Natural Resource Partners (NRP) 10-Q 5 Nov 20 2020 Q3 Quarterly report Financial data

Cover

Cover - shares	9 Months Ended
	Sep. 30, 2020	Nov. 04, 2020
Cover [Abstract]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Sep. 30, 2020
Document Transition Report	false
Entity File Number	001-31465
Entity Registrant Name	NATURAL RESOURCE PARTNERS LP
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	35-2164875
Entity Address, Address Line One	1201 Louisiana Street, Suite 3400
Entity Address, City or Town	Houston
Entity Address, State or Province	TX
Entity Address, Postal Zip Code	77002
City Area Code	713
Local Phone Number	751-7507
Title of 12(b) Security	Common Units representing limited partner interests
Trading Symbol	NRP
Security Exchange Name	NYSE
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		12,261,199
Amendment Flag	false
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	Q3
Entity Central Index Key	0001171486
Current Fiscal Year End Date	--12-31

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Current assets
Cash and cash equivalents	$ 115,573	$ 98,265
Accounts receivable, net	17,462	30,869
Other current assets, net	3,972	1,244
Current assets of discontinued operations	0	1,706
Total current assets	137,007	132,084
Land	24,008	24,008
Mineral rights, net	465,870	605,096
Intangible assets, net	17,601	17,687
Equity in unconsolidated investment	256,834	263,080
Long-term contract receivable, net	33,791	36,963
Other long-term assets, net	7,447	6,989
Total assets	942,558	1,085,907
Current liabilities
Accounts payable	1,372	1,179
Accrued liabilities	6,859	8,764
Accrued interest	9,273	2,316
Current portion of deferred revenue	11,035	4,608
Current portion of long-term debt, net	39,072	45,776
Current liabilities of discontinued operations	0	65
Total current liabilities	67,611	62,708
Deferred revenue	50,980	47,213
Long-term debt, net	452,401	470,422
Other non-current liabilities	5,020	4,949
Total liabilities	576,012	585,292
Commitments and contingencies (see Note 12)
Class A Convertible Preferred Units (250,000 units issued and outstanding at September 30, 2020 and December 31, 2019, at $1,000 par value per unit; liquidation preference of $1,700 per unit at September 30, 2020 and $1,500 per unit at December 31, 2019)	164,587	164,587
Partners’ capital
Common unitholders’ interest (12,261,199 units issued and outstanding at September 30, 2020 and December 31, 2019)	134,545	271,471
General partner’s interest	428	3,270
Warrant holders’ interest	66,816	66,816
Accumulated other comprehensive income (loss)	170	(2,594)
Total partners’ capital	201,959	338,963
Non-controlling interest	0	(2,935)
Total capital	201,959	336,028
Total liabilities and capital	$ 942,558	$ 1,085,907

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - $ / shares	Sep. 30, 2020	Dec. 31, 2019
Statement of Financial Position [Abstract]
Preferred Units, Issued	250,000	250,000
Preferred units outstanding (in shares)	250,000	250,000
Preferred unit par value per unit	$ 1,000	$ 1,000
Preferred unit liquidation preference per unit	$ 1,700	$ 1,500
Common units issued (in shares)	12,261,199	12,261,199
Common units outstanding (in shares)	12,261,199	12,261,199

