, Interest Rate, Paid in Kind		8%
Investment, Acquisition Date		Dec. 21, 2021
Investment Maturity Date		Dec. 21, 2026
Investment Owned, Balance, Principal Amount		$ 43
Investment, Identifier [Axis]: V H T Solutions, Senior Secured Loans, due 12/21/2026
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:VHTAcquisitionsLLCMember
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Telecommunications
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Basis Spread, Variable Rate		7%
Investment, Interest Rate, Paid in Kind		8%
Investment, Acquisition Date		Dec. 21, 2021
Investment Maturity Date		Dec. 21, 2026
Investment Owned, Balance, Principal Amount		$ 1,500
Investment Owned, at Fair Value		$ 1,470
Investment, Identifier [Axis]: V P S Holdings, L L C ( Revolver), Senior Secured Loans, due 10/4/2024
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:VPSHoldingsLLCMember	mrcc:VPSHoldingsLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Services: Business	Services: Business
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR	LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Basis Spread, Variable Rate	9%	9%
Investment, Interest Rate, Paid in Cash	11.39%	8%
Investment, Interest Rate, Paid in Kind	2%	2%
Investment, Acquisition Date	Oct. 05, 2018	Oct. 05, 2018
Investment Maturity Date	Oct. 04, 2024	Oct. 04, 2024
Investment Owned, Balance, Principal Amount	$ 1,002	$ 1,001
Investment Owned, at Fair Value	$ 102	$ 97
Investment, Identifier [Axis]: V P S Holdings, L L C, Senior Secured Loans, One, due 10/4/2024
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:VPSHoldingsLLCMember	mrcc:VPSHoldingsLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Services: Business	Services: Business
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR	LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Basis Spread, Variable Rate	9%	9%
Investment, Interest Rate, Paid in Cash	11.39%	8%
Investment, Interest Rate, Paid in Kind	2%	2%
Investment, Acquisition Date	Oct. 05, 2018	Oct. 05, 2018
Investment Maturity Date	Oct. 04, 2024	Oct. 04, 2024
Investment Owned, Balance, Principal Amount	$ 3,246	$ 3,447
Investment Owned, at Fair Value	$ 3,252	$ 3,325
Investment, Identifier [Axis]: V P S Holdings, L L C, Senior Secured Loans, Two, due 10/4/2024
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:VPSHoldingsLLCMember	mrcc:VPSHoldingsLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Services: Business	Services: Business
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR	LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Basis Spread, Variable Rate	9%	9%
Investment, Interest Rate, Paid in Cash	11.39%	8%
Investment, Interest Rate, Paid in Kind	2%	2%
Investment, Acquisition Date	Oct. 05, 2018	Oct. 05, 2018
Investment Maturity Date	Oct. 04, 2024	Oct. 04, 2024
Investment Owned, Balance, Principal Amount	$ 2,656	$ 2,817
Investment Owned, at Fair Value	$ 2,661	$ 2,717
Investment, Identifier [Axis]: Valudor Products L L C ( Revolver), Senior Secured Loans, due 6/19/2023
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:ValudorProductsLLCMember	mrcc:ValudorProductsLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Chemicals, Plastics & Rubber	Chemicals, Plastics & Rubber
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR	LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Basis Spread, Variable Rate	9.50%	9.50%
Investment Interest Rate	13.89%	10.50%
Investment, Acquisition Date	Jun. 18, 2018	Jun. 18, 2018
Investment Maturity Date	Jun. 19, 2023	Jun. 19, 2023
Investment Owned, Balance, Principal Amount	$ 1,095	$ 1,095
Investment Owned, at Fair Value	$ 55	$ 479
Investment, Identifier [Axis]: Valudor Products L L C , Equity Securities, Class A-1 units
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:ValudorProductsLLCMember	mrcc:ValudorProductsLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Equity Securities [Member]
Investment, Industry Sector [Extensible Enumeration]	Chemicals, Plastics & Rubber	Chemicals, Plastics & Rubber
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment Interest Rate	10%
Investment, Interest Rate, Paid in Kind		10%
Investment, Acquisition Date	Jun. 18, 2018	Jun. 18, 2018
Investment Owned, at Fair Value	$ 555	$ 16
Investment, Identifier [Axis]: Valudor Products L L C, Senior Secured Loans, One, due 6/19/2023,
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:ValudorProductsLLCMember	mrcc:ValudorProductsLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Chemicals, Plastics & Rubber	Chemicals, Plastics & Rubber
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR	LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Basis Spread, Variable Rate	7.50%	7.50%
Investment, Interest Rate, Paid in Cash	10.39%	7%
Investment, Interest Rate, Paid in Kind	1.50%	1.50%
Investment, Acquisition Date	Jun. 18, 2018	Jun. 18, 2018
Investment Maturity Date	Jun. 19, 2023	Jun. 19, 2023
Investment Owned, Balance, Principal Amount	$ 1,609	$ 1,585
Investment Owned, at Fair Value	$ 1,958	$ 1,871
Investment, Identifier [Axis]: Valudor Products L L C, Senior Secured Loans, Three, due 6/19/2023
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:ValudorProductsLLCMember	mrcc:ValudorProductsLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Chemicals, Plastics & Rubber	Chemicals, Plastics & Rubber
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR	LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Basis Spread, Variable Rate	7.50%	7.50%
Investment Interest Rate	11.89%
Investment, Interest Rate, Paid in Kind		8.50%
Investment, Acquisition Date	Dec. 22, 2021	Jun. 18, 2018
Investment Maturity Date	Jun. 19, 2023	Jun. 19, 2023
Investment Owned, Balance, Principal Amount	$ 502	$ 237
Investment Owned, at Fair Value	$ 1,565	$ 230
Investment, Identifier [Axis]: Valudor Products L L C, Senior Secured Loans, Two, due 6/19/2023
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:ValudorProductsLLCMember	mrcc:ValudorProductsLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Chemicals, Plastics & Rubber	Chemicals, Plastics & Rubber
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR	LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Basis Spread, Variable Rate	7.50%	7.50%
Investment Interest Rate		8.50%
Investment, Interest Rate, Paid in Kind	11.89%
Investment, Acquisition Date	Jun. 18, 2018	Dec. 22, 2021
Investment Maturity Date	Jun. 19, 2023	Jun. 19, 2023
Investment Owned, Balance, Principal Amount	$ 260	$ 548
Investment Owned, at Fair Value	$ 312	$ 1,469
Investment, Identifier [Axis]: Vice Group Holding Inc., Senior Secured Loans, Four, due 5/12/2023
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:ViceGroupHoldingIncMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Media: Broadcasting & Subscription
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Basis Spread, Variable Rate	12%
Investment, Interest Rate, Paid in Cash	4.25%
Investment, Interest Rate, Paid in Kind	12%
Investment, Acquisition Date	May 02, 2019
Investment Maturity Date	May 12, 2023
Investment Owned, Balance, Principal Amount	$ 200
Investment Owned, at Fair Value	$ 196
Investment, Identifier [Axis]: Vice Group Holding Inc., Senior Secured Loans, Four, due, 11/2/2022
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:ViceGroupHoldingIncMember
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Media: Broadcasting & Subscription
Investment, Variable Interest Rate, Type [Extensible Enumeration]		us-gaap:LondonInterbankOfferedRateLiborSwapRateMember
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Basis Spread, Variable Rate		12%
Investment, Interest Rate, Paid in Cash		5.50%
Investment, Interest Rate, Paid in Kind		8%
Investment, Acquisition Date		May 02, 2019
Investment Maturity Date		Nov. 02, 2022
Investment Owned, Balance, Principal Amount		$ 180
Investment Owned, at Fair Value		$ 180
Investment, Identifier [Axis]: Vice Group Holding Inc., Senior Secured Loans, One, due 11/2/2022
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:ViceGroupHoldingIncMember
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Media: Broadcasting & Subscription
Investment, Variable Interest Rate, Type [Extensible Enumeration]		us-gaap:LondonInterbankOfferedRateLiborSwapRateMember
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Basis Spread, Variable Rate		12%
Investment, Interest Rate, Paid in Cash		5.50%
Investment, Interest Rate, Paid in Kind		8%
Investment, Acquisition Date		May 02, 2019
Investment Maturity Date		Nov. 02, 2022
Investment Owned, Balance, Principal Amount		$ 1,526
Investment Owned, at Fair Value		$ 1,526
Investment, Identifier [Axis]: Vice Group Holding Inc., Senior Secured Loans, One, due 5/12/2023
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:ViceGroupHoldingIncMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Media: Broadcasting & Subscription
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Basis Spread, Variable Rate	12%
Investment, Interest Rate, Paid in Cash	4.51%
Investment, Interest Rate, Paid in Kind	12%
Investment, Acquisition Date	May 02, 2019
Investment Maturity Date	May 12, 2023
Investment Owned, Balance, Principal Amount	$ 1,691
Investment Owned, at Fair Value	$ 1,657
Investment, Identifier [Axis]: Vice Group Holding Inc., Senior Secured Loans, Three, due 11/2/2022
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:ViceGroupHoldingIncMember
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Media: Broadcasting & Subscription
Investment, Variable Interest Rate, Type [Extensible Enumeration]		us-gaap:LondonInterbankOfferedRateLiborSwapRateMember
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Basis Spread, Variable Rate		12%
Investment, Interest Rate, Paid in Cash		5.50%
Investment, Interest Rate, Paid in Kind		8%
Investment, Acquisition Date		May 02, 2019
Investment Maturity Date		Nov. 02, 2022
Investment Owned, Balance, Principal Amount		$ 478
Investment Owned, at Fair Value		$ 478
Investment, Identifier [Axis]: Vice Group Holding Inc., Senior Secured Loans, Three, due 5/12/2023
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:ViceGroupHoldingIncMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Media: Broadcasting & Subscription
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Basis Spread, Variable Rate	12%
Investment, Interest Rate, Paid in Cash	4.42%
Investment, Interest Rate, Paid in Kind	12%
Investment, Acquisition Date	May 02, 2019
Investment Maturity Date	May 12, 2023
Investment Owned, Balance, Principal Amount	$ 531
Investment Owned, at Fair Value	$ 520
Investment, Identifier [Axis]: Vice Group Holding Inc., Senior Secured Loans, Two, due 11/2/2022
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:ViceGroupHoldingIncMember
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Media: Broadcasting & Subscription
Investment, Variable Interest Rate, Type [Extensible Enumeration]		us-gaap:LondonInterbankOfferedRateLiborSwapRateMember
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Basis Spread, Variable Rate		12%
Investment, Interest Rate, Paid in Cash		5.50%
Investment, Interest Rate, Paid in Kind		8%
Investment, Acquisition Date		Nov. 04, 2019
Investment Maturity Date		Nov. 02, 2022
Investment Owned, Balance, Principal Amount		$ 293
Investment Owned, at Fair Value		$ 293
Investment, Identifier [Axis]: Vice Group Holding Inc., Senior Secured Loans, Two, due 5/12/2023
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:ViceGroupHoldingIncMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Media: Broadcasting & Subscription
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Basis Spread, Variable Rate	12%
Investment, Interest Rate, Paid in Cash	4.51%
Investment, Interest Rate, Paid in Kind	12%
Investment, Acquisition Date	Nov. 04, 2019
Investment Maturity Date	May 12, 2023
Investment Owned, Balance, Principal Amount	$ 325
Investment Owned, at Fair Value	$ 318
Investment, Identifier [Axis]: Vinci Brands L L C (fka Incipio, L L C) ( Junior secured loan), One
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	Vinci Brands L L C (fka Incipio, L L C) [ Member]	Vinci Brands L L C (fka Incipio, L L C) [ Member]
Investment, Identifier [Axis]: Vinci Brands L L C (fka Incipio, L L C) ( Junior secured loan), Two
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	Vinci Brands L L C (fka Incipio, L L C) [ Member]	Vinci Brands L L C (fka Incipio, L L C) [ Member]
Investment, Identifier [Axis]: Vinci Brands L L C (fka Incipio, L L C), (Delayed Draw)
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	Vinci Brands L L C (fka Incipio, L L C) [ Member]
Investment, Identifier [Axis]: Vinci Brands L L C (fka Incipio, L L C), Equity Securities, Series C common units)
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	Vinci Brands L L C (fka Incipio, L L C) [ Member]	Vinci Brands L L C (fka Incipio, L L C) [ Member]
Investment, Identifier [Axis]: Vinci Brands L L C (fka Incipio, L L C), Loan Five
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	Vinci Brands L L C (fka Incipio, L L C) [ Member]	Vinci Brands L L C (fka Incipio, L L C) [ Member]
Investment Owned, at Fair Value			1,519
Investment, Identifier [Axis]: Vinci Brands L L C (fka Incipio, L L C), Loan Four
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	Vinci Brands L L C (fka Incipio, L L C) [ Member]	Vinci Brands L L C (fka Incipio, L L C) [ Member]
Investment Owned, at Fair Value			761
Investment, Identifier [Axis]: Vinci Brands L L C (fka Incipio, L L C), Loan One
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	Vinci Brands L L C (fka Incipio, L L C) [ Member]	Vinci Brands L L C (fka Incipio, L L C) [ Member]
Investment Owned, at Fair Value			1,764
Investment, Identifier [Axis]: Vinci Brands L L C (fka Incipio, L L C), Loan Six
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		Vinci Brands L L C (fka Incipio, L L C) [ Member]
Investment Owned, at Fair Value			1,488
Investment, Identifier [Axis]: Vinci Brands L L C (fka Incipio, L L C), Loan Three
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	Vinci Brands L L C (fka Incipio, L L C) [ Member]	Vinci Brands L L C (fka Incipio, L L C) [ Member]
Investment Owned, at Fair Value			1,805
Investment, Identifier [Axis]: Vinci Brands L L C (fka Incipio, L L C), Loan Two
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	Vinci Brands L L C (fka Incipio, L L C) [ Member]	Vinci Brands L L C (fka Incipio, L L C) [ Member]
Investment Owned, at Fair Value			4,227
Investment, Identifier [Axis]: Vinci Brands L L C, Unitranche Secured Loans, Four, due 2/6/2024
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:VinciBrandsLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Unitranche Debt [Member]
Investment, Industry Sector [Extensible Enumeration]	Consumer Sector, Non- Durable [ Member]	Consumer Sector, Non- Durable [ Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Interest Rate, Paid in Kind	2%	2%
Investment, Acquisition Date	Dec. 26, 2014	Dec. 26, 2014
Investment Maturity Date	Feb. 06, 2024	Feb. 06, 2024
Investment Owned, Balance, Principal Amount	$ 1,149	$ 1,149
Investment, Identifier [Axis]: Vinci Brands L L C, Unitranche Secured Loans, One, due 2/6/2024
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:VinciBrandsLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Unitranche Debt [Member]
Investment, Industry Sector [Extensible Enumeration]	Consumer Sector, Non- Durable [ Member]	Consumer Sector, Non- Durable [ Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Interest Rate, Paid in Kind	2%	2%
Investment, Acquisition Date	Jul. 06, 2018	Jul. 06, 2018
Investment Maturity Date	Feb. 06, 2024	Feb. 06, 2024
Investment Owned, Balance, Principal Amount	$ 7,026	$ 7,026
Investment Owned, at Fair Value		$ 4,950
Investment, Identifier [Axis]: Vinci Brands L L C, Unitranche Secured Loans, Three, due 2/6/2024
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:VinciBrandsLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Unitranche Debt [Member]
Investment, Industry Sector [Extensible Enumeration]	Consumer Sector, Non- Durable [ Member]	Consumer Sector, Non- Durable [ Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Interest Rate, Paid in Kind	2%	2%
Investment, Acquisition Date	Dec. 26, 2014	Dec. 26, 2014
Investment Maturity Date	Feb. 06, 2024	Feb. 06, 2024
Investment Owned, Balance, Principal Amount	$ 13,552	$ 13,552
Investment, Identifier [Axis]: Vinci Brands L L C, Unitranche Secured Loans, Two, due 2/6/2024
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:VinciBrandsLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Unitranche Debt [Member]
Investment, Industry Sector [Extensible Enumeration]	Consumer Sector, Non- Durable [ Member]	Consumer Sector, Non- Durable [ Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Interest Rate, Paid in Kind	2%	2%
Investment, Acquisition Date	Mar. 09, 2018	Mar. 09, 2018
Investment Maturity Date	Feb. 06, 2024	Feb. 06, 2024
Investment Owned, Balance, Principal Amount	$ 3,065	$ 3,065
Investment, Identifier [Axis]: W3 Monroe R E Debt L L C, Senior Secured Loans, due 2/4/2028
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:W3MonroeREDebtLLCMember	mrcc:W3MonroeREDebtLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	mrcc:FireFinanceMember	mrcc:FireFinanceMember
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Interest Rate, Paid in Kind	10%	10%
Investment, Acquisition Date	Feb. 05, 2021	Feb. 05, 2021
Investment Maturity Date	Feb. 04, 2028	Feb. 04, 2028
Investment Owned, Balance, Principal Amount	$ 3,210	$ 2,906
Investment Owned, at Fair Value	$ 3,210	$ 2,906
Investment, Identifier [Axis]: Wheel Pros, Inc., Senior Secured Loans, due 5/11/2028
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:WheelProsIncMember	mrcc:WheelProsIncMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Automotive	Automotive
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR	LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Basis Spread, Variable Rate	4.50%	4.50%
Investment Interest Rate	8.82%	5.25%
Investment Maturity Date	May 11, 2028	May 11, 2028
Investment Owned, Balance, Principal Amount	$ 1,932	$ 1,952
Investment Owned, at Fair Value	$ 1,321	$ 1,951
Investment, Identifier [Axis]: Whistler Parent Holdings I I I, Inc. ( Delayed Draw), Senior Secured Loans, due 6/2/2028
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:WhistlerParentHoldingsIIIIncMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Healthcare & Pharmaceuticals Sector [Member]
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Basis Spread, Variable Rate	6.75%
Investment Interest Rate	11.17%
Investment, Acquisition Date	Jun. 03, 2022
Investment Maturity Date	Jun. 02, 2028
Investment Owned, Balance, Principal Amount	$ 1,406
Investment Owned, at Fair Value	$ 56
Investment, Identifier [Axis]: Whistler Parent Holdings I I I, Inc. ( Revolver), Senior Secured Loans, due 6/2/2028
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:WhistlerParentHoldingsIIIIncMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Healthcare & Pharmaceuticals Sector [Member]
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Basis Spread, Variable Rate	6.75%
Investment Interest Rate	11.17%
Investment, Acquisition Date	Jun. 03, 2022
Investment Maturity Date	Jun. 02, 2028
Investment Owned, Balance, Principal Amount	$ 563
Investment Owned, at Fair Value	$ 84
Investment, Identifier [Axis]: Whistler Parent Holdings I I I, Inc., Senior Secured Loans, due 6/2/2028
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:WhistlerParentHoldingsIIIIncMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Healthcare & Pharmaceuticals Sector [Member]
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Basis Spread, Variable Rate	6.75%
Investment Interest Rate	11.17%
Investment, Acquisition Date	Jun. 03, 2022
Investment Maturity Date	Jun. 02, 2028
Investment Owned, Balance, Principal Amount	$ 4,500
Investment Owned, at Fair Value	$ 4,457
Investment, Identifier [Axis]: WillowTree, LLC, Unitranche Secured Loans, due 10/9/2023
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:WillowTreeLLCMember	mrcc:WillowTreeLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Unitranche Debt [Member]
Investment, Industry Sector [Extensible Enumeration]	High Tech Industries Sector [Member]	High Tech Industries Sector [Member]
Investment, Variable Interest Rate, Type [Extensible Enumeration]	LIBOR	LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Basis Spread, Variable Rate	5%	5%
Investment Interest Rate	9.39%	6%
Investment, Acquisition Date	Oct. 09, 2018	Oct. 09, 2018
Investment Maturity Date	Oct. 09, 2023	Oct. 09, 2023
Investment Owned, Balance, Principal Amount	$ 7,326	$ 7,639
Investment Owned, at Fair Value	$ 7,326	$ 7,651
Investment, Identifier [Axis]: Witkoff/ Monroe 700 J V L L C ( Delayed Draw), Junior Secured Loans, due 7/2/2026
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:WitkoffMonroe700JVLLCMember
Investment, Type [Extensible Enumeration]	Junior Loans [Member]	Junior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	FIRE: Real Estate	FIRE: Real Estate
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment Interest Rate	4%
Investment, Interest Rate, Paid in Cash	10.23%	8%
Investment, Interest Rate, Paid in Kind		4%
Investment, Acquisition Date	Jul. 02, 2021	Jul. 02, 2021
Investment Maturity Date	Jul. 02, 2026	Jul. 02, 2026
Investment Owned, Balance, Principal Amount	$ 6,708	$ 5,576
Investment Owned, at Fair Value	$ 6,014	$ 4,886
Investment, Identifier [Axis]: Witkoff/ Monroe 700 J V L L C, Equity Securities, Preferred units
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:WitkoffMonroe700JVLLCMember	mrcc:WitkoffMonroe700JVLLCMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Equity Securities [Member]
Investment, Industry Sector [Extensible Enumeration]	FIRE: Real Estate	FIRE: Real Estate
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Interest Rate, Paid in Cash	8%	8%
Investment, Interest Rate, Paid in Kind	4%	4%
Investment, Acquisition Date	Jul. 02, 2021	Jul. 02, 2021
Investment Owned, at Fair Value	$ 1,047	$ 2
Investment, Identifier [Axis]: Xan Edu Publishing, Inc, Equity Securities, Class A units
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:XanEduPublishingIncMember	mrcc:XanEduPublishingIncMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Equity Securities [Member]
Investment, Industry Sector [Extensible Enumeration]	Media: Advertising, Printing & Publishing	Media: Advertising, Printing & Publishing
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Interest Rate, Paid in Kind	8%	8%
Investment, Acquisition Date	Jan. 28, 2020	Jan. 28, 2020
Investment Owned, at Fair Value	$ 223	$ 106
Investment, Identifier [Axis]: Xan Edu Publishing, Inc. ( Revolver), Senior Secured Loans, due, 1/28/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:XanEduPublishingIncMember	mrcc:XanEduPublishingIncMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Media: Advertising, Printing & Publishing	Media: Advertising, Printing & Publishing
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]	us-gaap:LondonInterbankOfferedRateLiborSwapRateMember
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US	country:US
Investment, Basis Spread, Variable Rate	6.50%	6.50%
Investment Interest Rate	10.94%	7.50%
Investment, Acquisition Date	Jan. 28, 2020	Jan. 28, 2020
Investment Maturity Date	Jan. 28, 2025	Jan. 28, 2025
Investment Owned, Balance, Principal Amount	$ 742	$ 742
Investment, Identifier [Axis]: Xan Edu Publishing, Inc., Senior Secured Loans, One, due, 1/28/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:XanEduPublishingIncMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Media: Advertising, Printing & Publishing
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Basis Spread, Variable Rate	6.50%
Investment Interest Rate	10.94%
Investment, Acquisition Date	Jan. 28, 2020
Investment Maturity Date	Jan. 28, 2025
Investment Owned, Balance, Principal Amount	$ 4,584
Investment Owned, at Fair Value	$ 4,602
Investment, Identifier [Axis]: Xan Edu Publishing, Inc., Senior Secured Loans, Two, due, 1/28/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:XanEduPublishingIncMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Media: Advertising, Printing & Publishing
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Basis Spread, Variable Rate	6.50%
Investment Interest Rate	10.94%
Investment, Acquisition Date	Aug. 31, 2022
Investment Maturity Date	Jan. 28, 2025
Investment Owned, Balance, Principal Amount	$ 1,822
Investment Owned, at Fair Value	$ 1,829
Investment, Identifier [Axis]: Xan Edu Publishing, Inc., Senior Secured Loans, due, 1/28/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:XanEduPublishingIncMember
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Media: Advertising, Printing & Publishing
Investment, Variable Interest Rate, Type [Extensible Enumeration]		us-gaap:LondonInterbankOfferedRateLiborSwapRateMember
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Basis Spread, Variable Rate		6.50%
Investment Interest Rate		7.50%
Investment, Acquisition Date		Jan. 28, 2020
Investment Maturity Date		Jan. 28, 2025
Investment Owned, Balance, Principal Amount		$ 4,631
Investment Owned, at Fair Value		4,647
Investment, Identifier [Axis]: Y S W H 4, L L C (Revolver), Senior Secured Loans, Due 11/20/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:YSWH4LLCRevolverMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	mrcc:FireFinanceMember
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Basis Spread, Variable Rate	7%
Investment Interest Rate	11.44%
Investment, Acquisition Date	Jul. 20, 2022
Investment Maturity Date	Nov. 20, 2025
Investment Owned, Balance, Principal Amount	$ 5,250
Investment Owned, at Fair Value	$ 1,776
Investment, Identifier [Axis]: iCIMS, Inc, Due 8/18/2028
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:IcimsIncMember
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Services: Business
Investment, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]	country:US
Investment, Basis Spread, Variable Rate	7.25%
Investment Interest Rate	11.52%
Investment, Acquisition Date	Oct. 24, 2022
Investment Maturity Date	Aug. 18, 2028
Investment Owned, Balance, Principal Amount	$ 2,500
Investment Owned, at Fair Value	2,456
Non-US [Member]
Schedule of Investments [Line Items]
Investment Owned, at Fair Value	$ 10,405	$ 11,093
T J Management Hold Co L L C [ Member]
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment Owned, at Fair Value	$ 2,846	$ 3,148	3,323
Ascent Midco, L L C [ Member]
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment Owned, at Fair Value	$ 8,186	$ 8,946	10,013
Familia Dental Group Holdings, L L C [ Member]
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment Owned, at Fair Value	$ 2,625	$ 1,919	3,118
Mnine Holdings, Inc [ Member]
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment Owned, at Fair Value	$ 5,706	$ 5,771	12,356
American Community Homes, Inc. [ Member]
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment Owned, at Fair Value	$ 19,546	$ 23,748	$ 24,271
Automotive
Schedule of Investments [Line Items]
Investment Owned, at Fair Value	16,637	21,556
Banking
Schedule of Investments [Line Items]
Investment Owned, at Fair Value	19,817	6,712
Beverage, Food & Tobacco
Schedule of Investments [Line Items]
Investment Owned, at Fair Value	12,470	19,133
Capital Equipment
Schedule of Investments [Line Items]
Investment Owned, at Fair Value	19,012	12,839
Chemicals, Plastics & Rubber
Schedule of Investments [Line Items]
Investment Owned, at Fair Value	4,445	10,163
Construction & Building
Schedule of Investments [Line Items]
Investment Owned, at Fair Value	6,706	16,636
Environmental Industries
Schedule of Investments [Line Items]
Investment Owned, at Fair Value	$ 6,558	17,693
FIRE: Real Estate
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	FIRE Real Estate Sector [Member]
Investment Owned, Balance, Principal Amount	$ 7,857
Investment Owned, at Fair Value	$ 6,926
Healthcare & Pharmaceuticals
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Type [Extensible Enumeration]	Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]	Healthcare & Pharmaceuticals Sector [Member]
Investment Owned, Balance, Principal Amount	$ 61,092
Investment Owned, at Fair Value	46,159
Hotels, Gaming & Leisure
Schedule of Investments [Line Items]
Investment Owned, at Fair Value	2,720	2,706
Media: Advertising, Printing & Publishing
Schedule of Investments [Line Items]
Investment Owned, at Fair Value	19,777	16,794
Media: Broadcasting & Subscription
Schedule of Investments [Line Items]
Investment Owned, at Fair Value	2,691	2,477
Media: Diversified & Production
Schedule of Investments [Line Items]
Investment Owned, at Fair Value	36,164	24,220
Retail
Schedule of Investments [Line Items]
Investment Owned, at Fair Value	9,306	11,478
Telecommunications
Schedule of Investments [Line Items]
Investment Owned, at Fair Value	7,595	5,988
Wholesale
Schedule of Investments [Line Items]
Investment Owned, at Fair Value	14,165	15,576
Aerospace & Defense
Schedule of Investments [Line Items]
Investment Owned, at Fair Value	7,436	7,972
Senior Loans [Member]
Schedule of Investments [Line Items]
Investment Owned, at Fair Value	434,023	423,700
Non-controlled/non-affiliate company investments
Schedule of Investments [Line Items]
Investment Owned, at Fair Value	418,913	$ 430,287
Non-controlled/non-affiliate company investments | Senior Loans [Member]
Schedule of Investments [Line Items]
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment Owned, Balance, Principal Amount	425,065	$ 398,010
Investment Owned, at Fair Value	365,806	351,698
Non-controlled/non-affiliate company investments | Senior Loans [Member] | Automotive
Schedule of Investments [Line Items]
Investment Owned, Balance, Principal Amount	20,441	24,730
Investment Owned, at Fair Value	16,326	21,154
Non-controlled/non-affiliate company investments | Senior Loans [Member] | Banking
Schedule of Investments [Line Items]
Investment Owned, Balance, Principal Amount	10,773	10,658
Investment Owned, at Fair Value	10,345	3,625
Non-controlled/non-affiliate company investments | Senior Loans [Member] | Beverage, Food & Tobacco
Schedule of Investments [Line Items]
Investment Owned, Balance, Principal Amount	9,782	15,431
Investment Owned, at Fair Value	8,358	$ 12,286
Non-controlled/non-affiliate company investments | Senior Loans [Member] | Capital Equipment
Schedule of Investments [Line Items]
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment Owned, Balance, Principal Amount	20,572	$ 15,502
Investment Owned, at Fair Value	18,808	$ 12,691
Non-controlled/non-affiliate company investments | Senior Loans [Member] | Chemicals, Plastics & Rubber
Schedule of Investments [Line Items]
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment Owned, Balance, Principal Amount	3,466	$ 3,465
Investment Owned, at Fair Value	3,890	$ 4,049
Non-controlled/non-affiliate company investments | Senior Loans [Member] | Construction & Building
Schedule of Investments [Line Items]
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment Owned, Balance, Principal Amount	6,698	$ 17,970
Investment Owned, at Fair Value	6,706	$ 16,636
Non-controlled/non-affiliate company investments | Senior Loans [Member] | Consumer Goods: Durable
Schedule of Investments [Line Items]
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment Owned, Balance, Principal Amount	11,292	$ 11,387
Investment Owned, at Fair Value	9,236	$ 9,633
Non-controlled/non-affiliate company investments | Senior Loans [Member] | Consumer Sector, Non- Durable [ Member]
Schedule of Investments [Line Items]
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment Owned, Balance, Principal Amount	3,536	$ 3,568
Investment Owned, at Fair Value	3,508	$ 3,510
Non-controlled/non-affiliate company investments | Senior Loans [Member] | Environmental Industries
Schedule of Investments [Line Items]
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment Owned, Balance, Principal Amount	7,608	$ 20,124
Investment Owned, at Fair Value	6,201	17,238
Non-controlled/non-affiliate company investments | Senior Loans [Member] | FIRE: Finance
Schedule of Investments [Line Items]
Investment Owned, Balance, Principal Amount	29,660	17,453
Investment Owned, at Fair Value	23,495	15,389
Non-controlled/non-affiliate company investments | Senior Loans [Member] | FIRE: Real Estate
Schedule of Investments [Line Items]
Investment Owned, Balance, Principal Amount		5,522
Investment Owned, at Fair Value		5,526
Non-controlled/non-affiliate company investments | Senior Loans [Member] | Healthcare & Pharmaceuticals
Schedule of Investments [Line Items]
Investment Owned, Balance, Principal Amount		32,977
Investment Owned, at Fair Value		27,724
Non-controlled/non-affiliate company investments | Senior Loans [Member] | High Tech Industries
Schedule of Investments [Line Items]
Investment Owned, Balance, Principal Amount	42,877	32,968
Investment Owned, at Fair Value	38,519	30,154
Non-controlled/non-affiliate company investments | Senior Loans [Member] | Hotels, Gaming & Leisure
Schedule of Investments [Line Items]
Investment Owned, Balance, Principal Amount	3,097	3,123
Investment Owned, at Fair Value	2,611	$ 2,604
Non-controlled/non-affiliate company investments | Senior Loans [Member] | Media: Advertising, Printing & Publishing
Schedule of Investments [Line Items]
Investment Owned, Balance, Principal Amount	20,507
Investment Owned, at Fair Value	17,345
Non-controlled/non-affiliate company investments | Senior Loans [Member] | Media: Broadcasting & Subscription
Schedule of Investments [Line Items]
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment Owned, Balance, Principal Amount	2,747	$ 2,477
Investment Owned, at Fair Value	2,691	2,477
Non-controlled/non-affiliate company investments | Senior Loans [Member] | Media: Diversified & Production
Schedule of Investments [Line Items]
Investment Owned, Balance, Principal Amount	43,230	26,929
Investment Owned, at Fair Value	35,592	$ 23,687
Non-controlled/non-affiliate company investments | Senior Loans [Member] | Retail
Schedule of Investments [Line Items]
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment Owned, Balance, Principal Amount	8,772	$ 10,388
Investment Owned, at Fair Value	8,522	$ 10,278
Non-controlled/non-affiliate company investments | Senior Loans [Member] | Services: Business
Schedule of Investments [Line Items]
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment Owned, Balance, Principal Amount	58,660	$ 67,071
Investment Owned, at Fair Value	52,627	$ 64,220
Non-controlled/non-affiliate company investments | Senior Loans [Member] | Services: Consumer
Schedule of Investments [Line Items]
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment Owned, Balance, Principal Amount	30,570	$ 38,763
Investment Owned, at Fair Value	28,507	$ 35,123
Non-controlled/non-affiliate company investments | Senior Loans [Member] | Telecommunications
Schedule of Investments [Line Items]
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment Owned, Balance, Principal Amount	5,998	$ 5,472
Investment Owned, at Fair Value	5,269	$ 4,870
Non-controlled/non-affiliate company investments | Senior Loans [Member] | Wholesale
Schedule of Investments [Line Items]
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment Owned, Balance, Principal Amount	15,830	$ 15,695
Investment Owned, at Fair Value	$ 14,165	$ 15,502
MRCC Senior Loan Fund I, LLC
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
MRCC Senior Loan Fund I, LLC | Investment, Identifier [Axis]: 360 Holdco, Inc. ( Delayed Draw), Senior Secured Loans, due 8/2/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:ThreeSixty360HoldcoIncMember
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Services: Consumer
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Basis Spread, Variable Rate		4.75%
Investment Interest Rate		5.75%
Investment Maturity Date		Aug. 02, 2025
Investment Owned, Balance, Principal Amount		$ 827
MRCC Senior Loan Fund I, LLC | Investment, Identifier [Axis]: 360 Holdco, Inc., Senior Secured Loans, due 8/2/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:ThreeSixty360HoldcoIncMember
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Services: Consumer
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Basis Spread, Variable Rate		4.75%
Investment Interest Rate		5.75%
Investment Maturity Date		Aug. 02, 2025
Investment Owned, Balance, Principal Amount		$ 2,168
Investment Owned, at Fair Value		$ 2,161
MRCC Senior Loan Fund I, LLC | Investment, Identifier [Axis]: A Q Carver Buyer, Inc., Senior Secured Loans, due 9/23/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:AQCarverBuyerIncMember
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Services: Business
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Basis Spread, Variable Rate		5%
Investment Interest Rate		6%
Investment Maturity Date		Sep. 23, 2025
Investment Owned, Balance, Principal Amount		$ 4,888
Investment Owned, at Fair Value		$ 4,900
MRCC Senior Loan Fund I, LLC | Investment, Identifier [Axis]: Analogic Corporation, Senior Secured Loans, due 6/24/2024
Schedule of Investments [Line Items]
Investment, Basis Spread, Variable Rate	5.25%
Investment Interest Rate	9.66%
Investment Maturity Date	Jun. 24, 2024
Investment Owned, Balance, Principal Amount	$ 4,703
Investment Owned, at Fair Value	$ 4,433
MRCC Senior Loan Fund I, LLC | Investment, Identifier [Axis]: B M C Acquisition, Inc., Senior Secured Loans, due 12/30/2024
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:BMCAcquisitionIncMember
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Wholesale
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Basis Spread, Variable Rate		5.25%
Investment Interest Rate		6.25%
Investment Maturity Date		Dec. 30, 2024
Investment Owned, Balance, Principal Amount		$ 4,486
Investment Owned, at Fair Value		$ 4,469
MRCC Senior Loan Fund I, LLC | Investment, Identifier [Axis]: C H A Holdings, Inc, Senior Secured Loans, One, due 4/10/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:CHAHoldingsIncMember
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Services: Business
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Basis Spread, Variable Rate		4.50%
Investment Interest Rate		5.50%
Investment Maturity Date		Apr. 10, 2025
Investment Owned, Balance, Principal Amount		$ 1,980
Investment Owned, at Fair Value		$ 1,901
MRCC Senior Loan Fund I, LLC | Investment, Identifier [Axis]: C H A Holdings, Inc, Senior Secured Loans, Two, due 4/10/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:CHAHoldingsIncMember
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Services: Business
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Basis Spread, Variable Rate		4.50%
Investment Interest Rate		5.50%
Investment Maturity Date		Apr. 10, 2025
Investment Owned, Balance, Principal Amount		$ 418
Investment Owned, at Fair Value		$ 401
MRCC Senior Loan Fund I, LLC | Investment, Identifier [Axis]: Cadent, L L C ( Revolver), Senior Secured Loans, due 9/11/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:CadentLLCMember
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Media: Advertising, Printing & Publishing
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Basis Spread, Variable Rate		5%
Investment Interest Rate		6%
Investment Maturity Date		Sep. 11, 2023
Investment Owned, Balance, Principal Amount		$ 167
MRCC Senior Loan Fund I, LLC | Investment, Identifier [Axis]: Cadent, L L C, Senior Secured Loans, due 9/11/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:CadentLLCMember
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Media: Advertising, Printing & Publishing
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Basis Spread, Variable Rate		5%
Investment Interest Rate		6%
Investment Maturity Date		Sep. 11, 2023
Investment Owned, Balance, Principal Amount		$ 4,339
Investment Owned, at Fair Value		$ 4,296
MRCC Senior Loan Fund I, LLC | Investment, Identifier [Axis]: Corel Inc. (c), Senior Secured Loans, due 7/2/2026
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:CorelIncMember
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		High Tech Industries Sector [Member]
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]		Non-US [Member]
Investment, Basis Spread, Variable Rate		5%
Investment Interest Rate		5.18%
Investment Maturity Date		Jul. 02, 2026
Investment Owned, Balance, Principal Amount		$ 3,800
Investment Owned, at Fair Value		$ 3,797
MRCC Senior Loan Fund I, LLC | Investment, Identifier [Axis]: D S Parent, Inc., Senior Secured Loans, due 12/8/2028
Schedule of Investments [Line Items]
Investment, Basis Spread, Variable Rate	5.75%
Investment Interest Rate	9.92%
Investment Maturity Date	Dec. 08, 2028
Investment Owned, Balance, Principal Amount	$ 2,850
Investment Owned, at Fair Value	$ 2,725
MRCC Senior Loan Fund I, LLC | Investment, Identifier [Axis]: Dresser Utility Solutions, L L C (fka N G S U S Finco, L L C), Senior Secured Loans, One, due 10/1/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:DresserUtilitySolutionsLLCfkaNGSUSFincoLLCMember
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Utilities, Oil & Gas Sector [Member]
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Basis Spread, Variable Rate		4.25%
Investment Interest Rate		5.25%
Investment Maturity Date		Oct. 01, 2025
Investment Owned, Balance, Principal Amount		$ 1,695
Investment Owned, at Fair Value		$ 1,644
MRCC Senior Loan Fund I, LLC | Investment, Identifier [Axis]: Dresser Utility Solutions, L L C (fka N G S U S Finco, L L C), Senior Secured Loans, Two, due 10/1/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:DresserUtilitySolutionsLLCfkaNGSUSFincoLLCMember
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Utilities, Oil & Gas Sector [Member]
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Basis Spread, Variable Rate		5.25%
Investment Interest Rate		6.25%
Investment Maturity Date		Oct. 01, 2025
Investment Owned, Balance, Principal Amount		$ 248
Investment Owned, at Fair Value		$ 244
MRCC Senior Loan Fund I, LLC | Investment, Identifier [Axis]: Drilling Info Holdings, Inc., Senior Secured Loans, due 7/30/2025
Schedule of Investments [Line Items]
Investment, Basis Spread, Variable Rate	4.25%
Investment Interest Rate	8.63%
Investment Maturity Date	Jul. 30, 2025
Investment Owned, Balance, Principal Amount	$ 4,469
Investment Owned, at Fair Value	$ 4,313
MRCC Senior Loan Fund I, LLC | Investment, Identifier [Axis]: Eliassen Group, L L C, Senior Secured Loans, due 4/14/2028
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:EliassenGroupLLCMember
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Services: Business
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Basis Spread, Variable Rate		4.25%
Investment Interest Rate		4.35%
Investment Maturity Date		Nov. 05, 2024
Investment Owned, Balance, Principal Amount		$ 3,956
Investment Owned, at Fair Value		$ 3,956
MRCC Senior Loan Fund I, LLC | Investment, Identifier [Axis]: Engage2 Excel, Inc. ( Revolver), Senior Secured Loans, due 3/7/2023
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:Engage2ExcelIncMember
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Services: Business
Investment, Variable Interest Rate, Type [Extensible Enumeration]		Prime Rate [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Basis Spread, Variable Rate		8%
Investment, Interest Rate, Paid in Cash		7%
Investment, Interest Rate, Paid in Kind		2%
Investment Maturity Date		Mar. 07, 2023
Investment Owned, Balance, Principal Amount		$ 555
Investment Owned, at Fair Value		$ 541
MRCC Senior Loan Fund I, LLC | Investment, Identifier [Axis]: Engage2 Excel, Inc., Senior Secured Loans, One, due 3/7/2023
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:Engage2ExcelIncMember
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Services: Business
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Basis Spread, Variable Rate		8%
Investment, Interest Rate, Paid in Cash		7%
Investment, Interest Rate, Paid in Kind		2%
Investment Maturity Date		Mar. 07, 2023
Investment Owned, Balance, Principal Amount		$ 4,326
Investment Owned, at Fair Value		$ 4,329
MRCC Senior Loan Fund I, LLC | Investment, Identifier [Axis]: Engage2 Excel, Inc., Senior Secured Loans, Two,due 3/7/2023
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:Engage2ExcelIncMember
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Services: Business
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Basis Spread, Variable Rate		8%
Investment, Interest Rate, Paid in Cash		7%
Investment, Interest Rate, Paid in Kind		2%
Investment Maturity Date		Mar. 07, 2023
Investment Owned, Balance, Principal Amount		$ 781
Investment Owned, at Fair Value		$ 781
MRCC Senior Loan Fund I, LLC | Investment, Identifier [Axis]: Excel Fitness Holdings, Inc., Senior Secured Loans, due 4/27/2029
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:ExcelFitnessHoldingsIncMember
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Hotels, Gaming & Leisure
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Basis Spread, Variable Rate		5.25%
Investment Interest Rate		6.25%
Investment Maturity Date		Oct. 07, 2025
Investment Owned, Balance, Principal Amount		$ 4,165
Investment Owned, at Fair Value		$ 4,155
MRCC Senior Loan Fund I, LLC | Investment, Identifier [Axis]: H A L O Buyer, Inc., Senior Secured Loans, due 6/30/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:HALOBuyerIncMember
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Wholesale
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Basis Spread, Variable Rate		4.50%
Investment Interest Rate		5.50%
Investment Maturity Date		Jun. 30, 2025
Investment Owned, Balance, Principal Amount		$ 4,824
Investment Owned, at Fair Value		$ 4,547
MRCC Senior Loan Fund I, LLC | Investment, Identifier [Axis]: Intermedia Holdings, Inc., Senior Secured Loans, due 7/21/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:IntermediaHoldingsIncMember
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Telecommunications
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Basis Spread, Variable Rate		6%
Investment Interest Rate		7%
Investment Maturity Date		Jul. 21, 2025
Investment Owned, Balance, Principal Amount		$ 1,778
Investment Owned, at Fair Value		$ 1,770
MRCC Senior Loan Fund I, LLC | Investment, Identifier [Axis]: International Textile Group, Inc., Senior Secured Loans, due 5/1/2024
Schedule of Investments [Line Items]
Investment, Basis Spread, Variable Rate	5%
Investment Interest Rate	9.21%
Investment Maturity Date	May 01, 2024
Investment Owned, Balance, Principal Amount	$ 1,664
Investment Owned, at Fair Value	$ 1,166
MRCC Senior Loan Fund I, LLC | Investment, Identifier [Axis]: Keystone Purchaser, L L C, Senior Secured Loans, due 5/7/2027
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:KeystonePurchaserLLCMember
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Transportation Sector [Member]
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Basis Spread, Variable Rate		6.25%
Investment Interest Rate		7.25%
Investment Maturity Date		May 07, 2027
Investment Owned, Balance, Principal Amount		$ 3,000
Investment Owned, at Fair Value		$ 2,947
MRCC Senior Loan Fund I, LLC | Investment, Identifier [Axis]: L W Buyer, L L C, Senior Secured Loans, due 12/30/2024
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:LWBuyerLLCMember
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		High Tech Industries Sector [Member]
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Basis Spread, Variable Rate		5%
Investment Interest Rate		5.14%
Investment Maturity Date		Dec. 30, 2024
Investment Owned, Balance, Principal Amount		$ 4,875
Investment Owned, at Fair Value		$ 4,863
MRCC Senior Loan Fund I, LLC | Investment, Identifier [Axis]: Laseraway Intermediate Holdings I I, L L C, Senior Secured Loans, due 10/14/2027
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:LaserawayIntermediateHoldingsIILLCMember
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Services: Consumer
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Basis Spread, Variable Rate		5.75%
Investment Interest Rate		6.50%
Investment Maturity Date		Oct. 14, 2027
Investment Owned, Balance, Principal Amount		$ 2,222
Investment Owned, at Fair Value		$ 2,214
MRCC Senior Loan Fund I, LLC | Investment, Identifier [Axis]: Lightbox Intermediate, L. P., Senior Secured Loans, due 5/11/2026
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:LightboxIntermediateL.PMember
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		High Tech Industries Sector [Member]
Investment, Variable Interest Rate, Type [Extensible Enumeration]		us-gaap:LondonInterbankOfferedRateLiborSwapRateMember
Investment, Issuer Geographic Region [Extensible Enumeration]		Non-US [Member]
Investment, Basis Spread, Variable Rate		5%
Investment Interest Rate		5.13%
Investment Maturity Date		May 11, 2026
Investment Owned, Balance, Principal Amount		$ 4,875
Investment Owned, at Fair Value		$ 4,814
MRCC Senior Loan Fund I, LLC | Investment, Identifier [Axis]: Liqui- Box Holdings, Inc., Senior Secured Loans, due 2/26/2027
Schedule of Investments [Line Items]
Investment, Basis Spread, Variable Rate	4.50%
Investment Interest Rate	9.23%
Investment Maturity Date	Feb. 26, 2027
Investment Owned, Balance, Principal Amount	$ 4,225
Investment Owned, at Fair Value	$ 4,186
MRCC Senior Loan Fund I, LLC | Investment, Identifier [Axis]: Mac Queen Equipment, L L C ( Delayed Draw), Senior Secured Loans, due 1/7/2028
Schedule of Investments [Line Items]
Investment, Basis Spread, Variable Rate	5.25%
Investment Interest Rate	9.98%
Investment Maturity Date	Jan. 07, 2028
Investment Owned, Balance, Principal Amount	$ 592
Investment Owned, at Fair Value	$ 69
MRCC Senior Loan Fund I, LLC | Investment, Identifier [Axis]: Mac Queen Equipment, L L C ( Revolver), Senior Secured Loans, due 1/7/2028
Schedule of Investments [Line Items]
Investment, Basis Spread, Variable Rate	5.25%
Investment Interest Rate	9.98%
Investment Maturity Date	Jan. 07, 2028
Investment Owned, Balance, Principal Amount	$ 296
MRCC Senior Loan Fund I, LLC | Investment, Identifier [Axis]: Mac Queen Equipment, L L C, Senior Secured Loans, due 1/7/2028
Schedule of Investments [Line Items]
Investment, Basis Spread, Variable Rate	5.25%
Investment Interest Rate	9.98%
Investment Maturity Date	Jan. 07, 2028
Investment Owned, Balance, Principal Amount	$ 2,096
Investment Owned, at Fair Value	$ 2,096
MRCC Senior Loan Fund I, LLC | Investment, Identifier [Axis]: Mavenir Systems, Inc., Senior Secured Loans, due 8/18/2028
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:MavenirSystemsIncMember
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Telecommunications
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Basis Spread, Variable Rate		4.75%
Investment Interest Rate		5.25%
Investment Maturity Date		Aug. 18, 2028
Investment Owned, Balance, Principal Amount		$ 1,667
Investment Owned, at Fair Value		$ 1,669
MRCC Senior Loan Fund I, LLC | Investment, Identifier [Axis]: North Haven Spartan U S Holdco, L L C, Senior Secured Loans, due 6/6/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:NorthHavenSpartanUSHoldcoLLCMember
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Hotels, Gaming & Leisure
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Basis Spread, Variable Rate		5%
Investment Interest Rate		6%
Investment Maturity Date		Jun. 06, 2025
Investment Owned, Balance, Principal Amount		$ 2,297
Investment Owned, at Fair Value		$ 2,037
MRCC Senior Loan Fund I, LLC | Investment, Identifier [Axis]: Offen, Inc., Senior Secured Loans, One, due 6/22/2026
Schedule of Investments [Line Items]
Investment, Basis Spread, Variable Rate	5%
Investment Interest Rate	9.38%
Investment Maturity Date	Jun. 22, 2026
Investment Owned, Balance, Principal Amount	$ 2,249
Investment Owned, at Fair Value	$ 2,249
MRCC Senior Loan Fund I, LLC | Investment, Identifier [Axis]: Offen, Inc., Senior Secured Loans, Two, due 6/22/2026
Schedule of Investments [Line Items]
Investment, Basis Spread, Variable Rate	5%
Investment Interest Rate	9.38%
Investment Maturity Date	Jun. 22, 2026
Investment Owned, Balance, Principal Amount	$ 867
Investment Owned, at Fair Value	$ 867
MRCC Senior Loan Fund I, LLC | Investment, Identifier [Axis]: Orbit Purchaser L L C, Senior Secured Loans, One, due 10/21/2024
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:OrbitPurchaserLLCMember
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Services: Business
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Basis Spread, Variable Rate		4.50%
Investment Interest Rate		5.50%
Investment Maturity Date		Oct. 21, 2024
Investment Owned, Balance, Principal Amount		$ 2,431
Investment Owned, at Fair Value		$ 2,425
MRCC Senior Loan Fund I, LLC | Investment, Identifier [Axis]: Orbit Purchaser L L C, Senior Secured Loans, Three, due 10/21/2024
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:OrbitPurchaserLLCMember
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Services: Business
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Basis Spread, Variable Rate		4.50%
Investment Interest Rate		5.50%
Investment Maturity Date		Oct. 21, 2024
Investment Owned, Balance, Principal Amount		$ 549
Investment Owned, at Fair Value		$ 548
MRCC Senior Loan Fund I, LLC | Investment, Identifier [Axis]: Orbit Purchaser L L C, Senior Secured Loans, Two, due 10/21/2024
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:OrbitPurchaserLLCMember
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Services: Business
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Basis Spread, Variable Rate		4.50%
Investment Interest Rate		5.50%
Investment Maturity Date		Oct. 21, 2024
Investment Owned, Balance, Principal Amount		$ 1,877
Investment Owned, at Fair Value		$ 1,873
MRCC Senior Loan Fund I, LLC | Investment, Identifier [Axis]: Output Services Group, Inc., Senior Secured Loans, due 3/27/2024
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:OutputServicesGroupIncMember
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Services: Business
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Basis Spread, Variable Rate		4.50%
Investment Interest Rate		5.50%
Investment Maturity Date		Mar. 27, 2024
Investment Owned, Balance, Principal Amount		$ 4,815
Investment Owned, at Fair Value		$ 4,145
MRCC Senior Loan Fund I, LLC | Investment, Identifier [Axis]: P H Beauty Holdings I I I, I N C., Senior Secured Loans, due 9/26/2025
Schedule of Investments [Line Items]
Investment, Basis Spread, Variable Rate	5%
Investment Interest Rate	9.73%
Investment Maturity Date	Sep. 26, 2025
Investment Owned, Balance, Principal Amount	$ 2,393
Investment Owned, at Fair Value	$ 1,950
MRCC Senior Loan Fund I, LLC | Investment, Identifier [Axis]: P V H C Holding Corp, Senior Secured Loans, due 8/5/2024
Schedule of Investments [Line Items]
Investment, Basis Spread, Variable Rate	4.75%
Investment Interest Rate	9.48%
Investment Maturity Date	Aug. 05, 2024
Investment Owned, Balance, Principal Amount	$ 3,184
Investment Owned, at Fair Value	$ 3,072
MRCC Senior Loan Fund I, LLC | Investment, Identifier [Axis]: Phoenix Chemical Holding Company L L C (fka Polymer Solutions Group), Senior Secured Loans, due 1/3/2023
Schedule of Investments [Line Items]
Investment, Basis Spread, Variable Rate	7%
Investment Interest Rate	11.39%
Investment Maturity Date	Jun. 15, 2023
Investment Owned, Balance, Principal Amount	$ 1,139
Investment Owned, at Fair Value	$ 1,132
MRCC Senior Loan Fund I, LLC | Investment, Identifier [Axis]: Polychem Acquisition, L L C, Senior Secured Loans, due 3/17/2025
Schedule of Investments [Line Items]
Investment, Basis Spread, Variable Rate	5%
Investment Interest Rate	9.38%
Investment Maturity Date	Mar. 17, 2025
Investment Owned, Balance, Principal Amount	$ 2,888
Investment Owned, at Fair Value	$ 2,888
MRCC Senior Loan Fund I, LLC | Investment, Identifier [Axis]: Research Now Group, Inc. and Survey Sampling International, L L C, Senior Secured Loans, due 12/20/2024
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:ResearchNowGroupInc.andSurveySamplingInternationalLLCMember
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Media: Diversified & Production
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Basis Spread, Variable Rate		5.50%
Investment Interest Rate		6.50%
Investment Maturity Date		Dec. 20, 2024
Investment Owned, Balance, Principal Amount		$ 6,720
Investment Owned, at Fair Value		$ 6,645
MRCC Senior Loan Fund I, LLC | Investment, Identifier [Axis]: Runner Buyer I N C., Senior Secured Loans, due 10/23/2028
Schedule of Investments [Line Items]
Investment, Basis Spread, Variable Rate	5.50%
Investment Interest Rate	10.23%
Investment Maturity Date	Oct. 23, 2028
Investment Owned, Balance, Principal Amount	$ 2,978
Investment Owned, at Fair Value	$ 2,114
MRCC Senior Loan Fund I, LLC | Investment, Identifier [Axis]: S I R V A Worldwide Inc., Senior Secured Loans, due 8/4/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:SIRVAWorldwideIncMember
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Services: Business
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Basis Spread, Variable Rate		5.50%
Investment Interest Rate		5.60%
Investment Maturity Date		Aug. 04, 2025
Investment Owned, Balance, Principal Amount		$ 1,850
Investment Owned, at Fair Value		$ 1,683
MRCC Senior Loan Fund I, LLC | Investment, Identifier [Axis]: S T A T S Intermediate Holdings, L L C, Senior Secured Loans, due 7/10/2026
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:STATSIntermediateHoldingsLLCMember
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Media: Diversified & Production
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Basis Spread, Variable Rate		5.25%
Investment Interest Rate		5.41%
Investment Maturity Date		Jul. 10, 2026
Investment Owned, Balance, Principal Amount		$ 4,900
Investment Owned, at Fair Value		$ 4,897
MRCC Senior Loan Fund I, LLC | Investment, Identifier [Axis]: Sandvine Corporation, Senior Secured Loans, due 10/31/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:SandvineCorporationMember
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Telecommunications
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Basis Spread, Variable Rate		4.50%
Investment Interest Rate		4.60%
Investment Maturity Date		Oct. 31, 2025
Investment Owned, Balance, Principal Amount		$ 2,000
Investment Owned, at Fair Value		$ 1,999
MRCC Senior Loan Fund I, LLC | Investment, Identifier [Axis]: Secretariat Advisors L L C ( Delayed Draw), Senior Secured Loans, due 12/29/2028
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:SecretariatAdvisorsLLCMember
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Services: Business
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Basis Spread, Variable Rate		4.75%
Investment Interest Rate		5.50%
Investment Maturity Date		Dec. 29, 2028
Investment Owned, Balance, Principal Amount		$ 270
MRCC Senior Loan Fund I, LLC | Investment, Identifier [Axis]: Secretariat Advisors L L C, Senior Secured Loans, due 12/29/2028
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:SecretariatAdvisorsLLCMember
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Services: Business
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Basis Spread, Variable Rate		4.75%
Investment Interest Rate		5.50%
Investment Maturity Date		Dec. 29, 2028
Investment Owned, Balance, Principal Amount		$ 1,710
Investment Owned, at Fair Value		$ 1,693
MRCC Senior Loan Fund I, LLC | Investment, Identifier [Axis]: T G G T S Acquisition Company, Senior Secured Loans, due 12/12/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:TGGTSAcquisitionCompanyMember
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		High Tech Industries Sector [Member]
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Basis Spread, Variable Rate		6.50%
Investment Interest Rate		6.60%
Investment Maturity Date		Dec. 12, 2025
Investment Owned, Balance, Principal Amount		$ 3,435
Investment Owned, at Fair Value		$ 3,446
MRCC Senior Loan Fund I, LLC | Investment, Identifier [Axis]: T J C Spartech Acquisition Corp., Senior Secured Loans, due 5/5/2028
Schedule of Investments [Line Items]
Investment, Basis Spread, Variable Rate	4.75%
Investment Interest Rate	8.53%
Investment Maturity Date	May 05, 2028
Investment Owned, Balance, Principal Amount	$ 4,253
Investment Owned, at Fair Value	$ 4,131
MRCC Senior Loan Fund I, LLC | Investment, Identifier [Axis]: Tait L L C ( Revolver), Senior Secured Loans, due 3/28/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:TaitLLCMember
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Hotels, Gaming & Leisure
Investment, Variable Interest Rate, Type [Extensible Enumeration]		Prime Rate [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Basis Spread, Variable Rate		4%
Investment Interest Rate		7.25%
Investment Maturity Date		Mar. 28, 2025
Investment Owned, Balance, Principal Amount		$ 769
Investment Owned, at Fair Value		$ 728
MRCC Senior Loan Fund I, LLC | Investment, Identifier [Axis]: Tait L L C, Senior Secured Loans, due 3/28/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:TaitLLCMember
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Hotels, Gaming & Leisure
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Basis Spread, Variable Rate		5%
Investment Interest Rate		5.14%
Investment Maturity Date		Mar. 28, 2025
Investment Owned, Balance, Principal Amount		$ 4,125
Investment Owned, at Fair Value		$ 3,785
MRCC Senior Loan Fund I, LLC | Investment, Identifier [Axis]: Teneo Holdings L L C, Senior Secured Loans, due 7/11/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:TeneoHoldingsLLCMember
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Services: Business
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Basis Spread, Variable Rate		5.25%
Investment Interest Rate		6.25%
Investment Maturity Date		Jul. 11, 2025
Investment Owned, Balance, Principal Amount		$ 4,888
Investment Owned, at Fair Value		$ 4,908
MRCC Senior Loan Fund I, LLC | Investment, Identifier [Axis]: The Cook & Boardman Group L L C, Senior Secured Loans, due 10/20/2025
Schedule of Investments [Line Items]
Investment, Basis Spread, Variable Rate	5.75%
Investment Interest Rate	9.99%
Investment Maturity Date	Oct. 20, 2025
Investment Owned, Balance, Principal Amount	$ 2,879
Investment Owned, at Fair Value	2,458
MRCC Senior Loan Fund I, LLC | Investment, Identifier [Axis]: The Kleinfelder Group, Inc., Senior Secured Loans, due 11/29/2024
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:TheKleinfelderGroupIncMember
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Services: Business
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Basis Spread, Variable Rate		5.25%
Investment Interest Rate		6.25%
Investment Maturity Date		Nov. 29, 2024
Investment Owned, Balance, Principal Amount		$ 2,387
Investment Owned, at Fair Value		$ 2,387
MRCC Senior Loan Fund I, LLC | Investment, Identifier [Axis]: The Octave Music Group, Inc., Senior Secured Loans, due 5/29/2025
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:TheOctaveMusicGroupIncMember
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Industry Sector [Extensible Enumeration]		Media: Diversified & Production
Investment, Variable Interest Rate, Type [Extensible Enumeration]		LIBOR
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment, Basis Spread, Variable Rate		6%
Investment Interest Rate		7%
Investment Maturity Date		May 29, 2025
Investment Owned, Balance, Principal Amount		$ 3,866
Investment Owned, at Fair Value		3,871
MRCC Senior Loan Fund I, LLC | Non-controlled/non-affiliate company investments | Senior Loans [Member]
Schedule of Investments [Line Items]
Investment Owned, at Fair Value	183,150	$ 189,109
MRCC Senior Loan Fund I, LLC | Non-controlled/non-affiliate company investments | Senior Loans [Member] | Automotive
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment Owned, Balance, Principal Amount	5,828	$ 5,888
Investment Owned, at Fair Value	4,690	$ 5,360
MRCC Senior Loan Fund I, LLC | Non-controlled/non-affiliate company investments | Senior Loans [Member] | Beverage, Food & Tobacco
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment Owned, Balance, Principal Amount	4,647	$ 4,735
Investment Owned, at Fair Value	3,996	$ 4,691
MRCC Senior Loan Fund I, LLC | Non-controlled/non-affiliate company investments | Senior Loans [Member] | Capital Equipment
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment Owned, Balance, Principal Amount	10,537	$ 7,752
Investment Owned, at Fair Value	9,323	$ 7,672
MRCC Senior Loan Fund I, LLC | Non-controlled/non-affiliate company investments | Senior Loans [Member] | Chemicals, Plastics & Rubber
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment Owned, Balance, Principal Amount	5,392	$ 1,178
Investment Owned, at Fair Value	5,263	$ 1,169
MRCC Senior Loan Fund I, LLC | Non-controlled/non-affiliate company investments | Senior Loans [Member] | Construction & Building
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment Owned, Balance, Principal Amount	2,879	$ 2,910
Investment Owned, at Fair Value	2,458	$ 2,838
MRCC Senior Loan Fund I, LLC | Non-controlled/non-affiliate company investments | Senior Loans [Member] | Consumer Goods: Durable
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment Owned, Balance, Principal Amount	4,642	$ 4,711
Investment Owned, at Fair Value	3,280	$ 4,560
MRCC Senior Loan Fund I, LLC | Non-controlled/non-affiliate company investments | Senior Loans [Member] | Consumer Sector, Non- Durable [ Member]
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment Owned, Balance, Principal Amount	2,393	$ 2,418
Investment Owned, at Fair Value	1,950	2,284
MRCC Senior Loan Fund I, LLC | Non-controlled/non-affiliate company investments | Senior Loans [Member] | FIRE: Finance
Schedule of Investments [Line Items]
Investment Owned, Balance, Principal Amount	10,774	7,926
Investment Owned, at Fair Value	10,437	7,891
MRCC Senior Loan Fund I, LLC | Non-controlled/non-affiliate company investments | Senior Loans [Member] | FIRE: Real Estate
Schedule of Investments [Line Items]
Investment Owned, Balance, Principal Amount	4,800	4,850
Investment Owned, at Fair Value	4,020	$ 4,824
MRCC Senior Loan Fund I, LLC | Non-controlled/non-affiliate company investments | Senior Loans [Member] | Healthcare & Pharmaceuticals
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment Owned, Balance, Principal Amount	19,519	$ 11,593
Investment Owned, at Fair Value	17,250	$ 11,531
MRCC Senior Loan Fund I, LLC | Non-controlled/non-affiliate company investments | Senior Loans [Member] | High Tech Industries
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment Owned, Balance, Principal Amount	11,615	$ 16,985
Investment Owned, at Fair Value	11,164	$ 16,920
MRCC Senior Loan Fund I, LLC | Non-controlled/non-affiliate company investments | Senior Loans [Member] | Hotels, Gaming & Leisure
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment Owned, Balance, Principal Amount	12,121	$ 11,356
Investment Owned, at Fair Value	10,582	$ 10,705
MRCC Senior Loan Fund I, LLC | Non-controlled/non-affiliate company investments | Senior Loans [Member] | Media: Advertising, Printing & Publishing
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment Owned, Balance, Principal Amount	4,404	$ 4,506
Investment Owned, at Fair Value	4,131	$ 4,296
MRCC Senior Loan Fund I, LLC | Non-controlled/non-affiliate company investments | Senior Loans [Member] | Media: Diversified & Production
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment Owned, Balance, Principal Amount	14,825	$ 15,486
Investment Owned, at Fair Value	12,775	$ 15,413
MRCC Senior Loan Fund I, LLC | Non-controlled/non-affiliate company investments | Senior Loans [Member] | Energy Sector, Oil and Gas [Member]
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment Owned, Balance, Principal Amount	7,585	$ 7,780
Investment Owned, at Fair Value	7,429	$ 7,734
MRCC Senior Loan Fund I, LLC | Non-controlled/non-affiliate company investments | Senior Loans [Member] | Services: Business
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment Owned, Balance, Principal Amount	37,388	$ 37,681
Investment Owned, at Fair Value	34,118	$ 36,471
MRCC Senior Loan Fund I, LLC | Non-controlled/non-affiliate company investments | Senior Loans [Member] | Services: Consumer
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment Owned, Balance, Principal Amount	7,653	$ 5,217
Investment Owned, at Fair Value	6,880	$ 4,375
MRCC Senior Loan Fund I, LLC | Non-controlled/non-affiliate company investments | Senior Loans [Member] | Telecommunications
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment Owned, Balance, Principal Amount	5,414	$ 5,445
Investment Owned, at Fair Value	4,614	$ 5,438
MRCC Senior Loan Fund I, LLC | Non-controlled/non-affiliate company investments | Senior Loans [Member] | Transportation Sector [Member]
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment Owned, Balance, Principal Amount	4,955	$ 3,000
Investment Owned, at Fair Value	4,955	$ 2,947
MRCC Senior Loan Fund I, LLC | Non-controlled/non-affiliate company investments | Senior Loans [Member] | Utilities, Oil & Gas Sector [Member]
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment Owned, Balance, Principal Amount	1,923	$ 1,943
Investment Owned, at Fair Value	1,858	$ 1,888
MRCC Senior Loan Fund I, LLC | Non-controlled/non-affiliate company investments | Senior Loans [Member] | Wholesale
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment Owned, Balance, Principal Amount	4,774	$ 9,310
Investment Owned, at Fair Value	4,219	$ 9,016
MRCC Senior Loan Fund I, LLC | Non-controlled/non-affiliate company investments | Senior Loans [Member] | Aerospace & Defense
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment Owned, Balance, Principal Amount	8,083	$ 7,305
Investment Owned, at Fair Value	7,612	$ 6,964
MRCC Senior Loan Fund I, LLC | Non-controlled/non-affiliate company investments | Senior Loans [Member] | Container and Packaging Sector [Member]
Schedule of Investments [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Type [Extensible Enumeration]		Senior Loans [Member]
Investment, Issuer Geographic Region [Extensible Enumeration]		country:US
Investment Owned, Balance, Principal Amount	10,297	$ 15,154
Investment Owned, at Fair Value	$ 10,146	$ 14,122