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Revenues	$ 29,930	$ 57,602	$ 100,690	$ 205,610
Gain on asset sales and disposals	0	6,107	465	6,609
Total revenues and other income	29,930	63,709	101,155	212,219
Operating expenses
Operating and maintenance expenses	5,781	5,994	19,200	26,813
Depreciation, depletion and amortization	2,111	3,384	6,185	11,746
General and administrative expenses	3,634	4,253	11,168	12,799
Asset impairments	934	484	133,217	484
Total operating expenses	12,460	14,115	169,770	51,842
Income (loss) from operations	17,470	49,594	(68,615)	160,377
Other expenses, net
Interest expense, net	(10,254)	(10,431)	(30,891)	(37,061)
Loss on extinguishment of debt	0	0	0	(29,282)
Other Expenses	(10,254)	(10,431)	(30,891)	(66,343)
Net income (loss) from continuing operations	7,216	39,163	(99,506)	94,034
Income from discontinued operations	0	7	0	206
Net income (loss)	7,216	39,170	(99,506)	94,240
Less: income attributable to preferred unitholders	(7,500)	(7,500)	(22,613)	(22,500)
Net income (loss) attributable to common unitholders and general partner	(284)	31,670	(122,119)	71,740
Net income (loss) attributable to common unitholders	(279)	31,036	(119,677)	70,305
Net income (loss) attributable to the general partner	$ (5)	$ 634	$ (2,442)	$ 1,435
Income from continuing operations per common unit
Basic (in dollars per share)	$ (0.02)	$ 2.53	$ (9.76)	$ 5.72
Diluted (in dollars per share)	(0.02)	1.66	(9.76)	3.91
Net income per common unit
Basic (in dollars per share)	(0.02)	2.53	(9.76)	5.73
Diluted (in dollars per share)	$ (0.02)	$ 1.66	$ (9.76)	$ 3.92
Comprehensive income (loss) from unconsolidated investment and other	$ 2,428	$ (520)	$ 2,764	$ (340)
Comprehensive income (loss)	9,644	38,650	(96,742)	93,900
Coal Royalty and Other
Revenues	25,740	39,919	88,839	154,037
Soda Ash
Revenues	1,986	13,818	5,200	36,833
Transportation and processing services revenues | Coal Royalty and Other
Revenues	$ 2,204	$ 3,865	$ 6,651	$ 14,740