Investments - SLF Balance Sheet

Investments - SLF Balance Sheet (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Assets
Fair Value	$ 541,040	$ 561,693
Cash	5,450	2,622	$ 6,769
Restricted cash		15,459	$ 25,657
Interest receivable	16,457	9,476
Other assets	541	427
Total assets	564,995	590,458
Liabilities
Revolving credit facility	334,600	337,945
Less: Unamortized deferred financing costs	(4,486)	(5,794)
Total debt, less unamortized deferred financing costs	330,114	332,151
Interest payable	3,041	3,304
Accounts payable and accrued expenses	3,220	2,643
Total liabilities	339,976	340,987
Total net assets	225,019	249,471
SLF
Assets
Fair Value	183,150	189,109
Cash	1,608	40
Restricted cash	6,454	4,862
Interest receivable	1,613	600
Other assets	5	12
Total assets	192,830	194,623
Liabilities
Revolving credit facility	122,215	94,765
Less: Unamortized deferred financing costs	(1,518)	(2,319)
Total debt, less unamortized deferred financing costs	120,697	92,446
Payable for open trades		19,367
Interest payable	769	242
Accounts payable and accrued expenses	346	318
Total liabilities	121,812	112,373
Total net assets	71,018	82,250
Total liabilities and members' capital	$ 192,830	$ 194,623

Investments - SLF, Net increase

Investments - SLF, Net increase (decrease) in members' capital (Details) - USD ($) $ in Thousands	3 Months Ended												12 Months Ended
	Dec. 31, 2022	Sep. 30, 2022	Jun. 30, 2022	Mar. 31, 2022	Dec. 31, 2021	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Investment income:
Total investment income	$ 15,164	$ 15,916	$ 12,995	$ 12,491	$ 13,039	$ 15,214	$ 12,364	$ 13,213	$ 12,552	$ 13,385	$ 20,642	$ 15,002	$ 56,566	$ 53,830	$ 61,581
Expenses:
Interest and other debt financing expenses													17,080	16,074	17,989
Professional fees													894	1,013	1,023
Expenses before base management fee and incentive fee waivers													33,549	32,864	31,965
Net investment income	5,520	6,260	5,014	5,398	5,373	6,312	5,157	5,326	5,326	5,644	12,636	6,782	22,192	22,168	30,388
Net gain (loss):
Net change in unrealized gain (loss)													(22,892)	36,108	(31,263)
Net gain (loss)	(1,040)	(7,009)	(12,378)	(4,551)	1,462	927	6,173	1,729	3,751	9,541	1,598	(43,632)	(24,978)	10,291	(28,742)
Net increase (decrease) in net assets resulting from operations	$ 4,480	$ (749)	$ (7,364)	$ 847	$ 6,835	$ 7,239	$ 11,330	$ 7,055	$ 9,077	$ 15,185	$ 14,234	$ (36,850)	(2,786)	32,459	1,646
SLF
Investment income:
Interest income													15,400	13,164	15,578
Total investment income													15,400	13,164	15,578
Expenses:
Interest and other debt financing expenses													6,009	3,918	5,227
Professional fees													814	647	666
Expenses before base management fee and incentive fee waivers													6,823	4,565	5,893
Net investment income													8,577	8,599	9,685
Net gain (loss):
Net realized gain (loss)													(3,089)		(1,713)
Net change in unrealized gain (loss)													(10,520)	3,734	(5,429)
Net gain (loss)													(13,609)	3,734	(7,142)
Net increase (decrease) in net assets resulting from operations													$ (5,032)	$ 12,333	$ 2,543

Fair Value Measurements - Fair

Fair Value Measurements - Fair value measurements of investments and foreign currency forward contracts, by major class according to the fair value hierarchy (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Fair Value Measurements
Total investments	$ 502,980	$ 514,265
Recurring
Fair Value Measurements
Total investments	541,040	561,693
Foreign currency forward contracts asset (liability)	1,507	781
Recurring | Senior secured loans
Fair Value Measurements
Total investments	434,023	423,700
Recurring | Unitranche secured loans
Fair Value Measurements
Total investments	20,633	51,494
Recurring | Junior secured loans
Fair Value Measurements
Total investments	22,193	14,364
Recurring | Equity securities
Fair Value Measurements
Total investments	28,682	31,010
Recurring | Level 1
Fair Value Measurements
Total investments	294	1,041
Recurring | Level 1 | Equity securities
Fair Value Measurements
Total investments	294	1,041
Recurring | Level 2
Fair Value Measurements
Foreign currency forward contracts asset (liability)	1,507	781
Recurring | Level 3
Fair Value Measurements
Total investments	505,237	519,527
Recurring | Level 3 | Senior secured loans
Fair Value Measurements
Total investments	434,023	423,700
Recurring | Level 3 | Unitranche secured loans
Fair Value Measurements
Total investments	20,633	51,494
Recurring | Level 3 | Junior secured loans
Fair Value Measurements
Total investments	22,193	14,364
Recurring | Level 3 | Equity securities
Fair Value Measurements
Total investments	28,388	29,969
Recurring | Measured at NAV
Fair Value Measurements
Total investments	$ 35,509	$ 41,125

Fair Value Measurements - Contr

Fair Value Measurements - Contractual interest rates (Details)	Dec. 31, 2022	Dec. 31, 2021
Minimum
Fair Value Measurements
Contractual interest rates on loans	8%	6%
Maximum
Fair Value Measurements
Contractual interest rates on loans	19.50%	16%

Fair Value Measurements - Recon

Fair Value Measurements - Reconciliation of the beginning and ending balances for investments at fair value that use Level 3 inputs (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Reconciliation of beginning and ending balances for investments at fair value that use Level 3 inputs
Balance at the beginning	$ 519,527	$ 507,755
Net realized gain (loss) on investments	$ (1,130)	$ (21,764)
Fair Value, Asset, Recurring Basis, Unobservable Input Reconciliation, Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]	Derivative and Foreign Currency Transaction Price Change, Realized Gain (Loss), Operating, before Tax	Derivative and Foreign Currency Transaction Price Change, Realized Gain (Loss), Operating, before Tax
Net change in unrealized gain (loss) on investments	$ (16,919)	$ 32,738
Purchases of investments and other adjustments to cost	141,555	236,285
Proceeds from principal payments and sales of investments	(137,796)	(234,446)
Transfers in (out) of Level 3		(1,041)
Balance at the end	505,237	519,527
Total net change in unrealized gain (loss) on investments attributable to Level 3 investments still held	$ (15,399)	$ 7,402
Fair Value, Asset, Recurring Basis, Still Held, Unrealized Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]	Realized and Unrealized Gain (Loss), Investment, Derivative, and Foreign Currency Transaction Price Change, Operating, before Tax	Realized and Unrealized Gain (Loss), Investment, Derivative, and Foreign Currency Transaction Price Change, Operating, before Tax
Fair value, assets, transfers among Levels 1, 2 and 3	$ 0
Fair value investment transferred from Level 3 to Level 1		$ 1
Senior secured loans
Reconciliation of beginning and ending balances for investments at fair value that use Level 3 inputs
Balance at the beginning	423,700	405,224
Net realized gain (loss) on investments	(1,082)	(22,512)
Net change in unrealized gain (loss) on investments	(10,140)	30,041
Purchases of investments and other adjustments to cost	130,155	204,213
Proceeds from principal payments and sales of investments	(108,610)	(193,266)
Balance at the end	434,023	423,700
Unitranche secured loans
Reconciliation of beginning and ending balances for investments at fair value that use Level 3 inputs
Balance at the beginning	51,494	64,040
Net realized gain (loss) on investments	(94)
Net change in unrealized gain (loss) on investments	(5,238)	(6,054)
Purchases of investments and other adjustments to cost	3,319	10,815
Proceeds from principal payments and sales of investments	(28,848)	(17,307)
Balance at the end	20,633	51,494
Junior secured loans
Reconciliation of beginning and ending balances for investments at fair value that use Level 3 inputs
Balance at the beginning	14,364	14,592
Net realized gain (loss) on investments	(1)
Net change in unrealized gain (loss) on investments	1,003	218
Purchases of investments and other adjustments to cost	6,827	13,652
Proceeds from principal payments and sales of investments		(14,098)
Balance at the end	22,193	14,364
Equity securities
Reconciliation of beginning and ending balances for investments at fair value that use Level 3 inputs
Balance at the beginning	29,969	23,899
Net realized gain (loss) on investments	47	748
Net change in unrealized gain (loss) on investments	(2,544)	8,533
Purchases of investments and other adjustments to cost	1,254	7,605
Proceeds from principal payments and sales of investments	(338)	(9,775)
Transfers in (out) of Level 3		(1,041)
Balance at the end	$ 28,388	$ 29,969

Fair Value Measurements - Valua

Fair Value Measurements - Valuation techniques and significant unobservable inputs used in recurring Level 3 fair value measurements of assets and liabilities (Details) $ in Thousands	Dec. 31, 2022 USD ($) item	Dec. 31, 2021 USD ($) item
Fair Value Measurements
Fair Value | $	$ 502,980	$ 514,265
Investments at fair value where valuation (unadjusted) is obtained from third-party pricing service | $	2,257	5,262
2026 Notes
Fair Value Measurements
Estimated fair value of notes | $	116,995
Senior secured loans | Discounted cash flow | EBITDA multiples
Fair Value Measurements
Fair Value | $	$ 276,433	$ 305,252
Senior secured loans | Discounted cash flow | EBITDA multiples | Weighted Average Mean
Fair Value Measurements
Investments, measurement input	0.093	0.077
Senior secured loans | Discounted cash flow | EBITDA multiples | Minimum
Fair Value Measurements
Investments, measurement input	0.038	0.050
Senior secured loans | Discounted cash flow | EBITDA multiples | Maximum
Fair Value Measurements
Investments, measurement input	0.186	0.200
Senior secured loans | Discounted cash flow | EBITDA Market Yields | Weighted Average Mean
Fair Value Measurements
Investments, measurement input	0.124	0.096
Senior secured loans | Discounted cash flow | EBITDA Market Yields | Minimum
Fair Value Measurements
Investments, measurement input	0.087	0.053
Senior secured loans | Discounted cash flow | EBITDA Market Yields | Maximum
Fair Value Measurements
Investments, measurement input	0.223	0.200
Senior secured loans | Discounted cash flow | Revenue Market Yields | Weighted Average Mean
Fair Value Measurements
Investments, measurement input	0.134	0.084
Senior secured loans | Discounted cash flow | Revenue Market Yields | Minimum
Fair Value Measurements
Investments, measurement input	0.100	0.052
Senior secured loans | Discounted cash flow | Revenue Market Yields | Maximum
Fair Value Measurements
Investments, measurement input	0.220	0.131
Senior secured loans | Discounted cash flow | Revenue multiples
Fair Value Measurements
Fair Value | $	$ 130,199	$ 79,913
Senior secured loans | Discounted cash flow | Revenue multiples | Weighted Average Mean
Fair Value Measurements
Investments, measurement input	0.044	0.065
Senior secured loans | Discounted cash flow | Revenue multiples | Minimum
Fair Value Measurements
Investments, measurement input	0.002	0.005
Senior secured loans | Discounted cash flow | Revenue multiples | Maximum
Fair Value Measurements
Investments, measurement input	0.123	0.130
Senior secured loans | Enterprise value | EBITDA multiples
Fair Value Measurements
Fair Value | $	$ 80	$ 5,111
Senior secured loans | Enterprise value | EBITDA multiples | Weighted Average Mean
Fair Value Measurements
Investments, measurement input	0.080	0.065
Senior secured loans | Enterprise value | EBITDA multiples | Minimum
Fair Value Measurements
Investments, measurement input	0.080	0.065
Senior secured loans | Enterprise value | EBITDA multiples | Maximum
Fair Value Measurements
Investments, measurement input	0.080	0.065
Senior secured loans | Enterprise value | Revenue multiples
Fair Value Measurements
Fair Value | $	$ 5,706	$ 5,771
Senior secured loans | Enterprise value | Revenue multiples | Weighted Average Mean
Fair Value Measurements
Investments, measurement input	0.025	0.028
Senior secured loans | Enterprise value | Revenue multiples | Minimum
Fair Value Measurements
Investments, measurement input	0.025	0.028
Senior secured loans | Enterprise value | Revenue multiples | Maximum
Fair Value Measurements
Investments, measurement input	0.025	0.028
Senior secured loans | Enterprise value | Book value multiples
Fair Value Measurements
Fair Value | $	$ 19,546	$ 23,484
Senior secured loans | Enterprise value | Book value multiples | Weighted Average Mean
Fair Value Measurements
Investments, measurement input	0.012	0.015
Senior secured loans | Enterprise value | Book value multiples | Minimum
Fair Value Measurements
Investments, measurement input	0.012	0.015
Senior secured loans | Enterprise value | Book value multiples | Maximum
Fair Value Measurements
Investments, measurement input	0.012	0.015
Senior secured loans | Liquidation | Probability weighting of alternative outcomes
Fair Value Measurements
Fair Value | $	$ 1,488	$ 3,026
Senior secured loans | Liquidation | Probability weighting of alternative outcomes | Weighted Average Mean
Fair Value Measurements
Investments, measurement input	0.713	0.882
Senior secured loans | Liquidation | Probability weighting of alternative outcomes | Minimum
Fair Value Measurements
Investments, measurement input	0.291	0.482
Senior secured loans | Liquidation | Probability weighting of alternative outcomes | Maximum
Fair Value Measurements
Investments, measurement input	1	1
Unitranche secured loans | Discounted cash flow | EBITDA multiples
Fair Value Measurements
Fair Value | $	$ 17,019	$ 45,072
Unitranche secured loans | Discounted cash flow | EBITDA multiples | Weighted Average Mean
Fair Value Measurements
Investments, measurement input	0.088	0.084
Unitranche secured loans | Discounted cash flow | EBITDA multiples | Minimum
Fair Value Measurements
Investments, measurement input	0.088	0.055
Unitranche secured loans | Discounted cash flow | EBITDA multiples | Maximum
Fair Value Measurements
Investments, measurement input	0.088	0.110
Unitranche secured loans | Discounted cash flow | EBITDA Market Yields | Weighted Average Mean
Fair Value Measurements
Investments, measurement input	0.112	0.085
Unitranche secured loans | Discounted cash flow | EBITDA Market Yields | Minimum
Fair Value Measurements
Investments, measurement input	0.091	0.073
Unitranche secured loans | Discounted cash flow | EBITDA Market Yields | Maximum
Fair Value Measurements
Investments, measurement input	0.130	0.133
Unitranche secured loans | Discounted cash flow | Revenue Market Yields | Weighted Average Mean
Fair Value Measurements
Investments, measurement input	0.119	0.083
Unitranche secured loans | Discounted cash flow | Revenue Market Yields | Minimum
Fair Value Measurements
Investments, measurement input	0.116	0.083
Unitranche secured loans | Discounted cash flow | Revenue Market Yields | Maximum
Fair Value Measurements
Investments, measurement input	0.121	0.083
Unitranche secured loans | Discounted cash flow | Revenue multiples
Fair Value Measurements
Fair Value | $	$ 3,614	$ 1,472
Unitranche secured loans | Discounted cash flow | Revenue multiples | Weighted Average Mean
Fair Value Measurements
Investments, measurement input	0.089	0.140
Unitranche secured loans | Discounted cash flow | Revenue multiples | Minimum
Fair Value Measurements
Investments, measurement input	0.058	0.140
Unitranche secured loans | Discounted cash flow | Revenue multiples | Maximum
Fair Value Measurements
Investments, measurement input	0.125	0.140
Unitranche secured loans | Enterprise value | Revenue multiples
Fair Value Measurements
Fair Value | $		$ 4,950
Unitranche secured loans | Enterprise value | Revenue multiples | Weighted Average Mean
Fair Value Measurements
Investments, measurement input		0.006
Unitranche secured loans | Enterprise value | Revenue multiples | Minimum
Fair Value Measurements
Investments, measurement input		0.006
Unitranche secured loans | Enterprise value | Revenue multiples | Maximum
Fair Value Measurements
Investments, measurement input		0.006
Junior secured loans | Discounted cash flow | Market yields
Fair Value Measurements
Fair Value | $	$ 20,311	$ 12,266
Junior secured loans | Discounted cash flow | Market yields | Weighted Average Mean
Fair Value Measurements
Investments, measurement input	0.136	0.158
Junior secured loans | Discounted cash flow | Market yields | Minimum
Fair Value Measurements
Investments, measurement input	0.123	0.080
Junior secured loans | Discounted cash flow | Market yields | Maximum
Fair Value Measurements
Investments, measurement input	0.204	0.251
Junior secured loans | Discounted cash flow | Revenue Market Yields | Weighted Average Mean
Fair Value Measurements
Investments, measurement input		0.020
Junior secured loans | Discounted cash flow | Revenue Market Yields | Minimum
Fair Value Measurements
Investments, measurement input		0.020
Junior secured loans | Discounted cash flow | Revenue Market Yields | Maximum
Fair Value Measurements
Investments, measurement input		0.020
Junior secured loans | Discounted cash flow | Revenue multiples
Fair Value Measurements
Fair Value | $		$ 1,522
Junior secured loans | Discounted cash flow | Revenue multiples | Weighted Average Mean
Fair Value Measurements
Investments, measurement input		0.150
Junior secured loans | Discounted cash flow | Revenue multiples | Minimum
Fair Value Measurements
Investments, measurement input		0.150
Junior secured loans | Discounted cash flow | Revenue multiples | Maximum
Fair Value Measurements
Investments, measurement input		0.150
Junior secured loans | Liquidation | Probability weighting of alternative outcomes
Fair Value Measurements
Fair Value | $	$ 1,882	$ 576
Junior secured loans | Liquidation | Probability weighting of alternative outcomes | Weighted Average Mean
Fair Value Measurements
Investments, measurement input	2.258	0.691
Junior secured loans | Liquidation | Probability weighting of alternative outcomes | Minimum
Fair Value Measurements
Investments, measurement input	2.258	0.691
Junior secured loans | Liquidation | Probability weighting of alternative outcomes | Maximum
Fair Value Measurements
Investments, measurement input	2.258	0.691
Equity securities | Discounted cash flow | EBITDA multiples
Fair Value Measurements
Fair Value | $	$ 397	$ 714
Equity securities | Discounted cash flow | EBITDA multiples | Weighted Average Mean
Fair Value Measurements
Investments, measurement input	0.070	0.133
Equity securities | Discounted cash flow | EBITDA multiples | Minimum
Fair Value Measurements
Investments, measurement input	0.070	0.133
Equity securities | Discounted cash flow | EBITDA multiples | Maximum
Fair Value Measurements
Investments, measurement input	0.070	0.133
Equity securities | Discounted cash flow | EBITDA Market Yields | Weighted Average Mean
Fair Value Measurements
Investments, measurement input		0.123
Equity securities | Discounted cash flow | EBITDA Market Yields | Minimum
Fair Value Measurements
Investments, measurement input		0.123
Equity securities | Discounted cash flow | EBITDA Market Yields | Maximum
Fair Value Measurements
Investments, measurement input		0.123
Equity securities | Enterprise value | EBITDA multiples
Fair Value Measurements
Fair Value | $	$ 16,630	$ 15,688
Equity securities | Enterprise value | EBITDA multiples | Weighted Average Mean
Fair Value Measurements
Investments, measurement input	0.090	0.056
Equity securities | Enterprise value | EBITDA multiples | Minimum
Fair Value Measurements
Investments, measurement input	0.038	0.045
Equity securities | Enterprise value | EBITDA multiples | Maximum
Fair Value Measurements
Investments, measurement input	0.160	0.151
Equity securities | Enterprise value | Revenue multiples
Fair Value Measurements
Fair Value | $	$ 7,502	$ 6,448
Equity securities | Enterprise value | Revenue multiples | Weighted Average Mean
Fair Value Measurements
Investments, measurement input	0.023	0.048
Equity securities | Enterprise value | Revenue multiples | Minimum
Fair Value Measurements
Investments, measurement input	0.002	0.006
Equity securities | Enterprise value | Revenue multiples | Maximum
Fair Value Measurements
Investments, measurement input	0.123	0.123
Equity securities | Enterprise value | Book value multiples
Fair Value Measurements
Fair Value | $		$ 264
Equity securities | Enterprise value | Book value multiples | Weighted Average Mean
Fair Value Measurements
Investments, measurement input		0.015
Equity securities | Enterprise value | Book value multiples | Minimum
Fair Value Measurements
Investments, measurement input		0.015
Equity securities | Enterprise value | Book value multiples | Maximum
Fair Value Measurements
Investments, measurement input		0.015
Equity securities | Liquidation | Probability weighting of alternative outcomes
Fair Value Measurements
Fair Value | $		$ 2,281
Equity securities | Liquidation | Probability weighting of alternative outcomes | Weighted Average Mean
Fair Value Measurements
Investments, measurement input		0.244
Equity securities | Liquidation | Probability weighting of alternative outcomes | Minimum
Fair Value Measurements
Investments, measurement input		0.244
Equity securities | Liquidation | Probability weighting of alternative outcomes | Maximum
Fair Value Measurements
Investments, measurement input		0.244
Equity securities | Option pricing model | Volatility
Fair Value Measurements
Fair Value | $	$ 2,173	$ 455
Equity securities | Option pricing model | Volatility | Weighted Average Mean
Fair Value Measurements
Investments, measurement input	0.666	0.425
Equity securities | Option pricing model | Volatility | Minimum
Fair Value Measurements
Investments, measurement input	0.494	0.425
Equity securities | Option pricing model | Volatility | Maximum
Fair Value Measurements
Investments, measurement input	0.700	0.425

Transactions with Affiliated _3

Transactions with Affiliated Companies - Fair Value Roll Forward (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 561,693
Fair value at the ending	$ 541,040	$ 561,693
Number of units held	327,133
Number of shares held	81
Equity contribution	$ 4,758
Curion Holdings, LLC
Transactions with Affiliated Companies, Fair value Roll Forward
Equity contribution	$ 0
American Community Homes, Inc. [ Member]
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 23,748	$ 24,271
Sales and paydowns (cost)		(3,561)
PIK Interest (cost)	1,942	2,719
Net unrealized gain (loss)	(6,144)	319
Fair value at the ending	$ 19,546	$ 23,748
Number of shares held	4,940
Percentage of equity interest	22.30%
Ascent Midco, L L C [ Member]
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 8,946	$ 10,013
Sales and paydowns (cost)	(174)	(531)
Discount accretion	25	25
Net unrealized gain (loss)	(611)	(561)
Fair value at the ending	$ 8,186	$ 8,946
Curion Holdings, LLC
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 5,111	$ 3,979
Purchases (cost)	92	308
Sales and paydowns (cost)	(5,117)	(308)
Net realized gain (loss)	(1)
Net unrealized gain (loss)	61	1,132
Fair value at the ending	$ 146	$ 5,111
Familia Dental Group Holdings, LLC
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 1,919	$ 3,118
Purchases (cost)	245	183
Net unrealized gain (loss)	461	(1,382)
Fair value at the ending	$ 2,625	$ 1,919
H F Z Capital Group, L L C, M C Asset Management ( Corporate), L L C and M C Asset Management ( Industrial), L L C [ Member]
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 29,152	$ 30,179
Purchases (cost)		7,216
Sales and paydowns (cost)		(12,119)
PIK Interest (cost)		2,211
Discount accretion		1
Net unrealized gain (loss)		1,664
Fair value at the ending		29,152
H F Z Capital Group, L L C And M C Asset Management ( Corporate), L L C [ Member]
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 29,152
PIK Interest (cost)	1,417
Net unrealized gain (loss)	2,107
Fair value at the ending	$ 32,676	$ 29,152
Vinci Brands L L C (fka Incipio, L L C) [ Member]
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 11,564
Transfers in (out)		(7,009)
Purchases (cost)		108
PIK Interest (cost)		91
Net unrealized gain (loss)		$ (4,754)
Luxury Optical Holdings Co [ Member]
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 4,596
Transfers in (out)		(78)
Purchases (cost)		1,729
Sales and paydowns (cost)		(10,200)
PIK Interest (cost)		860
Net realized gain (loss)		1,807
Net unrealized gain (loss)		$ 1,286
Mnine Holdings, Inc [ Member]
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 5,771	$ 12,356
Purchases (cost)	587
Sales and paydowns (cost)	(396)	(7,137)
PIK Interest (cost)	321	603
Discount accretion	14	34
Net unrealized gain (loss)	(591)	(85)
Fair value at the ending	$ 5,706	$ 5,771
N E C B Collections, L L C [ Member]
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 632	$ 834
Net unrealized gain (loss)	(250)	(202)
Fair value at the ending	$ 382	$ 632
S H I Holdings, Inc [ Member]
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 485
Sales and paydowns (cost)		(315)
Net realized gain (loss)		(7,194)
Net unrealized gain (loss)		$ 7,024
Second Avenue S F R Holdings I I L L C [ Member]
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 11,854
Purchases (cost)		$ 11,854
Fair value at the ending		11,854
Second Avenue SFR Holdings II LLC (Revolver) [ Member]
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 2,104
Purchases (cost)	2,681
Net unrealized gain (loss)	(30)
Fair value at the ending	$ 4,755	$ 2,104
Summit Container Corporation [ Member]
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 4,997
Purchases (cost)		5,402
Sales and paydowns (cost)		(10,078)
Net realized gain (loss)		(250)
Net unrealized gain (loss)		(71)
S F R Holdco, L L C [ Member]
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 9,750
Fair value at the ending	$ 9,750	$ 9,750
T J Management Hold Co L L C [ Member]
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 3,148	$ 3,323
Purchases (cost)	80
Sales and paydowns (cost)		(755)
Net unrealized gain (loss)	(382)	580
Fair value at the ending	$ 2,846	$ 3,148
MRCC Senior Loan Fund I, LLC
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Controlled affiliate company investments	Controlled affiliate company investments
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 41,125	$ 39,284
Purchases (cost)	500
Net unrealized gain (loss)	(6,116)	1,841
Fair value at the ending	$ 35,509	$ 41,125
Investment, Identifier [Axis]: 360 Holdco, Inc. ( Delayed Draw), Senior Secured Loans, due 8/2/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:ThreeSixty360HoldcoIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending	$ 252
Investment, Identifier [Axis]: 360 Holdco, Inc., Senior Secured Loans, due 8/2/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:ThreeSixty360HoldcoIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending	$ 2,145
Investment, Identifier [Axis]: A P C O Worldwide, Inc, Equity Securities, Class A voting common stock
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:APCOWorldwideIncMember	mrcc:APCOWorldwideIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 737
Fair value at the ending	$ 921	$ 737
Number of units held		100
Number of shares held	100
Investment, Identifier [Axis]: A Q Carver Buyer, Inc., Senior Secured Loans, due 9/23/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:AQCarverBuyerIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending	$ 4,834
Investment, Identifier [Axis]: A S G I I, L L C ( Delayed Draw), Unitranche Secured Loans, 5/25/2028
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:ASGIILLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending	$ 51
Investment, Identifier [Axis]: A S G I I, L L C, Unitranche Secured Loans, due 5/25/2028
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:ASGIILLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending	$ 1,900
Investment, Identifier [Axis]: Accelerate Auto Works Intermediate, L L C ( Delayed Draw), Senior Secured Loans, due 12/1/2027
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:AccelerateAutoWorksIntermediateLLCMember	mrcc:AccelerateAutoWorksIntermediateLLCMember
Investment, Identifier [Axis]: Accelerate Auto Works Intermediate, L L C ( Revolver), Senior Secured Loans, due 12/1/2027
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:AccelerateAutoWorksIntermediateLLCMember	mrcc:AccelerateAutoWorksIntermediateLLCMember
Investment, Identifier [Axis]: Accelerate Auto Works Intermediate, L L C, Senior Secured Loans, due 12/1/2027
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:AccelerateAutoWorksIntermediateLLCMember	mrcc:AccelerateAutoWorksIntermediateLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 1,436
Fair value at the ending	$ 1,386	$ 1,436
Investment, Identifier [Axis]: Ad Theorent Holding Company, Inc. Equity Securities, common stock
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:AdTheorentHoldingCompanyIncMember	mrcc:AdTheorentHoldingCompanyIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 1,041
Fair value at the ending	$ 294	$ 1,041
Number of units held	177,362
Number of shares held		177,362
Investment, Identifier [Axis]: Amelia Holding II, LLC (Delayed Draw), Due 12/21/2027
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:AmeliaHoldingIiLlcDelayedDrawMember
Investment, Identifier [Axis]: Amelia Holding II, LLC (Revolver), Due 12/21/2027
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:AmeliaHoldingIiLlcRevolverMember
Investment, Identifier [Axis]: Amelia Holding II, LLC, Due 12/21/2027
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:AmeliaHoldingIiLlcMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending	$ 1,940
Investment, Identifier [Axis]: Amelia Holding II, LLC, Equity Securities
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:AmeliaHoldingIiLlcMember
Transactions with Affiliated Companies, Fair value Roll Forward
Warrants to purchase percentage of equity	0.10%
Investment, Identifier [Axis]: American Broadband and Telecommunications Company L L C ( Delayed Draw), Senior Secured Loans, due 6/10/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:AmericanBroadbandandTelecommunicationsCompanyLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending	$ 1,539
Investment, Identifier [Axis]: American Broadband and Telecommunications Company L L C ( Revolver), Senior Secured Loans, due 6/10/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:AmericanBroadbandandTelecommunicationsCompanyLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending	$ 118
Investment, Identifier [Axis]: American Broadband and Telecommunications Company L L C, Equity Securities, Warrants
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:AmericanBroadbandandTelecommunicationsCompanyLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending	$ 69
Warrants to purchase percentage of equity	0.20%
Investment, Identifier [Axis]: American Community Homes, Inc, Senior Secured Loans (Common stock)
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	American Community Homes, Inc. [ Member]
Transactions with Affiliated Companies, Fair value Roll Forward
Number of shares held	4,940
Investment, Identifier [Axis]: American Community Homes, Inc. ( Revolver), Senior Secured Loans Due 12/31/2026
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	American Community Homes, Inc. [ Member]	American Community Homes, Inc. [ Member]
Investment, Identifier [Axis]: American Community Homes, Inc., Equity Securities Due 12/18/2024, Warrants
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	American Community Homes, Inc. [ Member]	American Community Homes, Inc. [ Member]
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 264
Net unrealized gain (loss)	$ (264)	$ 264
Fair value at the ending		$ 264
Warrants to purchase percentage of equity	22.30%	22.30%
Investment, Identifier [Axis]: American Community Homes, Inc., Equity Securities, Common Stock
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	American Community Homes, Inc. [ Member]
Transactions with Affiliated Companies, Fair value Roll Forward
Number of shares held	4,940
Investment, Identifier [Axis]: American Community Homes, Inc., Loan Five
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	American Community Homes, Inc. [ Member]	American Community Homes, Inc. [ Member]
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 335
Sales and paydowns (cost)		(341)
PIK Interest (cost)		$ 6
Investment, Identifier [Axis]: American Community Homes, Inc., Loan Three
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	American Community Homes, Inc. [ Member]	American Community Homes, Inc. [ Member]
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 825
Sales and paydowns (cost)		(838)
PIK Interest (cost)		$ 13
Investment, Identifier [Axis]: American Community Homes, Inc., Senior Secured Loans, Eight, Acquisition Date 9/30/2019
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	American Community Homes, Inc. [ Member]	American Community Homes, Inc. [ Member]
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 20	$ 18
PIK Interest (cost)	2	2
Net unrealized gain (loss)	(5)
Fair value at the ending	$ 17	$ 20
Investment, Identifier [Axis]: American Community Homes, Inc., Senior Secured Loans, Five, Due 12/31/2026
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	American Community Homes, Inc. [ Member]
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending	$ 3,694
Investment, Identifier [Axis]: American Community Homes, Inc., Senior Secured Loans, Five, Due 3/31/2022
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		American Community Homes, Inc. [ Member]
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 4,357
Fair value at the ending		$ 4,357
Investment, Identifier [Axis]: American Community Homes, Inc., Senior Secured Loans, Four, Acquisition Date 5/24/2017
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	American Community Homes, Inc. [ Member]	American Community Homes, Inc. [ Member]
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 634	$ 570
Sales and paydowns (cost)		(5)
PIK Interest (cost)	48	69
Net unrealized gain (loss)	(139)
Fair value at the ending	$ 543	$ 634
Investment, Identifier [Axis]: American Community Homes, Inc., Senior Secured Loans, Four, Due 12/31/2026
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	American Community Homes, Inc. [ Member]
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending	$ 1,996
Investment, Identifier [Axis]: American Community Homes, Inc., Senior Secured Loans, Four, Due 3/31/2022
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		American Community Homes, Inc. [ Member]
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 3,164
Fair value at the ending		$ 3,164
Investment, Identifier [Axis]: American Community Homes, Inc., Senior Secured Loans, Nine, Acquisition Date 12/30/2019
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	American Community Homes, Inc. [ Member]	American Community Homes, Inc. [ Member]
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 99	$ 89
Sales and paydowns (cost)		(1)
PIK Interest (cost)	7	11
Net unrealized gain (loss)	(21)
Fair value at the ending	$ 85	$ 99
Investment, Identifier [Axis]: American Community Homes, Inc., Senior Secured Loans, One, Acquisition Date 7/22/2014
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	American Community Homes, Inc. [ Member]	American Community Homes, Inc. [ Member]
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 10,457	$ 9,401
Sales and paydowns (cost)		(90)
PIK Interest (cost)	789	1,146
Net unrealized gain (loss)	(2,293)
Fair value at the ending	$ 8,953	$ 10,457
Investment, Identifier [Axis]: American Community Homes, Inc., Senior Secured Loans, One, Due 12/31/2026
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	American Community Homes, Inc. [ Member]
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending	$ 8,953
Investment, Identifier [Axis]: American Community Homes, Inc., Senior Secured Loans, One, Due 3/31/2022
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		American Community Homes, Inc. [ Member]
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 10,457
Fair value at the ending		$ 10,457
Investment, Identifier [Axis]: American Community Homes, Inc., Senior Secured Loans, Seven, Acquisition Date 3/29/2019
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	American Community Homes, Inc. [ Member]	American Community Homes, Inc. [ Member]
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 4,357	$ 3,879
Sales and paydowns (cost)		(37)
PIK Interest (cost)	325	473
Net unrealized gain (loss)	(988)	42
Fair value at the ending	$ 3,694	$ 4,357
Investment, Identifier [Axis]: American Community Homes, Inc., Senior Secured Loans, Seven, Due 12/31/2026
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	American Community Homes, Inc. [ Member]
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending	$ 85
Investment, Identifier [Axis]: American Community Homes, Inc., Senior Secured Loans, Seven, Due 3/31/2022
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		American Community Homes, Inc. [ Member]
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 99
Fair value at the ending		$ 99
Investment, Identifier [Axis]: American Community Homes, Inc., Senior Secured Loans, Six, Acquisition Date 8/10/2018
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	American Community Homes, Inc. [ Member]	American Community Homes, Inc. [ Member]
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 3,164	$ 2,915
Sales and paydowns (cost)		(20)
PIK Interest (cost)	176	256
Net unrealized gain (loss)	(1,344)	13
Fair value at the ending	$ 1,996	$ 3,164
Investment, Identifier [Axis]: American Community Homes, Inc., Senior Secured Loans, Six, Due 12/31/2026
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	American Community Homes, Inc. [ Member]
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending	$ 17
Investment, Identifier [Axis]: American Community Homes, Inc., Senior Secured Loans, Six, Due 3/31/2022
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		American Community Homes, Inc. [ Member]
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 20
Fair value at the ending		$ 20
Investment, Identifier [Axis]: American Community Homes, Inc., Senior Secured Loans, Three, Due 12/31/2026
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	American Community Homes, Inc. [ Member]
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending	$ 543
Investment, Identifier [Axis]: American Community Homes, Inc., Senior Secured Loans, Three, Due 3/31/2022
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		American Community Homes, Inc. [ Member]
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 634
Fair value at the ending		$ 634
Investment, Identifier [Axis]: American Community Homes, Inc., Senior Secured Loans, Two, Acquisition Date 7/22/2014
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	American Community Homes, Inc. [ Member]	American Community Homes, Inc. [ Member]
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 4,753	$ 6,239
Sales and paydowns (cost)		(2,229)
PIK Interest (cost)	595	743
Net unrealized gain (loss)	(1,090)
Fair value at the ending	$ 4,258	$ 4,753
Investment, Identifier [Axis]: American Community Homes, Inc., Senior Secured Loans, Two, Due 12/31/2026
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	American Community Homes, Inc. [ Member]
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending	$ 4,258
Investment, Identifier [Axis]: American Community Homes, Inc., Senior Secured Loans, Two, Due 3/31/2022
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		American Community Homes, Inc. [ Member]
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 4,753
Fair value at the ending		$ 4,753
Investment, Identifier [Axis]: Analogic Corporation, Senior Secured Loans, due 6/24/2024
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:AnalogicCorporationMember	mrcc:AnalogicCorporationMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 4,702
Fair value at the ending		$ 4,702
Investment, Identifier [Axis]: Apotheco, L L C ( Revolver), Senior Secured Loans, due 4/8/2024
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:ApothecoLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	910
Fair value at the ending		$ 910
Investment, Identifier [Axis]: Apotheco, L L C, Senior Secured Loans, due 4/8/2024
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:ApothecoLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 3,462
Fair value at the ending		$ 3,462
Investment, Identifier [Axis]: Aras Corporation ( Revolver), Senior Secured Loans, due 4/13/2027
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:ArasCorporationMember	mrcc:ArasCorporationMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending	$ 50
Investment, Identifier [Axis]: Aras Corporation, Senior Secured Loans, due 4/13/2027
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:ArasCorporationMember	mrcc:ArasCorporationMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 2,103
Fair value at the ending	$ 2,167	$ 2,103
Investment, Identifier [Axis]: Arcstor Midco, L L C, Senior Secured Loans, due 3/16/2027
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:ArcstorMidcoLLCMember	mrcc:ArcstorMidcoLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 4,433
Fair value at the ending	$ 4,122	$ 4,433
Investment, Identifier [Axis]: Ascent Midco, L L C ( Revolver), Senior Secured Loans Due 2/5/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	Ascent Midco, L L C [ Member]	Ascent Midco, L L C [ Member]
Investment, Identifier [Axis]: Ascent Midco, L L C, ( Delayed Draw) Loan
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	Ascent Midco, L L C [ Member]	Ascent Midco, L L C [ Member]
Investment, Identifier [Axis]: Ascent Midco, L L C, Equity Securities, Class A units
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	Ascent Midco, L L C [ Member]	Ascent Midco, L L C [ Member]
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 2,554	$ 3,016
Net unrealized gain (loss)	(585)	(462)
Fair value at the ending	$ 1,969	$ 2,554
Number of units held	2,032,258	2,032,258
Investment, Identifier [Axis]: Ascent Midco, L L C, Senior Secured Loans Due 2/5/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	Ascent Midco, L L C [ Member]	Ascent Midco, L L C [ Member]
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 6,392	$ 6,997
Sales and paydowns (cost)	(174)	(531)
Discount accretion	25	25
Net unrealized gain (loss)	(26)	(99)
Fair value at the ending	6,217	$ 6,392
Investment, Identifier [Axis]: Attom Intermediate Holdco, L L C ( Revolver), Senior Secured Loans, due 1/4/2024
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:AttomIntermediateHoldcoLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 160
Fair value at the ending		$ 160
Investment, Identifier [Axis]: Attom Intermediate Holdco, L L C, Equity Securities, Class A units
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:AttomIntermediateHoldcoLLCMember	mrcc:AttomIntermediateHoldcoLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 446
Fair value at the ending	$ 522	$ 446
Number of units held	297,197	297,197
Investment, Identifier [Axis]: Attom Intermediate Holdco, L L C, Senior Secured Loans, Five, due 7/3/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:AttomIntermediateHoldcoLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending	$ 399
Investment, Identifier [Axis]: Attom Intermediate Holdco, L L C, Senior Secured Loans, Four, due 7/3/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:AttomIntermediateHoldcoLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending	$ 794
Investment, Identifier [Axis]: Attom Intermediate Holdco, L L C, Senior Secured Loans, One, due 1/4/2024
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:AttomIntermediateHoldcoLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 1,937
Fair value at the ending		$ 1,937
Investment, Identifier [Axis]: Attom Intermediate Holdco, L L C, Senior Secured Loans, One, due 7/3/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:AttomIntermediateHoldcoLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending	$ 1,915
Investment, Identifier [Axis]: Attom Intermediate Holdco, L L C, Senior Secured Loans, Three, due 1/4/2024
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:AttomIntermediateHoldcoLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 278
Fair value at the ending		$ 278
Investment, Identifier [Axis]: Attom Intermediate Holdco, L L C, Senior Secured Loans, Three, due 7/3/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:AttomIntermediateHoldcoLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending	$ 275
Investment, Identifier [Axis]: Attom Intermediate Holdco, L L C, Senior Secured Loans, Two, due 1/4/2024
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:AttomIntermediateHoldcoLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 472
Fair value at the ending		$ 472
Investment, Identifier [Axis]: Attom Intermediate Holdco, L L C, Senior Secured Loans, Two, due 7/3/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:AttomIntermediateHoldcoLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending	$ 467
Investment, Identifier [Axis]: Attom Intermediate Holdco, LLC (Revolver), Senior Secured Loans, due 7/3/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:AttomIntermediateHoldcoLLCMember
Investment, Identifier [Axis]: Avalara, Inc. (Revolver), Senior Secured Loans, due 10/19/2028
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:AvalaraInc.Member
Investment, Identifier [Axis]: Avalara, Inc. Senior Secured Loans, due 10/19/2028
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:AvalaraInc.Member
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending	$ 3,900
Investment, Identifier [Axis]: Avison Young ( U S A) Inc., Senior Secured Loans, due 1/30/2026
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:AvisonYoungUSAIncMember	mrcc:AvisonYoungUSAIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 4,824
Fair value at the ending	$ 4,020	$ 4,824
Investment, Identifier [Axis]: B L S T Operating Company, L L C, Equity Securities, Class A units
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:BLSTOperatingCompanyLLCMember	mrcc:BLSTOperatingCompanyLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 420
Fair value at the ending	$ 420	$ 420
Number of units held	139,883	139,883
Investment, Identifier [Axis]: B L S T Operating Company, L L C, Senior Secured Loans, due 8/28/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:BLSTOperatingCompanyLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 1,143
Fair value at the ending		$ 1,143
Investment, Identifier [Axis]: BLST Operating Company, LLC, Due 8/28/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:BLSTOperatingCompanyLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending	$ 571
Investment, Identifier [Axis]: Bonterra, L L C (fka Cybergrants Holdings) ( Delayed Draw) , Senior Secured Loans, due 9/8/2027
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:BonterraLLCfkaCybergrantsHoldingsMember	mrcc:BonterraLLCfkaCybergrantsHoldingsMember
Investment, Identifier [Axis]: Bonterra, L L C (fka Cybergrants Holdings) ( Revolver), Senior Secured Loans, due 9/8/2027
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:BonterraLLCfkaCybergrantsHoldingsMember	mrcc:BonterraLLCfkaCybergrantsHoldingsMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending	$ 389
Investment, Identifier [Axis]: Bonterra, L L C (fka Cybergrants Holdings), Senior Secured Loans, due 9/8/2027
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:BonterraLLCfkaCybergrantsHoldingsMember	mrcc:BonterraLLCfkaCybergrantsHoldingsMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 10,900
Fair value at the ending	$ 12,898	$ 10,900
Investment, Identifier [Axis]: Born To Run, L L C ( Delayed Draw) Senior Secured Loans, due 4/1/2027
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:BornToRunLLCMember	mrcc:BornToRunLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 34
Fair value at the ending	$ 452	$ 34
Investment, Identifier [Axis]: Born To Run, L L C, Equity Securities, Class A units
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:BornToRunLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 293
Fair value at the ending	$ 233	$ 293
Number of units held	269,438	269,438
Investment, Identifier [Axis]: Born To Run, L L C, Senior Secured Loans, due 4/1/2027
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:BornToRunLLCMember	mrcc:BornToRunLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 3,544
Fair value at the ending	$ 3,318	$ 3,544
Investment, Identifier [Axis]: Brickell Bay Acquisition Corp, Senior Secured Loans, due 2/12/2026
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:BrickellBayAcquisitionCorpMember	mrcc:BrickellBayAcquisitionCorpMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 1,889
Fair value at the ending	$ 1,847	$ 1,889
Investment, Identifier [Axis]: Brickell Bay Acquisition Corp. ( Delayed Draw), Senior Secured Loans, due 2/12/2026
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:BrickellBayAcquisitionCorpMember
Investment, Identifier [Axis]: Brickell Bay Acquisition Corp., Senior Secured Loans, due 6/30/2027
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:BrickellBayAcquisitionCorpMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending	$ 4,630
Investment, Identifier [Axis]: Brightly Software Holdings, Inc. (fka Dude Solutions Holdings, Inc.), Senior Secured Loans, ( Revolver), due 6/13/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:BrightlySoftwareHoldingsInc.fkaDudeSolutionsHoldingsInc.Member
Investment, Identifier [Axis]: Brightly Software Holdings, Inc. (fka Dude Solutions Holdings, Inc.), Senior Secured Loans, due 6/13/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:BrightlySoftwareHoldingsInc.fkaDudeSolutionsHoldingsInc.Member
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 9,870
Fair value at the ending		$ 9,870
Investment, Identifier [Axis]: Bromford Industries Limited, Senior Secured Loans, One, due 11/5/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:BromfordIndustriesLimitedMember	mrcc:BromfordIndustriesLimitedMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 2,692
Fair value at the ending	$ 2,581	$ 2,692
Investment, Identifier [Axis]: Bromford Industries Limited, Senior Secured Loans, Two, due 11/5/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:BromfordIndustriesLimitedMember	mrcc:BromfordIndustriesLimitedMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 1,794
Fair value at the ending	$ 1,720	$ 1,794
Investment, Identifier [Axis]: Burroughs, Inc. ( Revolver), Senior Secured Loans, due 12/22/2022
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:BurroughsInc.Member
Investment, Identifier [Axis]: Burroughs, Inc. ( Revolver), Senior Secured Loans, due 12/22/2023
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:BurroughsInc.Member
Investment, Identifier [Axis]: Burroughs, Inc., Senior Secured Loans, due 12/22/2022
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:BurroughsInc.Member
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 5,480
Fair value at the ending		$ 5,480
Investment, Identifier [Axis]: Burroughs, Inc., Senior Secured Loans, due 12/22/2023
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:BurroughsInc.Member
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending	$ 5,201
Investment, Identifier [Axis]: C B C Restaurant Corp., Senior Secured Loans, due 12/30/2022
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Name [Extensible Enumeration]		mrcc:CBCRestaurantCorpMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	1,072
Fair value at the ending	$ 415	$ 1,072
Investment, Identifier [Axis]: C H A Holdings, Inc, Senior Secured Loans, One, due 4/10/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:CHAHoldingsIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending	$ 1,886
Investment, Identifier [Axis]: C H A Holdings, Inc, Senior Secured Loans, Two, due 4/10/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:CHAHoldingsIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending	$ 398
Investment, Identifier [Axis]: C Parent Holdings, LLC. (fka Curion Holdings, LLC), Equity Securities, Common Stock
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:CParentHoldingsLlc.Member
Transactions with Affiliated Companies, Fair value Roll Forward
Number of shares held	58,779
Investment, Identifier [Axis]: C Parent Holdings, LLC. (fka Curion Holdings, LLC), Senior Secured Loan
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:CParentHoldingsLlc.Member
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending	$ 146
Investment, Identifier [Axis]: CGI Automated Manufacturing, LLC, Senior Secured Loans, One, due 12/17/2026
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:CgiAutomatedManufacturingLlcMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending	$ 3,975
Investment, Identifier [Axis]: CGI Automated Manufacturing, LLC, Senior Secured Loans, Two, due 12/17/2026
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:CgiAutomatedManufacturingLlcMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending	$ 1,141
Investment, Identifier [Axis]: Cadent, L L C ( Revolver), Senior Secured Loans, due 9/11/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:CadentLLCMember
Investment, Identifier [Axis]: Cadent, L L C, Senior Secured Loans, due 9/11/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:CadentLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending	$ 4,131
Investment, Identifier [Axis]: Calabrio, Inc. ( Revolver), Senior Secured Loans, due 4/16/2027
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:CalabrioIncMember	mrcc:CalabrioIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending	$ 233
Investment, Identifier [Axis]: Calabrio, Inc., Senior Secured Loans, due 4/16/2027
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:CalabrioIncMember	mrcc:CalabrioIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 3,400
Fair value at the ending	$ 3,379	$ 3,400
Investment, Identifier [Axis]: California Pizza Kitchen, Inc., Equity Securities, Common units
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:CaliforniaPizzaKitchenInc.Member	mrcc:CaliforniaPizzaKitchenInc.Member
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 3,699
Fair value at the ending	$ 1,266	$ 3,699
Number of units held		78,699
Number of shares held	78,699
Investment, Identifier [Axis]: Cano Health, L L C, Senior Secured Loans, due 11/23/2027
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:CanoHealthLLMember	mrcc:CanoHealthLLMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 1,997
Fair value at the ending	$ 1,572	$ 1,997
Investment, Identifier [Axis]: Caravel Autism Health, L L C ( Delayed Draw), Senior Secured Loans, due 6/30/2027
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:CaravelAutismHealthLLCMember	mrcc:CaravelAutismHealthLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 176
Fair value at the ending	$ 173	$ 176
Investment, Identifier [Axis]: Caravel Autism Health, L L C ( Revolver), Senior Secured Loans, due 6/30/2027
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:CaravelAutismHealthLLCMember	mrcc:CaravelAutismHealthLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 587
Fair value at the ending	$ 1,048	$ 587
Investment, Identifier [Axis]: Caravel Autism Health, L L C, Senior Secured Loans, due 6/30/2027
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:CaravelAutismHealthLLCMember	mrcc:CaravelAutismHealthLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 4,699
Fair value at the ending		$ 4,699
Investment, Identifier [Axis]: Cassavant Holdings, L L C, Unitranche Secured Loans, due 9/8/2026
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:CassavantHoldingsLLCMember	mrcc:CassavantHoldingsLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 7,972
Fair value at the ending	$ 7,436	$ 7,972
Investment, Identifier [Axis]: Centaur ( Palm Beach) Owner L L C and Panther National Golf Club L L C ( Delayed Draw), Senior Secured Loans, due 4/30/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:CentaurPalmBeachOwnerLLCandPantherNationalGolfClubLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending	$ 337
Investment, Identifier [Axis]: Centaur ( Palm Beach) Owner L L C and Panther National Golf Club L L C ( Revolver), Senior Secured Loans, due 4/30/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:CentaurPalmBeachOwnerLLCandPantherNationalGolfClubLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending	$ 719
Investment, Identifier [Axis]: Centaur ( Palm Beach) Owner L L C and Panther National Golf Club L L C, Senior Secured Loans, due 4/30/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:CentaurPalmBeachOwnerLLCandPantherNationalGolfClubLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending	$ 3,296
Investment, Identifier [Axis]: Certify, Inc, Senior Secured Loans, One, due 2/28/2024
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:CertifyIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	9,000
Fair value at the ending		$ 9,000
Investment, Identifier [Axis]: Certify, Inc, Senior Secured Loans, Two, due 2/28/2024
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:CertifyIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	1,227
Fair value at the ending		$ 1,227
Investment, Identifier [Axis]: Certify, Inc. (Revolver), Senior Secured Loans, due 2/28/2024
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:CertifyIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 102
Fair value at the ending		$ 102
Investment, Identifier [Axis]: Chess.com, L L C ( Revolver), Senior Secured Loans, due 12/31/2027
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:Chess.comLLCMember	mrcc:Chess.comLLCMember
Investment, Identifier [Axis]: Chess.com, L L C, Equity Securities, Class A units
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:Chess.comLLCMember	mrcc:Chess.comLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 87
Fair value at the ending	$ 50	$ 87
Number of units held		2
Investment, Identifier [Axis]: Chess.com, L L C, Senior Secured Loans, due 12/31/2027
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:Chess.comLLCMember	mrcc:Chess.comLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 5,880
Fair value at the ending	$ 5,866	$ 5,880
Investment, Identifier [Axis]: Corel Inc. (c), Senior Secured Loans, due 7/2/2026
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:CorelIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending	$ 3,365
Investment, Identifier [Axis]: Crownpeak Technology Inc. (Revolver) Senior Secured Loans, Due 2/28/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:CrownpeakTechnologyIncMember
Investment, Identifier [Axis]: Crownpeak Technology Inc. Senior Secured Loans Four, Due 2/28/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:CrownpeakTechnologyIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending	$ 3,333
Investment, Identifier [Axis]: Crownpeak Technology Inc. Senior Secured Loans One, Due 2/28/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:CrownpeakTechnologyIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending	$ 4,000
Investment, Identifier [Axis]: Crownpeak Technology Inc. Senior Secured Loans Three, Due 2/28/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:CrownpeakTechnologyIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending	$ 60
Investment, Identifier [Axis]: Crownpeak Technology Inc. Senior Secured Loans Two, Due 2/28/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:CrownpeakTechnologyIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending	$ 1,273
Investment, Identifier [Axis]: Crownpeak Technology, Inc. ( Revolver), Senior Secured Loans, due 2/28/2024
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:CrownpeakTechnologyIncMember
Investment, Identifier [Axis]: Crownpeak Technology, Inc., Senior Secured Loans, One, due 2/28/2024
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:CrownpeakTechnologyIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	4,000
Fair value at the ending		$ 4,000
Investment, Identifier [Axis]: Crownpeak Technology, Inc., Senior Secured Loans, Two, due 2/28/2024
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:CrownpeakTechnologyIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	60
Fair value at the ending		$ 60
Investment, Identifier [Axis]: Curion Holdings, L L C ( Revolver), Senior Secured Loans, Due 8/31/2022
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		Curion Holdings, LLC
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 550
Fair value at the ending		$ 550
Investment, Identifier [Axis]: Curion Holdings, L L C, Equity Securities, Common stock
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	Curion Holdings, LLC	Curion Holdings, LLC
Transactions with Affiliated Companies, Fair value Roll Forward
Number of shares held	58,779	58,779
Investment, Identifier [Axis]: Curion Holdings, L L C, Junior Secured Loans, One, Due 1/2/2023
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	Curion Holdings, LLC	Curion Holdings, LLC
Investment, Identifier [Axis]: Curion Holdings, L L C, Junior Secured Loans, Two, Due 1/2/2023
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	Curion Holdings, LLC	Curion Holdings, LLC
Transactions with Affiliated Companies, Fair value Roll Forward
Net realized gain (loss)	$ (1)
Net unrealized gain (loss)	1
Investment, Identifier [Axis]: Curion Holdings, L L C, Senior Secured Loans, Due 8/31/2022
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		Curion Holdings, LLC
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 4,561
Fair value at the ending		$ 4,561
Investment, Identifier [Axis]: Curion Holdings, L L C, Senior Secured Loans, One, Acquisition Date 5/2/2017
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	Curion Holdings, LLC	Curion Holdings, LLC
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 4,561	$ 3,159
Purchases (cost)		308
Sales and paydowns (cost)	(4,497)
Net unrealized gain (loss)	82	1,094
Fair value at the ending	$ 146	$ 4,561
Investment, Identifier [Axis]: Curion Holdings, LLC (Revolver), Senior Secured Loans, Two, Acquisition Date 5/2/2017
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	Curion Holdings, LLC	Curion Holdings, LLC
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 550	$ 820
Purchases (cost)	92
Sales and paydowns (cost)	(620)	(308)
Net unrealized gain (loss)	$ (22)	38
Fair value at the ending		$ 550
Investment, Identifier [Axis]: D S Parent, Inc., Senior Secured Loans, due 12/8/2028
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:DSParentIncMember	mrcc:DSParentIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 2,970
Fair value at the ending		$ 2,970
Investment, Identifier [Axis]: Destination Media, Inc (Revolver), Senior Secured Loans, due 4/7/2023
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:DestinationMediaIncMember
Investment, Identifier [Axis]: Destination Media, Inc, Senior Secured Loans, due 4/7/2023
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:DestinationMediaIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending	$ 377
Investment, Identifier [Axis]: Destination Media, Inc. ( Revolver), Senior Secured Loans, due 4/7/2022
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:DestinationMediaIncMember
Investment, Identifier [Axis]: Destination Media, Inc., Senior Secured Loans, due 4/7/2022
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:DestinationMediaIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 1,738
Fair value at the ending		$ 1,738
Investment, Identifier [Axis]: Dorado Acquisition, Inc, Equity Securities, One, Class A-1 units
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:DoradoAcquisitionIncMember	mrcc:DoradoAcquisitionIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 179
Fair value at the ending	$ 215	$ 179
Number of units held	189,922	178,891
Investment, Identifier [Axis]: Dorado Acquisition, Inc, Equity Securities, Two, Class A-2 units
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:DoradoAcquisitionIncMember	mrcc:DoradoAcquisitionIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 9
Fair value at the ending	$ 224	$ 9
Number of units held	189,922	178,891
Investment, Identifier [Axis]: Dorado Acquisition, Inc. ( Delayed Draw) , Senior Secured Loans, due 6/30/2026
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:DoradoAcquisitionInc.Member	mrcc:DoradoAcquisitionInc.Member
Investment, Identifier [Axis]: Dorado Acquisition, Inc. ( Revolver) , Senior Secured Loans, due 6/30/2026
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:DoradoAcquisitionInc.Member	mrcc:DoradoAcquisitionInc.Member
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending	$ 596
Investment, Identifier [Axis]: Dorado Acquisition, Inc., Senior Secured Loans, One, due 6/30/2026
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:DoradoAcquisitionInc.Member
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending	$ 4,074
Investment, Identifier [Axis]: Dorado Acquisition, Inc., Senior Secured Loans, due 6/30/2026
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:DoradoAcquisitionInc.Member	mrcc:DoradoAcquisitionInc.Member
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 4,983
Fair value at the ending	$ 4,928	$ 4,983
Investment, Identifier [Axis]: Drawbridge Partners, LLC (Delayed Draw), Senior Secured Loans, due 9/1/2028
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:DrawbridgePartnersLlcMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending	$ 102
Investment, Identifier [Axis]: Drawbridge Partners, LLC (Revolver), Senior Secured Loans, due 9/1/2028
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:DrawbridgePartnersLlcMember
Investment, Identifier [Axis]: Drawbridge Partners, LLC, Equity Securities, Class A Units
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:DrawbridgePartnersLlcMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending	$ 126
Number of units held	130,433
Investment, Identifier [Axis]: Drawbridge Partners, LLC, Senior Secured Loans, due 9/1/2028
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:DrawbridgePartnersLlcMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending	$ 2,971
Investment, Identifier [Axis]: Dresser Utility Solutions, L L C (fka N G S U S Finco, L L C), Senior Secured Loans, One, due 10/1/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:DresserUtilitySolutionsLLCfkaNGSUSFincoLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending	$ 1,619
Investment, Identifier [Axis]: Dresser Utility Solutions, L L C (fka N G S U S Finco, L L C), Senior Secured Loans, Two, due 10/1/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:DresserUtilitySolutionsLLCfkaNGSUSFincoLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending	$ 239
Investment, Identifier [Axis]: Drilling Info Holdings, Inc., Senior Secured Loans, due 7/30/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:DrillingInfoHoldingsIncMember	mrcc:DrillingInfoHoldingsIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 4,471
Fair value at the ending		$ 4,471
Investment, Identifier [Axis]: Education Corporation of America, Equity Securities, Series G Preferred Stock
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:EducationCorporationofAmericaMember	mrcc:EducationCorporationofAmericaMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 2,281
Fair value at the ending		$ 2,281
Number of units held	8,333
Number of shares held		8,333
Investment, Identifier [Axis]: Education Corporation of America, Junior Secured Loans
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:EducationCorporationofAmericaMember	mrcc:EducationCorporationofAmericaMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 576
Fair value at the ending	$ 1,882	$ 576
Investment, Identifier [Axis]: Eliassen Group, L L C ( Delayed Draw), Senior Secured Loans, due 4/14/2028
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:EliassenGroupLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending	$ 109
Investment, Identifier [Axis]: Eliassen Group, L L C, Senior Secured Loans, due 4/14/2028
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:EliassenGroupLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending	$ 3,194
Investment, Identifier [Axis]: Energy Services Group, L L C, Unitranche Secured Loans, One, Due 5/4/2022
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:EnergyServicesGroupLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	3,725
Fair value at the ending		$ 3,725
Investment, Identifier [Axis]: Energy Services Group, L L C, Unitranche Secured Loans, Three, Due 5/4/2022
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:EnergyServicesGroupLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	1,060
Fair value at the ending		$ 1,060
Investment, Identifier [Axis]: Energy Services Group, L L C, Unitranche Secured Loans, Two, Due 5/4/2022
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:EnergyServicesGroupLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 4,541
Fair value at the ending		$ 4,541
Investment, Identifier [Axis]: Engage2 Excel, Inc. ( Revolver), Senior Secured Loans, due 3/7/2023
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:Engage2ExcelIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending	$ 509
Investment, Identifier [Axis]: Engage2 Excel, Inc., Senior Secured Loans, One, due 3/7/2023
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:Engage2ExcelIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending	$ 4,242
Investment, Identifier [Axis]: Engage2 Excel, Inc., Senior Secured Loans, Two,due 3/7/2023
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:Engage2ExcelIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending	$ 766
Investment, Identifier [Axis]: Equine Network, L L C ( Delayed Draw), Senior Secured Loans, due 12/13/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:EquineNetworkLLCMember
Investment, Identifier [Axis]: Equine Network, L L C ( Revolver) , Senior Secured Loans, due 12/13/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:EquineNetworkLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 85
Fair value at the ending		$ 85
Investment, Identifier [Axis]: Equine Network, L L C, (Delayed Draw), Senior Secured Loans, due 12/31/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:EquineNetworkLLCMember
Investment, Identifier [Axis]: Equine Network, L L C, (Revolver), Senior Secured Loans, due 12/31/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:EquineNetworkLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending	$ 127
Investment, Identifier [Axis]: Equine Network, L L C, Equity Securities, Class A units
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:EquineNetworkLLCMember	mrcc:EquineNetworkLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 102
Fair value at the ending	$ 109	$ 102
Number of units held	108	99
Investment, Identifier [Axis]: Equine Network, L L C, Senior Secured Loans, One, due 12/13/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:EquineNetworkLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 1,733
Fair value at the ending		$ 1,733
Investment, Identifier [Axis]: Equine Network, L L C, Senior Secured Loans, One, due 12/31/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:EquineNetworkLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending	$ 1,709
Investment, Identifier [Axis]: Equine Network, L L C, Senior Secured Loans, Two, due 12/13/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:EquineNetworkLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 786
Fair value at the ending		$ 786
Investment, Identifier [Axis]: Equine Network, L L C, Senior Secured Loans, Two, due 12/31/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:EquineNetworkLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending	$ 775
Investment, Identifier [Axis]: Excel Fitness Holdings, Inc. ( Revolver), Senior Secured Loans, due 4/28/2028