Consolidated Statements of Part

Consolidated Statements of Partners' Capital - USD ($) shares in Thousands, $ in Thousands		Total		General Partner		Common Unitholders		Warrant Holders	Accumulated Other Comprehensive Income (Loss)	Partners' Capital Excluding Non-Controlling Interest		Non-Controlling Interest	Common Unitholders	Common UnitholdersCommon Unitholders	Common unitholders and general partner	Common unitholders and general partnerPartners' Capital Excluding Non-Controlling Interest	General Partner	General PartnerGeneral Partner	Preferred Partner	Preferred PartnerGeneral Partner	Preferred PartnerCommon Unitholders	Preferred PartnerPartners' Capital Excluding Non-Controlling Interest
Balance, beginning of period (in units) at Dec. 31, 2018						12,249
Balance, beginning of period at Dec. 31, 2018		$ 420,546		$ 5,014		$ 355,113		$ 66,816	$ (3,462)	$ 423,481		$ (2,935)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income attributable to NRP	[1]			714		$ 35,005				35,719
Net income (loss)	[1]	35,719
Distributions to unitholders														$ (5,513)	$ (5,625)	$ (5,625)		$ (112)	$ (7,500)	$ (150)	$ (7,350)	$ (7,500)
Issuance of unit-based awards (units)						12
Issuance of unit-based awards		486				$ 486				486
Unit-based awards amortization and vesting		399				$ 399				399
Comprehensive loss from unconsolidated investment and other		1,015		10					1,005	1,015
Balance, end of period (in units) at Mar. 31, 2019						12,261
Balance, end of period at Mar. 31, 2019		445,040		5,476		$ 378,140		66,816	(2,457)	447,975		(2,935)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Income attributable to preferred unitholders		7,500											$ 7,350				$ 150
Balance, beginning of period (in units) at Dec. 31, 2018						12,249
Balance, beginning of period at Dec. 31, 2018		420,546		5,014		$ 355,113		66,816	(3,462)	423,481		(2,935)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)		94,240
Balance, end of period (in units) at Sep. 30, 2019						12,261
Balance, end of period at Sep. 30, 2019		466,254		5,909		$ 400,266		66,816	(3,802)	469,189		(2,935)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Income attributable to preferred unitholders		22,500
Balance, beginning of period (in units) at Mar. 31, 2019						12,261
Balance, beginning of period at Mar. 31, 2019		445,040		5,476		$ 378,140		66,816	(2,457)	447,975		(2,935)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income attributable to NRP				387	[1],[2]	18,964				19,351	[1]
Net income (loss)		19,351	[1]									0
Distributions to unitholders														(15,939)	(16,265)	(16,265)		(326)	(7,500)	(150)	(7,350)	(7,500)
Unit-based awards amortization and vesting		460				$ 460				460
Comprehensive loss from unconsolidated investment and other		(825)							(825)	(825)
Balance, end of period (in units) at Jun. 30, 2019						12,261
Balance, end of period at Jun. 30, 2019		440,261		5,387		$ 374,275		66,816	(3,282)	443,196		(2,935)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Income attributable to preferred unitholders		7,500											7,350				150
Net income attributable to NRP				784		38,386				39,170
Net income (loss)		39,170
Distributions to unitholders														(5,518)	(5,630)	(5,630)		(112)	(7,500)	(150)	(7,350)	(7,500)
Unit-based awards amortization and vesting		473				$ 473				473
Comprehensive loss from unconsolidated investment and other		(520)							(520)	(520)
Balance, end of period (in units) at Sep. 30, 2019						12,261
Balance, end of period at Sep. 30, 2019		466,254		5,909		$ 400,266		66,816	(3,802)	469,189		(2,935)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Income attributable to preferred unitholders		7,500											7,350				150
Balance, beginning of period (in units) at Dec. 31, 2019						12,261
Balance, beginning of period at Dec. 31, 2019		336,028		3,270		$ 271,471		66,816	(2,594)	338,963		(2,935)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income attributable to NRP				376		18,403				18,779	[3]
Net income (loss)	[3]	18,779
Distributions to unitholders														(5,517)	$ (5,630)	$ (5,630)		(113)	(7,500)	(150)	(7,350)	(7,500)
Unit-based awards amortization and vesting		673				$ 673				673
Comprehensive loss from unconsolidated investment and other		(1,023)							(1,023)	(1,023)
Balance, end of period (in units) at Mar. 31, 2020						12,261
Balance, end of period at Mar. 31, 2020		337,416		3,305		$ 273,847		66,816	(3,617)	340,351		(2,935)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Income attributable to preferred unitholders		7,500											7,350				150
Balance, beginning of period (in units) at Dec. 31, 2019						12,261
Balance, beginning of period at Dec. 31, 2019		336,028		3,270		$ 271,471		66,816	(2,594)	338,963		(2,935)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)		(99,506)
Balance, end of period (in units) at Sep. 30, 2020						12,261
Balance, end of period at Sep. 30, 2020		201,959		428		$ 134,545		66,816	170	201,959		0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Income attributable to preferred unitholders		22,613
Balance, beginning of period (in units) at Mar. 31, 2020						12,261
Balance, beginning of period at Mar. 31, 2020		337,416		3,305		$ 273,847		66,816	(3,617)	340,351		(2,935)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income attributable to NRP				(2,510)		(122,991)				(125,501)	[2]
Net income (loss)	[2]	(125,501)
Distributions to unitholders																			(7,613)	(152)	(7,461)	(7,613)
Acquisition of non-controlling interest in BRP		(1,909)		(97)		(4,747)				(4,844)		2,935
Unit-based awards amortization and vesting		869				$ 869				869
Comprehensive loss from unconsolidated investment and other		1,359							1,359	1,359
Balance, end of period (in units) at Jun. 30, 2020						12,261
Balance, end of period at Jun. 30, 2020		204,621		546		$ 139,517		66,816	(2,258)	204,621		0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Income attributable to preferred unitholders		7,600											7,460				150
Net income attributable to NRP				144	[3]	7,072	[3]			7,216
Net income (loss)		7,216
Distributions to unitholders														$ (5,518)				$ (112)	$ (5,630)	$ (150)	$ (7,350)	$ (5,630)
Acquisition of non-controlling interest in BRP		(7,500)								(7,500)
Unit-based awards amortization and vesting		824				$ 824				824
Comprehensive loss from unconsolidated investment and other		2,428							2,428	2,428
Balance, end of period (in units) at Sep. 30, 2020						12,261
Balance, end of period at Sep. 30, 2020		201,959		$ 428		$ 134,545		$ 66,816	$ 170	$ 201,959		$ 0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Income attributable to preferred unitholders		$ 7,500											$ 7,350				$ 150
[1]	Net income includes $7.5 million attributable to preferred unitholders that accumulated during the period, of which $7.35 million is allocated to the common unitholders and $0.15 million is allocated to the general partner.
[2]	Net loss includes $7.6 million attributable to preferred unitholders that accumulated during the period, of which $7.46 million is allocated to the common unitholders and $0.15 million is allocated to the general partner.
[3]	Net income includes $7.5 million attributable to preferred unitholders that accumulated during the period, of which $7.35 million is allocated to the common unitholders and $0.15 million is allocated to the general partner.