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:ExcelFitnessHoldingsIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending	$ 306
Investment, Identifier [Axis]: Excel Fitness Holdings, Inc., Senior Secured Loans, due 4/27/2029
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:ExcelFitnessHoldingsIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending	$ 4,102
Investment, Identifier [Axis]: Express Wash Acquisition Company, L L C ( Delayed Draw), Senior Secured Loans, Four, due 12/26/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:ExpressWashAcquisitionCompanyLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	925
Fair value at the ending		$ 925
Investment, Identifier [Axis]: Express Wash Acquisition Company, L L C ( Revolver), Senior Secured Loans, due 12/26/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:ExpressWashAcquisitionCompanyLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 400
Fair value at the ending		$ 400
Investment, Identifier [Axis]: Express Wash Acquisition Company, L L C, Equity Securities, Class A units
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:ExpressWashAcquisitionCompanyLLCMember	mrcc:ExpressWashAcquisitionCompanyLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 208
Fair value at the ending	$ 118	$ 208
Number of units held	121,311	121,311
Investment, Identifier [Axis]: Express Wash Acquisition Company, L L C, Senior Secured Loans, One, due 12/26/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:ExpressWashAcquisitionCompanyLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 3,203
Fair value at the ending		$ 3,203
Investment, Identifier [Axis]: Express Wash Acquisition Company, L L C, Senior Secured Loans, Three, due 12/26/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:ExpressWashAcquisitionCompanyLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	3,500
Fair value at the ending		$ 3,500
Investment, Identifier [Axis]: Express Wash Acquisition Company, L L C, Senior Secured Loans, Two, due 12/26/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:ExpressWashAcquisitionCompanyLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 7,275
Fair value at the ending		$ 7,275
Investment, Identifier [Axis]: Express Wash Acquisition Company, LLC (Revolver), Senior Secured Loans, due 7/14/2028
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:ExpressWashAcquisitionCompanyLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending	$ 208
Investment, Identifier [Axis]: Express Wash Acquisition Company, LLC, Senior Secured Loans, One, Due 7/14/2028
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:ExpressWashAcquisitionCompanyLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending	$ 8,119
Investment, Identifier [Axis]: Express Wash Acquisition Company, LLC, Senior Secured Loans, Two, Due 7/14/2028
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:ExpressWashAcquisitionCompanyLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending	$ 1,521
Investment, Identifier [Axis]: Familia Dental Group Holdings, L L C, Equity Securities, Class A units
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	Familia Dental Group Holdings, LLC	Familia Dental Group Holdings, LLC
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 1,919	$ 3,118
Purchases (cost)	245	183
Net unrealized gain (loss)	461	(1,382)
Fair value at the ending	$ 2,625	$ 1,919
Number of units held	1,176	1,105
Investment, Identifier [Axis]: Florida East Coast Industries, L L C, Junior Secured Loans, due 6/28/2024
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:FloridaEastCoastIndustriesLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 1,530
Fair value at the ending	1,784	$ 1,530
Investment, Identifier [Axis]: Florida East Coast Industries, L L C, Senior Secured Loans, due 6/28/2024
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:FloridaEastCoastIndustriesLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	3,571
Fair value at the ending	$ 619	$ 3,571
Investment, Identifier [Axis]: Forman Mills, Inc, Equity Securities, Warrants
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:FormanMillsIncMember	mrcc:FormanMillsInc.Member
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 702
Fair value at the ending	$ 155	$ 702
Warrants to purchase percentage of equity		2.60%
Percentage of equity interest	2.60%
Investment, Identifier [Axis]: Forman Mills, Inc, Senior Secured Loans, One, due 4/30/2024
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:FormanMillsIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending	$ 1,253
Investment, Identifier [Axis]: Forman Mills, Inc, Senior Secured Loans, Two, due 4/30/2024
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:FormanMillsIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending	$ 6,698
Investment, Identifier [Axis]: Forman Mills, Inc., Senior Secured Loans, One, due 12/30/2022
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:FormanMillsInc.Member
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	1,330
Fair value at the ending		$ 1,330
Investment, Identifier [Axis]: Forman Mills, Inc., Senior Secured Loans, Three, due 12/30/2022
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:FormanMillsInc.Member
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	7,524
Fair value at the ending		$ 7,524
Investment, Identifier [Axis]: Forman Mills, Inc., Senior Secured Loans, Two, due 12/30/2022
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:FormanMillsInc.Member
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 281
Fair value at the ending		$ 281
Investment, Identifier [Axis]: GC Champion Acquisition LLC (Delayed Draw), Senior Notes, Due 8/18/2028
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:GCChampionAcquisitionLLCMember
Investment, Identifier [Axis]: GC Champion Acquisition LLC, Senior Notes, Due 8/18/2028
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:GCChampionAcquisitionLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending	$ 2,503
Investment, Identifier [Axis]: H A H Group Holding Company L L C, Senior Secured Loans, due 10/29/2027
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:HAHGroupHoldingCompanyLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending	$ 2,847
Investment, Identifier [Axis]: H A L O Buyer, Inc., Senior Secured Loans, due 6/30/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:HALOBuyerIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending	$ 4,219
Investment, Identifier [Axis]: H F Z Capital Group L L C, Senior Secured Loans , Two
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:HFZCapitalGroupLLCMember	mrcc:HFZCapitalGroupLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 5,420	$ 4,709
Net unrealized gain (loss)	385	711
Fair value at the ending	$ 5,805	$ 5,420
Investment, Identifier [Axis]: H F Z Capital Group L L C, Senior Secured Loans, One
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:HFZCapitalGroupLLCMember	mrcc:HFZCapitalGroupLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 15,084	$ 13,106
Net unrealized gain (loss)	1,075	1,978
Fair value at the ending	$ 16,159	$ 15,084
Investment, Identifier [Axis]: H S4 Acquisitionco, Inc. ( Revolver), Senior Secured Loans, due 7/9/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:HS4AcquisitioncoIncMember	mrcc:HS4AcquisitioncoIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending	$ 407
Investment, Identifier [Axis]: H S4 Acquisitionco, Inc., Senior Secured Loans, due 7/9/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:HS4AcquisitioncoIncMember	mrcc:HS4AcquisitioncoIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 9,910
Fair value at the ending	$ 9,855	$ 9,910
Investment, Identifier [Axis]: Harbour Benefit Holdings, Inc., Senior Secured Loans, One, due 12/13/2024
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:HarbourBenefitHoldingsIncMember	mrcc:HarbourBenefitHoldingsIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 2,932
Fair value at the ending	$ 2,898	$ 2,932
Investment, Identifier [Axis]: Harbour Benefit Holdings, Inc., Senior Secured Loans, Two, due 12/13/2024
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:HarbourBenefitHoldingsIncMember	mrcc:HarbourBenefitHoldingsIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 65
Fair value at the ending	$ 61	$ 65
Investment, Identifier [Axis]: Hastings Manufacturing Company, Senior Secured Loans, due 4/24/2023
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:HastingsManufacturingCompanyMember	mrcc:HastingsManufacturingCompanyMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 2,524
Fair value at the ending	$ 2,026	$ 2,524
Investment, Identifier [Axis]: I D I G Parent, L L C ( Revolver), Senior Secured Loans, due 12/15/2026
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		I D I G Parent, L L C [ Member]
Investment, Identifier [Axis]: I D I G Parent, L L C, Equity Securities, Common stock
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	I D I G Parent, L L C [ Member]	I D I G Parent, L L C [ Member]
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 428
Fair value at the ending	$ 324	$ 428
Number of shares held	245,958	245,958
Investment, Identifier [Axis]: I D I G Parent, L L C, Senior Secured Loans, One, due 12/15/2026
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		I D I G Parent, L L C [ Member]
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 5,530
Fair value at the ending		$ 5,530
Investment, Identifier [Axis]: I D I G Parent, L L C, Senior Secured Loans, Two, due 12/15/2026
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		I D I G Parent, L L C [ Member]
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 920
Fair value at the ending		$ 920
Investment, Identifier [Axis]: I N H Buyer, Inc., Senior Secured Loans, due 6/28/2028
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:INHBuyerInc.Member	mrcc:INHBuyerInc.Member
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 2,857
Fair value at the ending	2,832	$ 2,857
Investment, Identifier [Axis]: I T Global Holding L L C ( Revolver), Senior Secured Loans, due 11/10/2023
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:ITGlobalHoldingLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	1,060
Fair value at the ending		$ 1,060
Investment, Identifier [Axis]: I T Global Holding L L C, Senior Secured Loans, One, due 11/10/2023
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:ITGlobalHoldingLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	4,411
Fair value at the ending		$ 4,411
Investment, Identifier [Axis]: I T Global Holding L L C, Senior Secured Loans, Two, due 11/10/2023
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:ITGlobalHoldingLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 1,645
Fair value at the ending		$ 1,645
Investment, Identifier [Axis]: In Mobi Pte, Ltd, Media: Equity Securities, due 9/18/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:InMobiPteLtdMember	mrcc:InMobiPteLtdMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 2,204
Fair value at the ending	$ 1,816	$ 2,204
Warrants to purchase percentage of equity	2.80%	2.80%
Number of units held	40
Investment, Identifier [Axis]: Independence Buyer, Inc, Senior Secured Loans, due 8/3/2026
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:IndependenceBuyerInc.Member	mrcc:IndependenceBuyerInc.Member
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 6,000
Fair value at the ending	$ 5,866	$ 6,000
Investment, Identifier [Axis]: Independence Buyer, Inc. ( Revolver), Senior Secured Loans, due 8/3/2026
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:IndependenceBuyerInc.Member	mrcc:IndependenceBuyerInc.Member
Investment, Identifier [Axis]: Independence Buyer, Inc., Equity Securities, Class A units
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:IndependenceBuyerInc.Member	mrcc:IndependenceBuyerInc.Member
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 101
Fair value at the ending	$ 102	$ 101
Number of units held		81
Investment, Identifier [Axis]: Intermedia Holdings, Inc., Senior Secured Loans, due 7/21/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:IntermediaHoldingsIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending	$ 1,360
Investment, Identifier [Axis]: International Textile Group, Inc., Senior Secured Loans, due 5/1/2024
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:InternationalTextileGroupIncMember	mrcc:InternationalTextileGroupIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 1,590
Fair value at the ending		$ 1,590
Investment, Identifier [Axis]: J2 B W A Funding L L C ( Delayed Draw), Senior Secured Loans, due 12/24/2026
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:J2BWAFundingLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 677
Fair value at the ending		$ 677
Investment, Identifier [Axis]: J2 B W A Funding L L C, Equity Securities
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:J2BWAFundingLLCMember	mrcc:J2BWAFundingLLCMember
Investment, Identifier [Axis]: J2 BWA Funding LLC (Delayed Draw), Senior Notes, Due 12/24/2026
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:J2BWAFundingLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending	$ 1,298
Investment, Identifier [Axis]: Kar Wash Holdings, L L C ( Delayed Draw), Senior Secured Loans, due 2/26/2027
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:KarWashHoldingsLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending	$ 1,782
Investment, Identifier [Axis]: Kar Wash Holdings, L L C ( Revolver), Senior Secured Loans, due 2/26/2027
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:KarWashHoldingsLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending	$ 303
Investment, Identifier [Axis]: Kar Wash Holdings, L L C, Equity Securities, Class A units
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:KarWashHoldingsLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending	$ 111
Number of units held	99,807
Investment, Identifier [Axis]: Kar Wash Holdings, LLC, Senior Secured Loans, One, due 2/26/2027
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:KarWashHoldingsLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending	$ 1,585
Investment, Identifier [Axis]: Kar Wash Holdings, LLC, Senior Secured Loans, Two, due 2/26/2027
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:KarWashHoldingsLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending	$ 1,135
Investment, Identifier [Axis]: Keystone Purchaser, L L C, Senior Secured Loans, due 5/7/2027
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:KeystonePurchaserLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending	$ 4,955
Investment, Identifier [Axis]: Kingsley Gate Partners, LLC (Delayed Draw), One, Due 12/11/2028
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:KingsleyGatePartnersLlcMember
Investment, Identifier [Axis]: Kingsley Gate Partners, LLC (Delayed Draw), Two, Due 12/11/2028
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:KingsleyGatePartnersLlcMember
Investment, Identifier [Axis]: Kingsley Gate Partners, LLC (Revolver), Due 12/11/2028
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:KingsleyGatePartnersLlcMember
Investment, Identifier [Axis]: Kingsley Gate Partners, LLC, Due 12/11/2028
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:KingsleyGatePartnersLlcMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending	$ 588
Investment, Identifier [Axis]: L S C S Holdings, Inc., Senior Secured Loans, due 12/15/2028
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:LSCSHoldingsIncMember	mrcc:LSCSHoldingsIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 1,849
Fair value at the ending	$ 1,751	$ 1,849
Investment, Identifier [Axis]: L V F Holdings, Inc. ( Revolver), Senior Secured Loans, due 6/10/2027
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:LVFHoldingsIncMember	mrcc:LVFHoldingsIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 119
Fair value at the ending	$ 152	$ 119
Investment, Identifier [Axis]: L V F Holdings, Inc., Senior Secured Loans, ( Delayed Draw) due 6/10/2027
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:LVFHoldingsIncMember	mrcc:LVFHoldingsIncMember
Investment, Identifier [Axis]: L V F Holdings, Inc., Senior Secured Loans, One, due 6/10/2027
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:LVFHoldingsIncMember	mrcc:LVFHoldingsIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 1,496
Fair value at the ending	$ 1,437	$ 1,496
Investment, Identifier [Axis]: L V F Holdings, Inc., Senior Secured Loans, Two, due 6/10/2027
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:LVFHoldingsIncMember	mrcc:LVFHoldingsIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 1,432
Fair value at the ending	$ 1,375	$ 1,432
Investment, Identifier [Axis]: L X/ J T Intermediate Holdings, Inc. ( Revolver), Senior Secured Loans, due 3/11/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:LXJTIntermediateHoldingsIncMember	mrcc:LXJTIntermediateHoldingsIncMember
Investment, Identifier [Axis]: L X/ J T Intermediate Holdings, Inc., Senior Secured Loans, due 3/11/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:LXJTIntermediateHoldingsIncMember	mrcc:LXJTIntermediateHoldingsIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 9,239
Fair value at the ending	$ 5,394	$ 9,239
Investment, Identifier [Axis]: Laseraway Intermediate Holdings I I, L L C, Senior Secured Loans, due 10/14/2027
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:LaserawayIntermediateHoldingsIILLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending	$ 2,161
Investment, Identifier [Axis]: Lifted Trucks Holdings, L L C ( Delayed Draw), Senior Secured Loans, due 8/2/2027
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:LiftedTrucksHoldingsLLCMember	mrcc:LiftedTrucksHoldingsLLCMember
Investment, Identifier [Axis]: Lifted Trucks Holdings, L L C ( Revolver), Senior Secured Loans, due 8/2/2027
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:LiftedTrucksHoldingsLLCMember	mrcc:LiftedTrucksHoldingsLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 443
Fair value at the ending		$ 443
Investment, Identifier [Axis]: Lifted Trucks Holdings, L L C, Equity Securities, Class A units
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:LiftedTrucksHoldingsLLCMember	mrcc:LiftedTrucksHoldingsLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 109
Fair value at the ending	$ 78	$ 109
Number of units held		111,111
Number of shares held	111,111
Investment, Identifier [Axis]: Lifted Trucks Holdings, L L C, Senior Secured Loans, due 8/2/2027
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:LiftedTrucksHoldingsLLCMember	mrcc:LiftedTrucksHoldingsLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 6,979
Fair value at the ending	6,840	$ 6,979
Investment, Identifier [Axis]: Liftforward S P V I I, L L C, Senior Secured Loans, due 9/30/2022
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:LiftforwardSPVIILLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 713
Fair value at the ending		$ 713
Investment, Identifier [Axis]: Liftforward SPV II, LLC, Senior Secured Loans, due 3/31/2023
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:LiftforwardSPVIILLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending	$ 403
Investment, Identifier [Axis]: Lightbox Intermediate, L. P., Senior Secured Loans, due 5/11/2026
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:LightboxIntermediateL.PMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending	$ 4,656
Investment, Identifier [Axis]: Liqui- Box Holdings, Inc., Senior Secured Loans, due 2/26/2027
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:Liqui-BoxHoldingsIncMember	mrcc:Liqui-BoxHoldingsIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 3,991
Fair value at the ending		$ 3,991
Investment, Identifier [Axis]: Luxury Optical Holdings Co. ( Delayed Draw)
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	Luxury Optical Holdings Co [ Member]	Luxury Optical Holdings Co [ Member]
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 624
Purchases (cost)		1,729
Sales and paydowns (cost)		$ (2,353)
Investment, Identifier [Axis]: Luxury Optical Holdings Co. Investment, One
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	Luxury Optical Holdings Co [ Member]	Luxury Optical Holdings Co [ Member]
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 1,430
Sales and paydowns (cost)		(1,640)
PIK Interest (cost)		159
Net unrealized gain (loss)		$ 51
Investment, Identifier [Axis]: Luxury Optical Holdings Co.( Revolver)
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	Luxury Optical Holdings Co [ Member]	Luxury Optical Holdings Co [ Member]
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 66
Sales and paydowns (cost)		(75)
PIK Interest (cost)		7
Net unrealized gain (loss)		$ 2
Investment, Identifier [Axis]: Luxury Optical Holdings Co., Equity Securities
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	Luxury Optical Holdings Co [ Member]	mrcc:LuxuryOpticalHoldingsCo.Member
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 78
Fair value at the ending	$ 209	$ 78
Investment, Identifier [Axis]: Luxury Optical Holdings Co., Equity Securities, Common Stock
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	Luxury Optical Holdings Co [ Member]	Luxury Optical Holdings Co [ Member]
Transactions with Affiliated Companies, Fair value Roll Forward
Number of shares held		86
Investment, Identifier [Axis]: Luxury Optical Holdings Co., Equity Securities, Preferred Units
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	Luxury Optical Holdings Co [ Member]	Luxury Optical Holdings Co [ Member]
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 2,476
Transfers in (out)		(78)
Sales and paydowns (cost)		(6,132)
PIK Interest (cost)		694
Net realized gain (loss)		1,807
Net unrealized gain (loss)		$ 1,233
Number of units held		91
Investment, Identifier [Axis]: M C Asset Management ( Corporate), L L C ( Delayed Draw), Senior Secured Loans Due 1/26/2024
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:MCAssetManagementCorporateLLCMember	mrcc:MCAssetManagementCorporateLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 850
Purchases (cost)		$ 793
PIK Interest (cost)		57
Fair value at the ending	$ 1,000	$ 850
Investment, Identifier [Axis]: M C Asset Management ( Corporate), L L C, Equity Securites
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:MCAssetManagementCorporateLLCMember	mrcc:MCAssetManagementCorporateLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 644
Fair value at the ending	$ 1,291	$ 644
Warrants to purchase percentage of equity		15.90%
Percentage of equity interest	15.90%
Investment, Identifier [Axis]: M C Asset Management ( Corporate), L L C, Equity Securities
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:MCAssetManagementCorporateLLCMember	mrcc:MCAssetManagementCorporateLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 644	$ 785
Net unrealized gain (loss)	647	(141)
Fair value at the ending	$ 1,291	$ 644
Percentage of equity interest	15.90%	15.90%
Investment, Identifier [Axis]: M C Asset Management ( Corporate), L L C, Senior Secured Loans Due 1/26/2024
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:MCAssetManagementCorporateLLCMember	mrcc:MCAssetManagementCorporateLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 7,154
Purchases (cost)		$ 6,423
PIK Interest (cost)	1,267	731
Fair value at the ending	$ 8,421	$ 7,154
Investment, Identifier [Axis]: M C Asset Management ( Industrial), L L C Promissory Note
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:MCAssetManagementIndustrialLLCMember	mrcc:MCAssetManagementIndustrialLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 11,579
Sales and paydowns (cost)		(12,119)
PIK Interest (cost)		1,423
Discount accretion		1
Net unrealized gain (loss)		$ (884)
Investment, Identifier [Axis]: M C P Shaw Acquisitionco, L L C ( Delayed Draw), Senior Secured Loans, due 11/28/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:MCPShawAcquisitioncoLLCMember	mrcc:MCPShawAcquisitioncoLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending	$ 979
Investment, Identifier [Axis]: M C P Shaw Acquisitionco, L L C ( Revolver), Senior Secured Loans, due 11/28/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:MCPShawAcquisitioncoLLCMember	mrcc:MCPShawAcquisitioncoLLCMember
Investment, Identifier [Axis]: M C P Shaw Acquisitionco, L L C , Equity Securities, Class A-2 units
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:MCPShawAcquisitioncoLLCMember	mrcc:MCPShawAcquisitioncoLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 148
Fair value at the ending	$ 204	$ 148
Number of units held		118,906
Number of shares held	118,906
Investment, Identifier [Axis]: M C P Shaw Acquisitionco, L L C, Senior Secured Loans, One, due 11/28/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:MCPShawAcquisitioncoLLCMember	mrcc:MCPShawAcquisitioncoLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 9,699
Fair value at the ending	$ 9,736	$ 9,699
Investment, Identifier [Axis]: M C P Shaw Acquisitionco, L L C, Senior Secured Loans, Two, due 11/28/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:MCPShawAcquisitioncoLLCMember	mrcc:MCPShawAcquisitioncoLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 2,992
Fair value at the ending	2,977	$ 2,992
Investment, Identifier [Axis]: M F G Chemical, L L C, Unitranche Secured Loans, One, Due 6/23/2022
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:MFGChemicalLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	5,555
Fair value at the ending		$ 5,555
Investment, Identifier [Axis]: M F G Chemical, L L C, Unitranche Secured Loans, Two, Due 6/23/2022
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:MFGChemicalLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 543
Fair value at the ending		$ 543
Investment, Identifier [Axis]: M R C C Senior Loan Fund I, L L C, Equity Securities
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Controlled affiliate company investments	Controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	MRCC Senior Loan Fund I, LLC	MRCC Senior Loan Fund I, LLC
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 41,125	$ 39,284
Purchases (cost)	500
Net unrealized gain (loss)	(6,116)	1,841
Fair value at the ending	$ 35,509	$ 41,125
Percentage of equity interest	50%	50%
Investment, Identifier [Axis]: M V Receivables I I, L L C ( Delayed Draw), Senior Secured Loans, due 7/29/2026
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:MVReceivablesIILLCMember	mrcc:MVReceivablesIILLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 1,289
Fair value at the ending	$ 7,968	$ 1,289
Investment, Identifier [Axis]: M V Receivables I I, L L C, Equity Securities, Common units
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:MVReceivablesIILLCMember	mrcc:MVReceivablesIILLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 558
Fair value at the ending	$ 1,154	$ 558
Number of units held		729
Number of shares held	1,458
Investment, Identifier [Axis]: M V Receivables I I, L L C, Equity Securities, Due 7/28/2031, Warrants
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:MVReceivablesIILLCMember	mrcc:MVReceivablesIILLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 1,007
Fair value at the ending	$ 1,655	$ 1,007
Warrants to purchase percentage of equity	0.80%	0.80%
Investment, Identifier [Axis]: MC Asset Management (Corporate), LLC (Delayed Draw)
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:MCAssetManagementCorporateLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 850
PIK Interest (cost)	150
Fair value at the ending	$ 1,000	$ 850
Investment, Identifier [Axis]: Mac Queen Equipment, L L C ( Delayed Draw), Senior Secured Loans, due 1/7/2028
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:MacQueenEquipmentLLCMember
Investment, Identifier [Axis]: Mac Queen Equipment, L L C ( Revolver), Senior Secured Loans, due 1/7/2028
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:MacQueenEquipmentLLCMember
Investment, Identifier [Axis]: Mac Queen Equipment, L L C, Senior Secured Loans, due 1/7/2028
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:MacQueenEquipmentLLCMember
Investment, Identifier [Axis]: Magneto & Diesel Acquisition, Inc, Senior Secured Loans, One, due 12/18/2023
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:MagnetoDieselAcquisitionInc.Member
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 4,850
Fair value at the ending		$ 4,850
Investment, Identifier [Axis]: Magneto & Diesel Acquisition, Inc, Senior Secured Loans, Three, due 12/8/2023
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:MagnetoDieselAcquisitionInc.Member
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	842
Fair value at the ending		$ 842
Investment, Identifier [Axis]: Magneto & Diesel Acquisition, Inc, Senior Secured Loans, Two, due 12/8/2023
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:MagnetoDieselAcquisitionInc.Member
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	1,938
Fair value at the ending		$ 1,938
Investment, Identifier [Axis]: Magneto & Diesel Acquisition, Inc. ( Revolver), Senior Secured Loans, due 12/8/2023
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:MagnetoDieselAcquisitionInc.Member
Investment, Identifier [Axis]: Mammoth Holdings, L L C ( Delayed Draw), Senior Secured Loans, due 10/16/2023
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:MammothHoldingsLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	989
Fair value at the ending		$ 989
Investment, Identifier [Axis]: Mammoth Holdings, L L C ( Revolver), Senior Secured Loans, due 10/16/2023
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:MammothHoldingsLLCMember
Investment, Identifier [Axis]: Mammoth Holdings, L L C, Senior Secured Loans, One, due 10/16/2023
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:MammothHoldingsLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	1,940
Fair value at the ending		$ 1,940
Investment, Identifier [Axis]: Mammoth Holdings, L L C, Senior Secured Loans, Three, due 10/16/2023
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:MammothHoldingsLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	6,368
Fair value at the ending		$ 6,368
Investment, Identifier [Axis]: Mammoth Holdings, L L C, Senior Secured Loans, Two, due 10/16/2023
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:MammothHoldingsLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 4,073
Fair value at the ending		$ 4,073
Investment, Identifier [Axis]: Mammoth Holdings, LLC (Revolver), Senior Secured Loans, Due, 10/16/2024
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:MammothHoldingsLLCMember
Investment, Identifier [Axis]: Mammoth Holdings, LLC, Senior Secured Loans, Four, due 10/16/2024
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:MammothHoldingsLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending	$ 1,630
Investment, Identifier [Axis]: Mammoth Holdings, LLC, Senior Secured Loans, One, due 10/16/2024
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:MammothHoldingsLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending	$ 1,917
Investment, Identifier [Axis]: Mammoth Holdings, LLC, Senior Secured Loans, Three, due 10/16/2024
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:MammothHoldingsLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending	$ 6,282
Investment, Identifier [Axis]: Mammoth Holdings, LLC, Senior Secured Loans, Two, due 10/16/2024
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:MammothHoldingsLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending	$ 4,025
Investment, Identifier [Axis]: Mark Logic Corporation ( Revolver), Senior Secured Loans, due 10/20/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:MarkLogicCorporationMember	mrcc:MarkLogicCorporationMember
Investment, Identifier [Axis]: Mark Logic Corporation, Equity Securities, Class A units
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:MarkLogicCorporationMember	mrcc:MarkLogicCorporationMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 423
Fair value at the ending	$ 426	$ 423
Number of units held		290,239
Number of shares held	290,239
Investment, Identifier [Axis]: Mark Logic Corporation, Senior Secured Loans, Four, due 10/20/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:MarkLogicCorporationMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending	$ 213
Investment, Identifier [Axis]: Mark Logic Corporation, Senior Secured Loans, One, due 10/20/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:MarkLogicCorporationMember	mrcc:MarkLogicCorporationMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 3,517
Fair value at the ending	$ 3,414	$ 3,517
Investment, Identifier [Axis]: Mark Logic Corporation, Senior Secured Loans, Three, due 10/20/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:MarkLogicCorporationMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending	$ 2,656
Investment, Identifier [Axis]: Mark Logic Corporation, Senior Secured Loans, Two, due 10/20/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:MarkLogicCorporationMember	mrcc:MarkLogicCorporationMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 330
Fair value at the ending	$ 318	$ 330
Investment, Identifier [Axis]: MarkLogic Corporation (Delayed Draw), Senior Secured Loans 10/20/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:MarkLogicCorporationMember
Investment, Identifier [Axis]: Mavenir Systems, Inc., Senior Secured Loans, due 8/18/2028
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:MavenirSystemsIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending	$ 1,350
Investment, Identifier [Axis]: Mc Kissock Investment Holdings, L L C, Senior Secured Loans, due 3/9/2029
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:McKissockInvestmentHoldingsLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending	$ 2,322
Investment, Identifier [Axis]: Medallia, Inc, Senior Secured Loans, due 10/27/2028
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:MedalliaIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending	$ 2,041
Investment, Identifier [Axis]: Mindbody, Inc. ( Revolver) (f), Senior Secured Loans, due 2/14/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:MindbodyIncMember	mrcc:MindbodyIncMember
Investment, Identifier [Axis]: Mindbody, Inc., Senior Secured Loans, One, due 2/14/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:MindbodyIncMember	mrcc:MindbodyIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 6,438
Fair value at the ending	$ 6,526	$ 6,438
Investment, Identifier [Axis]: Mindbody, Inc., Senior Secured Loans, Two, due 2/14/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:MindbodyIncMember	mrcc:MindbodyIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 664
Fair value at the ending	$ 673	$ 664
Investment, Identifier [Axis]: Minotaur Acquisition, Inc., Senior Secured Loans, due 3/27/2026
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:MinotaurAcquisitionIncMember	mrcc:MinotaurAcquisitionIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 4,894
Fair value at the ending	$ 4,656	$ 4,894
Investment, Identifier [Axis]: Mnine Holdings Inc. (Revolver)
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	Mnine Holdings, Inc [ Member]
Transactions with Affiliated Companies, Fair value Roll Forward
Purchases (cost)	$ 587
Sales and paydowns (cost)	(374)
PIK Interest (cost)	1
Fair value at the ending	$ 214
Investment, Identifier [Axis]: Mnine Holdings, Inc. (Revolver), Senior Secured Loans
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	Mnine Holdings, Inc [ Member]	Mnine Holdings, Inc [ Member]
Investment, Identifier [Axis]: Mnine Holdings, Inc. (Revolver), Senior Secured Loans, due 12/30/2023
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	Mnine Holdings, Inc [ Member]
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending	$ 214
Investment, Identifier [Axis]: Mnine Holdings, Inc., Equity Securities, Class B units
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	Mnine Holdings, Inc [ Member]	Mnine Holdings, Inc [ Member]
Transactions with Affiliated Companies, Fair value Roll Forward
Number of units held	6,400	6,400
Investment, Identifier [Axis]: Mnine Holdings, Inc., Senior Secured Loans Due 12/30/2022
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	Mnine Holdings, Inc [ Member]	Mnine Holdings, Inc [ Member]
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 5,771	$ 12,356
Sales and paydowns (cost)	(22)	(7,137)
PIK Interest (cost)	320	603
Discount accretion	14	34
Net unrealized gain (loss)	(591)	(85)
Fair value at the ending	$ 5,492	$ 5,771
Investment, Identifier [Axis]: Money Lion, Inc. ( Delayed Draw), Junior Secured Loans, due 3/24/2026
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:MoneyLionIncMember
Investment, Identifier [Axis]: Money Lion, Inc., Junior Secured Loans, due 3/24/2026
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:MoneyLionIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending	$ 5,165
Investment, Identifier [Axis]: Money Lion, Inc., Junior Secured Loans, due 5/1/2023
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:MoneyLionIncMember	mrcc:MoneyLionIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 1,522
Fair value at the ending	$ 1,498	$ 1,522
Investment, Identifier [Axis]: N C B P Property, L L C, Senior Secured Loans, due 12/16/2022
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:NCBPPropertyLLCMember	mrcc:NCBPPropertyLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 1,955
Fair value at the ending	$ 1,955	$ 1,955
Investment, Identifier [Axis]: N E C B Collections, L L C ( Revolver), Senior Secured Loans
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	N E C B Collections, L L C [ Member]	N E C B Collections, L L C [ Member]
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 632	$ 834
Net unrealized gain (loss)	(250)	(202)
Fair value at the ending	$ 382	$ 632
Investment, Identifier [Axis]: N E C B Collections, L L C, Equity Securities
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	N E C B Collections, L L C [ Member]	N E C B Collections, L L C [ Member]
Transactions with Affiliated Companies, Fair value Roll Forward
Percentage of units held	20.80%	20.80%
Investment, Identifier [Axis]: N E C B Collections, L L C, Equity Securities, Common stock
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	N E C B Collections, L L C [ Member]
Transactions with Affiliated Companies, Fair value Roll Forward
Percentage of units held	20.80%
Investment, Identifier [Axis]: NQ PE Project Colosseum Midco Inc. (Delayed Draw), Senior Secured Loans, Due 10/4/2028
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:NqPeProjectColosseumMidcoInc.Member
Investment, Identifier [Axis]: NQ PE Project Colosseum Midco Inc. (Revolver), Senior Secured Loans, Due 10/4/2028
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:NqPeProjectColosseumMidcoInc.Member
Investment, Identifier [Axis]: NQ PE Project Colosseum Midco Inc., Equity Securities, Common Units
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:NqPeProjectColosseumMidcoInc.Member
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending	$ 327
Number of shares held	327,133
Investment, Identifier [Axis]: NQ PE Project Colosseum Midco Inc., Senior Secured Loans, Due 10/4/2028
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:NqPeProjectColosseumMidcoInc.Member
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending	$ 3,430
Investment, Identifier [Axis]: Nations Benefits L L C, Senior Secured Loans, One, Due 8/26/2027
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:NationsBenefitsLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending	$ 4,039
Investment, Identifier [Axis]: Nations Benefits L L C, Senior Secured Loans, Two, Due 8/26/2027
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:NationsBenefitsLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending	$ 4,813
Investment, Identifier [Axis]: Nations Benefits LLC Delayed Draw
Transactions with Affiliated Companies, Fair value Roll Forward
Number of shares held	106,667
Investment, Identifier [Axis]: Nations Benefits LLC Delayed Draw, Senior Secured Loans Due 8/26/2027
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:NationsBenefitsLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending	$ 961
Investment, Identifier [Axis]: Nations Benefits, L L C ( Revolver), Senior Secured Loans, due 8/20/2026
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:NationsBenefitsLLCMember
Investment, Identifier [Axis]: Nations Benefits, L L C (Revolver), Senior Secured Loans, Due 8/26/2027
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:NationsBenefitsLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending	$ 889
Investment, Identifier [Axis]: Nations Benefits, L L C, Equity Securities, One, Series B units
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:NationsBenefitsLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending	$ 934
Number of shares held	116,460
Investment, Identifier [Axis]: Nations Benefits, L L C, Equity Securities, Three, Series A units
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:NationsBenefitsLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 714
Fair value at the ending		$ 714
Number of units held		888,889
Investment, Identifier [Axis]: Nations Benefits, L L C, Equity Securities, Two, common units
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:NationsBenefitsLLCMember	mrcc:NationsBenefitsLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 67
Fair value at the ending	66	$ 67
Number of units held		106,667
Investment, Identifier [Axis]: Nations Benefits, L L C, Senior Secured Loans, due 8/20/2026
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:NationsBenefitsLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 3,993
Fair value at the ending		$ 3,993
Investment, Identifier [Axis]: Natus Medical Incorporated, Senior Secured Loans, due 7/20/2029
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:NatusMedicalIncorporatedMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending	$ 4,650
Investment, Identifier [Axis]: Nearly Natural Inc. (Revolver) Senior Secured Loans due 3/31/2024
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:NearlyNaturalIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending	$ 2,241
Investment, Identifier [Axis]: Nearly Natural Inc. Senior Secured Loans Four due 3/31/2024
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:NearlyNaturalIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending	$ 1,672
Investment, Identifier [Axis]: Nearly Natural Inc. Senior Secured Loans One due 3/31/2024
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:NearlyNaturalIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending	$ 5,931
Investment, Identifier [Axis]: Nearly Natural Inc. Senior Secured Loans Three due 3/31/2024
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:NearlyNaturalIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending	$ 2,787
Investment, Identifier [Axis]: Nearly Natural Inc. Senior Secured Loans Two due 3/31/2024
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:NearlyNaturalIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending	$ 1,534
Investment, Identifier [Axis]: Nearly Natural, Inc, Equity Securities, One, Class A units
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:NearlyNaturalIncMember	mrcc:NearlyNaturalInc.Member
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 69
Fair value at the ending		$ 69
Number of units held	152,174	152,174
Investment, Identifier [Axis]: Nearly Natural, Inc, Equity Securities, Two, Class A A units
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:NearlyNaturalIncMember	mrcc:NearlyNaturalInc.Member
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 5
Fair value at the ending		$ 5
Number of units held	61,087	39,394
Investment, Identifier [Axis]: Nearly Natural, Inc.( Revolver), Senior Secured loans, due 12/15/2022
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:NearlyNaturalIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 2,400
Fair value at the ending		$ 2,400
Investment, Identifier [Axis]: Nearly Natural, Inc., Senior Secured loans, Four, due 12/15/2022
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:NearlyNaturalIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	1,836
Fair value at the ending		$ 1,836
Investment, Identifier [Axis]: Nearly Natural, Inc., Senior Secured loans, One, due 12/15/2022
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:NearlyNaturalIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	6,520
Fair value at the ending		$ 6,520
Investment, Identifier [Axis]: Nearly Natural, Inc., Senior Secured loans, Three, due 12/15/2022
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:NearlyNaturalIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	1,685
Fair value at the ending		$ 1,685
Investment, Identifier [Axis]: Nearly Natural, Inc., Senior Secured loans, Two, due 12/15/2022
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:NearlyNaturalIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 3,061
Fair value at the ending		$ 3,061
Investment, Identifier [Axis]: Newforma, Inc. ( Revolver), Senior Secured Loans, due 6/30/2022
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:NewformaIncMember
Investment, Identifier [Axis]: Newforma, Inc. ( Revolver) (f), Senior Secured Loans, due 3/31/2023
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:NewformaIncMember
Investment, Identifier [Axis]: Newforma, Inc., Senior Secured Loans, due 3/31/2023
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:NewformaIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending	$ 938
Investment, Identifier [Axis]: Newforma, Inc., Senior Secured Loans, due 6/30/2022
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:NewformaIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 3,890
Fair value at the ending		$ 3,890
Investment, Identifier [Axis]: North Haven Spartan U S Holdco, L L C, Senior Secured Loans, due 6/6/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:NorthHavenSpartanUSHoldcoLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending	$ 2,202
Investment, Identifier [Axis]: North Haven U S H C Acquisition, Inc. ( Delayed Draw), Senior Secured Loans, due, 10/30/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:NorthHavenUSHCAcquisitionIncMember	mrcc:NorthHavenUSHCAcquisitionIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 487
Fair value at the ending		$ 487
Investment, Identifier [Axis]: North Haven U S H C Acquisition, Inc. ( Revolver), Senior Secured Loans, due, 10/30/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:NorthHavenUSHCAcquisitionIncMember	mrcc:NorthHavenUSHCAcquisitionIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending	$ 187
Investment, Identifier [Axis]: North Haven U S H C Acquisition, Inc., Senior Secured Loans, due, One, 10/30/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:NorthHavenUSHCAcquisitionIncMember	mrcc:NorthHavenUSHCAcquisitionIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 2,475
Fair value at the ending	$ 2,448	$ 2,475
Investment, Identifier [Axis]: North Haven U S H C Acquisition, Inc., Senior Secured Loans, due, Two, 10/30/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:NorthHavenUSHCAcquisitionIncMember	mrcc:NorthHavenUSHCAcquisitionIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 717
Fair value at the ending	$ 2,575	$ 717
Investment, Identifier [Axis]: North Haven USHC Acquisition, Inc, Senior Secured Loans, Four, due 10/30/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:NorthHavenUSHCAcquisitionIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending	$ 1,433
Investment, Identifier [Axis]: North Haven USHC Acquisition, Inc, Senior Secured Loans, Three, due 10/30/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:NorthHavenUSHCAcquisitionIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending	$ 709
Investment, Identifier [Axis]: Oceana Australian Fixed Income Trust, Senior Secured Loans, One, due 6/29/2026
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:OceanaAustralianFixedIncomeTrustMember	mrcc:OceanaAustralianFixedIncomeTrustMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 3,288
Fair value at the ending	$ 3,084	$ 3,288
Investment, Identifier [Axis]: Oceana Australian Fixed Income Trust, Senior Secured Loans, Two, due 2/25/2026
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:OceanaAustralianFixedIncomeTrustMember	mrcc:OceanaAustralianFixedIncomeTrustMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 7,805
Fair value at the ending	$ 7,321	$ 7,805
Investment, Identifier [Axis]: Offen, Inc., Senior Secured Loans, One, due 6/22/2026
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:OffenIncMember	mrcc:OffenIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 2,387
Fair value at the ending		$ 2,387
Investment, Identifier [Axis]: Offen, Inc., Senior Secured Loans, Two, due 6/22/2026
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:OffenIncMember	mrcc:OffenIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 876
Fair value at the ending		$ 876
Investment, Identifier [Axis]: Onit, Inc., Unitranche Secured Loans, due 5/2/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:OnitInc.Member	mrcc:OnitInc.Member
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 1,472
Fair value at the ending	$ 1,663	$ 1,472
Investment, Identifier [Axis]: Orbit Purchaser L L C, Senior Secured Loans, One, due 10/21/2024
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:OrbitPurchaserLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending	$ 2,190
Investment, Identifier [Axis]: Orbit Purchaser L L C, Senior Secured Loans, Three, due 10/21/2024
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:OrbitPurchaserLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending	$ 494
Investment, Identifier [Axis]: Orbit Purchaser L L C, Senior Secured Loans, Two, due 10/21/2024
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:OrbitPurchaserLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending	$ 1,691
Investment, Identifier [Axis]: Output Services Group Inc. Senior Secured Loans Due 6/29/2026
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:OutputServicesGroupIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending	$ 3,275
Investment, Identifier [Axis]: P H Beauty Holdings I I I, I N C., Senior Secured Loans, due 9/26/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:PHBeautyHoldingsIIIINCMember	mrcc:PHBeautyHoldingsIIIINCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 2,284
Fair value at the ending		$ 2,284
Investment, Identifier [Axis]: P K S Holdings, L L C, Equity Securities, Four, Preferred units
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:PKSHoldingsLLCMember	mrcc:PKSHoldingsLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 34
Fair value at the ending	$ 46	$ 34
Number of units held	916	916
Investment, Identifier [Axis]: P K S Holdings, L L C, Equity Securities, One, Preferred units
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:PKSHoldingsLLCMember	mrcc:PKSHoldingsLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 219
Fair value at the ending	$ 298	$ 219
Number of units held		5,680
Number of shares held	5,680
Investment, Identifier [Axis]: P K S Holdings, L L C, Equity Securities, Three, Preferred units
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:PKSHoldingsLLCMember	mrcc:PKSHoldingsLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 5
Fair value at the ending	$ 7	$ 5
Number of units held	132	132
Investment, Identifier [Axis]: P K S Holdings, L L C, Equity Securities, Two, Preferred units
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:PKSHoldingsLLCMember	mrcc:PKSHoldingsLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 34
Fair value at the ending	$ 46	$ 34
Number of units held	5,714	5,714
Investment, Identifier [Axis]: P V H C Holding Corp, Senior Secured Loans, due 8/5/2024
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:PVHCHoldingCorpMember	mrcc:PVHCHoldingCorpMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 2,976
Fair value at the ending		$ 2,976
Investment, Identifier [Axis]: Panda Acquisition, LLC, Senior Secured Loans, due 10/18/2028
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:PandaAcquisitionLlcMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending	$ 3,690
Investment, Identifier [Axis]: Paragon Healthcare Inc. Senior Secured Loan Due 1/19/2027
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:ParagonHealthcareIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending	$ 2,109
Investment, Identifier [Axis]: Paragon HealthcareInc. Delayed Draw Senior Secured Loans due 1/19/2027
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:ParagonHealthcareIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending	$ 242
Investment, Identifier [Axis]: Paragon HealthcareInc. Revolver Senior Secured Loan Due 1/19/2027
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:ParagonHealthcareIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending	$ 61
Investment, Identifier [Axis]: Phoenix Chemical Holding Company L L C (fka Polymer Solutions Group), Senior Secured Loans, due 1/3/2023
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:PhoenixChemicalHoldingCompanyLLCMember
Investment, Identifier [Axis]: Planful Inc. Senior Secured Loans, One, due 12/30/2024
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:PlanfulIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 9,472
Fair value at the ending		$ 9,472
Investment, Identifier [Axis]: Planful Inc. Senior Secured Loans, Two, due 12/30/2024
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:PlanfulIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	1,322
Fair value at the ending		$ 1,322
Investment, Identifier [Axis]: Planful, Inc, Equity Securities, Class A units
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:PlanfulIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 557
Fair value at the ending		$ 557
Number of units held		473,082
Investment, Identifier [Axis]: Planful, Inc, Senior Secured Loans, Four, due 12/28/2026
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:PlanfulIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending	$ 878
Investment, Identifier [Axis]: Planful, Inc, Senior Secured Loans, One, due 12/28/2026
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:PlanfulIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending	$ 9,443
Investment, Identifier [Axis]: Planful, Inc, Senior Secured Loans, Three, due 12/28/2026
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:PlanfulIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending	$ 1,318
Investment, Identifier [Axis]: Planful, Inc, Senior Secured Loans, Two, due 12/28/2026
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:PlanfulIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending	$ 527
Investment, Identifier [Axis]: Planful, Inc. ( Revolver), Senior Secured Loans, due 12/28/2026
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:PlanfulIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending	$ 439
Investment, Identifier [Axis]: Planful, Inc. ( Revolver), Senior Secured Loans, due 12/30/2024
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:PlanfulIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 88
Fair value at the ending		$ 88
Investment, Identifier [Axis]: Planful, Inc., Equity Securities, Class A Units
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:PlanfulInc.Member
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending	$ 563
Number of units held	473,082
Investment, Identifier [Axis]: Polychem Acquisition, L L C, Senior Secured Loans, due 3/17/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:PolychemAcquisitionLLCMember	mrcc:PolychemAcquisitionLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 2,917
Fair value at the ending		$ 2,917
Investment, Identifier [Axis]: Polymer Solutions Group Senior Secured Loans Due 1/3/2023
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:PhoenixChemicalHoldingCompanyLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	1,169
Fair value at the ending		$ 1,169
Investment, Identifier [Axis]: Port Townsend Holdings Company, Inc. and Crown Corrugated Company, Senior Secured Loans, due 4/3/2024
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:PortTownsendHoldingsCompanyInc.andCrownCorrugatedCompanyMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	4,238
Fair value at the ending		$ 4,238
Investment, Identifier [Axis]: Priority Ambulance, L L C, Unitranche Secured Loans, Four, due 4/12/2022
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:PriorityAmbulanceLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	989
Fair value at the ending		$ 989
Investment, Identifier [Axis]: Priority Ambulance, L L C, Unitranche Secured Loans, One, due 4/12/2022
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:PriorityAmbulanceLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	10,010
Fair value at the ending		$ 10,010
Investment, Identifier [Axis]: Priority Ambulance, L L C, Unitranche Secured Loans, Three, due 4/12/2022
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:PriorityAmbulanceLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	655
Fair value at the ending		$ 655
Investment, Identifier [Axis]: Priority Ambulance, L L C, Unitranche Secured Loans, Two, due 4/12/2022
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:PriorityAmbulanceLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 1,253
Fair value at the ending		$ 1,253
Investment, Identifier [Axis]: Prototek LLC (Delayed Draw), Due 12/8/2027
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:PrototekLlcMember
Investment, Identifier [Axis]: Prototek LLC (Revolver), Due,12/8/2027
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:PrototekLlcMember
Investment, Identifier [Axis]: Prototek LLC, Due 12/8/2027
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:PrototekLlcMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending	$ 2,425
Investment, Identifier [Axis]: Quest Resource Management Group, L L C ( Delayed Draw), Senior Secured Loans, due 10/20/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:QuestResourceManagementGroupLLCMember	mrcc:QuestResourceManagementGroupLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending	$ 381
Investment, Identifier [Axis]: Quest Resource Management Group, L L C, Equity Securites, Two, Warrants
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:QuestResourceManagementGroupLLCMember	mrcc:QuestResourceManagementGroupLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 169
Fair value at the ending	$ 147	$ 169
Warrants to purchase percentage of equity	0.20%	0.20%
Investment, Identifier [Axis]: Quest Resource Management Group, L L C, Equity Securities, One, Warrants
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:QuestResourceManagementGroupLLCMember	mrcc:QuestResourceManagementGroupLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 286
Fair value at the ending	$ 210	$ 286
Warrants to purchase percentage of equity	0.20%	0.20%
Investment, Identifier [Axis]: Quest Resource Management Group, L L C, Senior Secured Loans, One, due 10/20/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:QuestResourceManagementGroupLLCMember	mrcc:QuestResourceManagementGroupLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 989
Fair value at the ending	$ 972	$ 989
Investment, Identifier [Axis]: Quest Resource Management Group, L L C, Senior Secured Loans, Three, due 10/20/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:QuestResourceManagementGroupLLCMember	mrcc:QuestResourceManagementGroupLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 3,853
Fair value at the ending	$ 3,781	$ 3,853
Investment, Identifier [Axis]: Quest Resource Management Group, L L C, Senior Secured Loans, Two, due 10/20/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:QuestResourceManagementGroupLLCMember	mrcc:QuestResourceManagementGroupLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 1,086
Fair value at the ending	$ 1,067	$ 1,086
Investment, Identifier [Axis]: Radiology Partners, Inc., Senior Secured Loans, due 7/9/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:RadiologyPartnersIncMember	mrcc:RadiologyPartnersIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 4,700
Fair value at the ending	$ 4,018	$ 4,700
Investment, Identifier [Axis]: Recorded Future, Inc, Equity Securities, Class A units
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	Recorded Future, Inc [ Member]	Recorded Future, Inc [ Member]
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 203
Fair value at the ending	$ 225	$ 203
Number of units held	80,486	80,486
Investment, Identifier [Axis]: Recycled Plastics Industries, L L C ( Revolver), Senior Secured Loans, due 8/4/2026
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:RecycledPlasticsIndustriesLLCMember	mrcc:RecycledPlasticsIndustriesLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 142
Fair value at the ending		$ 142
Investment, Identifier [Axis]: Recycled Plastics Industries, L L C, Senior Secured Loans, due 8/4/2026
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:RecycledPlasticsIndustriesLLCMember	mrcc:RecycledPlasticsIndustriesLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 3,491
Fair value at the ending	3,370	$ 3,491
Investment, Identifier [Axis]: Red Zone Robotics, Inc. ( Revolver) , Senior Secured Loans, due 6/5/2023
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:RedZoneRoboticsIncMember
Investment, Identifier [Axis]: Red Zone Robotics, Inc., Senior Secured Loans, due 6/5/2023
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:RedZoneRoboticsIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 213
Fair value at the ending		$ 213
Investment, Identifier [Axis]: Relativity O D A L L C ( Revolver), Senior Secured Loans, due 5/12/2027
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:RelativityODALLCMember	mrcc:RelativityODALLCMember
Investment, Identifier [Axis]: Relativity O D A L L C, Senior Secured Loans, due 5/12/2027
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:RelativityODALLCMember	mrcc:RelativityODALLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 1,894
Fair value at the ending	$ 2,060	$ 1,894
Investment, Identifier [Axis]: Relevate Health Group, L L C ( Delayed Draw), Senior Secured Loans, due, 11/20/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:RelevateHealthGroupLLCMember	mrcc:RelevateHealthGroupLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 673
Fair value at the ending	$ 648	$ 673
Investment, Identifier [Axis]: Relevate Health Group, L L C ( Revolver), Senior Secured Loans, due, 11/20/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:RelevateHealthGroupLLCMember	mrcc:RelevateHealthGroupLLCMember
Investment, Identifier [Axis]: Relevate Health Group, L L C, Equity Securities, Class B common units
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:RelevateHealthGroupLLCMember	mrcc:RelevateHealthGroupLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Number of units held		40
Investment, Identifier [Axis]: Relevate Health Group, L L C, Equity Securities, preferred units
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:RelevateHealthGroupLLCMember	mrcc:RelevateHealthGroupLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 40
Fair value at the ending	$ 36	$ 40
Number of units held		40
Number of shares held	40
Investment, Identifier [Axis]: Relevate Health Group, L L C, Senior Secured Loans, due, 11/20/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:RelevateHealthGroupLLCMember	mrcc:RelevateHealthGroupLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 1,504
Fair value at the ending	$ 1,449	$ 1,504
Investment, Identifier [Axis]: Research Now Group, Inc. and Survey Sampling International, L L C, Senior Secured Loans, due 12/20/2024
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:ResearchNowGroupInc.andSurveySamplingInternationalLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending	$ 5,035
Investment, Identifier [Axis]: Rockdale Blackhawk, L L C, Senior Secured Loans, no stated maturity
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:RockdaleBlackhawkLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	1,681
Fair value at the ending	$ 557	$ 1,681
Investment, Identifier [Axis]: Runner Buyer I N C., Senior Secured Loans, due 10/23/2028
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:RunnerBuyerINCMember	mrcc:RunnerBuyerINCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 2,970
Fair value at the ending		$ 2,970
Investment, Identifier [Axis]: S F R Holdco, L L C Equity Securities
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	S F R Holdco, L L C [ Member]
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 3,900
Fair value at the ending	$ 3,900	3,900
Percentage of equity interest	24.40%
Investment, Identifier [Axis]: S F R Holdco, L L C, Junior Secured Loans Due 7/28/2028
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	S F R Holdco, L L C [ Member]
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 5,850
Fair value at the ending	$ 5,850	$ 5,850
Investment, Identifier [Axis]: S H I Holdings, Inc. ( Common stock)
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	S H I Holdings, Inc [ Member]	S H I Holdings, Inc [ Member]
Transactions with Affiliated Companies, Fair value Roll Forward
Net realized gain (loss)		$ (27)
Net unrealized gain (loss)		$ 27
Number of shares held		24
Investment, Identifier [Axis]: S H I Holdings, Inc. ( Revolver)
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	S H I Holdings, Inc [ Member]	S H I Holdings, Inc [ Member]
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 297
Sales and paydowns (cost)		(315)
Net realized gain (loss)		(4,270)
Net unrealized gain (loss)		$ 4,288
Investment, Identifier [Axis]: S H I Holdings, Inc., Investment One
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	S H I Holdings, Inc [ Member]	S H I Holdings, Inc [ Member]
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 188
Net realized gain (loss)		(2,897)
Net unrealized gain (loss)		$ 2,709
Investment, Identifier [Axis]: S I R V A Worldwide Inc., Senior Secured Loans, due 8/4/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:SIRVAWorldwideIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending	$ 1,606
Investment, Identifier [Axis]: S T A T S Intermediate Holdings, L L C, Senior Secured Loans, due 7/10/2026
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:STATSIntermediateHoldingsLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending	$ 4,498
Investment, Identifier [Axis]: S W Ingredients Holdings, L L C, Senior Secured Loans, due 7/3/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:SWIngredientsHoldingsLLCMember	mrcc:SWIngredientsHoldingsLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 3,619
Fair value at the ending	$ 3,581	$ 3,619
Investment, Identifier [Axis]: SFR Holdco, LLC (Junior secured loan)
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	Second Avenue S F R Holdings I I L L C [ Member]	Second Avenue S F R Holdings I I L L C [ Member]
Investment, Identifier [Axis]: SFR Holdco, LLC (LLC interest)
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	Second Avenue S F R Holdings I I L L C [ Member]	Second Avenue S F R Holdings I I L L C [ Member]
Investment, Identifier [Axis]: Sandvine Corporation, Senior Secured Loans, due 10/31/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:SandvineCorporationMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending	$ 1,904
Investment, Identifier [Axis]: Second Avenue S F R Holdings I I L L C ( Revolver), Senior Secured Loans, Due 8/9/2024
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	Second Avenue S F R Holdings I I L L C [ Member]	Second Avenue S F R Holdings I I L L C [ Member]
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 2,104
Purchases (cost)	2,681	$ 2,104
Net unrealized gain (loss)	(30)
Fair value at the ending	4,755	$ 2,104
Investment, Identifier [Axis]: Second Avenue S F R Holdings I I L L C, Equity Securities
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		Second Avenue S F R Holdings I I L L C [ Member]
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	3,900
Purchases (cost)		$ 3,900
Fair value at the ending		$ 3,900
Warrants to purchase percentage of equity		24.40%
Percentage of equity interest		24.40%
Investment, Identifier [Axis]: Second Avenue S F R Holdings I I L L C, Junior Secured Loans, Due 7/28/2028
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		Second Avenue S F R Holdings I I L L C [ Member]
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 5,850
Fair value at the ending		$ 5,850
Investment, Identifier [Axis]: Second Avenue SFR Holdings II LLC (Delayed Draw) Loan
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	Second Avenue S F R Holdings I I L L C [ Member]	Second Avenue S F R Holdings I I L L C [ Member]
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 5,850
Purchases (cost)		$ 5,850
Fair value at the ending		$ 5,850
Investment, Identifier [Axis]: Secretariat Advisors L L C ( Delayed Draw), Senior Secured Loans, due 12/29/2028
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:SecretariatAdvisorsLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending	$ 260
Investment, Identifier [Axis]: Secretariat Advisors L L C, Senior Secured Loans, due 12/29/2028
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:SecretariatAdvisorsLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending	$ 1,634
Investment, Identifier [Axis]: Security Services Acquisition Sub Corp., Senior Secured Loans, Five, due 9/30/2026
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:SecurityServicesAcquisitionSubCorpMember	mrcc:SecurityServicesAcquisitionSubCorpMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 1,549
Fair value at the ending	$ 1,532	$ 1,549
Investment, Identifier [Axis]: Security Services Acquisition Sub Corp., Senior Secured Loans, Four, due 9/30/2026
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:SecurityServicesAcquisitionSubCorpMember	mrcc:SecurityServicesAcquisitionSubCorpMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 2,154
Fair value at the ending	$ 2,131	$ 2,154
Investment, Identifier [Axis]: Security Services Acquisition Sub Corp., Senior Secured Loans, One, due 9/30/2026
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:SecurityServicesAcquisitionSubCorpMember	mrcc:SecurityServicesAcquisitionSubCorpMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 7,972
Fair value at the ending	$ 3,372	$ 7,972
Investment, Identifier [Axis]: Security Services Acquisition Sub Corp., Senior Secured Loans, Three, due 9/30/2026
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:SecurityServicesAcquisitionSubCorpMember	mrcc:SecurityServicesAcquisitionSubCorpMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 2,452
Fair value at the ending	$ 7,884	$ 2,452
Investment, Identifier [Axis]: Security Services Acquisition Sub Corp., Senior Secured Loans, Two, due 9/30/2026
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:SecurityServicesAcquisitionSubCorpMember	mrcc:SecurityServicesAcquisitionSubCorpMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 3,409
Fair value at the ending	$ 2,425	$ 3,409
Investment, Identifier [Axis]: Seran Bio Science, L L C ( Revolver), Senior Secured Loans, due 7/8/2027
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:SeranBioScienceLLCMember
Investment, Identifier [Axis]: Seran Bio Science, L L C (Revolver), Senior Secured Loans, Due 12/31/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:SeranBioScienceLLCMember
Investment, Identifier [Axis]: Seran Bio Science, L L C, Equity Securities, common units
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:SeranBioScienceLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 714
Fair value at the ending		$ 714
Number of units held		33,333
Investment, Identifier [Axis]: Seran Bio Science, L L C, Senior Secured Loans, Due 12/31/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:SeranBioScienceLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 2,487
Fair value at the ending		$ 2,487
Investment, Identifier [Axis]: Seran Bio Science, L L C, Senior Secured Loans, due 7/8/2027
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:SeranBioScienceLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending	$ 2,435
Investment, Identifier [Axis]: Seran BioScience, LLC (Delayed Draw), Senior Secured Loans, Due 7/8/2027
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:SeranBioScienceLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending	$ 1,320
Investment, Identifier [Axis]: Seran BioScience, LLC, Equity Security, Common Units
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:SeranBioScienceLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending	$ 537
Number of units held	33,333
Investment, Identifier [Axis]: Service Max, Inc. ( Revolver) , Senior Secured Loans, due 11/1/2027
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:ServiceMaxIncMember	mrcc:ServiceMaxIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending	$ 175
Investment, Identifier [Axis]: Service Max, Inc., Senior Secured Loans, due 11/1/2027
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:ServiceMaxIncMember	mrcc:ServiceMaxIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 3,500
Fair value at the ending	$ 3,884	$ 3,500
Investment, Identifier [Axis]: Spectrum Science Communications, L L C ( Revolver), Senior Secured Loans, due 1/25/2027
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:SpectrumScienceCommunicationsLLCMember
Investment, Identifier [Axis]: Spectrum Science Communications, L L C, Senior Secured Loans, due 1/25/2027
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:SpectrumScienceCommunicationsLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending	$ 1,005
Investment, Identifier [Axis]: Spherix Global Inc, Equity Securities, Class A units
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:SpherixGlobalInc.Member	mrcc:SpherixGlobalInc.Member
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 81
Fair value at the ending	$ 63	$ 81
Number of units held	81	81
Investment, Identifier [Axis]: Spherix Global Inc. ( Revolver), Senior Secured Loans, due, 12/22/2026
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:SpherixGlobalInc.Member	mrcc:SpherixGlobalInc.Member
Investment, Identifier [Axis]: Spherix Global Inc. , Senior Secured Loans, due, 12/22/2026
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:SpherixGlobalInc.Member	mrcc:SpherixGlobalInc.Member
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 1,081
Fair value at the ending	$ 1,088	$ 1,081
Investment, Identifier [Axis]: Sports Operating Holdings II, LLC (Delayed Draw), Due 11/3/2027
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:SportsOperatingHoldingsIiLlcMember
Investment, Identifier [Axis]: Sports Operating Holdings II, LLC (Revolver), Due, 11/3/2027
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:SportsOperatingHoldingsIiLlcMember
Investment, Identifier [Axis]: Sports Operating Holdings II, LLC, Due, 11/3/2027
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:SportsOperatingHoldingsIiLlcMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending	$ 2,918
Investment, Identifier [Axis]: Star Compliance Mid Co, L L C, ( Revolver), Senior Secured Loans, due 1/12/2027
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:StarComplianceMidCoLLCMember	mrcc:StarComplianceMidCoLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending	$ 79
Investment, Identifier [Axis]: Star Compliance Mid Co, L L C, Senior Secured Loans, One, due 1/12/2027
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:StarComplianceMidCoLLCMember	mrcc:StarComplianceMidCoLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 2,000
Fair value at the ending	$ 1,968	$ 2,000
Investment, Identifier [Axis]: Star Compliance Mid Co, L L C, Senior Secured Loans, Two, due 1/12/2027
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:StarComplianceMidCoLLCMember	mrcc:StarComplianceMidCoLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 336
Fair value at the ending	330	$ 336
Investment, Identifier [Axis]: Storm Trap, L L C ( Revolver), Senior Secured Loans, due 12/8/2023
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:StormTrapLLCMember
Investment, Identifier [Axis]: Storm Trap, L L C, Senior Secured Loans, due 12/8/2023
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:StormTrapLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 7,170
Fair value at the ending		$ 7,170
Investment, Identifier [Axis]: Summit Container Corporation ( Revolver)
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	Summit Container Corporation [ Member]	Summit Container Corporation [ Member]
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 1,654
Purchases (cost)		5,402
Sales and paydowns (cost)		(7,059)
Net unrealized gain (loss)		$ 3
Investment, Identifier [Axis]: Summit Container Corporation, Equity Securities, Warrants
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	Summit Container Corporation [ Member]	Summit Container Corporation [ Member]
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 139
Net unrealized gain (loss)		$ (139)
Warrants to purchase percentage of equity		19.50%
Investment, Identifier [Axis]: Summit Container Corporation, Investment One
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	Summit Container Corporation [ Member]	Summit Container Corporation [ Member]
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 3,204
Sales and paydowns (cost)		(3,019)
Net realized gain (loss)		(250)
Net unrealized gain (loss)		$ 65
Investment, Identifier [Axis]: Synergy Environmental Corporation ( Revolver), Senior Secured Loans, due 9/29/2023
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:SynergyEnvironmentalCorporationMember
Investment, Identifier [Axis]: Synergy Environmental Corporation, Senior Secured Loans, One, due 9/29/2023
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:SynergyEnvironmentalCorporationMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 2,853
Fair value at the ending		$ 2,853
Investment, Identifier [Axis]: Synergy Environmental Corporation, Senior Secured Loans, Three, due 9/29/2023
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:SynergyEnvironmentalCorporationMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	810
Fair value at the ending		$ 810
Investment, Identifier [Axis]: Synergy Environmental Corporation, Senior Secured Loans, Two, due 9/29/2023
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:SynergyEnvironmentalCorporationMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 477
Fair value at the ending		$ 477
Investment, Identifier [Axis]: T A T T Buyer, L L C, Senior Secured Loans, due 3/30/2029
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:TATTBuyerLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending	$ 3,242
Investment, Identifier [Axis]: T C F I I I O W L Buyer L L C, Senior Secured Loans, One, due 4/17/2026
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:TCFIIIOWLBuyerLLCMember	mrcc:TCFIIIOWLBuyerLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 2,040
Fair value at the ending	$ 2,022	$ 2,040
Investment, Identifier [Axis]: T C F I I I O W L Buyer L L C, Senior Secured Loans, Three, due 4/17/2026
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:TCFIIIOWLBuyerLLCMember	mrcc:TCFIIIOWLBuyerLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 2,235
Fair value at the ending	$ 2,215	$ 2,235
Investment, Identifier [Axis]: T C F I I I O W L Buyer L L C, Senior Secured Loans, Two, due 4/17/2026
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:TCFIIIOWLBuyerLLCMember	mrcc:TCFIIIOWLBuyerLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 2,491
Fair value at the ending	$ 2,469	$ 2,491
Investment, Identifier [Axis]: T E A M Public Choices, L L C, Senior Secured Loans, due 12/17/2027
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:TEAMPublicChoicesLLCMember	mrcc:TEAMPublicChoicesLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 2,985
Fair value at the ending	$ 2,822	$ 2,985
Investment, Identifier [Axis]: T G G T S Acquisition Company, Senior Secured Loans, due 12/12/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:TGGTSAcquisitionCompanyMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending	$ 3,143
Investment, Identifier [Axis]: T J C Spartech Acquisition Corp., Senior Secured Loans, due 5/5/2028
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:TJCSpartechAcquisitionCorpMember
Investment, Identifier [Axis]: T J Management Hold Co L L C ( Revolver), Senior Secured Loans, Due 6/28/2024
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	T J Management Hold Co L L C [ Member]	T J Management Hold Co L L C [ Member]
Transactions with Affiliated Companies, Fair value Roll Forward
Purchases (cost)	$ 80
Fair value at the ending	$ 80
Investment, Identifier [Axis]: T J Management Hold Co L L C, Equity Securities, Common stock
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	T J Management Hold Co L L C [ Member]	T J Management Hold Co L L C [ Member]
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 3,148	$ 3,323
Sales and paydowns (cost)		(755)
Net unrealized gain (loss)	(382)	580
Fair value at the ending	$ 2,766	$ 3,148
Number of shares held	16	16
Investment, Identifier [Axis]: Tait L L C ( Revolver), Senior Secured Loans, due 3/28/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:TaitLLCMember
Investment, Identifier [Axis]: Tait L L C, Senior Secured Loans, due 3/28/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:TaitLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending	$ 3,972
Investment, Identifier [Axis]: Teneo Holdings L L C, Senior Secured Loans, due 7/11/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:TeneoHoldingsLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending	$ 4,668
Investment, Identifier [Axis]: The Cook & Boardman Group L L C, Senior Secured Loans, due 10/20/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:TheCookBoardmanGroupLLCMember	mrcc:TheCookBoardmanGroupLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 2,838
Fair value at the ending		$ 2,838
Investment, Identifier [Axis]: The Kleinfelder Group, Inc., Senior Secured Loans, due 11/29/2024
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:TheKleinfelderGroupIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending	$ 2,362
Investment, Identifier [Axis]: The Kyjen Company, L L C ( Revolver), Senior Secured Loans, due 4/3/2026
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:TheKyjenCompanyLLCMember	mrcc:TheKyjenCompanyLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 43
Fair value at the ending	$ 88	$ 43
Investment, Identifier [Axis]: The Kyjen Company, L L C, Senior SEcured Loans, Two, Due 4/3/2026
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:TheKyjenCompanyLLCMember
Investment, Identifier [Axis]: The Kyjen Company, L L C, Senior Secured Loans, due 4/3/2026
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:TheKyjenCompanyLLCMember	mrcc:TheKyjenCompanyLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 997
Fair value at the ending	$ 975	$ 997
Investment, Identifier [Axis]: Thrasio, L L C, Senior Secured Loans, due 12/18/2026
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:ThrasioLLCMember	mrcc:ThrasioLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 2,470
Fair value at the ending	$ 2,445	$ 2,470
Investment, Identifier [Axis]: Tiger Connect, Inc. ( Delayed Draw), Senior Secured Loans, due 2/16/2028
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:TigerConnectIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending	$ 27
Investment, Identifier [Axis]: Tiger Connect, Inc. ( Revolver), Senior Secured Loans, due 2/16/2028
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:TigerConnectIncMember
Investment, Identifier [Axis]: Tiger Connect, Inc., Senior Secured Loans, due 2/16/2028
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:TigerConnectIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending	$ 2,963
Investment, Identifier [Axis]: Toojay’s Management L L C ( Revolver), Senior Secured Loans, due 10/26/2022
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:ToojaysManagementLLCMember
Investment, Identifier [Axis]: Toojay’s Management L L C, Senior Secured Loans, One, due 10/26/2022
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:ToojaysManagementLLCMember
Investment, Identifier [Axis]: Toojay’s Management L L C, Senior Secured Loans, Two, due 10/26/2022
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:ToojaysManagementLLCMember
Investment, Identifier [Axis]: Trident Maritime Systems, Inc ( Revolver), Senior Secured Loans, due 2/26/2027
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:TridentMaritimeSystemsIncMember	mrcc:TridentMaritimeSystemsIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending	$ 122
Investment, Identifier [Axis]: Trident Maritime Systems, Inc, Senior Secured Loans, One, due 2/26/2027
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:TridentMaritimeSystemsIncMember	mrcc:TridentMaritimeSystemsIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 2,478
Fair value at the ending	$ 2,443	$ 2,478
Investment, Identifier [Axis]: Trident Maritime Systems, Inc, Senior Secured Loans, Two, due 2/26/2027
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:TridentMaritimeSystemsIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending	$ 746
Investment, Identifier [Axis]: Truck- Lite Co., L L C, Senior Secured Loans, One, due 12/14/2026
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:Truck-LiteCo.LLCMember	mrcc:Truck-LiteCo.LLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 1,718
Fair value at the ending	$ 1,690	$ 1,718
Investment, Identifier [Axis]: Truck- Lite Co., L L C, Senior Secured Loans, Two, due 12/14/2026
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:Truck-LiteCo.LLCMember	mrcc:Truck-LiteCo.LLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 255
Fair value at the ending	$ 250	$ 255
Investment, Identifier [Axis]: Truck-Lite Co., LLC, Senior Secured Loans, Three, due 12/14/2026
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:Truck-LiteCo.LLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending	$ 43
Investment, Identifier [Axis]: V B E1, L L C ( Delayed Draw), Unitranche Secured Loans, due 11/18/2026
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:VBE1LLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 1,118
Fair value at the ending		$ 1,118
Investment, Identifier [Axis]: V B E1, L L C, Unitranche Secured Loans, due 11/18/2026
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:VBE1LLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending	$ 2,257
Investment, Identifier [Axis]: V H T Solutions ( Delayed Draw), Senior Secured Loans, due 12/21/2026
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:VHTAcquisitionsLLCMember
Investment, Identifier [Axis]: V H T Solutions ( Revolver), Senior Secured Loans, due 12/21/2026
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:VHTAcquisitionsLLCMember
Investment, Identifier [Axis]: V H T Solutions, Senior Secured Loans, due 12/21/2026
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:VHTAcquisitionsLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 1,470
Fair value at the ending		$ 1,470
Investment, Identifier [Axis]: V P S Holdings, L L C ( Revolver), Senior Secured Loans, due 10/4/2024
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:VPSHoldingsLLCMember	mrcc:VPSHoldingsLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 97
Fair value at the ending	$ 102	$ 97
Investment, Identifier [Axis]: V P S Holdings, L L C, Senior Secured Loans, One, due 10/4/2024
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:VPSHoldingsLLCMember	mrcc:VPSHoldingsLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 3,325
Fair value at the ending	$ 3,252	$ 3,325
Investment, Identifier [Axis]: V P S Holdings, L L C, Senior Secured Loans, Two, due 10/4/2024
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:VPSHoldingsLLCMember	mrcc:VPSHoldingsLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 2,717
Fair value at the ending	$ 2,661	$ 2,717
Investment, Identifier [Axis]: Valudor Products L L C ( Revolver), Senior Secured Loans, due 6/19/2023
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:ValudorProductsLLCMember	mrcc:ValudorProductsLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 479
Fair value at the ending	$ 55	$ 479
Investment, Identifier [Axis]: Valudor Products L L C , Equity Securities, Class A-1 units
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:ValudorProductsLLCMember	mrcc:ValudorProductsLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 16
Fair value at the ending	$ 555	$ 16
Number of units held		501,014
Number of shares held	501,014
Investment, Identifier [Axis]: Valudor Products L L C, Senior Secured Loans, One, due 6/19/2023,
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:ValudorProductsLLCMember	mrcc:ValudorProductsLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 1,871
Fair value at the ending	$ 1,958	$ 1,871
Investment, Identifier [Axis]: Valudor Products L L C, Senior Secured Loans, Three, due 6/19/2023
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:ValudorProductsLLCMember	mrcc:ValudorProductsLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 230
Fair value at the ending	$ 1,565	$ 230
Investment, Identifier [Axis]: Valudor Products L L C, Senior Secured Loans, Two, due 6/19/2023
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:ValudorProductsLLCMember	mrcc:ValudorProductsLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 1,469
Fair value at the ending	$ 312	$ 1,469
Investment, Identifier [Axis]: Vice Group Holding Inc., Senior Secured Loans, Four, due 5/12/2023
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:ViceGroupHoldingIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending	$ 196
Investment, Identifier [Axis]: Vice Group Holding Inc., Senior Secured Loans, Four, due, 11/2/2022
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:ViceGroupHoldingIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	180
Fair value at the ending		$ 180
Investment, Identifier [Axis]: Vice Group Holding Inc., Senior Secured Loans, One, due 11/2/2022
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:ViceGroupHoldingIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 1,526
Fair value at the ending		$ 1,526
Investment, Identifier [Axis]: Vice Group Holding Inc., Senior Secured Loans, One, due 5/12/2023
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:ViceGroupHoldingIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending	$ 1,657
Investment, Identifier [Axis]: Vice Group Holding Inc., Senior Secured Loans, Three, due 11/2/2022
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:ViceGroupHoldingIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 478
Fair value at the ending		$ 478
Investment, Identifier [Axis]: Vice Group Holding Inc., Senior Secured Loans, Three, due 5/12/2023
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:ViceGroupHoldingIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending	$ 520
Investment, Identifier [Axis]: Vice Group Holding Inc., Senior Secured Loans, Two, due 11/2/2022
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:ViceGroupHoldingIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 293
Fair value at the ending		$ 293
Investment, Identifier [Axis]: Vice Group Holding Inc., Senior Secured Loans, Two, due 5/12/2023
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:ViceGroupHoldingIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending	$ 318
Investment, Identifier [Axis]: Vinci Brands L L C (fka Incipio, L L C) ( Junior secured loan), One
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	Vinci Brands L L C (fka Incipio, L L C) [ Member]	Vinci Brands L L C (fka Incipio, L L C) [ Member]
Investment, Identifier [Axis]: Vinci Brands L L C (fka Incipio, L L C) ( Junior secured loan), Two
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	Vinci Brands L L C (fka Incipio, L L C) [ Member]	Vinci Brands L L C (fka Incipio, L L C) [ Member]
Investment, Identifier [Axis]: Vinci Brands L L C (fka Incipio, L L C), (Delayed Draw)
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	Vinci Brands L L C (fka Incipio, L L C) [ Member]
Investment, Identifier [Axis]: Vinci Brands L L C (fka Incipio, L L C), Equity Securities, Series C common units)
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	Vinci Brands L L C (fka Incipio, L L C) [ Member]	Vinci Brands L L C (fka Incipio, L L C) [ Member]
Transactions with Affiliated Companies, Fair value Roll Forward
Number of shares held		1,774
Investment, Identifier [Axis]: Vinci Brands L L C (fka Incipio, L L C), Loan Five
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	Vinci Brands L L C (fka Incipio, L L C) [ Member]	Vinci Brands L L C (fka Incipio, L L C) [ Member]
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 1,519
Transfers in (out)		(1,458)
PIK Interest (cost)		13
Net unrealized gain (loss)		$ (74)
Investment, Identifier [Axis]: Vinci Brands L L C (fka Incipio, L L C), Loan Four
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	Vinci Brands L L C (fka Incipio, L L C) [ Member]	Vinci Brands L L C (fka Incipio, L L C) [ Member]
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 761
Transfers in (out)		(730)
PIK Interest (cost)		6
Net unrealized gain (loss)		$ (37)
Investment, Identifier [Axis]: Vinci Brands L L C (fka Incipio, L L C), Loan One
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	Vinci Brands L L C (fka Incipio, L L C) [ Member]	Vinci Brands L L C (fka Incipio, L L C) [ Member]
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 1,764
Net unrealized gain (loss)		$ (1,764)
Investment, Identifier [Axis]: Vinci Brands L L C (fka Incipio, L L C), Loan Six
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		Vinci Brands L L C (fka Incipio, L L C) [ Member]
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 1,488
Transfers in (out)		(1,527)
Purchases (cost)		108
PIK Interest (cost)		9
Net unrealized gain (loss)		$ (78)
Investment, Identifier [Axis]: Vinci Brands L L C (fka Incipio, L L C), Loan Three
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	Vinci Brands L L C (fka Incipio, L L C) [ Member]	Vinci Brands L L C (fka Incipio, L L C) [ Member]
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 1,805
Transfers in (out)		(1,732)
PIK Interest (cost)		15
Net unrealized gain (loss)		$ (88)
Investment, Identifier [Axis]: Vinci Brands L L C (fka Incipio, L L C), Loan Two
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	Vinci Brands L L C (fka Incipio, L L C) [ Member]	Vinci Brands L L C (fka Incipio, L L C) [ Member]
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 4,227
Transfers in (out)		(1,562)
PIK Interest (cost)		48
Net unrealized gain (loss)		$ (2,713)
Investment, Identifier [Axis]: Vinci Brands L L C, Unitranche Secured Loans, Four, due 2/6/2024
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:VinciBrandsLLCMember
Investment, Identifier [Axis]: Vinci Brands L L C, Unitranche Secured Loans, One, due 2/6/2024
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:VinciBrandsLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 4,950
Fair value at the ending		$ 4,950
Investment, Identifier [Axis]: Vinci Brands L L C, Unitranche Secured Loans, Three, due 2/6/2024
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:VinciBrandsLLCMember
Investment, Identifier [Axis]: Vinci Brands L L C, Unitranche Secured Loans, Two, due 2/6/2024
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:VinciBrandsLLCMember
Investment, Identifier [Axis]: W3 Monroe R E Debt L L C, Senior Secured Loans, due 2/4/2028
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:W3MonroeREDebtLLCMember	mrcc:W3MonroeREDebtLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 2,906
Fair value at the ending	$ 3,210	$ 2,906
Investment, Identifier [Axis]: Wheel Pros, Inc., Senior Secured Loans, due 5/11/2028
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:WheelProsIncMember	mrcc:WheelProsIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 1,951
Fair value at the ending	$ 1,321	$ 1,951
Investment, Identifier [Axis]: Whistler Parent Holdings I I I, Inc. ( Delayed Draw), Senior Secured Loans, due 6/2/2028
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:WhistlerParentHoldingsIIIIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending	$ 56
Investment, Identifier [Axis]: Whistler Parent Holdings I I I, Inc. ( Revolver), Senior Secured Loans, due 6/2/2028
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:WhistlerParentHoldingsIIIIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending	$ 84
Investment, Identifier [Axis]: Whistler Parent Holdings I I I, Inc., Senior Secured Loans, due 6/2/2028
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:WhistlerParentHoldingsIIIIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending	$ 4,457
Investment, Identifier [Axis]: WillowTree, LLC, Unitranche Secured Loans, due 10/9/2023
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:WillowTreeLLCMember	mrcc:WillowTreeLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 7,651
Fair value at the ending	$ 7,326	$ 7,651
Investment, Identifier [Axis]: Witkoff/ Monroe 700 J V L L C ( Delayed Draw), Junior Secured Loans, due 7/2/2026
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:WitkoffMonroe700JVLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 4,886
Fair value at the ending	$ 6,014	$ 4,886
Investment, Identifier [Axis]: Witkoff/ Monroe 700 J V L L C, Equity Securities, Preferred units
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:WitkoffMonroe700JVLLCMember	mrcc:WitkoffMonroe700JVLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 2
Fair value at the ending	$ 1,047	$ 2
Number of units held	2,141	2,141
Investment, Identifier [Axis]: Xan Edu Publishing, Inc, Equity Securities, Class A units
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:XanEduPublishingIncMember	mrcc:XanEduPublishingIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 106
Fair value at the ending	$ 223	$ 106
Number of units held	49,479	49,479
Investment, Identifier [Axis]: Xan Edu Publishing, Inc. ( Revolver), Senior Secured Loans, due, 1/28/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:XanEduPublishingIncMember	mrcc:XanEduPublishingIncMember
Investment, Identifier [Axis]: Xan Edu Publishing, Inc., Senior Secured Loans, One, due, 1/28/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:XanEduPublishingIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending	$ 4,602
Investment, Identifier [Axis]: Xan Edu Publishing, Inc., Senior Secured Loans, Two, due, 1/28/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:XanEduPublishingIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending	$ 1,829
Investment, Identifier [Axis]: Xan Edu Publishing, Inc., Senior Secured Loans, due, 1/28/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:XanEduPublishingIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	$ 4,647
Fair value at the ending		$ 4,647
Investment, Identifier [Axis]: Y S W H 4, L L C (Revolver), Senior Secured Loans, Due 11/20/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:YSWH4LLCRevolverMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending	$ 1,776
Investment, Identifier [Axis]: iCIMS, Inc, Due 8/18/2028
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:IcimsIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending	$ 2,456
Non-controlled affiliate company investments
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	90,281	109,715
Transfers in (out)		(7,087)
Purchases (cost)	3,685	26,800
Sales and paydowns (cost)	(5,687)	(45,004)
PIK Interest (cost)	3,680	6,484
Discount accretion	39	60
Net realized gain (loss)	(1)	(5,637)
Net unrealized gain (loss)	(5,379)	4,950
Fair value at the ending	86,618	90,281
Controlled affiliate company investments
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning	41,125	39,284
Purchases (cost)	500
Net unrealized gain (loss)	(6,116)	1,841
Fair value at the ending	$ 35,509	$ 41,125