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019
Cash flows from operating activities
Net income (loss)	$ (99,506)	$ 94,240
Adjustments to reconcile net income (loss) to net cash provided by operating activities of continuing operations:
Depreciation, depletion and amortization	6,185	11,746
Distributions from unconsolidated investment	14,210	25,480
Gain on asset sales and disposals	(465)	(6,609)
Loss on extinguishment of debt	0	29,282
Income from discontinued operations	0	(206)
Asset impairments	133,217	484
Bad debt expense	3,915	6,842
Unit-based compensation expense	2,566	1,842
Amortization of debt issuance costs and other	491	3,223
Change in operating assets and liabilities:
Accounts receivable	7,994	(2,111)
Accounts payable	193	(822)
Accrued liabilities	(2,985)	(5,083)
Accrued interest	6,957	19
Deferred revenue	10,194	(3,920)
Other items, net	(3,353)	351
Net cash provided by operating activities of continuing operations	74,413	117,925
Net cash provided by (used in) operating activities of discontinued operations	1,706	(4)
Net cash provided by operating activities	76,119	117,921
Cash flows from investing activities
Proceeds from asset sales and disposals	507	6,611
Return of long-term contract receivable	1,462	1,351
Acquisition of non-controlling interest in BRP	1,000	0
Net cash provided by investing activities of continuing operations	969	7,962
Net cash used in investing activities of discontinued operations	(66)	(556)
Net cash provided by investing activities	903	7,406
Cash flows from financing activities
Debt borrowings	0	300,000
Debt repayments	(25,841)	(442,747)
Contributions from (to) discontinued operations	1,640	(560)
Debt issuance costs and other	0	26,427
Net cash used in financing activities of continuing operations	(58,074)	(219,754)
Net cash provided by (used in) financing activities of discontinued operations	(1,640)	560
Net cash used in financing activities	(59,714)	(219,194)
Net increase (decrease) in cash and cash equivalents	17,308	(93,867)
Cash and cash equivalents at beginning of period	98,265	206,030
Cash and cash equivalents at end of period	115,573	112,163
Supplemental cash flow information:
Cash paid during the period for interest	22,712	36,270
Plant, equipment, mineral rights and other funded with accounts payable or accrued liabilities	947	0
Ciner Wyoming
Adjustments to reconcile net income (loss) to net cash provided by operating activities of continuing operations:
Equity earnings from unconsolidated investment	5,200	36,833
General Partner
Cash flows from financing activities
Distributions to common unitholders and general partner	(11,260)	(27,520)
Preferred Partner
Cash flows from financing activities
Distributions to common unitholders and general partner	$ (22,613)	$ (22,500)

Basis of Presentation

Basis of Presentation	9 Months Ended
	Sep. 30, 2020
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation Nature of Business Natural Resource Partners L.P. (the "Partnership") engages principally in the business of owning, managing and leasing a diversified portfolio of mineral properties in the United States, including interests in coal and other natural resources and owns a non-controlling 49% interest in Ciner Wyoming LLC ("Ciner Wyoming"), a trona ore mining and soda ash production business. The Partnership is organized into two operating segments further described in Note 5. Segment Information . As used in these Notes to Consolidated Financial Statements, the terms "NRP," "we," "us" and "our" refer to Natural Resource Partners L.P. and its subsidiaries, unless otherwise stated or indicated by context. Principles of Consolidation and Reporting The accompanying unaudited Consolidated Financial Statements of the Partnership have been prepared in accordance with generally accepted accounting principles in the United States of America ("GAAP") for interim financial information and with Rule 10-01 of Regulation S-X. Accordingly, they do not include all of the information and footnotes required by GAAP for complete financial statements. These financial statements should be read in conjunction with the financial statements for the year ended December 31, 2019 and notes thereto included in the Partnership's Annual Report on Form 10-K, which was filed with the SEC on February 27, 2020. Recently Adopted Accounting Standards Credit Losses On January 1, 2020, the Partnership adopted ASU No. 2016-13, Financial Instruments—Credit Losses (Topic 326), and all the related amendments ("the new credit loss standard"). The Partnership recognized a $3.9 million cumulative effect of adoption in the opening balance of partners' capital on January 1, 2020 as a result of the adoption of the new credit loss standard. See Note 15. Credit Losses for more information.