Transactions with Affiliated _4

Transactions with Affiliated Companies - Income Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
American Community Homes, Inc. [ Member]
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Interest income	$ 2,877	$ 2,748
Ascent Midco, L L C [ Member]
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Interest income	$ 520	$ 484
Dividend income	$ 189	$ 174
Curion Holdings, L L C [ Member]
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Interest income	$ 2,060
Familia Dental Group Holdings, LLC
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
H F Z Capital Group, L L C, M C Asset Management ( Corporate), L L C and M C Asset Management ( Industrial), L L C [ Member]
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Interest income	$ 4,218	$ 5,806
Vinci Brands L L C (fka Incipio, L L C) [ Member]
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Luxury Optical Holdings Co [ Member]
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Interest income		$ 1,086
Dividend income		813
Fee income		$ 36
Mnine Holdings, Inc [ Member]
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Interest income	$ 796	$ 1,301
N E C B Collections, L L C [ Member]
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
S H I Holdings, Inc [ Member]
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Summit Container Corporation [ Member]
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Interest income		$ 92
Second Avenue S F R Holdings I I L L C [ Member]
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Interest income	$ 312	$ 105
S F R Holdco, L L C [ Member]
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Interest income	$ 468
T J Management Hold Co L L C [ Member]
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Interest income	$ 14	$ 12
MRCC Senior Loan Fund I, LLC
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Controlled affiliate company investments	Controlled affiliate company investments
Dividend income	$ 3,600	$ 4,325
Investment, Identifier [Axis]: 360 Holdco, Inc. ( Delayed Draw), Senior Secured Loans, due 8/2/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:ThreeSixty360HoldcoIncMember
Investment, Identifier [Axis]: 360 Holdco, Inc., Senior Secured Loans, due 8/2/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:ThreeSixty360HoldcoIncMember
Investment, Identifier [Axis]: A P C O Worldwide, Inc, Equity Securities, Class A voting common stock
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:APCOWorldwideIncMember	mrcc:APCOWorldwideIncMember
Investment, Identifier [Axis]: A Q Carver Buyer, Inc., Senior Secured Loans, due 9/23/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:AQCarverBuyerIncMember
Investment, Identifier [Axis]: A S G I I, L L C ( Delayed Draw), Unitranche Secured Loans, 5/25/2028
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:ASGIILLCMember
Investment, Identifier [Axis]: A S G I I, L L C, Unitranche Secured Loans, due 5/25/2028
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:ASGIILLCMember
Investment, Identifier [Axis]: Accelerate Auto Works Intermediate, L L C ( Delayed Draw), Senior Secured Loans, due 12/1/2027
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:AccelerateAutoWorksIntermediateLLCMember	mrcc:AccelerateAutoWorksIntermediateLLCMember
Investment, Identifier [Axis]: Accelerate Auto Works Intermediate, L L C ( Revolver), Senior Secured Loans, due 12/1/2027
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:AccelerateAutoWorksIntermediateLLCMember	mrcc:AccelerateAutoWorksIntermediateLLCMember
Investment, Identifier [Axis]: Accelerate Auto Works Intermediate, L L C, Senior Secured Loans, due 12/1/2027
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:AccelerateAutoWorksIntermediateLLCMember	mrcc:AccelerateAutoWorksIntermediateLLCMember
Investment, Identifier [Axis]: Ad Theorent Holding Company, Inc. Equity Securities, common stock
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:AdTheorentHoldingCompanyIncMember	mrcc:AdTheorentHoldingCompanyIncMember
Investment, Identifier [Axis]: Amelia Holding II, LLC (Delayed Draw), Due 12/21/2027
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:AmeliaHoldingIiLlcDelayedDrawMember
Investment, Identifier [Axis]: Amelia Holding II, LLC (Revolver), Due 12/21/2027
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:AmeliaHoldingIiLlcRevolverMember
Investment, Identifier [Axis]: Amelia Holding II, LLC, Due 12/21/2027
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:AmeliaHoldingIiLlcMember
Investment, Identifier [Axis]: Amelia Holding II, LLC, Equity Securities
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:AmeliaHoldingIiLlcMember
Investment, Identifier [Axis]: American Broadband and Telecommunications Company L L C ( Delayed Draw), Senior Secured Loans, due 6/10/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:AmericanBroadbandandTelecommunicationsCompanyLLCMember
Investment, Identifier [Axis]: American Broadband and Telecommunications Company L L C ( Revolver), Senior Secured Loans, due 6/10/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:AmericanBroadbandandTelecommunicationsCompanyLLCMember
Investment, Identifier [Axis]: American Broadband and Telecommunications Company L L C, Equity Securities, Warrants
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:AmericanBroadbandandTelecommunicationsCompanyLLCMember
Investment, Identifier [Axis]: American Community Homes, Inc, Senior Secured Loans (Common stock)
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	American Community Homes, Inc. [ Member]
Investment, Identifier [Axis]: American Community Homes, Inc. ( Revolver), Senior Secured Loans Due 12/31/2026
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	American Community Homes, Inc. [ Member]	American Community Homes, Inc. [ Member]
Interest income	$ 21
Investment, Identifier [Axis]: American Community Homes, Inc., Equity Securities Due 12/18/2024, Warrants
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	American Community Homes, Inc. [ Member]	American Community Homes, Inc. [ Member]
Investment, Identifier [Axis]: American Community Homes, Inc., Equity Securities, Common Stock
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	American Community Homes, Inc. [ Member]
Investment, Identifier [Axis]: American Community Homes, Inc., Loan Five
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	American Community Homes, Inc. [ Member]	American Community Homes, Inc. [ Member]
Interest income		$ 5
Investment, Identifier [Axis]: American Community Homes, Inc., Loan Three
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	American Community Homes, Inc. [ Member]	American Community Homes, Inc. [ Member]
Interest income		$ 13
Investment, Identifier [Axis]: American Community Homes, Inc., Senior Secured Loans, Eight, Acquisition Date 9/30/2019
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	American Community Homes, Inc. [ Member]	American Community Homes, Inc. [ Member]
Interest income	$ 3	$ 31
Investment, Identifier [Axis]: American Community Homes, Inc., Senior Secured Loans, Five, Due 12/31/2026
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	American Community Homes, Inc. [ Member]
Investment, Identifier [Axis]: American Community Homes, Inc., Senior Secured Loans, Five, Due 3/31/2022
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		American Community Homes, Inc. [ Member]
Investment, Identifier [Axis]: American Community Homes, Inc., Senior Secured Loans, Four, Acquisition Date 5/24/2017
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	American Community Homes, Inc. [ Member]	American Community Homes, Inc. [ Member]
Interest income	$ 73	$ 69
Investment, Identifier [Axis]: American Community Homes, Inc., Senior Secured Loans, Four, Due 12/31/2026
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	American Community Homes, Inc. [ Member]
Investment, Identifier [Axis]: American Community Homes, Inc., Senior Secured Loans, Four, Due 3/31/2022
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		American Community Homes, Inc. [ Member]
Investment, Identifier [Axis]: American Community Homes, Inc., Senior Secured Loans, Nine, Acquisition Date 12/30/2019
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	American Community Homes, Inc. [ Member]	American Community Homes, Inc. [ Member]
Interest income	$ 11	$ 12
Investment, Identifier [Axis]: American Community Homes, Inc., Senior Secured Loans, One, Acquisition Date 7/22/2014
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	American Community Homes, Inc. [ Member]	American Community Homes, Inc. [ Member]
Interest income	$ 1,209	$ 1,148
Investment, Identifier [Axis]: American Community Homes, Inc., Senior Secured Loans, One, Due 12/31/2026
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	American Community Homes, Inc. [ Member]
Investment, Identifier [Axis]: American Community Homes, Inc., Senior Secured Loans, One, Due 3/31/2022
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		American Community Homes, Inc. [ Member]
Investment, Identifier [Axis]: American Community Homes, Inc., Senior Secured Loans, Seven, Acquisition Date 3/29/2019
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	American Community Homes, Inc. [ Member]	American Community Homes, Inc. [ Member]
Interest income	$ 499	$ 473
Investment, Identifier [Axis]: American Community Homes, Inc., Senior Secured Loans, Seven, Due 12/31/2026
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	American Community Homes, Inc. [ Member]
Investment, Identifier [Axis]: American Community Homes, Inc., Senior Secured Loans, Seven, Due 3/31/2022
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		American Community Homes, Inc. [ Member]
Investment, Identifier [Axis]: American Community Homes, Inc., Senior Secured Loans, Six, Acquisition Date 8/10/2018
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	American Community Homes, Inc. [ Member]	American Community Homes, Inc. [ Member]
Interest income	$ 270	$ 255
Investment, Identifier [Axis]: American Community Homes, Inc., Senior Secured Loans, Six, Due 12/31/2026
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	American Community Homes, Inc. [ Member]
Investment, Identifier [Axis]: American Community Homes, Inc., Senior Secured Loans, Six, Due 3/31/2022
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		American Community Homes, Inc. [ Member]
Investment, Identifier [Axis]: American Community Homes, Inc., Senior Secured Loans, Three, Due 12/31/2026
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	American Community Homes, Inc. [ Member]
Investment, Identifier [Axis]: American Community Homes, Inc., Senior Secured Loans, Three, Due 3/31/2022
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		American Community Homes, Inc. [ Member]
Investment, Identifier [Axis]: American Community Homes, Inc., Senior Secured Loans, Two, Acquisition Date 7/22/2014
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	American Community Homes, Inc. [ Member]	American Community Homes, Inc. [ Member]
Interest income	$ 791	$ 742
Investment, Identifier [Axis]: American Community Homes, Inc., Senior Secured Loans, Two, Due 12/31/2026
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	American Community Homes, Inc. [ Member]
Investment, Identifier [Axis]: American Community Homes, Inc., Senior Secured Loans, Two, Due 3/31/2022
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		American Community Homes, Inc. [ Member]
Investment, Identifier [Axis]: Analogic Corporation, Senior Secured Loans, due 6/24/2024
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:AnalogicCorporationMember	mrcc:AnalogicCorporationMember
Investment, Identifier [Axis]: Apotheco, L L C ( Revolver), Senior Secured Loans, due 4/8/2024
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:ApothecoLLCMember
Investment, Identifier [Axis]: Apotheco, L L C, Senior Secured Loans, due 4/8/2024
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:ApothecoLLCMember
Investment, Identifier [Axis]: Aras Corporation ( Revolver), Senior Secured Loans, due 4/13/2027
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:ArasCorporationMember	mrcc:ArasCorporationMember
Investment, Identifier [Axis]: Aras Corporation, Senior Secured Loans, due 4/13/2027
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:ArasCorporationMember	mrcc:ArasCorporationMember
Investment, Identifier [Axis]: Arcstor Midco, L L C, Senior Secured Loans, due 3/16/2027
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:ArcstorMidcoLLCMember	mrcc:ArcstorMidcoLLCMember
Investment, Identifier [Axis]: Ascent Midco, L L C ( Revolver), Senior Secured Loans Due 2/5/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	Ascent Midco, L L C [ Member]	Ascent Midco, L L C [ Member]
Interest income	$ 4	$ 4
Investment, Identifier [Axis]: Ascent Midco, L L C, ( Delayed Draw) Loan
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	Ascent Midco, L L C [ Member]	Ascent Midco, L L C [ Member]
Interest income		$ 9
Investment, Identifier [Axis]: Ascent Midco, L L C, Equity Securities, Class A units
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	Ascent Midco, L L C [ Member]	Ascent Midco, L L C [ Member]
Dividend income	$ 189	$ 174
Investment, Identifier [Axis]: Ascent Midco, L L C, Senior Secured Loans Due 2/5/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	Ascent Midco, L L C [ Member]	Ascent Midco, L L C [ Member]
Interest income	$ 516	$ 471
Investment, Identifier [Axis]: Attom Intermediate Holdco, L L C ( Revolver), Senior Secured Loans, due 1/4/2024
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:AttomIntermediateHoldcoLLCMember
Investment, Identifier [Axis]: Attom Intermediate Holdco, L L C, Equity Securities, Class A units
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:AttomIntermediateHoldcoLLCMember	mrcc:AttomIntermediateHoldcoLLCMember
Investment, Identifier [Axis]: Attom Intermediate Holdco, L L C, Senior Secured Loans, Five, due 7/3/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:AttomIntermediateHoldcoLLCMember
Investment, Identifier [Axis]: Attom Intermediate Holdco, L L C, Senior Secured Loans, Four, due 7/3/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:AttomIntermediateHoldcoLLCMember
Investment, Identifier [Axis]: Attom Intermediate Holdco, L L C, Senior Secured Loans, One, due 1/4/2024
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:AttomIntermediateHoldcoLLCMember
Investment, Identifier [Axis]: Attom Intermediate Holdco, L L C, Senior Secured Loans, One, due 7/3/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:AttomIntermediateHoldcoLLCMember
Investment, Identifier [Axis]: Attom Intermediate Holdco, L L C, Senior Secured Loans, Three, due 1/4/2024
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:AttomIntermediateHoldcoLLCMember
Investment, Identifier [Axis]: Attom Intermediate Holdco, L L C, Senior Secured Loans, Three, due 7/3/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:AttomIntermediateHoldcoLLCMember
Investment, Identifier [Axis]: Attom Intermediate Holdco, L L C, Senior Secured Loans, Two, due 1/4/2024
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:AttomIntermediateHoldcoLLCMember
Investment, Identifier [Axis]: Attom Intermediate Holdco, L L C, Senior Secured Loans, Two, due 7/3/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:AttomIntermediateHoldcoLLCMember
Investment, Identifier [Axis]: Attom Intermediate Holdco, LLC (Revolver), Senior Secured Loans, due 7/3/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:AttomIntermediateHoldcoLLCMember
Investment, Identifier [Axis]: Avalara, Inc. (Revolver), Senior Secured Loans, due 10/19/2028
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:AvalaraInc.Member
Investment, Identifier [Axis]: Avalara, Inc. Senior Secured Loans, due 10/19/2028
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:AvalaraInc.Member
Investment, Identifier [Axis]: Avison Young ( U S A) Inc., Senior Secured Loans, due 1/30/2026
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:AvisonYoungUSAIncMember	mrcc:AvisonYoungUSAIncMember
Investment, Identifier [Axis]: B L S T Operating Company, L L C, Equity Securities, Class A units
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:BLSTOperatingCompanyLLCMember	mrcc:BLSTOperatingCompanyLLCMember
Investment, Identifier [Axis]: B L S T Operating Company, L L C, Senior Secured Loans, due 8/28/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:BLSTOperatingCompanyLLCMember
Investment, Identifier [Axis]: BLST Operating Company, LLC, Due 8/28/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:BLSTOperatingCompanyLLCMember
Investment, Identifier [Axis]: Bonterra, L L C (fka Cybergrants Holdings) ( Delayed Draw) , Senior Secured Loans, due 9/8/2027
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:BonterraLLCfkaCybergrantsHoldingsMember	mrcc:BonterraLLCfkaCybergrantsHoldingsMember
Investment, Identifier [Axis]: Bonterra, L L C (fka Cybergrants Holdings) ( Revolver), Senior Secured Loans, due 9/8/2027
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:BonterraLLCfkaCybergrantsHoldingsMember	mrcc:BonterraLLCfkaCybergrantsHoldingsMember
Investment, Identifier [Axis]: Bonterra, L L C (fka Cybergrants Holdings), Senior Secured Loans, due 9/8/2027
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:BonterraLLCfkaCybergrantsHoldingsMember	mrcc:BonterraLLCfkaCybergrantsHoldingsMember
Investment, Identifier [Axis]: Born To Run, L L C ( Delayed Draw) Senior Secured Loans, due 4/1/2027
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:BornToRunLLCMember	mrcc:BornToRunLLCMember
Investment, Identifier [Axis]: Born To Run, L L C, Equity Securities, Class A units
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:BornToRunLLCMember
Investment, Identifier [Axis]: Born To Run, L L C, Senior Secured Loans, due 4/1/2027
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:BornToRunLLCMember	mrcc:BornToRunLLCMember
Investment, Identifier [Axis]: Brickell Bay Acquisition Corp, Senior Secured Loans, due 2/12/2026
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:BrickellBayAcquisitionCorpMember	mrcc:BrickellBayAcquisitionCorpMember
Investment, Identifier [Axis]: Brickell Bay Acquisition Corp. ( Delayed Draw), Senior Secured Loans, due 2/12/2026
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:BrickellBayAcquisitionCorpMember
Investment, Identifier [Axis]: Brickell Bay Acquisition Corp., Senior Secured Loans, due 6/30/2027
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:BrickellBayAcquisitionCorpMember
Investment, Identifier [Axis]: Brightly Software Holdings, Inc. (fka Dude Solutions Holdings, Inc.), Senior Secured Loans, ( Revolver), due 6/13/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:BrightlySoftwareHoldingsInc.fkaDudeSolutionsHoldingsInc.Member
Investment, Identifier [Axis]: Brightly Software Holdings, Inc. (fka Dude Solutions Holdings, Inc.), Senior Secured Loans, due 6/13/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:BrightlySoftwareHoldingsInc.fkaDudeSolutionsHoldingsInc.Member
Investment, Identifier [Axis]: Bromford Industries Limited, Senior Secured Loans, One, due 11/5/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:BromfordIndustriesLimitedMember	mrcc:BromfordIndustriesLimitedMember
Investment, Identifier [Axis]: Bromford Industries Limited, Senior Secured Loans, Two, due 11/5/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:BromfordIndustriesLimitedMember	mrcc:BromfordIndustriesLimitedMember
Investment, Identifier [Axis]: Burroughs, Inc. ( Revolver), Senior Secured Loans, due 12/22/2022
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:BurroughsInc.Member
Investment, Identifier [Axis]: Burroughs, Inc. ( Revolver), Senior Secured Loans, due 12/22/2023
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:BurroughsInc.Member
Investment, Identifier [Axis]: Burroughs, Inc., Senior Secured Loans, due 12/22/2022
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:BurroughsInc.Member
Investment, Identifier [Axis]: Burroughs, Inc., Senior Secured Loans, due 12/22/2023
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:BurroughsInc.Member
Investment, Identifier [Axis]: C B C Restaurant Corp., Senior Secured Loans, due 12/30/2022
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Name [Extensible Enumeration]		mrcc:CBCRestaurantCorpMember
Investment, Identifier [Axis]: C H A Holdings, Inc, Senior Secured Loans, One, due 4/10/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:CHAHoldingsIncMember
Investment, Identifier [Axis]: C H A Holdings, Inc, Senior Secured Loans, Two, due 4/10/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:CHAHoldingsIncMember
Investment, Identifier [Axis]: C Parent Holdings, LLC. (fka Curion Holdings, LLC), Equity Securities, Common Stock
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:CParentHoldingsLlc.Member
Investment, Identifier [Axis]: C Parent Holdings, LLC. (fka Curion Holdings, LLC), Senior Secured Loan
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:CParentHoldingsLlc.Member
Investment, Identifier [Axis]: CGI Automated Manufacturing, LLC, Senior Secured Loans, One, due 12/17/2026
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:CgiAutomatedManufacturingLlcMember
Investment, Identifier [Axis]: CGI Automated Manufacturing, LLC, Senior Secured Loans, Two, due 12/17/2026
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:CgiAutomatedManufacturingLlcMember
Investment, Identifier [Axis]: Cadent, L L C ( Revolver), Senior Secured Loans, due 9/11/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:CadentLLCMember
Investment, Identifier [Axis]: Cadent, L L C, Senior Secured Loans, due 9/11/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:CadentLLCMember
Investment, Identifier [Axis]: Calabrio, Inc. ( Revolver), Senior Secured Loans, due 4/16/2027
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:CalabrioIncMember	mrcc:CalabrioIncMember
Investment, Identifier [Axis]: Calabrio, Inc., Senior Secured Loans, due 4/16/2027
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:CalabrioIncMember	mrcc:CalabrioIncMember
Investment, Identifier [Axis]: California Pizza Kitchen, Inc., Equity Securities, Common units
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:CaliforniaPizzaKitchenInc.Member	mrcc:CaliforniaPizzaKitchenInc.Member
Investment, Identifier [Axis]: Cano Health, L L C, Senior Secured Loans, due 11/23/2027
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:CanoHealthLLMember	mrcc:CanoHealthLLMember
Investment, Identifier [Axis]: Caravel Autism Health, L L C ( Delayed Draw), Senior Secured Loans, due 6/30/2027
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:CaravelAutismHealthLLCMember	mrcc:CaravelAutismHealthLLCMember
Investment, Identifier [Axis]: Caravel Autism Health, L L C ( Revolver), Senior Secured Loans, due 6/30/2027
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:CaravelAutismHealthLLCMember	mrcc:CaravelAutismHealthLLCMember
Investment, Identifier [Axis]: Caravel Autism Health, L L C, Senior Secured Loans, due 6/30/2027
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:CaravelAutismHealthLLCMember	mrcc:CaravelAutismHealthLLCMember
Investment, Identifier [Axis]: Cassavant Holdings, L L C, Unitranche Secured Loans, due 9/8/2026
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:CassavantHoldingsLLCMember	mrcc:CassavantHoldingsLLCMember
Investment, Identifier [Axis]: Centaur ( Palm Beach) Owner L L C and Panther National Golf Club L L C ( Delayed Draw), Senior Secured Loans, due 4/30/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:CentaurPalmBeachOwnerLLCandPantherNationalGolfClubLLCMember
Investment, Identifier [Axis]: Centaur ( Palm Beach) Owner L L C and Panther National Golf Club L L C ( Revolver), Senior Secured Loans, due 4/30/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:CentaurPalmBeachOwnerLLCandPantherNationalGolfClubLLCMember
Investment, Identifier [Axis]: Centaur ( Palm Beach) Owner L L C and Panther National Golf Club L L C, Senior Secured Loans, due 4/30/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:CentaurPalmBeachOwnerLLCandPantherNationalGolfClubLLCMember
Investment, Identifier [Axis]: Certify, Inc, Senior Secured Loans, One, due 2/28/2024
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:CertifyIncMember
Investment, Identifier [Axis]: Certify, Inc, Senior Secured Loans, Two, due 2/28/2024
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:CertifyIncMember
Investment, Identifier [Axis]: Certify, Inc. (Revolver), Senior Secured Loans, due 2/28/2024
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:CertifyIncMember
Investment, Identifier [Axis]: Chess.com, L L C ( Revolver), Senior Secured Loans, due 12/31/2027
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:Chess.comLLCMember	mrcc:Chess.comLLCMember
Investment, Identifier [Axis]: Chess.com, L L C, Equity Securities, Class A units
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:Chess.comLLCMember	mrcc:Chess.comLLCMember
Investment, Identifier [Axis]: Chess.com, L L C, Senior Secured Loans, due 12/31/2027
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:Chess.comLLCMember	mrcc:Chess.comLLCMember
Investment, Identifier [Axis]: Corel Inc. (c), Senior Secured Loans, due 7/2/2026
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:CorelIncMember
Investment, Identifier [Axis]: Crownpeak Technology Inc. (Revolver) Senior Secured Loans, Due 2/28/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:CrownpeakTechnologyIncMember
Investment, Identifier [Axis]: Crownpeak Technology Inc. Senior Secured Loans Four, Due 2/28/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:CrownpeakTechnologyIncMember
Investment, Identifier [Axis]: Crownpeak Technology Inc. Senior Secured Loans One, Due 2/28/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:CrownpeakTechnologyIncMember
Investment, Identifier [Axis]: Crownpeak Technology Inc. Senior Secured Loans Three, Due 2/28/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:CrownpeakTechnologyIncMember
Investment, Identifier [Axis]: Crownpeak Technology Inc. Senior Secured Loans Two, Due 2/28/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:CrownpeakTechnologyIncMember
Investment, Identifier [Axis]: Crownpeak Technology, Inc. ( Revolver), Senior Secured Loans, due 2/28/2024
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:CrownpeakTechnologyIncMember
Investment, Identifier [Axis]: Crownpeak Technology, Inc., Senior Secured Loans, One, due 2/28/2024
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:CrownpeakTechnologyIncMember
Investment, Identifier [Axis]: Crownpeak Technology, Inc., Senior Secured Loans, Two, due 2/28/2024
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:CrownpeakTechnologyIncMember
Investment, Identifier [Axis]: Curion Holdings, L L C ( Revolver), Senior Secured Loans, Due 8/31/2022
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		Curion Holdings, L L C [ Member]
Investment, Identifier [Axis]: Curion Holdings, L L C, Equity Securities, Common stock
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	Curion Holdings, L L C [ Member]	Curion Holdings, L L C [ Member]
Investment, Identifier [Axis]: Curion Holdings, L L C, Junior Secured Loans, One, Due 1/2/2023
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	Curion Holdings, L L C [ Member]	Curion Holdings, L L C [ Member]
Investment, Identifier [Axis]: Curion Holdings, L L C, Junior Secured Loans, Two, Due 1/2/2023
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	Curion Holdings, L L C [ Member]	Curion Holdings, L L C [ Member]
Investment, Identifier [Axis]: Curion Holdings, L L C, Senior Secured Loans, Due 8/31/2022
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		Curion Holdings, L L C [ Member]
Investment, Identifier [Axis]: Curion Holdings, L L C, Senior Secured Loans, One, Acquisition Date 5/2/2017
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	Curion Holdings, L L C [ Member]	Curion Holdings, L L C [ Member]
Interest income	$ 1,766
Investment, Identifier [Axis]: Curion Holdings, LLC (Revolver), Senior Secured Loans, Two, Acquisition Date 5/2/2017
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	Curion Holdings, L L C [ Member]	Curion Holdings, L L C [ Member]
Interest income	$ 294
Investment, Identifier [Axis]: D S Parent, Inc., Senior Secured Loans, due 12/8/2028
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:DSParentIncMember	mrcc:DSParentIncMember
Investment, Identifier [Axis]: Destination Media, Inc (Revolver), Senior Secured Loans, due 4/7/2023
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:DestinationMediaIncMember
Investment, Identifier [Axis]: Destination Media, Inc, Senior Secured Loans, due 4/7/2023
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:DestinationMediaIncMember
Investment, Identifier [Axis]: Destination Media, Inc. ( Revolver), Senior Secured Loans, due 4/7/2022
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:DestinationMediaIncMember
Investment, Identifier [Axis]: Destination Media, Inc., Senior Secured Loans, due 4/7/2022
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:DestinationMediaIncMember
Investment, Identifier [Axis]: Dorado Acquisition, Inc, Equity Securities, One, Class A-1 units
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:DoradoAcquisitionIncMember	mrcc:DoradoAcquisitionIncMember
Investment, Identifier [Axis]: Dorado Acquisition, Inc, Equity Securities, Two, Class A-2 units
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:DoradoAcquisitionIncMember	mrcc:DoradoAcquisitionIncMember
Investment, Identifier [Axis]: Dorado Acquisition, Inc. ( Delayed Draw) , Senior Secured Loans, due 6/30/2026
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:DoradoAcquisitionInc.Member	mrcc:DoradoAcquisitionInc.Member
Investment, Identifier [Axis]: Dorado Acquisition, Inc. ( Revolver) , Senior Secured Loans, due 6/30/2026
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:DoradoAcquisitionInc.Member	mrcc:DoradoAcquisitionInc.Member
Investment, Identifier [Axis]: Dorado Acquisition, Inc., Senior Secured Loans, One, due 6/30/2026
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:DoradoAcquisitionInc.Member
Investment, Identifier [Axis]: Dorado Acquisition, Inc., Senior Secured Loans, due 6/30/2026
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:DoradoAcquisitionInc.Member	mrcc:DoradoAcquisitionInc.Member
Investment, Identifier [Axis]: Drawbridge Partners, LLC (Delayed Draw), Senior Secured Loans, due 9/1/2028
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:DrawbridgePartnersLlcMember
Investment, Identifier [Axis]: Drawbridge Partners, LLC (Revolver), Senior Secured Loans, due 9/1/2028
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:DrawbridgePartnersLlcMember
Investment, Identifier [Axis]: Drawbridge Partners, LLC, Equity Securities, Class A Units
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:DrawbridgePartnersLlcMember
Investment, Identifier [Axis]: Drawbridge Partners, LLC, Senior Secured Loans, due 9/1/2028
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:DrawbridgePartnersLlcMember
Investment, Identifier [Axis]: Dresser Utility Solutions, L L C (fka N G S U S Finco, L L C), Senior Secured Loans, One, due 10/1/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:DresserUtilitySolutionsLLCfkaNGSUSFincoLLCMember
Investment, Identifier [Axis]: Dresser Utility Solutions, L L C (fka N G S U S Finco, L L C), Senior Secured Loans, Two, due 10/1/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:DresserUtilitySolutionsLLCfkaNGSUSFincoLLCMember
Investment, Identifier [Axis]: Drilling Info Holdings, Inc., Senior Secured Loans, due 7/30/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:DrillingInfoHoldingsIncMember	mrcc:DrillingInfoHoldingsIncMember
Investment, Identifier [Axis]: Education Corporation of America, Equity Securities, Series G Preferred Stock
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:EducationCorporationofAmericaMember	mrcc:EducationCorporationofAmericaMember
Investment, Identifier [Axis]: Education Corporation of America, Junior Secured Loans
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:EducationCorporationofAmericaMember	mrcc:EducationCorporationofAmericaMember
Investment, Identifier [Axis]: Eliassen Group, L L C ( Delayed Draw), Senior Secured Loans, due 4/14/2028
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:EliassenGroupLLCMember
Investment, Identifier [Axis]: Eliassen Group, L L C, Senior Secured Loans, due 4/14/2028
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:EliassenGroupLLCMember
Investment, Identifier [Axis]: Energy Services Group, L L C, Unitranche Secured Loans, One, Due 5/4/2022
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:EnergyServicesGroupLLCMember
Investment, Identifier [Axis]: Energy Services Group, L L C, Unitranche Secured Loans, Three, Due 5/4/2022
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:EnergyServicesGroupLLCMember
Investment, Identifier [Axis]: Energy Services Group, L L C, Unitranche Secured Loans, Two, Due 5/4/2022
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:EnergyServicesGroupLLCMember
Investment, Identifier [Axis]: Engage2 Excel, Inc. ( Revolver), Senior Secured Loans, due 3/7/2023
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:Engage2ExcelIncMember
Investment, Identifier [Axis]: Engage2 Excel, Inc., Senior Secured Loans, One, due 3/7/2023
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:Engage2ExcelIncMember
Investment, Identifier [Axis]: Engage2 Excel, Inc., Senior Secured Loans, Two,due 3/7/2023
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:Engage2ExcelIncMember
Investment, Identifier [Axis]: Equine Network, L L C ( Delayed Draw), Senior Secured Loans, due 12/13/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:EquineNetworkLLCMember
Investment, Identifier [Axis]: Equine Network, L L C ( Revolver) , Senior Secured Loans, due 12/13/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:EquineNetworkLLCMember
Investment, Identifier [Axis]: Equine Network, L L C, (Delayed Draw), Senior Secured Loans, due 12/31/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:EquineNetworkLLCMember
Investment, Identifier [Axis]: Equine Network, L L C, (Revolver), Senior Secured Loans, due 12/31/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:EquineNetworkLLCMember
Investment, Identifier [Axis]: Equine Network, L L C, Equity Securities, Class A units
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:EquineNetworkLLCMember	mrcc:EquineNetworkLLCMember
Investment, Identifier [Axis]: Equine Network, L L C, Senior Secured Loans, One, due 12/13/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:EquineNetworkLLCMember
Investment, Identifier [Axis]: Equine Network, L L C, Senior Secured Loans, One, due 12/31/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:EquineNetworkLLCMember
Investment, Identifier [Axis]: Equine Network, L L C, Senior Secured Loans, Two, due 12/13/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:EquineNetworkLLCMember
Investment, Identifier [Axis]: Equine Network, L L C, Senior Secured Loans, Two, due 12/31/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:EquineNetworkLLCMember
Investment, Identifier [Axis]: Excel Fitness Holdings, Inc. ( Revolver), Senior Secured Loans, due 4/28/2028
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:ExcelFitnessHoldingsIncMember
Investment, Identifier [Axis]: Excel Fitness Holdings, Inc., Senior Secured Loans, due 4/27/2029
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:ExcelFitnessHoldingsIncMember
Investment, Identifier [Axis]: Express Wash Acquisition Company, L L C ( Delayed Draw), Senior Secured Loans, Four, due 12/26/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:ExpressWashAcquisitionCompanyLLCMember
Investment, Identifier [Axis]: Express Wash Acquisition Company, L L C ( Revolver), Senior Secured Loans, due 12/26/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:ExpressWashAcquisitionCompanyLLCMember
Investment, Identifier [Axis]: Express Wash Acquisition Company, L L C, Equity Securities, Class A units
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:ExpressWashAcquisitionCompanyLLCMember	mrcc:ExpressWashAcquisitionCompanyLLCMember
Investment, Identifier [Axis]: Express Wash Acquisition Company, L L C, Senior Secured Loans, One, due 12/26/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:ExpressWashAcquisitionCompanyLLCMember
Investment, Identifier [Axis]: Express Wash Acquisition Company, L L C, Senior Secured Loans, Three, due 12/26/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:ExpressWashAcquisitionCompanyLLCMember
Investment, Identifier [Axis]: Express Wash Acquisition Company, L L C, Senior Secured Loans, Two, due 12/26/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:ExpressWashAcquisitionCompanyLLCMember
Investment, Identifier [Axis]: Express Wash Acquisition Company, LLC (Revolver), Senior Secured Loans, due 7/14/2028
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:ExpressWashAcquisitionCompanyLLCMember
Investment, Identifier [Axis]: Express Wash Acquisition Company, LLC, Senior Secured Loans, One, Due 7/14/2028
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:ExpressWashAcquisitionCompanyLLCMember
Investment, Identifier [Axis]: Express Wash Acquisition Company, LLC, Senior Secured Loans, Two, Due 7/14/2028
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:ExpressWashAcquisitionCompanyLLCMember
Investment, Identifier [Axis]: Familia Dental Group Holdings, L L C, Equity Securities, Class A units
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	Familia Dental Group Holdings, LLC	Familia Dental Group Holdings, LLC
Investment, Identifier [Axis]: Florida East Coast Industries, L L C, Junior Secured Loans, due 6/28/2024
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:FloridaEastCoastIndustriesLLCMember
Investment, Identifier [Axis]: Florida East Coast Industries, L L C, Senior Secured Loans, due 6/28/2024
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:FloridaEastCoastIndustriesLLCMember
Investment, Identifier [Axis]: Forman Mills, Inc, Equity Securities, Warrants
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:FormanMillsIncMember	mrcc:FormanMillsInc.Member
Investment, Identifier [Axis]: Forman Mills, Inc, Senior Secured Loans, One, due 4/30/2024
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:FormanMillsIncMember
Investment, Identifier [Axis]: Forman Mills, Inc, Senior Secured Loans, Two, due 4/30/2024
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:FormanMillsIncMember
Investment, Identifier [Axis]: Forman Mills, Inc., Senior Secured Loans, One, due 12/30/2022
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:FormanMillsInc.Member
Investment, Identifier [Axis]: Forman Mills, Inc., Senior Secured Loans, Three, due 12/30/2022
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:FormanMillsInc.Member
Investment, Identifier [Axis]: Forman Mills, Inc., Senior Secured Loans, Two, due 12/30/2022
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:FormanMillsInc.Member
Investment, Identifier [Axis]: GC Champion Acquisition LLC (Delayed Draw), Senior Notes, Due 8/18/2028
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:GCChampionAcquisitionLLCMember
Investment, Identifier [Axis]: GC Champion Acquisition LLC, Senior Notes, Due 8/18/2028
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:GCChampionAcquisitionLLCMember
Investment, Identifier [Axis]: H A H Group Holding Company L L C, Senior Secured Loans, due 10/29/2027
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:HAHGroupHoldingCompanyLLCMember
Investment, Identifier [Axis]: H A L O Buyer, Inc., Senior Secured Loans, due 6/30/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:HALOBuyerIncMember
Investment, Identifier [Axis]: H F Z Capital Group L L C, Senior Secured Loans , Two
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:HFZCapitalGroupLLCMember	mrcc:HFZCapitalGroupLLCMember
Interest income	$ 710	$ 675
Investment, Identifier [Axis]: H F Z Capital Group L L C, Senior Secured Loans, One
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:HFZCapitalGroupLLCMember	mrcc:HFZCapitalGroupLLCMember
Interest income	$ 1,977	$ 1,880
Investment, Identifier [Axis]: H S4 Acquisitionco, Inc. ( Revolver), Senior Secured Loans, due 7/9/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:HS4AcquisitioncoIncMember	mrcc:HS4AcquisitioncoIncMember
Investment, Identifier [Axis]: H S4 Acquisitionco, Inc., Senior Secured Loans, due 7/9/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:HS4AcquisitioncoIncMember	mrcc:HS4AcquisitioncoIncMember
Investment, Identifier [Axis]: Harbour Benefit Holdings, Inc., Senior Secured Loans, One, due 12/13/2024
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:HarbourBenefitHoldingsIncMember	mrcc:HarbourBenefitHoldingsIncMember
Investment, Identifier [Axis]: Harbour Benefit Holdings, Inc., Senior Secured Loans, Two, due 12/13/2024
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:HarbourBenefitHoldingsIncMember	mrcc:HarbourBenefitHoldingsIncMember
Investment, Identifier [Axis]: Hastings Manufacturing Company, Senior Secured Loans, due 4/24/2023
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:HastingsManufacturingCompanyMember	mrcc:HastingsManufacturingCompanyMember
Investment, Identifier [Axis]: I D I G Parent, L L C ( Revolver), Senior Secured Loans, due 12/15/2026
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		I D I G Parent, L L C [ Member]
Investment, Identifier [Axis]: I D I G Parent, L L C, Equity Securities, Common stock
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	I D I G Parent, L L C [ Member]	I D I G Parent, L L C [ Member]
Investment, Identifier [Axis]: I D I G Parent, L L C, Senior Secured Loans, One, due 12/15/2026
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		I D I G Parent, L L C [ Member]
Investment, Identifier [Axis]: I D I G Parent, L L C, Senior Secured Loans, Two, due 12/15/2026
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		I D I G Parent, L L C [ Member]
Investment, Identifier [Axis]: I N H Buyer, Inc., Senior Secured Loans, due 6/28/2028
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:INHBuyerInc.Member	mrcc:INHBuyerInc.Member
Investment, Identifier [Axis]: I T Global Holding L L C ( Revolver), Senior Secured Loans, due 11/10/2023
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:ITGlobalHoldingLLCMember
Investment, Identifier [Axis]: I T Global Holding L L C, Senior Secured Loans, One, due 11/10/2023
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:ITGlobalHoldingLLCMember
Investment, Identifier [Axis]: I T Global Holding L L C, Senior Secured Loans, Two, due 11/10/2023
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:ITGlobalHoldingLLCMember
Investment, Identifier [Axis]: In Mobi Pte, Ltd, Media: Equity Securities, due 9/18/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:InMobiPteLtdMember	mrcc:InMobiPteLtdMember
Investment, Identifier [Axis]: Independence Buyer, Inc, Senior Secured Loans, due 8/3/2026
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:IndependenceBuyerInc.Member	mrcc:IndependenceBuyerInc.Member
Investment, Identifier [Axis]: Independence Buyer, Inc. ( Revolver), Senior Secured Loans, due 8/3/2026
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:IndependenceBuyerInc.Member	mrcc:IndependenceBuyerInc.Member
Investment, Identifier [Axis]: Independence Buyer, Inc., Equity Securities, Class A units
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:IndependenceBuyerInc.Member	mrcc:IndependenceBuyerInc.Member
Investment, Identifier [Axis]: Intermedia Holdings, Inc., Senior Secured Loans, due 7/21/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:IntermediaHoldingsIncMember
Investment, Identifier [Axis]: International Textile Group, Inc., Senior Secured Loans, due 5/1/2024
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:InternationalTextileGroupIncMember	mrcc:InternationalTextileGroupIncMember
Investment, Identifier [Axis]: J2 B W A Funding L L C ( Delayed Draw), Senior Secured Loans, due 12/24/2026
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:J2BWAFundingLLCMember
Investment, Identifier [Axis]: J2 B W A Funding L L C, Equity Securities
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:J2BWAFundingLLCMember	mrcc:J2BWAFundingLLCMember
Investment, Identifier [Axis]: J2 BWA Funding LLC (Delayed Draw), Senior Notes, Due 12/24/2026
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:J2BWAFundingLLCMember
Investment, Identifier [Axis]: Kar Wash Holdings, L L C ( Delayed Draw), Senior Secured Loans, due 2/26/2027
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:KarWashHoldingsLLCMember
Investment, Identifier [Axis]: Kar Wash Holdings, L L C ( Revolver), Senior Secured Loans, due 2/26/2027
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:KarWashHoldingsLLCMember
Investment, Identifier [Axis]: Kar Wash Holdings, L L C, Equity Securities, Class A units
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:KarWashHoldingsLLCMember
Investment, Identifier [Axis]: Kar Wash Holdings, LLC, Senior Secured Loans, One, due 2/26/2027
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:KarWashHoldingsLLCMember
Investment, Identifier [Axis]: Kar Wash Holdings, LLC, Senior Secured Loans, Two, due 2/26/2027
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:KarWashHoldingsLLCMember
Investment, Identifier [Axis]: Keystone Purchaser, L L C, Senior Secured Loans, due 5/7/2027
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:KeystonePurchaserLLCMember
Investment, Identifier [Axis]: Kingsley Gate Partners, LLC (Delayed Draw), One, Due 12/11/2028
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:KingsleyGatePartnersLlcMember
Investment, Identifier [Axis]: Kingsley Gate Partners, LLC (Delayed Draw), Two, Due 12/11/2028
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:KingsleyGatePartnersLlcMember
Investment, Identifier [Axis]: Kingsley Gate Partners, LLC (Revolver), Due 12/11/2028
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:KingsleyGatePartnersLlcMember
Investment, Identifier [Axis]: Kingsley Gate Partners, LLC, Due 12/11/2028
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:KingsleyGatePartnersLlcMember
Investment, Identifier [Axis]: L S C S Holdings, Inc., Senior Secured Loans, due 12/15/2028
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:LSCSHoldingsIncMember	mrcc:LSCSHoldingsIncMember
Investment, Identifier [Axis]: L V F Holdings, Inc. ( Revolver), Senior Secured Loans, due 6/10/2027
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:LVFHoldingsIncMember	mrcc:LVFHoldingsIncMember
Investment, Identifier [Axis]: L V F Holdings, Inc., Senior Secured Loans, ( Delayed Draw) due 6/10/2027
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:LVFHoldingsIncMember	mrcc:LVFHoldingsIncMember
Investment, Identifier [Axis]: L V F Holdings, Inc., Senior Secured Loans, One, due 6/10/2027
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:LVFHoldingsIncMember	mrcc:LVFHoldingsIncMember
Investment, Identifier [Axis]: L V F Holdings, Inc., Senior Secured Loans, Two, due 6/10/2027
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:LVFHoldingsIncMember	mrcc:LVFHoldingsIncMember
Investment, Identifier [Axis]: L X/ J T Intermediate Holdings, Inc. ( Revolver), Senior Secured Loans, due 3/11/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:LXJTIntermediateHoldingsIncMember	mrcc:LXJTIntermediateHoldingsIncMember
Investment, Identifier [Axis]: L X/ J T Intermediate Holdings, Inc., Senior Secured Loans, due 3/11/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:LXJTIntermediateHoldingsIncMember	mrcc:LXJTIntermediateHoldingsIncMember
Investment, Identifier [Axis]: Laseraway Intermediate Holdings I I, L L C, Senior Secured Loans, due 10/14/2027
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:LaserawayIntermediateHoldingsIILLCMember
Investment, Identifier [Axis]: Lifted Trucks Holdings, L L C ( Delayed Draw), Senior Secured Loans, due 8/2/2027
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:LiftedTrucksHoldingsLLCMember	mrcc:LiftedTrucksHoldingsLLCMember
Investment, Identifier [Axis]: Lifted Trucks Holdings, L L C ( Revolver), Senior Secured Loans, due 8/2/2027
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:LiftedTrucksHoldingsLLCMember	mrcc:LiftedTrucksHoldingsLLCMember
Investment, Identifier [Axis]: Lifted Trucks Holdings, L L C, Equity Securities, Class A units
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:LiftedTrucksHoldingsLLCMember	mrcc:LiftedTrucksHoldingsLLCMember
Investment, Identifier [Axis]: Lifted Trucks Holdings, L L C, Senior Secured Loans, due 8/2/2027
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:LiftedTrucksHoldingsLLCMember	mrcc:LiftedTrucksHoldingsLLCMember
Investment, Identifier [Axis]: Liftforward S P V I I, L L C, Senior Secured Loans, due 9/30/2022
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:LiftforwardSPVIILLCMember
Investment, Identifier [Axis]: Liftforward SPV II, LLC, Senior Secured Loans, due 3/31/2023
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:LiftforwardSPVIILLCMember
Investment, Identifier [Axis]: Lightbox Intermediate, L. P., Senior Secured Loans, due 5/11/2026
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:LightboxIntermediateL.PMember
Investment, Identifier [Axis]: Liqui- Box Holdings, Inc., Senior Secured Loans, due 2/26/2027
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:Liqui-BoxHoldingsIncMember	mrcc:Liqui-BoxHoldingsIncMember
Investment, Identifier [Axis]: Luxury Optical Holdings Co. ( Delayed Draw)
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	Luxury Optical Holdings Co [ Member]	Luxury Optical Holdings Co [ Member]
Interest income		$ 219
Fee income		$ 36
Investment, Identifier [Axis]: Luxury Optical Holdings Co. Investment, One
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	Luxury Optical Holdings Co [ Member]	Luxury Optical Holdings Co [ Member]
Interest income		$ 166
Investment, Identifier [Axis]: Luxury Optical Holdings Co.( Revolver)
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	Luxury Optical Holdings Co [ Member]	Luxury Optical Holdings Co [ Member]
Interest income		$ 7
Investment, Identifier [Axis]: Luxury Optical Holdings Co., Equity Securities
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	Luxury Optical Holdings Co [ Member]	mrcc:LuxuryOpticalHoldingsCo.Member
Investment, Identifier [Axis]: Luxury Optical Holdings Co., Equity Securities, Common Stock
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	Luxury Optical Holdings Co [ Member]	Luxury Optical Holdings Co [ Member]
Investment, Identifier [Axis]: Luxury Optical Holdings Co., Equity Securities, Preferred Units
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	Luxury Optical Holdings Co [ Member]	Luxury Optical Holdings Co [ Member]
Interest income		$ 694
Dividend income		$ 813
Investment, Identifier [Axis]: M C Asset Management ( Corporate), L L C ( Delayed Draw), Senior Secured Loans Due 1/26/2024
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:MCAssetManagementCorporateLLCMember	mrcc:MCAssetManagementCorporateLLCMember
Interest income	$ 162	$ 91
Investment, Identifier [Axis]: M C Asset Management ( Corporate), L L C, Equity Securites
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:MCAssetManagementCorporateLLCMember	mrcc:MCAssetManagementCorporateLLCMember
Investment, Identifier [Axis]: M C Asset Management ( Corporate), L L C, Equity Securities
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:MCAssetManagementCorporateLLCMember	mrcc:MCAssetManagementCorporateLLCMember
Investment, Identifier [Axis]: M C Asset Management ( Corporate), L L C, Senior Secured Loans Due 1/26/2024
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:MCAssetManagementCorporateLLCMember	mrcc:MCAssetManagementCorporateLLCMember
Interest income	$ 1,369	$ 1,024
Investment, Identifier [Axis]: M C Asset Management ( Industrial), L L C Promissory Note
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:MCAssetManagementIndustrialLLCMember	mrcc:MCAssetManagementIndustrialLLCMember
Interest income		$ 2,136
Investment, Identifier [Axis]: M C P Shaw Acquisitionco, L L C ( Delayed Draw), Senior Secured Loans, due 11/28/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:MCPShawAcquisitioncoLLCMember	mrcc:MCPShawAcquisitioncoLLCMember
Investment, Identifier [Axis]: M C P Shaw Acquisitionco, L L C ( Revolver), Senior Secured Loans, due 11/28/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:MCPShawAcquisitioncoLLCMember	mrcc:MCPShawAcquisitioncoLLCMember
Investment, Identifier [Axis]: M C P Shaw Acquisitionco, L L C , Equity Securities, Class A-2 units
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:MCPShawAcquisitioncoLLCMember	mrcc:MCPShawAcquisitioncoLLCMember
Investment, Identifier [Axis]: M C P Shaw Acquisitionco, L L C, Senior Secured Loans, One, due 11/28/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:MCPShawAcquisitioncoLLCMember	mrcc:MCPShawAcquisitioncoLLCMember
Investment, Identifier [Axis]: M C P Shaw Acquisitionco, L L C, Senior Secured Loans, Two, due 11/28/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:MCPShawAcquisitioncoLLCMember	mrcc:MCPShawAcquisitioncoLLCMember
Investment, Identifier [Axis]: M F G Chemical, L L C, Unitranche Secured Loans, One, Due 6/23/2022
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:MFGChemicalLLCMember
Investment, Identifier [Axis]: M F G Chemical, L L C, Unitranche Secured Loans, Two, Due 6/23/2022
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:MFGChemicalLLCMember
Investment, Identifier [Axis]: M R C C Senior Loan Fund I, L L C, Equity Securities