Revenue from Contracts with Cus

Revenue from Contracts with Customers	9 Months Ended
	Sep. 30, 2020
Revenue from Contract with Customer [Abstract]
Revenue from Contracts with Customers	Revenues from Contracts with Customers The following table presents the Partnership's Coal Royalty and Other segment revenues by major source: For the Three Months Ended For the Nine Months Ended September 30, (In thousands) 2020 2019 2020 2019 Coal royalty revenues (1) $ 10,610 $ 24,727 $ 40,559 $ 87,561 Production lease minimum revenues (1) 4,267 2,752 13,554 21,331 Minimum lease straight-line revenues (1) 3,553 3,982 12,349 11,152 Property tax revenues 1,896 1,606 4,256 4,416 Wheelage revenues 1,680 1,675 5,468 5,035 Coal overriding royalty revenues 1,314 2,189 3,319 10,163 Lease amendment revenues 858 1,535 2,591 6,720 Aggregates royalty revenues 221 954 1,068 3,655 Oil and gas royalty revenues 1,078 374 4,923 2,575 Other revenues 263 125 752 1,429 Coal royalty and other revenues $ 25,740 $ 39,919 $ 88,839 $ 154,037 Transportation and processing services revenues (2) 2,204 3,865 6,651 14,740 Total coal royalty and other segment revenues $ 27,944 $ 43,784 $ 95,490 $ 168,777 (1) Effective January 1, 2020, certain revenues previously classified as coal royalty revenues are classified as production lease minimum revenues or minimum lease straight-line revenues due to contract modifications to certain leases that fixed consideration paid to the Partnership over a two year period. (2) Transportation and processing services revenues from contracts with customers as defined under ASC 606 was $1.2 million and $1.7 million for the three months ended September 30, 2020 and 2019, respectively and $3.7 million and $7.3 million for the nine months ended September 30, 2020 and 2019, respectively. The remaining transportation and processing services revenues of $1.0 million and $2.2 million for the three months ended September 30, 2020 and 2019, respectively, and $2.9 million and $7.5 million for the nine months ended September 30, 2020 and 2019, respectively, related to other NRP-owned infrastructure leased to and operated by third-party operators accounted for under other guidance. See Note 14. Financing Transaction for more information. The following table details the Partnership's Coal Royalty and Other segment receivables and liabilities resulting from contracts with customers: September 30, December 31, (In thousands) 2020 2019 Receivables Accounts receivable, net $ 15,371 $ 27,915 Other current assets, net (1) 3,696 90 Other long-term assets, net (2) 691 — Contract liabilities Current portion of deferred revenue $ 11,035 $ 4,608 Deferred revenue 50,980 47,213 (1) Other current assets, net includes short-term notes receivables from contracts with customers. (2) Other long-term assets, net includes long-term notes receivables from contracts with customers. The following table shows the activity related to the Partnership's Coal Royalty and Other segment deferred revenue: For the Nine Months Ended September 30, (In thousands) 2020 2019 Balance at beginning of period (current and non-current) $ 51,821 $ 52,553 Increase due to minimums and lease amendment fees 38,005 37,315 Recognition of previously deferred revenue (27,811) (41,234) Balance at end of period (current and non-current) $ 62,015 $ 48,634 The Partnership's non-cancelable annual minimum payments due under the lease terms of its coal and aggregates royalty and overriding royalty leases are as follows as of September 30, 2020 (in thousands): Lease Term (1) Weighted Average Remaining Years Annual Minimum Payments (2) 0 - 5 years 3.7 $ 14,792 5 - 10 years 5.7 7,478 10+ years 13.5 30,922 Total 9.3 $ 53,192 (1) Lease term does not include renewal periods. (2) Annual minimum payments do not include $40.0 million of annual fixed consideration owed to NRP in 2020 and 2021 resulting from contract modifications entered into during the second quarter of 2020. Additionally, $5.0 million of this $40.0 million annual fixed consideration amount relates to a coal infrastructure lease that is accounted for as a financing transaction. See Note 14. Financing Transaction

Common and Preferred Unit Distr

Common and Preferred Unit Distributions	9 Months Ended
	Sep. 30, 2020
Equity [Abstract]
Common and Preferred Unit Distributions	Common and Preferred Unit Distributions The Partnership makes cash distributions to common and preferred unitholders on a quarterly basis, subject to approval by the Board of Directors of GP Natural Resource Partners LLC (the "Board of Directors"). NRP recognizes both common unit and preferred unit distributions on the date the distribution is declared. Distributions made on the common units and the general partner's general partner ("GP") interest are made on a pro-rata basis in accordance with their relative percentage interests in the Partnership. The general partner is entitled to receive 2% of such distributions. Income (loss) available to common unitholders and the general partner is reduced by preferred unit distributions that accumulated during the period. NRP reduced net income (loss) available to common unitholders and the general partner by $7.5 million during the three months ended September 30, 2020 and 2019, and $22.6 million and $22.5 million during the nine months ended September 30, 2020 and 2019, respectively, as a result of accumulated preferred unit distributions earned during the period. In May 2020, the Partnership paid in kind one-half of the preferred unit distribution related to the three months ended March 31, 2020. In June 2020, the Partnership redeemed all of the outstanding preferred units paid in kind. The following table shows the cash distributions declared and paid to common and preferred unitholders during the nine months ended September 30, 2020 and 2019, respectively: Common Units Preferred Units Date Paid Period Covered by Distribution Distribution per Unit Total Distribution (1) (In thousands) Distribution per Unit Total Distribution 2020 February 2020 October 1 - December 31, 2019 $ 0.45 $ 5,630 $ 30.00 $ 7,500 May 2020 January 1 - March 31, 2020 — — 15.00 3,750 June 2020 (2) January 1 - March 31, 2020 — — 15.45 3,863 August 2020 April 1 - June 30, 2020 0.45 5,630 30.00 7,500 2019 February 2019 October 1 - December 31, 2018 $ 0.45 $ 5,625 $ 30.00 $ 7,500 May 2019 January 1 - March 31, 2019 0.45 5,630 30.00 7,500 May 2019 (3) Special Distribution 0.85 10,635 — — August 2019 April 1 - June 30, 2019 0.45 5,630 30.00 7,500 (1) Total common unit distribution includes the amount paid to NRP's general partner in accordance with the general partner's 2% general partner interest. (2) Redemption of preferred units paid in kind plus accrued interest. (3) Special distribution was made to cover the common unitholders’ tax liability resulting from the sale of NRP’s construction aggregates business in December 2018.