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Controlled affiliate company investments	Controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	MRCC Senior Loan Fund I, LLC	MRCC Senior Loan Fund I, LLC
Dividend income	$ 3,600	$ 4,325
Investment, Identifier [Axis]: M V Receivables I I, L L C ( Delayed Draw), Senior Secured Loans, due 7/29/2026
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:MVReceivablesIILLCMember	mrcc:MVReceivablesIILLCMember
Investment, Identifier [Axis]: M V Receivables I I, L L C, Equity Securities, Common units
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:MVReceivablesIILLCMember	mrcc:MVReceivablesIILLCMember
Investment, Identifier [Axis]: M V Receivables I I, L L C, Equity Securities, Due 7/28/2031, Warrants
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:MVReceivablesIILLCMember	mrcc:MVReceivablesIILLCMember
Investment, Identifier [Axis]: MC Asset Management (Corporate), LLC (Delayed Draw)
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:MCAssetManagementCorporateLLCMember
Investment, Identifier [Axis]: Mac Queen Equipment, L L C ( Delayed Draw), Senior Secured Loans, due 1/7/2028
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:MacQueenEquipmentLLCMember
Investment, Identifier [Axis]: Mac Queen Equipment, L L C ( Revolver), Senior Secured Loans, due 1/7/2028
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:MacQueenEquipmentLLCMember
Investment, Identifier [Axis]: Mac Queen Equipment, L L C, Senior Secured Loans, due 1/7/2028
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:MacQueenEquipmentLLCMember
Investment, Identifier [Axis]: Magneto & Diesel Acquisition, Inc, Senior Secured Loans, One, due 12/18/2023
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:MagnetoDieselAcquisitionInc.Member
Investment, Identifier [Axis]: Magneto & Diesel Acquisition, Inc, Senior Secured Loans, Three, due 12/8/2023
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:MagnetoDieselAcquisitionInc.Member
Investment, Identifier [Axis]: Magneto & Diesel Acquisition, Inc, Senior Secured Loans, Two, due 12/8/2023
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:MagnetoDieselAcquisitionInc.Member
Investment, Identifier [Axis]: Magneto & Diesel Acquisition, Inc. ( Revolver), Senior Secured Loans, due 12/8/2023
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:MagnetoDieselAcquisitionInc.Member
Investment, Identifier [Axis]: Mammoth Holdings, L L C ( Delayed Draw), Senior Secured Loans, due 10/16/2023
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:MammothHoldingsLLCMember
Investment, Identifier [Axis]: Mammoth Holdings, L L C ( Revolver), Senior Secured Loans, due 10/16/2023
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:MammothHoldingsLLCMember
Investment, Identifier [Axis]: Mammoth Holdings, L L C, Senior Secured Loans, One, due 10/16/2023
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:MammothHoldingsLLCMember
Investment, Identifier [Axis]: Mammoth Holdings, L L C, Senior Secured Loans, Three, due 10/16/2023
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:MammothHoldingsLLCMember
Investment, Identifier [Axis]: Mammoth Holdings, L L C, Senior Secured Loans, Two, due 10/16/2023
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:MammothHoldingsLLCMember
Investment, Identifier [Axis]: Mammoth Holdings, LLC (Revolver), Senior Secured Loans, Due, 10/16/2024
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:MammothHoldingsLLCMember
Investment, Identifier [Axis]: Mammoth Holdings, LLC, Senior Secured Loans, Four, due 10/16/2024
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:MammothHoldingsLLCMember
Investment, Identifier [Axis]: Mammoth Holdings, LLC, Senior Secured Loans, One, due 10/16/2024
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:MammothHoldingsLLCMember
Investment, Identifier [Axis]: Mammoth Holdings, LLC, Senior Secured Loans, Three, due 10/16/2024
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:MammothHoldingsLLCMember
Investment, Identifier [Axis]: Mammoth Holdings, LLC, Senior Secured Loans, Two, due 10/16/2024
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:MammothHoldingsLLCMember
Investment, Identifier [Axis]: Mark Logic Corporation ( Revolver), Senior Secured Loans, due 10/20/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:MarkLogicCorporationMember	mrcc:MarkLogicCorporationMember
Investment, Identifier [Axis]: Mark Logic Corporation, Equity Securities, Class A units
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:MarkLogicCorporationMember	mrcc:MarkLogicCorporationMember
Investment, Identifier [Axis]: Mark Logic Corporation, Senior Secured Loans, Four, due 10/20/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:MarkLogicCorporationMember
Investment, Identifier [Axis]: Mark Logic Corporation, Senior Secured Loans, One, due 10/20/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:MarkLogicCorporationMember	mrcc:MarkLogicCorporationMember
Investment, Identifier [Axis]: Mark Logic Corporation, Senior Secured Loans, Three, due 10/20/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:MarkLogicCorporationMember
Investment, Identifier [Axis]: Mark Logic Corporation, Senior Secured Loans, Two, due 10/20/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:MarkLogicCorporationMember	mrcc:MarkLogicCorporationMember
Investment, Identifier [Axis]: MarkLogic Corporation (Delayed Draw), Senior Secured Loans 10/20/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:MarkLogicCorporationMember
Investment, Identifier [Axis]: Mavenir Systems, Inc., Senior Secured Loans, due 8/18/2028
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:MavenirSystemsIncMember
Investment, Identifier [Axis]: Mc Kissock Investment Holdings, L L C, Senior Secured Loans, due 3/9/2029
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:McKissockInvestmentHoldingsLLCMember
Investment, Identifier [Axis]: Medallia, Inc, Senior Secured Loans, due 10/27/2028
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:MedalliaIncMember
Investment, Identifier [Axis]: Mindbody, Inc. ( Revolver) (f), Senior Secured Loans, due 2/14/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:MindbodyIncMember	mrcc:MindbodyIncMember
Investment, Identifier [Axis]: Mindbody, Inc., Senior Secured Loans, One, due 2/14/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:MindbodyIncMember	mrcc:MindbodyIncMember
Investment, Identifier [Axis]: Mindbody, Inc., Senior Secured Loans, Two, due 2/14/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:MindbodyIncMember	mrcc:MindbodyIncMember
Investment, Identifier [Axis]: Minotaur Acquisition, Inc., Senior Secured Loans, due 3/27/2026
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:MinotaurAcquisitionIncMember	mrcc:MinotaurAcquisitionIncMember
Investment, Identifier [Axis]: Mnine Holdings Inc. (Revolver)
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	Mnine Holdings, Inc [ Member]
Investment, Identifier [Axis]: Mnine Holdings, Inc. (Revolver), Senior Secured Loans
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	Mnine Holdings, Inc [ Member]	Mnine Holdings, Inc [ Member]
Interest income	$ 9
Investment, Identifier [Axis]: Mnine Holdings, Inc. (Revolver), Senior Secured Loans, due 12/30/2023
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	Mnine Holdings, Inc [ Member]
Investment, Identifier [Axis]: Mnine Holdings, Inc., Equity Securities, Class B units
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	Mnine Holdings, Inc [ Member]	Mnine Holdings, Inc [ Member]
Investment, Identifier [Axis]: Mnine Holdings, Inc., Senior Secured Loans Due 12/30/2022
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	Mnine Holdings, Inc [ Member]	Mnine Holdings, Inc [ Member]
Interest income	$ 787	$ 1,301
Investment, Identifier [Axis]: Money Lion, Inc. ( Delayed Draw), Junior Secured Loans, due 3/24/2026
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:MoneyLionIncMember
Investment, Identifier [Axis]: Money Lion, Inc., Junior Secured Loans, due 3/24/2026
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:MoneyLionIncMember
Investment, Identifier [Axis]: Money Lion, Inc., Junior Secured Loans, due 5/1/2023
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:MoneyLionIncMember	mrcc:MoneyLionIncMember
Investment, Identifier [Axis]: N C B P Property, L L C, Senior Secured Loans, due 12/16/2022
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:NCBPPropertyLLCMember	mrcc:NCBPPropertyLLCMember
Investment, Identifier [Axis]: N E C B Collections, L L C ( Revolver), Senior Secured Loans
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	N E C B Collections, L L C [ Member]	N E C B Collections, L L C [ Member]
Investment, Identifier [Axis]: N E C B Collections, L L C, Equity Securities
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	N E C B Collections, L L C [ Member]	N E C B Collections, L L C [ Member]
Investment, Identifier [Axis]: N E C B Collections, L L C, Equity Securities, Common stock
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	N E C B Collections, L L C [ Member]
Investment, Identifier [Axis]: NQ PE Project Colosseum Midco Inc. (Delayed Draw), Senior Secured Loans, Due 10/4/2028
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:NqPeProjectColosseumMidcoInc.Member
Investment, Identifier [Axis]: NQ PE Project Colosseum Midco Inc. (Revolver), Senior Secured Loans, Due 10/4/2028
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:NqPeProjectColosseumMidcoInc.Member
Investment, Identifier [Axis]: NQ PE Project Colosseum Midco Inc., Equity Securities, Common Units
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:NqPeProjectColosseumMidcoInc.Member
Investment, Identifier [Axis]: NQ PE Project Colosseum Midco Inc., Senior Secured Loans, Due 10/4/2028
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:NqPeProjectColosseumMidcoInc.Member
Investment, Identifier [Axis]: Nations Benefits L L C, Senior Secured Loans, One, Due 8/26/2027
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:NationsBenefitsLLCMember
Investment, Identifier [Axis]: Nations Benefits L L C, Senior Secured Loans, Two, Due 8/26/2027
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:NationsBenefitsLLCMember
Investment, Identifier [Axis]: Nations Benefits LLC Delayed Draw, Senior Secured Loans Due 8/26/2027
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:NationsBenefitsLLCMember
Investment, Identifier [Axis]: Nations Benefits, L L C ( Revolver), Senior Secured Loans, due 8/20/2026
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:NationsBenefitsLLCMember
Investment, Identifier [Axis]: Nations Benefits, L L C (Revolver), Senior Secured Loans, Due 8/26/2027
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:NationsBenefitsLLCMember
Investment, Identifier [Axis]: Nations Benefits, L L C, Equity Securities, One, Series B units
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:NationsBenefitsLLCMember
Investment, Identifier [Axis]: Nations Benefits, L L C, Equity Securities, Three, Series A units
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:NationsBenefitsLLCMember
Investment, Identifier [Axis]: Nations Benefits, L L C, Equity Securities, Two, common units
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:NationsBenefitsLLCMember	mrcc:NationsBenefitsLLCMember
Investment, Identifier [Axis]: Nations Benefits, L L C, Senior Secured Loans, due 8/20/2026
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:NationsBenefitsLLCMember
Investment, Identifier [Axis]: Natus Medical Incorporated, Senior Secured Loans, due 7/20/2029
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:NatusMedicalIncorporatedMember
Investment, Identifier [Axis]: Nearly Natural Inc. (Revolver) Senior Secured Loans due 3/31/2024
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:NearlyNaturalIncMember
Investment, Identifier [Axis]: Nearly Natural Inc. Senior Secured Loans Four due 3/31/2024
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:NearlyNaturalIncMember
Investment, Identifier [Axis]: Nearly Natural Inc. Senior Secured Loans One due 3/31/2024
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:NearlyNaturalIncMember
Investment, Identifier [Axis]: Nearly Natural Inc. Senior Secured Loans Three due 3/31/2024
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:NearlyNaturalIncMember
Investment, Identifier [Axis]: Nearly Natural Inc. Senior Secured Loans Two due 3/31/2024
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:NearlyNaturalIncMember
Investment, Identifier [Axis]: Nearly Natural, Inc, Equity Securities, One, Class A units
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:NearlyNaturalIncMember	mrcc:NearlyNaturalInc.Member
Investment, Identifier [Axis]: Nearly Natural, Inc, Equity Securities, Two, Class A A units
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:NearlyNaturalIncMember	mrcc:NearlyNaturalInc.Member
Investment, Identifier [Axis]: Nearly Natural, Inc.( Revolver), Senior Secured loans, due 12/15/2022
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:NearlyNaturalIncMember
Investment, Identifier [Axis]: Nearly Natural, Inc., Senior Secured loans, Four, due 12/15/2022
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:NearlyNaturalIncMember
Investment, Identifier [Axis]: Nearly Natural, Inc., Senior Secured loans, One, due 12/15/2022
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:NearlyNaturalIncMember
Investment, Identifier [Axis]: Nearly Natural, Inc., Senior Secured loans, Three, due 12/15/2022
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:NearlyNaturalIncMember
Investment, Identifier [Axis]: Nearly Natural, Inc., Senior Secured loans, Two, due 12/15/2022
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:NearlyNaturalIncMember
Investment, Identifier [Axis]: Newforma, Inc. ( Revolver), Senior Secured Loans, due 6/30/2022
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:NewformaIncMember
Investment, Identifier [Axis]: Newforma, Inc. ( Revolver) (f), Senior Secured Loans, due 3/31/2023
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:NewformaIncMember
Investment, Identifier [Axis]: Newforma, Inc., Senior Secured Loans, due 3/31/2023
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:NewformaIncMember
Investment, Identifier [Axis]: Newforma, Inc., Senior Secured Loans, due 6/30/2022
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:NewformaIncMember
Investment, Identifier [Axis]: North Haven Spartan U S Holdco, L L C, Senior Secured Loans, due 6/6/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:NorthHavenSpartanUSHoldcoLLCMember
Investment, Identifier [Axis]: North Haven U S H C Acquisition, Inc. ( Delayed Draw), Senior Secured Loans, due, 10/30/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:NorthHavenUSHCAcquisitionIncMember	mrcc:NorthHavenUSHCAcquisitionIncMember
Investment, Identifier [Axis]: North Haven U S H C Acquisition, Inc. ( Revolver), Senior Secured Loans, due, 10/30/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:NorthHavenUSHCAcquisitionIncMember	mrcc:NorthHavenUSHCAcquisitionIncMember
Investment, Identifier [Axis]: North Haven U S H C Acquisition, Inc., Senior Secured Loans, due, One, 10/30/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:NorthHavenUSHCAcquisitionIncMember	mrcc:NorthHavenUSHCAcquisitionIncMember
Investment, Identifier [Axis]: North Haven U S H C Acquisition, Inc., Senior Secured Loans, due, Two, 10/30/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:NorthHavenUSHCAcquisitionIncMember	mrcc:NorthHavenUSHCAcquisitionIncMember
Investment, Identifier [Axis]: North Haven USHC Acquisition, Inc, Senior Secured Loans, Four, due 10/30/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:NorthHavenUSHCAcquisitionIncMember
Investment, Identifier [Axis]: North Haven USHC Acquisition, Inc, Senior Secured Loans, Three, due 10/30/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:NorthHavenUSHCAcquisitionIncMember
Investment, Identifier [Axis]: Oceana Australian Fixed Income Trust, Senior Secured Loans, One, due 6/29/2026
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:OceanaAustralianFixedIncomeTrustMember	mrcc:OceanaAustralianFixedIncomeTrustMember
Investment, Identifier [Axis]: Oceana Australian Fixed Income Trust, Senior Secured Loans, Two, due 2/25/2026
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:OceanaAustralianFixedIncomeTrustMember	mrcc:OceanaAustralianFixedIncomeTrustMember
Investment, Identifier [Axis]: Offen, Inc., Senior Secured Loans, One, due 6/22/2026
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:OffenIncMember	mrcc:OffenIncMember
Investment, Identifier [Axis]: Offen, Inc., Senior Secured Loans, Two, due 6/22/2026
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:OffenIncMember	mrcc:OffenIncMember
Investment, Identifier [Axis]: Onit, Inc., Unitranche Secured Loans, due 5/2/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:OnitInc.Member	mrcc:OnitInc.Member
Investment, Identifier [Axis]: Orbit Purchaser L L C, Senior Secured Loans, One, due 10/21/2024
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:OrbitPurchaserLLCMember
Investment, Identifier [Axis]: Orbit Purchaser L L C, Senior Secured Loans, Three, due 10/21/2024
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:OrbitPurchaserLLCMember
Investment, Identifier [Axis]: Orbit Purchaser L L C, Senior Secured Loans, Two, due 10/21/2024
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:OrbitPurchaserLLCMember
Investment, Identifier [Axis]: Output Services Group Inc. Senior Secured Loans Due 6/29/2026
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:OutputServicesGroupIncMember
Investment, Identifier [Axis]: P H Beauty Holdings I I I, I N C., Senior Secured Loans, due 9/26/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:PHBeautyHoldingsIIIINCMember	mrcc:PHBeautyHoldingsIIIINCMember
Investment, Identifier [Axis]: P K S Holdings, L L C, Equity Securities, Four, Preferred units
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:PKSHoldingsLLCMember	mrcc:PKSHoldingsLLCMember
Investment, Identifier [Axis]: P K S Holdings, L L C, Equity Securities, One, Preferred units
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:PKSHoldingsLLCMember	mrcc:PKSHoldingsLLCMember
Investment, Identifier [Axis]: P K S Holdings, L L C, Equity Securities, Three, Preferred units
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:PKSHoldingsLLCMember	mrcc:PKSHoldingsLLCMember
Investment, Identifier [Axis]: P K S Holdings, L L C, Equity Securities, Two, Preferred units
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:PKSHoldingsLLCMember	mrcc:PKSHoldingsLLCMember
Investment, Identifier [Axis]: P V H C Holding Corp, Senior Secured Loans, due 8/5/2024
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:PVHCHoldingCorpMember	mrcc:PVHCHoldingCorpMember
Investment, Identifier [Axis]: Panda Acquisition, LLC, Senior Secured Loans, due 10/18/2028
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:PandaAcquisitionLlcMember
Investment, Identifier [Axis]: Paragon Healthcare Inc. Senior Secured Loan Due 1/19/2027
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:ParagonHealthcareIncMember
Investment, Identifier [Axis]: Paragon HealthcareInc. Delayed Draw Senior Secured Loans due 1/19/2027
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:ParagonHealthcareIncMember
Investment, Identifier [Axis]: Paragon HealthcareInc. Revolver Senior Secured Loan Due 1/19/2027
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:ParagonHealthcareIncMember
Investment, Identifier [Axis]: Phoenix Chemical Holding Company L L C (fka Polymer Solutions Group), Senior Secured Loans, due 1/3/2023
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:PhoenixChemicalHoldingCompanyLLCMember
Investment, Identifier [Axis]: Planful Inc. Senior Secured Loans, One, due 12/30/2024
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:PlanfulIncMember
Investment, Identifier [Axis]: Planful Inc. Senior Secured Loans, Two, due 12/30/2024
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:PlanfulIncMember
Investment, Identifier [Axis]: Planful, Inc, Equity Securities, Class A units
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:PlanfulIncMember
Investment, Identifier [Axis]: Planful, Inc, Senior Secured Loans, Four, due 12/28/2026
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:PlanfulIncMember
Investment, Identifier [Axis]: Planful, Inc, Senior Secured Loans, One, due 12/28/2026
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:PlanfulIncMember
Investment, Identifier [Axis]: Planful, Inc, Senior Secured Loans, Three, due 12/28/2026
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:PlanfulIncMember
Investment, Identifier [Axis]: Planful, Inc, Senior Secured Loans, Two, due 12/28/2026
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:PlanfulIncMember
Investment, Identifier [Axis]: Planful, Inc. ( Revolver), Senior Secured Loans, due 12/28/2026
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:PlanfulIncMember
Investment, Identifier [Axis]: Planful, Inc. ( Revolver), Senior Secured Loans, due 12/30/2024
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:PlanfulIncMember
Investment, Identifier [Axis]: Planful, Inc., Equity Securities, Class A Units
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:PlanfulInc.Member
Investment, Identifier [Axis]: Polychem Acquisition, L L C, Senior Secured Loans, due 3/17/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:PolychemAcquisitionLLCMember	mrcc:PolychemAcquisitionLLCMember
Investment, Identifier [Axis]: Polymer Solutions Group Senior Secured Loans Due 1/3/2023
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:PhoenixChemicalHoldingCompanyLLCMember
Investment, Identifier [Axis]: Port Townsend Holdings Company, Inc. and Crown Corrugated Company, Senior Secured Loans, due 4/3/2024
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:PortTownsendHoldingsCompanyInc.andCrownCorrugatedCompanyMember
Investment, Identifier [Axis]: Priority Ambulance, L L C, Unitranche Secured Loans, Four, due 4/12/2022
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:PriorityAmbulanceLLCMember
Investment, Identifier [Axis]: Priority Ambulance, L L C, Unitranche Secured Loans, One, due 4/12/2022
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:PriorityAmbulanceLLCMember
Investment, Identifier [Axis]: Priority Ambulance, L L C, Unitranche Secured Loans, Three, due 4/12/2022
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:PriorityAmbulanceLLCMember
Investment, Identifier [Axis]: Priority Ambulance, L L C, Unitranche Secured Loans, Two, due 4/12/2022
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:PriorityAmbulanceLLCMember
Investment, Identifier [Axis]: Prototek LLC (Delayed Draw), Due 12/8/2027
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:PrototekLlcMember
Investment, Identifier [Axis]: Prototek LLC (Revolver), Due,12/8/2027
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:PrototekLlcMember
Investment, Identifier [Axis]: Prototek LLC, Due 12/8/2027
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:PrototekLlcMember
Investment, Identifier [Axis]: Quest Resource Management Group, L L C ( Delayed Draw), Senior Secured Loans, due 10/20/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:QuestResourceManagementGroupLLCMember	mrcc:QuestResourceManagementGroupLLCMember
Investment, Identifier [Axis]: Quest Resource Management Group, L L C, Equity Securites, Two, Warrants
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:QuestResourceManagementGroupLLCMember	mrcc:QuestResourceManagementGroupLLCMember
Investment, Identifier [Axis]: Quest Resource Management Group, L L C, Equity Securities, One, Warrants
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:QuestResourceManagementGroupLLCMember	mrcc:QuestResourceManagementGroupLLCMember
Investment, Identifier [Axis]: Quest Resource Management Group, L L C, Senior Secured Loans, One, due 10/20/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:QuestResourceManagementGroupLLCMember	mrcc:QuestResourceManagementGroupLLCMember
Investment, Identifier [Axis]: Quest Resource Management Group, L L C, Senior Secured Loans, Three, due 10/20/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:QuestResourceManagementGroupLLCMember	mrcc:QuestResourceManagementGroupLLCMember
Investment, Identifier [Axis]: Quest Resource Management Group, L L C, Senior Secured Loans, Two, due 10/20/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:QuestResourceManagementGroupLLCMember	mrcc:QuestResourceManagementGroupLLCMember
Investment, Identifier [Axis]: Radiology Partners, Inc., Senior Secured Loans, due 7/9/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:RadiologyPartnersIncMember	mrcc:RadiologyPartnersIncMember
Investment, Identifier [Axis]: Recorded Future, Inc, Equity Securities, Class A units
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	Recorded Future, Inc [ Member]	Recorded Future, Inc [ Member]
Investment, Identifier [Axis]: Recycled Plastics Industries, L L C ( Revolver), Senior Secured Loans, due 8/4/2026
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:RecycledPlasticsIndustriesLLCMember	mrcc:RecycledPlasticsIndustriesLLCMember
Investment, Identifier [Axis]: Recycled Plastics Industries, L L C, Senior Secured Loans, due 8/4/2026
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:RecycledPlasticsIndustriesLLCMember	mrcc:RecycledPlasticsIndustriesLLCMember
Investment, Identifier [Axis]: Red Zone Robotics, Inc. ( Revolver) , Senior Secured Loans, due 6/5/2023
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:RedZoneRoboticsIncMember
Investment, Identifier [Axis]: Red Zone Robotics, Inc., Senior Secured Loans, due 6/5/2023
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:RedZoneRoboticsIncMember
Investment, Identifier [Axis]: Relativity O D A L L C ( Revolver), Senior Secured Loans, due 5/12/2027
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:RelativityODALLCMember	mrcc:RelativityODALLCMember
Investment, Identifier [Axis]: Relativity O D A L L C, Senior Secured Loans, due 5/12/2027
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:RelativityODALLCMember	mrcc:RelativityODALLCMember
Investment, Identifier [Axis]: Relevate Health Group, L L C ( Delayed Draw), Senior Secured Loans, due, 11/20/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:RelevateHealthGroupLLCMember	mrcc:RelevateHealthGroupLLCMember
Investment, Identifier [Axis]: Relevate Health Group, L L C ( Revolver), Senior Secured Loans, due, 11/20/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:RelevateHealthGroupLLCMember	mrcc:RelevateHealthGroupLLCMember
Investment, Identifier [Axis]: Relevate Health Group, L L C, Equity Securities, Class B common units
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:RelevateHealthGroupLLCMember	mrcc:RelevateHealthGroupLLCMember
Investment, Identifier [Axis]: Relevate Health Group, L L C, Equity Securities, preferred units
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:RelevateHealthGroupLLCMember	mrcc:RelevateHealthGroupLLCMember
Investment, Identifier [Axis]: Relevate Health Group, L L C, Senior Secured Loans, due, 11/20/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:RelevateHealthGroupLLCMember	mrcc:RelevateHealthGroupLLCMember
Investment, Identifier [Axis]: Research Now Group, Inc. and Survey Sampling International, L L C, Senior Secured Loans, due 12/20/2024
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:ResearchNowGroupInc.andSurveySamplingInternationalLLCMember
Investment, Identifier [Axis]: Rockdale Blackhawk, L L C, Senior Secured Loans, no stated maturity
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:RockdaleBlackhawkLLCMember
Investment, Identifier [Axis]: Runner Buyer I N C., Senior Secured Loans, due 10/23/2028
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:RunnerBuyerINCMember	mrcc:RunnerBuyerINCMember
Investment, Identifier [Axis]: S F R Holdco, L L C Equity Securities
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	S F R Holdco, L L C [ Member]
Investment, Identifier [Axis]: S F R Holdco, L L C, Junior Secured Loans Due 7/28/2028
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	S F R Holdco, L L C [ Member]
Investment, Identifier [Axis]: S H I Holdings, Inc. ( Common stock)
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	S H I Holdings, Inc [ Member]	S H I Holdings, Inc [ Member]
Investment, Identifier [Axis]: S H I Holdings, Inc. ( Revolver)
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	S H I Holdings, Inc [ Member]	S H I Holdings, Inc [ Member]
Investment, Identifier [Axis]: S H I Holdings, Inc., Investment One
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	S H I Holdings, Inc [ Member]	S H I Holdings, Inc [ Member]
Investment, Identifier [Axis]: S I R V A Worldwide Inc., Senior Secured Loans, due 8/4/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:SIRVAWorldwideIncMember
Investment, Identifier [Axis]: S T A T S Intermediate Holdings, L L C, Senior Secured Loans, due 7/10/2026
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:STATSIntermediateHoldingsLLCMember
Investment, Identifier [Axis]: S W Ingredients Holdings, L L C, Senior Secured Loans, due 7/3/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:SWIngredientsHoldingsLLCMember	mrcc:SWIngredientsHoldingsLLCMember
Investment, Identifier [Axis]: SFR Holdco, LLC (Junior secured loan)
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	Second Avenue S F R Holdings I I L L C [ Member]	Second Avenue S F R Holdings I I L L C [ Member]
Interest income	$ 468
Investment, Identifier [Axis]: SFR Holdco, LLC (LLC interest)
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	Second Avenue S F R Holdings I I L L C [ Member]	Second Avenue S F R Holdings I I L L C [ Member]
Investment, Identifier [Axis]: Sandvine Corporation, Senior Secured Loans, due 10/31/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:SandvineCorporationMember
Investment, Identifier [Axis]: Second Avenue S F R Holdings I I L L C ( Revolver), Senior Secured Loans, Due 8/9/2024
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	Second Avenue S F R Holdings I I L L C [ Member]	Second Avenue S F R Holdings I I L L C [ Member]
Interest income		$ 83
Investment, Identifier [Axis]: Second Avenue S F R Holdings I I L L C, Equity Securities
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		Second Avenue S F R Holdings I I L L C [ Member]
Investment, Identifier [Axis]: Second Avenue S F R Holdings I I L L C, Junior Secured Loans, Due 7/28/2028
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		Second Avenue S F R Holdings I I L L C [ Member]
Investment, Identifier [Axis]: Second Avenue SFR Holdings II LLC (Delayed Draw) Loan
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	Second Avenue S F R Holdings I I L L C [ Member]	Second Avenue S F R Holdings I I L L C [ Member]
Interest income	$ 312	$ 22
Investment, Identifier [Axis]: Secretariat Advisors L L C ( Delayed Draw), Senior Secured Loans, due 12/29/2028
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:SecretariatAdvisorsLLCMember
Investment, Identifier [Axis]: Secretariat Advisors L L C, Senior Secured Loans, due 12/29/2028
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:SecretariatAdvisorsLLCMember
Investment, Identifier [Axis]: Security Services Acquisition Sub Corp., Senior Secured Loans, Five, due 9/30/2026
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:SecurityServicesAcquisitionSubCorpMember	mrcc:SecurityServicesAcquisitionSubCorpMember
Investment, Identifier [Axis]: Security Services Acquisition Sub Corp., Senior Secured Loans, Four, due 9/30/2026
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:SecurityServicesAcquisitionSubCorpMember	mrcc:SecurityServicesAcquisitionSubCorpMember
Investment, Identifier [Axis]: Security Services Acquisition Sub Corp., Senior Secured Loans, One, due 9/30/2026
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:SecurityServicesAcquisitionSubCorpMember	mrcc:SecurityServicesAcquisitionSubCorpMember
Investment, Identifier [Axis]: Security Services Acquisition Sub Corp., Senior Secured Loans, Three, due 9/30/2026
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:SecurityServicesAcquisitionSubCorpMember	mrcc:SecurityServicesAcquisitionSubCorpMember
Investment, Identifier [Axis]: Security Services Acquisition Sub Corp., Senior Secured Loans, Two, due 9/30/2026
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:SecurityServicesAcquisitionSubCorpMember	mrcc:SecurityServicesAcquisitionSubCorpMember
Investment, Identifier [Axis]: Seran Bio Science, L L C ( Revolver), Senior Secured Loans, due 7/8/2027
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:SeranBioScienceLLCMember
Investment, Identifier [Axis]: Seran Bio Science, L L C (Revolver), Senior Secured Loans, Due 12/31/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:SeranBioScienceLLCMember
Investment, Identifier [Axis]: Seran Bio Science, L L C, Equity Securities, common units
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:SeranBioScienceLLCMember
Investment, Identifier [Axis]: Seran Bio Science, L L C, Senior Secured Loans, Due 12/31/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:SeranBioScienceLLCMember
Investment, Identifier [Axis]: Seran Bio Science, L L C, Senior Secured Loans, due 7/8/2027
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:SeranBioScienceLLCMember
Investment, Identifier [Axis]: Seran BioScience, LLC (Delayed Draw), Senior Secured Loans, Due 7/8/2027
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:SeranBioScienceLLCMember
Investment, Identifier [Axis]: Seran BioScience, LLC, Equity Security, Common Units
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:SeranBioScienceLLCMember
Investment, Identifier [Axis]: Service Max, Inc. ( Revolver) , Senior Secured Loans, due 11/1/2027
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:ServiceMaxIncMember	mrcc:ServiceMaxIncMember
Investment, Identifier [Axis]: Service Max, Inc., Senior Secured Loans, due 11/1/2027
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:ServiceMaxIncMember	mrcc:ServiceMaxIncMember
Investment, Identifier [Axis]: Spectrum Science Communications, L L C ( Revolver), Senior Secured Loans, due 1/25/2027
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:SpectrumScienceCommunicationsLLCMember
Investment, Identifier [Axis]: Spectrum Science Communications, L L C, Senior Secured Loans, due 1/25/2027
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:SpectrumScienceCommunicationsLLCMember
Investment, Identifier [Axis]: Spherix Global Inc, Equity Securities, Class A units
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:SpherixGlobalInc.Member	mrcc:SpherixGlobalInc.Member
Investment, Identifier [Axis]: Spherix Global Inc. ( Revolver), Senior Secured Loans, due, 12/22/2026
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:SpherixGlobalInc.Member	mrcc:SpherixGlobalInc.Member
Investment, Identifier [Axis]: Spherix Global Inc. , Senior Secured Loans, due, 12/22/2026
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:SpherixGlobalInc.Member	mrcc:SpherixGlobalInc.Member
Investment, Identifier [Axis]: Sports Operating Holdings II, LLC (Delayed Draw), Due 11/3/2027
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:SportsOperatingHoldingsIiLlcMember
Investment, Identifier [Axis]: Sports Operating Holdings II, LLC (Revolver), Due, 11/3/2027
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:SportsOperatingHoldingsIiLlcMember
Investment, Identifier [Axis]: Sports Operating Holdings II, LLC, Due, 11/3/2027
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:SportsOperatingHoldingsIiLlcMember
Investment, Identifier [Axis]: Star Compliance Mid Co, L L C, ( Revolver), Senior Secured Loans, due 1/12/2027
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:StarComplianceMidCoLLCMember	mrcc:StarComplianceMidCoLLCMember
Investment, Identifier [Axis]: Star Compliance Mid Co, L L C, Senior Secured Loans, One, due 1/12/2027
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:StarComplianceMidCoLLCMember	mrcc:StarComplianceMidCoLLCMember
Investment, Identifier [Axis]: Star Compliance Mid Co, L L C, Senior Secured Loans, Two, due 1/12/2027
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:StarComplianceMidCoLLCMember	mrcc:StarComplianceMidCoLLCMember
Investment, Identifier [Axis]: Storm Trap, L L C ( Revolver), Senior Secured Loans, due 12/8/2023
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:StormTrapLLCMember
Investment, Identifier [Axis]: Storm Trap, L L C, Senior Secured Loans, due 12/8/2023
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:StormTrapLLCMember
Investment, Identifier [Axis]: Summit Container Corporation ( Revolver)
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	Summit Container Corporation [ Member]	Summit Container Corporation [ Member]
Interest income		$ 35
Investment, Identifier [Axis]: Summit Container Corporation, Equity Securities, Warrants
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	Summit Container Corporation [ Member]	Summit Container Corporation [ Member]
Investment, Identifier [Axis]: Summit Container Corporation, Investment One
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	Summit Container Corporation [ Member]	Summit Container Corporation [ Member]
Interest income		$ 57
Investment, Identifier [Axis]: Synergy Environmental Corporation ( Revolver), Senior Secured Loans, due 9/29/2023
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:SynergyEnvironmentalCorporationMember
Investment, Identifier [Axis]: Synergy Environmental Corporation, Senior Secured Loans, One, due 9/29/2023
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:SynergyEnvironmentalCorporationMember
Investment, Identifier [Axis]: Synergy Environmental Corporation, Senior Secured Loans, Three, due 9/29/2023
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:SynergyEnvironmentalCorporationMember
Investment, Identifier [Axis]: Synergy Environmental Corporation, Senior Secured Loans, Two, due 9/29/2023
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:SynergyEnvironmentalCorporationMember
Investment, Identifier [Axis]: T A T T Buyer, L L C, Senior Secured Loans, due 3/30/2029
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:TATTBuyerLLCMember
Investment, Identifier [Axis]: T C F I I I O W L Buyer L L C, Senior Secured Loans, One, due 4/17/2026
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:TCFIIIOWLBuyerLLCMember	mrcc:TCFIIIOWLBuyerLLCMember
Investment, Identifier [Axis]: T C F I I I O W L Buyer L L C, Senior Secured Loans, Three, due 4/17/2026
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:TCFIIIOWLBuyerLLCMember	mrcc:TCFIIIOWLBuyerLLCMember
Investment, Identifier [Axis]: T C F I I I O W L Buyer L L C, Senior Secured Loans, Two, due 4/17/2026
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:TCFIIIOWLBuyerLLCMember	mrcc:TCFIIIOWLBuyerLLCMember
Investment, Identifier [Axis]: T E A M Public Choices, L L C, Senior Secured Loans, due 12/17/2027
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:TEAMPublicChoicesLLCMember	mrcc:TEAMPublicChoicesLLCMember
Investment, Identifier [Axis]: T G G T S Acquisition Company, Senior Secured Loans, due 12/12/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:TGGTSAcquisitionCompanyMember
Investment, Identifier [Axis]: T J C Spartech Acquisition Corp., Senior Secured Loans, due 5/5/2028
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:TJCSpartechAcquisitionCorpMember
Investment, Identifier [Axis]: T J Management Hold Co L L C ( Revolver), Senior Secured Loans, Due 6/28/2024
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	T J Management Hold Co L L C [ Member]	T J Management Hold Co L L C [ Member]
Interest income	$ 14	$ 12
Investment, Identifier [Axis]: T J Management Hold Co L L C, Equity Securities, Common stock
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	T J Management Hold Co L L C [ Member]	T J Management Hold Co L L C [ Member]
Investment, Identifier [Axis]: Tait L L C ( Revolver), Senior Secured Loans, due 3/28/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:TaitLLCMember
Investment, Identifier [Axis]: Tait L L C, Senior Secured Loans, due 3/28/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:TaitLLCMember
Investment, Identifier [Axis]: Teneo Holdings L L C, Senior Secured Loans, due 7/11/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:TeneoHoldingsLLCMember
Investment, Identifier [Axis]: The Cook & Boardman Group L L C, Senior Secured Loans, due 10/20/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:TheCookBoardmanGroupLLCMember	mrcc:TheCookBoardmanGroupLLCMember
Investment, Identifier [Axis]: The Kleinfelder Group, Inc., Senior Secured Loans, due 11/29/2024
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:TheKleinfelderGroupIncMember
Investment, Identifier [Axis]: The Kyjen Company, L L C ( Revolver), Senior Secured Loans, due 4/3/2026
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:TheKyjenCompanyLLCMember	mrcc:TheKyjenCompanyLLCMember
Investment, Identifier [Axis]: The Kyjen Company, L L C, Senior SEcured Loans, Two, Due 4/3/2026
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:TheKyjenCompanyLLCMember
Investment, Identifier [Axis]: The Kyjen Company, L L C, Senior Secured Loans, due 4/3/2026
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:TheKyjenCompanyLLCMember	mrcc:TheKyjenCompanyLLCMember
Investment, Identifier [Axis]: Thrasio, L L C, Senior Secured Loans, due 12/18/2026
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:ThrasioLLCMember	mrcc:ThrasioLLCMember
Investment, Identifier [Axis]: Tiger Connect, Inc. ( Delayed Draw), Senior Secured Loans, due 2/16/2028
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:TigerConnectIncMember
Investment, Identifier [Axis]: Tiger Connect, Inc. ( Revolver), Senior Secured Loans, due 2/16/2028
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:TigerConnectIncMember
Investment, Identifier [Axis]: Tiger Connect, Inc., Senior Secured Loans, due 2/16/2028
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:TigerConnectIncMember
Investment, Identifier [Axis]: Toojay’s Management L L C ( Revolver), Senior Secured Loans, due 10/26/2022
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:ToojaysManagementLLCMember
Investment, Identifier [Axis]: Toojay’s Management L L C, Senior Secured Loans, One, due 10/26/2022
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:ToojaysManagementLLCMember
Investment, Identifier [Axis]: Toojay’s Management L L C, Senior Secured Loans, Two, due 10/26/2022
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:ToojaysManagementLLCMember
Investment, Identifier [Axis]: Trident Maritime Systems, Inc ( Revolver), Senior Secured Loans, due 2/26/2027
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:TridentMaritimeSystemsIncMember	mrcc:TridentMaritimeSystemsIncMember
Investment, Identifier [Axis]: Trident Maritime Systems, Inc, Senior Secured Loans, One, due 2/26/2027
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:TridentMaritimeSystemsIncMember	mrcc:TridentMaritimeSystemsIncMember
Investment, Identifier [Axis]: Trident Maritime Systems, Inc, Senior Secured Loans, Two, due 2/26/2027
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:TridentMaritimeSystemsIncMember
Investment, Identifier [Axis]: Truck- Lite Co., L L C, Senior Secured Loans, One, due 12/14/2026
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:Truck-LiteCo.LLCMember	mrcc:Truck-LiteCo.LLCMember
Investment, Identifier [Axis]: Truck- Lite Co., L L C, Senior Secured Loans, Two, due 12/14/2026
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:Truck-LiteCo.LLCMember	mrcc:Truck-LiteCo.LLCMember
Investment, Identifier [Axis]: Truck-Lite Co., LLC, Senior Secured Loans, Three, due 12/14/2026
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:Truck-LiteCo.LLCMember
Investment, Identifier [Axis]: V B E1, L L C ( Delayed Draw), Unitranche Secured Loans, due 11/18/2026
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:VBE1LLCMember
Investment, Identifier [Axis]: V B E1, L L C, Unitranche Secured Loans, due 11/18/2026
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:VBE1LLCMember
Investment, Identifier [Axis]: V H T Solutions ( Delayed Draw), Senior Secured Loans, due 12/21/2026
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:VHTAcquisitionsLLCMember
Investment, Identifier [Axis]: V H T Solutions ( Revolver), Senior Secured Loans, due 12/21/2026
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:VHTAcquisitionsLLCMember
Investment, Identifier [Axis]: V H T Solutions, Senior Secured Loans, due 12/21/2026
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:VHTAcquisitionsLLCMember
Investment, Identifier [Axis]: V P S Holdings, L L C ( Revolver), Senior Secured Loans, due 10/4/2024
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:VPSHoldingsLLCMember	mrcc:VPSHoldingsLLCMember
Investment, Identifier [Axis]: V P S Holdings, L L C, Senior Secured Loans, One, due 10/4/2024
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:VPSHoldingsLLCMember	mrcc:VPSHoldingsLLCMember
Investment, Identifier [Axis]: V P S Holdings, L L C, Senior Secured Loans, Two, due 10/4/2024
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:VPSHoldingsLLCMember	mrcc:VPSHoldingsLLCMember
Investment, Identifier [Axis]: Valudor Products L L C ( Revolver), Senior Secured Loans, due 6/19/2023
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:ValudorProductsLLCMember	mrcc:ValudorProductsLLCMember
Investment, Identifier [Axis]: Valudor Products L L C , Equity Securities, Class A-1 units
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:ValudorProductsLLCMember	mrcc:ValudorProductsLLCMember
Investment, Identifier [Axis]: Valudor Products L L C, Senior Secured Loans, One, due 6/19/2023,
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:ValudorProductsLLCMember	mrcc:ValudorProductsLLCMember
Investment, Identifier [Axis]: Valudor Products L L C, Senior Secured Loans, Three, due 6/19/2023
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:ValudorProductsLLCMember	mrcc:ValudorProductsLLCMember
Investment, Identifier [Axis]: Valudor Products L L C, Senior Secured Loans, Two, due 6/19/2023
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:ValudorProductsLLCMember	mrcc:ValudorProductsLLCMember
Investment, Identifier [Axis]: Vice Group Holding Inc., Senior Secured Loans, Four, due 5/12/2023
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:ViceGroupHoldingIncMember
Investment, Identifier [Axis]: Vice Group Holding Inc., Senior Secured Loans, Four, due, 11/2/2022
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:ViceGroupHoldingIncMember
Investment, Identifier [Axis]: Vice Group Holding Inc., Senior Secured Loans, One, due 11/2/2022
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:ViceGroupHoldingIncMember
Investment, Identifier [Axis]: Vice Group Holding Inc., Senior Secured Loans, One, due 5/12/2023
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:ViceGroupHoldingIncMember
Investment, Identifier [Axis]: Vice Group Holding Inc., Senior Secured Loans, Three, due 11/2/2022
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:ViceGroupHoldingIncMember
Investment, Identifier [Axis]: Vice Group Holding Inc., Senior Secured Loans, Three, due 5/12/2023
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:ViceGroupHoldingIncMember
Investment, Identifier [Axis]: Vice Group Holding Inc., Senior Secured Loans, Two, due 11/2/2022
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:ViceGroupHoldingIncMember
Investment, Identifier [Axis]: Vice Group Holding Inc., Senior Secured Loans, Two, due 5/12/2023
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:ViceGroupHoldingIncMember
Investment, Identifier [Axis]: Vinci Brands L L C (fka Incipio, L L C) ( Junior secured loan), One
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	Vinci Brands L L C (fka Incipio, L L C) [ Member]	Vinci Brands L L C (fka Incipio, L L C) [ Member]
Investment, Identifier [Axis]: Vinci Brands L L C (fka Incipio, L L C) ( Junior secured loan), Two
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	Vinci Brands L L C (fka Incipio, L L C) [ Member]	Vinci Brands L L C (fka Incipio, L L C) [ Member]
Investment, Identifier [Axis]: Vinci Brands L L C (fka Incipio, L L C), (Delayed Draw)
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	Vinci Brands L L C (fka Incipio, L L C) [ Member]
Investment, Identifier [Axis]: Vinci Brands L L C (fka Incipio, L L C), Equity Securities, Series C common units)
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	Vinci Brands L L C (fka Incipio, L L C) [ Member]	Vinci Brands L L C (fka Incipio, L L C) [ Member]
Investment, Identifier [Axis]: Vinci Brands L L C (fka Incipio, L L C), Loan Five
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	Vinci Brands L L C (fka Incipio, L L C) [ Member]	Vinci Brands L L C (fka Incipio, L L C) [ Member]
Investment, Identifier [Axis]: Vinci Brands L L C (fka Incipio, L L C), Loan Four
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	Vinci Brands L L C (fka Incipio, L L C) [ Member]	Vinci Brands L L C (fka Incipio, L L C) [ Member]
Investment, Identifier [Axis]: Vinci Brands L L C (fka Incipio, L L C), Loan One
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	Vinci Brands L L C (fka Incipio, L L C) [ Member]	Vinci Brands L L C (fka Incipio, L L C) [ Member]
Investment, Identifier [Axis]: Vinci Brands L L C (fka Incipio, L L C), Loan Six
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		Vinci Brands L L C (fka Incipio, L L C) [ Member]
Investment, Identifier [Axis]: Vinci Brands L L C (fka Incipio, L L C), Loan Three
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	Vinci Brands L L C (fka Incipio, L L C) [ Member]	Vinci Brands L L C (fka Incipio, L L C) [ Member]
Investment, Identifier [Axis]: Vinci Brands L L C (fka Incipio, L L C), Loan Two
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	Vinci Brands L L C (fka Incipio, L L C) [ Member]	Vinci Brands L L C (fka Incipio, L L C) [ Member]
Investment, Identifier [Axis]: Vinci Brands L L C, Unitranche Secured Loans, Four, due 2/6/2024
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:VinciBrandsLLCMember
Investment, Identifier [Axis]: Vinci Brands L L C, Unitranche Secured Loans, One, due 2/6/2024
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:VinciBrandsLLCMember
Investment, Identifier [Axis]: Vinci Brands L L C, Unitranche Secured Loans, Three, due 2/6/2024
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:VinciBrandsLLCMember
Investment, Identifier [Axis]: Vinci Brands L L C, Unitranche Secured Loans, Two, due 2/6/2024
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:VinciBrandsLLCMember
Investment, Identifier [Axis]: W3 Monroe R E Debt L L C, Senior Secured Loans, due 2/4/2028
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:W3MonroeREDebtLLCMember	mrcc:W3MonroeREDebtLLCMember
Investment, Identifier [Axis]: Wheel Pros, Inc., Senior Secured Loans, due 5/11/2028
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:WheelProsIncMember	mrcc:WheelProsIncMember
Investment, Identifier [Axis]: Whistler Parent Holdings I I I, Inc. ( Delayed Draw), Senior Secured Loans, due 6/2/2028
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:WhistlerParentHoldingsIIIIncMember
Investment, Identifier [Axis]: Whistler Parent Holdings I I I, Inc. ( Revolver), Senior Secured Loans, due 6/2/2028
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:WhistlerParentHoldingsIIIIncMember
Investment, Identifier [Axis]: Whistler Parent Holdings I I I, Inc., Senior Secured Loans, due 6/2/2028
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:WhistlerParentHoldingsIIIIncMember
Investment, Identifier [Axis]: WillowTree, LLC, Unitranche Secured Loans, due 10/9/2023
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:WillowTreeLLCMember	mrcc:WillowTreeLLCMember
Investment, Identifier [Axis]: Witkoff/ Monroe 700 J V L L C ( Delayed Draw), Junior Secured Loans, due 7/2/2026
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:WitkoffMonroe700JVLLCMember
Investment, Identifier [Axis]: Witkoff/ Monroe 700 J V L L C, Equity Securities, Preferred units
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:WitkoffMonroe700JVLLCMember	mrcc:WitkoffMonroe700JVLLCMember
Investment, Identifier [Axis]: Xan Edu Publishing, Inc, Equity Securities, Class A units
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:XanEduPublishingIncMember	mrcc:XanEduPublishingIncMember
Investment, Identifier [Axis]: Xan Edu Publishing, Inc. ( Revolver), Senior Secured Loans, due, 1/28/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:XanEduPublishingIncMember	mrcc:XanEduPublishingIncMember
Investment, Identifier [Axis]: Xan Edu Publishing, Inc., Senior Secured Loans, One, due, 1/28/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:XanEduPublishingIncMember
Investment, Identifier [Axis]: Xan Edu Publishing, Inc., Senior Secured Loans, Two, due, 1/28/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:XanEduPublishingIncMember
Investment, Identifier [Axis]: Xan Edu Publishing, Inc., Senior Secured Loans, due, 1/28/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:XanEduPublishingIncMember
Investment, Identifier [Axis]: Y S W H 4, L L C (Revolver), Senior Secured Loans, Due 11/20/2025
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:YSWH4LLCRevolverMember
Investment, Identifier [Axis]: iCIMS, Inc, Due 8/18/2028
Investments in and Advances to Affiliates [Line Items]
Investment, Issuer Affiliation [Extensible Enumeration]	Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]	mrcc:IcimsIncMember
Non-controlled affiliate company investments
Investments in and Advances to Affiliates [Line Items]
Interest income	$ 11,265	$ 11,634
Dividend income	189	987	$ 147
Fee income		36
Controlled affiliate company investments
Investments in and Advances to Affiliates [Line Items]
Dividend income	$ 3,600	$ 4,325	$ 4,400