Net Income Per Common Unit

Net Income Per Common Unit	9 Months Ended
	Sep. 30, 2020
Earnings Per Share [Abstract]
Net Income Per Common Unit	Net Income (Loss) Per Common Unit Basic net income (loss) per common unit is computed by dividing net income (loss), after considering income attributable to preferred unitholders and the general partner’s general partner interest, by the weighted average number of common units outstanding. Diluted net income (loss) per common unit includes the effect of NRP's preferred units, warrants, and unvested unit-based awards if the inclusion of these items is dilutive. The dilutive effect of the preferred units is calculated using the if-converted method. Under the if-converted method, the preferred units are assumed to be converted at the beginning of the period, and the resulting common units are included in the denominator of the diluted net income (loss) per unit calculation for the period being presented. Distributions declared in the period and undeclared distributions on the preferred units that accumulated during the period are added back to the numerator for purposes of the if-converted calculation. The calculation of diluted net income (loss) per common unit for the three and nine months ended September 30, 2020 does not include the assumed conversion of the preferred units because the impact would have been anti-dilutive. The calculation of diluted net income per common unit for the three and nine months ended September 30, 2019 includes the assumed conversion of the preferred units. The dilutive effect of the warrants is calculated using the treasury stock method, which assumes that the proceeds from the exercise of these instruments are used to purchase common units at the average market price for the period. The calculation of diluted net income (loss) per common unit for the three and nine months ended September 30, 2020 did not include the net settlement of warrants to purchase 1.75 million common units at a strike price of $22.81 or the net settlement of warrants to purchase 2.25 million common units with a strike price of $34.00 because the impact would have been anti-dilutive. The calculation of the dilutive effect of the warrants for the three months ended September 30, 2019 includes the net settlement of warrants to purchase 1.75 million common units with a strike price of $22.81 but did not include the net settlement of warrants to purchase 2.25 million common units with a strike price of $34.00 because the impact would have been anti-dilutive. The calculation of the dilutive effect of the warrants for the nine months ended September 30, 2019 includes both the net settlement of warrants to purchase 1.75 million common units with a strike price of $22.81 and the net settlement of warrants to purchase 2.25 million common units with a strike price of $34.00. The following tables reconcile the numerator and denominator of the basic and diluted net income (loss) per common unit computations and calculates basic and diluted net income (loss) per common unit: For the Three Months Ended For the Nine Months Ended September 30, (In thousands, except per unit data) 2020 2019 2020 2019 Allocation of net income (loss) Net income (loss) from continuing operations $ 7,216 $ 39,163 $ (99,506) $ 94,034 Less: income attributable to preferred unitholders (7,500) (7,500) (22,613) (22,500) Net income (loss) from continuing operations attributable to common unitholders and general partner $ (284) $ 31,663 $ (122,119) $ 71,534 Add (less): net loss (income) from continuing operations attributable to the general partner 5 (634) 2,442 (1,431) Net income (loss) from continuing operations attributable to common unitholders $ (279) $ 31,029 $ (119,677) $ 70,103 Net income from discontinued operations $ — $ 7 $ — $ 206 Less: net income from discontinued operations attributable to the general partner — — — (4) Net income from discontinued operations attributable to common unitholders $ — $ 7 $ — $ 202 Net income (loss) $ 7,216 $ 39,170 $ (99,506) $ 94,240 Less: income attributable to preferred unitholders (7,500) (7,500) (22,613) (22,500) Net income (loss) attributable to common unitholders and general partner $ (284) $ 31,670 $ (122,119) $ 71,740 Add (less): net loss (income) attributable to the general partner 5 (634) 2,442 (1,435) Net income (loss) attributable to common unitholders $ (279) $ 31,036 $ (119,677) $ 70,305 Basic net income (loss) per common unit Weighted average common units—basic 12,261 12,261 12,261 12,259 Basic net income (loss) from continuing operations per common unit $ (0.02) $ 2.53 $ (9.76) $ 5.72 Basic net income from discontinued operations per common unit $ 0.00 $ 0.00 $ 0.00 $ 0.02 Basic net income (loss) per common unit $ (0.02) $ 2.53 $ (9.76) $ 5.73 For the Three Months Ended For the Nine Months Ended September 30, (In thousands, except per unit data) 2020 2019 2020 2019 Diluted income (loss) per common unit Weighted average common units—basic 12,261 12,261 12,261 12,259 Plus: dilutive effect of preferred units — 10,494 — 10,494 Plus: dilutive effect of warrants — 389 — 800 Plus: dilutive effect of unvested unit-based awards — 13 — 31 Weighted average common units—diluted 12,261 23,157 12,261 23,584 Net income (loss) from continuing operations $ 7,216 $ 39,163 $ (99,506) $ 94,034 Less: income attributable to preferred unitholders (7,500) — (22,613) — Diluted net income (loss) from continuing operations attributable to common unitholders and general partner $ (284) $ 39,163 $ (122,119) $ 94,034 Add (less): diluted net loss (income) from continuing operations attributable to the general partner 5 (784) 2,442 (1,881) Diluted net income (loss) from continuing operations attributable to common unitholders $ (279) $ 38,379 $ (119,677) $ 92,153 Diluted net income from discontinued operations attributable to common unitholders $ — $ 7 $ — $ 202 Net income (loss) $ 7,216 $ 39,170 $ (99,506) $ 94,240 Less: income attributable to preferred unitholders (7,500) — (22,613) — Diluted net income (loss) attributable to common unitholders and general partner $ (284) $ 39,170 $ (122,119) $ 94,240 Add (less): diluted net loss (income) attributable to the general partner 5 (784) 2,442 (1,885) Diluted net income (loss) attributable to common unitholders $ (279) $ 38,386 $ (119,677) $ 92,355 Diluted net income (loss) from continuing operations per common unit $ (0.02) $ 1.66 $ (9.76) $ 3.91 Diluted net income from discontinued operations per common unit $ 0.00 $ 0.00 $ 0.00 $ 0.01 Diluted net income (loss) per common unit $ (0.02) $ 1.66 $ (9.76) $ 3.92