Transactions with Related Par_3

Transactions with Related Parties (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2022 USD ($) item component	Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)
Transactions with Related Parties
Base management fees	$ 9,055	$ 9,514	$ 9,807
MC Advisors
Transactions with Related Parties
Number of components | component	2
Initial base management fee, Percentage	1.75%
Base management fee, percentage	1%
Percentage of average invested assets	200%
Leverage ratio	1
Base management fees	$ 9,055	9,514	9,807
Base management fees, voluntary waiver amount	$ 55	$ 0	$ 430
Incentive fee payable in arrears, percentage	20%
Incentive fee payable, threshold quarterly hurdle rate	2%
Incentive fee payable, threshold annual hurdle rate	8%
Incentive fee limitation, percentage	20%
Period of preceding calendar quarters | item	11
Threshold ordinary income incentive fee payable, percentage	20%
Threshold ordinary income incentive fee limitation, percentage	20%
Second part incentive fee payable, percentage	20%

Transactions with Related Par_4

Transactions with Related Parties - Composition of the Company's incentive fees (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Transactions with Related Parties
Total incentive fees, net of incentive fee waivers	$ 4,127	$ 3,690	$ 712
MC Advisors
Transactions with Related Parties
Part one incentive fees	4,127	3,690	5,724
Incentive Fee Limitation			(5,012)
Incentive fees, excluding the impact of the incentive fee waivers	4,127	3,690	712
Incentive fee waivers	(525)	(1,484)	$ (712)
Total incentive fees, net of incentive fee waivers	$ 3,602	$ 2,206
Second part incentive fee payable, percentage	20%

Transactions with Related Par_5

Transactions with Related Parties - Administrative agreement (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Transactions with Related Parties
Administrative agreement service fee	$ 1,163	$ 1,357	$ 1,300
MC Management
Transactions with Related Parties
Administrative expenses	3,139	3,442	3,312
Administrative agreement service fee	1,163	1,357	$ 1,300
MC Management | Accounts payable and accrued expenses
Transactions with Related Parties
Amount due to related party	255	337
Members of Board
Transactions with Related Parties
Accounts payable	$ 0	$ 0

Borrowings (Details)

Borrowings (Details) £ in Thousands, $ in Thousands		12 Months Ended
	Feb. 18, 2021 USD ($)	Dec. 31, 2022 USD ($)	Dec. 31, 2022 GBP (£)	Dec. 31, 2021 USD ($)	Dec. 31, 2021 GBP (£)	Dec. 31, 2020 USD ($)	Dec. 31, 2020 GBP (£)	Dec. 27, 2022 USD ($)	Dec. 31, 2021 GBP (£)
Borrowings
Minimum asset coverage ratio		150%
Asset coverage ratio		167%		189%					189%
Unrealized gain (loss) on foreign currency and other transactions		$ 164		$ 635		$ (650)
Realized gain (loss) on foreign currency and other transactions		(36)		(895)		(14)
Realized loss on extinguishment of debt		(1,039)		(3,110)
Outstanding borrowings		334,600		337,945
Note 2026
Borrowings
Outstanding borrowings		$ 130,000		130,000
Interest rate		4.75%
Notes 2023
Borrowings
Aggregate principal amount of debt redeemed	$ 109,000
Realized loss on extinguishment of debt	$ (2,335)
Revolving credit facility
Borrowings
Maximum borrowing capacity		$ 255,000
Capitalized unamortized deferred financing costs								$ 1,765
Maximum borrowing capacity, Percentage of the fair market value of its portfolio company investments		72.50%	72.50%
Consolidated total net assets		$ 150,000
Consolidated total net assets, Percentage of net proceeds from sales of equity securities after March 1, 2019		65%
Percentage of distributions in cash or property other than common stock		115%
Unrealized gain (loss) on foreign currency and other transactions		$ 157		660		$ (665)
Repayments of borrowings | £			£ 3,433		£ 12,667		£ 0
Realized gain (loss) on foreign currency and other transactions		$ (11)		$ (866)
Interest rate, daily rate per annum		1.625%
Weighted average interest rate		7%		3.10%					3.10%
Revolving credit facility | Minimum
Borrowings
Assets to debt ratio		1.5
Senior debt coverage ratio		2
Revolving credit facility | Maximum
Borrowings
Maximum borrowing capacity		$ 400,000
Revolving credit facility | Available maximum borrowing capacity percentage greater than 35%
Borrowings
Commitment fee (in percent)		0.50%	0.50%
Available maximum borrowing capacity, percentage		35%
Revolving credit facility | Available maximum borrowing capacity percentage equal to or less than 35%
Borrowings
Commitment fee (in percent)		1%	1%
Available maximum borrowing capacity, percentage		35%
Revolving credit facility | SOFR
Borrowings
Interest rate, basis spread		2.625%	2.625%
Interest rate, daily basis spread		1%	1%
Interest rate, floor		0.50%
Revolving credit facility | Prime rate
Borrowings
Interest rate, daily basis spread		1.50%	1.50%
Revolving credit facility | Federal funds rate
Borrowings
Interest rate, daily basis spread		0.50%	0.50%
Revolving credit facility | Denominated in U.S. dollar
Borrowings
Borrowings		$ 204,600		$ 146,400
Revolving credit facility | Denominated in non-U.S. dollar
Borrowings
Borrowings				$ 4,645					£ 3,433

Borrowings - SBA Debentures (De

Borrowings - SBA Debentures (Details) - USD ($) $ in Thousands		12 Months Ended
	Mar. 01, 2022	Dec. 31, 2022	Dec. 31, 2021
Borrowings
Realized loss on extinguishment of debt		$ (1,039)	$ (3,110)
Outstanding borrowings		330,114	332,151
SBA Debentures | Monroe Capital Corporation SBIC, LP
Borrowings
Realized loss on extinguishment of debt	$ (1,039)
Leverageable capital		$ 0	57,624
Outstanding borrowings			56,900
SBA Debentures, Interest rate 3.4% | Monroe Capital Corporation SBIC, LP
Borrowings
Interest Rate		3.40%
Outstanding borrowings			2,920
SBA Debentures, Interest rate 3.3% | Monroe Capital Corporation SBIC, LP
Borrowings
Interest Rate		3.30%
Outstanding borrowings			14,800
SBA Debentures, Interest rate 2.9% | Monroe Capital Corporation SBIC, LP
Borrowings
Interest Rate		2.90%
Outstanding borrowings			7,080
SBA Debentures, Interest rate 3.2% | Monroe Capital Corporation SBIC, LP
Borrowings
Interest Rate		3.20%
Outstanding borrowings			$ 32,100

Borrowings - Components of the

Borrowings - Components of the Company's interest expense and other debt financing expenses, average debt outstanding balances and average stated interest rates (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Borrowings
Amortization of deferred financing costs	$ 2,126	$ 2,205	$ 2,181
Total interest and other debt financing expenses	17,080	16,074	17,989
Average debt outstanding	$ 314,053	$ 332,034	$ 370,904
Average stated interest rate	4.70%	4.10%	4.20%
Notes 2023
Borrowings
Interest expense		$ 837	$ 6,270
Note 2026
Borrowings
Interest expense	$ 6,220	5,763
SBA Debentures
Borrowings
Interest expense	292	2,676	3,944
Revolving credit facility
Borrowings
Interest expense	$ 8,442	$ 4,593	$ 5,594

Derivative Instruments (Details

Derivative Instruments (Details) £ in Thousands, $ in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)	Dec. 31, 2022 AUD ($)	Dec. 31, 2021 AUD ($)	Dec. 31, 2021 GBP (£)
Derivative Instruments
Gross Amount of Unrealized Gain	$ 1,507	$ 804
Gross Amount of Unrealized Loss		(23)
Derivative Asset, Statement of Financial Position [Extensible Enumeration]				Derivative Asset	Derivative Asset	Derivative Asset
Net change in unrealized gain (loss) on foreign currency forward contracts	726	894	$ (54)
Foreign currency forward contracts
Derivative Instruments
Net change in unrealized gain (loss) on foreign currency forward contracts	726	894	(54)
Net realized gain (loss) on foreign currency forward contracts	119	(48)	$ (16)
Foreign currency forward contract with Settlement Date 1/3/2022
Derivative Instruments
Notional Amount to be Sold | £						£ 82
Gross Amount of Unrealized Loss		(10)
Foreign currency forward contract with Settlement Date 4/4/2022
Derivative Instruments
Notional Amount to be Sold | £						79
Gross Amount of Unrealized Loss		(10)
Foreign currency forward contract with Settlement Date 5/6/2022
Derivative Instruments
Notional Amount to be Sold | £						£ 29
Gross Amount of Unrealized Loss		(3)
Foreign currency forward contract with Settlement Date 1/19/2022
Derivative Instruments
Notional Amount to be Sold					$ 156
Gross Amount of Unrealized Gain		8
Foreign currency forward contract with Settlement Date 2/16/2022
Derivative Instruments
Notional Amount to be Sold					136
Gross Amount of Unrealized Gain		7
Foreign currency forward contract with Settlement Date 3/16/2022
Derivative Instruments
Notional Amount to be Sold					132
Gross Amount of Unrealized Gain		6
Foreign currency forward contract with Settlement Date 4/19/2022
Derivative Instruments
Notional Amount to be Sold					146
Gross Amount of Unrealized Gain		7
Foreign currency forward contract with Settlement Date 5/17/2022
Derivative Instruments
Notional Amount to be Sold					138
Gross Amount of Unrealized Gain		7
Foreign currency forward contract with Settlement Date 6/17/2022
Derivative Instruments
Notional Amount to be Sold					153
Gross Amount of Unrealized Gain		7
Foreign currency forward contract with Settlement Date 7/18/2022
Derivative Instruments
Notional Amount to be Sold					138
Gross Amount of Unrealized Gain		7
Foreign currency forward contract with Settlement Date 8/16/2022
Derivative Instruments
Notional Amount to be Sold					140
Gross Amount of Unrealized Gain		7
Foreign currency forward contract with Settlement Date 9/16/2022
Derivative Instruments
Notional Amount to be Sold					153
Gross Amount of Unrealized Gain		7
Foreign currency forward contract with Settlement Date 10/19/2022
Derivative Instruments
Notional Amount to be Sold					152
Gross Amount of Unrealized Gain		7
Foreign currency forward contract with Settlement Date 11/16/2022
Derivative Instruments
Notional Amount to be Sold					136
Gross Amount of Unrealized Gain		6
Foreign currency forward contract with Settlement Date 12/16/2022
Derivative Instruments
Notional Amount to be Sold					142
Gross Amount of Unrealized Gain		7
Foreign currency forward contract with Settlement Date 1/18/2023
Derivative Instruments
Notional Amount to be Sold				$ 153	153
Gross Amount of Unrealized Gain	14	7
Foreign currency forward contract with Settlement Date 2/16/2023
Derivative Instruments
Notional Amount to be Sold				140	140
Gross Amount of Unrealized Gain	13	6
Foreign currency forward contract with Settlement Date 3/16/2023
Derivative Instruments
Notional Amount to be Sold				132	132
Gross Amount of Unrealized Gain	12	6
Foreign currency forward contract with Settlement Date 4/20/2023
Derivative Instruments
Notional Amount to be Sold				160	160
Gross Amount of Unrealized Gain	14	7
Foreign currency forward contract with Settlement Date 5/16/2023
Derivative Instruments
Notional Amount to be Sold				121	121
Gross Amount of Unrealized Gain	11	5
Foreign currency forward contract with Settlement Date 6/19/2023
Derivative Instruments
Notional Amount to be Sold				156	156
Gross Amount of Unrealized Gain	14	7
Foreign currency forward contract with Settlement Date 7/18/2023
Derivative Instruments
Notional Amount to be Sold				138	138
Gross Amount of Unrealized Gain	12	6
Foreign currency forward contract with Settlement Date 8/16/2023
Derivative Instruments
Notional Amount to be Sold				146	146
Gross Amount of Unrealized Gain	13	6
Foreign currency forward contract with Settlement Date 9/18/2023
Derivative Instruments
Notional Amount to be Sold				146	146
Gross Amount of Unrealized Gain	13	6
Foreign currency forward contract with Settlement Date 10/18/2023
Derivative Instruments
Notional Amount to be Sold				148	148
Gross Amount of Unrealized Gain	13	6
Foreign currency forward contract with Settlement Date 11/16/2023
Derivative Instruments
Notional Amount to be Sold				140	140
Gross Amount of Unrealized Gain	12	6
Foreign currency forward contract with Settlement Date 12/18/2023
Derivative Instruments
Notional Amount to be Sold				142	142
Gross Amount of Unrealized Gain	12	6
Foreign currency forward contract with Settlement Date 1/17/2024
Derivative Instruments
Notional Amount to be Sold				150	150
Gross Amount of Unrealized Gain	13	6
Foreign currency forward contract with Settlement Date 2/16/2024
Derivative Instruments
Notional Amount to be Sold				143	143
Gross Amount of Unrealized Gain	12	6
Foreign currency forward contract with Settlement Date 3/18/2024
Derivative Instruments
Notional Amount to be Sold				$ 15,410	$ 15,410
Gross Amount of Unrealized Gain	$ 1,329	$ 635

Income Taxes (Details)

Income Taxes (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Income Taxes
Provision for federal income tax	$ 0
Increase (decrease) in capital in excess of par value	13	$ (301)	$ (447)
Increase (decrease) in accumulated undistributed (overdistributed) earnings	(13)	301	$ 447
Short-term capital loss carryforwards	0	0
Long-term capital loss carryforwards	$ 41,826	$ 40,696

Income Taxes - Reconciliation (

Income Taxes - Reconciliation (Details) - USD ($) $ in Thousands	3 Months Ended												12 Months Ended
	Dec. 31, 2022	Sep. 30, 2022	Jun. 30, 2022	Mar. 31, 2022	Dec. 31, 2021	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Income Taxes
Net increase (decrease) in net assets resulting from operations	$ 4,480	$ (749)	$ (7,364)	$ 847	$ 6,835	$ 7,239	$ 11,330	$ 7,055	$ 9,077	$ 15,185	$ 14,234	$ (36,850)	$ (2,786)	$ 32,459	$ 1,646
Net change in unrealized (gain) loss for book but not tax													22,892	(36,108)	31,263
Other realized gain (loss) for tax but not book															(857)
Other income (loss) for tax but not book													84	(961)	217
Expenses not currently deductible													1,405	282	370
Net capital loss carryforward	$ 1,130				$ 20,040				$ 1,694				1,130	20,040	1,694
Total taxable income													$ 23,451	$ 15,712	$ 30,945

Income Taxes - Tax character of

Income Taxes - Tax character of distributions (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Tax character of distributions
Ordinary income	$ 21,666	$ 21,514	$ 23,064
Total	21,666	21,514	23,064
Tax expense for taxable subsidiaries	1,311	4	$ 2
Estimated cost basis of investment for U.S. federal income tax purposes	579,604	576,327
Estimated net unrealized loss	38,563	14,634
Estimated gross unrealized gains	20,104	22,135
Estimated gross unrealized losses	$ 58,667	$ 36,769

Distributions (Details)

Distributions (Details) - USD ($) $ / shares in Units, $ in Thousands	1 Months Ended											2 Months Ended	12 Months Ended
	Dec. 31, 2022	Sep. 30, 2022	Jun. 30, 2022	Mar. 31, 2022	Dec. 31, 2021	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Dec. 31, 2020	Sep. 30, 2020	Mar. 31, 2020	Jun. 30, 2020	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Distributions
Date Declared	Dec. 05, 2022	Sep. 01, 2022	Jun. 01, 2022	Mar. 02, 2022	Dec. 02, 2021	Sep. 02, 2021	Jun. 02, 2021	Mar. 02, 2021	Dec. 04, 2020	Sep. 04, 2020	Mar. 03, 2020	May 08, 2020
Record Date	Dec. 15, 2022	Sep. 15, 2022	Jun. 15, 2022	Mar. 16, 2022	Dec. 16, 2021	Sep. 16, 2021	Jun. 16, 2021	Mar. 16, 2021	Dec. 16, 2020	Sep. 16, 2020	Mar. 16, 2020	Jun. 15, 2020
Payment Date	Dec. 30, 2022	Sep. 30, 2022	Jun. 30, 2022	Mar. 31, 2022	Dec. 31, 2021	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Dec. 31, 2020	Sep. 30, 2020	Mar. 31, 2020	Jun. 30, 2020
Amount Per Share	$ 0.25	$ 0.25	$ 0.25	$ 0.25	$ 0.25	$ 0.25	$ 0.25	$ 0.25	$ 0.25	$ 0.25	$ 0.35	$ 0.25	$ 1	$ 1	$ 1.10
Cash Distribution	$ 5,417	$ 5,416	$ 5,416	$ 5,417	$ 5,416	$ 5,386	$ 5,386	$ 5,326	$ 5,326	$ 5,326	$ 7,155	$ 5,257	$ 21,666	$ 21,514	$ 23,064
DRIP Shares Purchased in the Open Market	17,017	20,789	29,655	25,229	27,905	35,623	31,277	35,611	45,667	44,246	55,938	40,612	92,690	130,416	186,463
Cost of DRIP Shares Purchased	$ 149	$ 164	$ 280	$ 276	$ 315	$ 369	$ 343	$ 364	$ 365	$ 305	$ 374	$ 283	$ 869	$ 1,391	$ 1,327

Stock Issuances and Repurchas_2

Stock Issuances and Repurchases (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020	May 12, 2017
Stock Issuances and Repurchases
Gross proceeds from issue of common stock		$ 4,092	$ 6,495
ATM offering
Stock Issuances and Repurchases
Maximum value of common stock available for sale				$ 50,000
Number of stock issued	0	362,800	858,976
Average price		$ 11.53	$ 7.78
Gross proceeds from issue of common stock		$ 4,182	$ 6,684
Underwriter's discounts and commissions		63	100
Offering costs		27	89
Net proceeds from issuance of shares		$ 4,092	$ 6,495

Commitments and Contingencies (

Commitments and Contingencies (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Commitments
Unfunded commitments	$ 63,450	$ 55,483
SLF
Commitments
Unfunded commitments	$ 7,350	$ 7,850

Financial Highlights - Financia

Financial Highlights - Financial highlights (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Per share data:
Net asset value at beginning of year	$ 11.51	$ 11	$ 12.20	$ 12.66	$ 13.77	$ 14.52	$ 14.19	$ 14.05	$ 13.92	$ 14.54
Net investment income	1.02	1.03	1.45	1.42	1.57	1.40	1.55	1.60	1.57	1.13
Net gain (loss)	(1.15)	0.48	(1.37)	(0.48)	(1.28)	(0.75)	0.13	(0.07)	(0.12)	0.15
Net increase (decrease) in net assets resulting from operations	(0.13)	1.51	0.08	0.94	0.29	0.65	1.68	1.53	1.45	1.28
Stockholder distributions - income	(1)	(1)	(1.10)	(1.40)	(1.40)	(1.37)	(1.40)	(1.37)	(1.36)	(1.15)
Stockholder distributions - capital gains						(0.03)		(0.03)
Stockholder distributions - return of capital										(0.21)
Effect of share issuance above (below) NAV			(0.18)				0.05			(0.57)
Effect of share repurchases									0.04	0.03
Other	0.01							0.01
Net asset value at end of year	$ 10.39	$ 11.51	$ 11	$ 12.20	$ 12.66	$ 13.77	$ 14.52	$ 14.19	$ 14.05	$ 13.92
Net assets at end of year	$ 225,019	$ 249,471	$ 234,434	$ 249,357	$ 258,767	$ 278,699	$ 240,850	$ 184,535	$ 133,738	$ 138,092
Shares outstanding at end of year	21,666,340	21,666,340	21,303,540	20,444,564	20,444,564	20,239,957	16,581,869	13,008,007	9,517,910	9,918,269
Per share market value at end of year	$ 8.54	$ 11.22	$ 8.03	$ 10.86	$ 9.60	$ 13.75	$ 15.38	$ 13.09	$ 14.46	$ 12.20
Total return based on market value	(15.20%)	53.26%	(13.86%)	27.68%	(21.74%)	(1.82%)	28.95%	(0.21%)	30.67%	(9.29%)
Total return based on average net asset value	(1.18%)	13.40%	0.72%	7.53%	2.17%	4.58%	11.70%	11.04%	10.34%	9.17%
Ratio/Supplemental data:
Ratio of net investment income to average net assets	9.42%	9.15%	13.32%	11.38%	11.85%	9.80%	10.81%	11.56%	11.20%	7.71%
Ratio of total expenses, net of base management fee and incentive fee waivers, to average net assets	14.60%	13.07%	13.68%	15.35%	9.84%	9.46%	10.81%	11.20%	11.03%	8.53%
Portfolio turnover	24.93%	41.80%	25.24%	27.18%	31.53%	39.39%	22.41%	30.70%	47.03%	39.77%

Financial Highlights - (Details

Financial Highlights - (Details)	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Financial Highlights
Ratio of total investment income to average net assets	24.02%	22.22%	27%	26.73%	21.69%	19.26%	21.62%	22.76%	22.23%	17.10%
Ratio of interest and other debt financing expenses to average net assets	7.25%	6.63%	7.89%	7.95%	4.56%	3.13%	3.26%	3.33%	3.23%	2.59%
Ratio of total expenses (without base management fee waivers and incentive fees) to average net assets	13.09%	12.16%	13.86%	13.61%	9.19%	7.43%	8.17%	8.31%	8.42%	7.15%
Ratio of incentive fees, net of incentive fee waivers, to average net assets	1.53%	0.91%	0%	1.74%	0.65%	2.03%	2.64%	2.89%	2.61%	1.38%
Ratio of waived incentive fees to average net assets	0.22%	0.61%	0.31%	0.46%	0%	0.12%	0.13%	0%	0%	0%

Subsequent Events (Details)

Subsequent Events (Details) - $ / shares		12 Months Ended
	Mar. 01, 2023	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Subsequent Event
Stockholder distributions - income		$ 1	$ 1	$ 1.10	$ 1.40	$ 1.40	$ 1.37	$ 1.40	$ 1.37	$ 1.36	$ 1.15
Subsequent Events
Subsequent Event
Stockholder distributions - income	$ 0.25

Selected Quarterly Financial _3

Selected Quarterly Financial Data (unaudited) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended												12 Months Ended
	Dec. 31, 2022	Sep. 30, 2022	Jun. 30, 2022	Mar. 31, 2022	Dec. 31, 2021	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Selected Quarterly Financial Data (unaudited)
Total investment income	$ 15,164	$ 15,916	$ 12,995	$ 12,491	$ 13,039	$ 15,214	$ 12,364	$ 13,213	$ 12,552	$ 13,385	$ 20,642	$ 15,002	$ 56,566	$ 53,830	$ 61,581
Net investment income	5,520	6,260	5,014	5,398	5,373	6,312	5,157	5,326	5,326	5,644	12,636	6,782	22,192	22,168	30,388
Net gain (loss)	(1,040)	(7,009)	(12,378)	(4,551)	1,462	927	6,173	1,729	3,751	9,541	1,598	(43,632)	(24,978)	10,291	(28,742)
Net increase (decrease) in net assets resulting from operations	$ 4,480	$ (749)	$ (7,364)	$ 847	$ 6,835	$ 7,239	$ 11,330	$ 7,055	$ 9,077	$ 15,185	$ 14,234	$ (36,850)	$ (2,786)	$ 32,459	$ 1,646
Net investment income per share - basic	$ 0.25	$ 0.29	$ 0.23	$ 0.25	$ 0.25	$ 0.29	$ 0.24	$ 0.25	$ 0.25	$ 0.26	$ 0.61	$ 0.33	$ 1.02	$ 1.03	$ 1.45
Net investment income per share - diluted	0.25	0.29	0.23	0.25	0.25	0.29	0.24	0.25		0.26	0.61	0.33	1.02	1.03	1.45
Net increase (decrease) in net assets resulting from operations per share - basic	0.21	(0.03)	(0.34)	0.04	0.32	0.34	0.53	0.33	0.42	0.71	0.69	(1.81)	(0.13)	1.51	0.08
Net increase (decrease) in net assets resulting from operations per share - diluted	0.21	(0.03)	(0.34)	0.04	0.32		0.53	0.33	0.42	0.71	0.69	(1.81)	$ (0.13)	$ 1.51	$ 0.08
Net asset value per share at period end	$ 10.39	$ 10.43	$ 10.71	$ 11.30	$ 11.51	$ 11.45	$ 11.36	$ 11.08	$ 11	$ 10.83	$ 10.37	$ 10.04