Segment Information

Segment Information	9 Months Ended
	Sep. 30, 2020
Segment Reporting [Abstract]
Segment Information	Segment Information The Partnership's segments are strategic business units that offer distinct products and services to different customers in different geographies within the U.S. and that are managed accordingly. NRP has the following two operating segments: Coal Royalty and Other —consists primarily of coal royalty properties and coal-related transportation and processing assets. Other assets include industrial mineral royalty properties, aggregates royalty properties, oil and gas royalty properties and timber. The Partnership's coal reserves are primarily located in Appalachia, the Illinois Basin and the Northern Powder River Basin in the United States. The Partnership's industrial minerals and aggregates properties are located in various states across the United States. The Partnership's oil and gas royalty assets are primarily located in Louisiana and its timber assets are primarily located in West Virginia. Soda Ash —consists of the Partnership's 49% non-controlling equity interest in Ciner Wyoming, a trona ore mining operation and soda ash refinery in the Green River Basin of Wyoming. Ciner Resources LP, the Partnership's operating partner, mines the trona, processes it into soda ash, and distributes the soda ash both domestically and internationally to the glass and chemicals industries. Direct segment costs and certain other costs incurred at the corporate level that are identifiable and that benefit the Partnership's segments are allocated to the operating segments accordingly. These allocated costs generally include salaries and benefits, insurance, property taxes, legal, royalty, information technology and shared facilities services and are included in operating and maintenance expenses on the Partnership's Consolidated Statements of Comprehensive Income (Loss). Corporate and Financing includes functional corporate departments that do not earn revenues. Costs incurred by these departments include interest and financing, corporate headquarters and overhead, centralized treasury, legal and accounting and other corporate-level activity not specifically allocated to a segment and are included in general and administrative expenses on the Partnership's Consolidated Statements of Comprehensive Income (Loss). The following table summarizes certain financial information for each of the Partnership's business segments: Operating Segments (In thousands) Coal Royalty and Other Soda Ash Corporate and Financing Total For the Three Months Ended September 30, 2020 Revenues $ 27,944 $ 1,986 $ — $ 29,930 Operating and maintenance expenses 5,685 96 — 5,781 Depreciation, depletion and amortization 2,111 — — 2,111 General and administrative expenses — — 3,634 3,634 Asset impairments 934 — — 934 Other expenses, net 41 — 10,213 10,254 Net income (loss) from continuing operations 19,173 1,890 (13,847) 7,216 For the Three Months Ended September 30, 2019 Revenues $ 43,784 $ 13,818 $ — $ 57,602 Gain on asset sales and disposals 6,107 — — 6,107 Operating and maintenance expenses 5,771 223 — 5,994 Depreciation, depletion and amortization 3,384 — — 3,384 General and administrative expenses — — 4,253 4,253 Asset impairments 484 — — 484 Other expenses, net — — 10,431 10,431 Net income (loss) from continuing operations 40,252 13,595 (14,684) 39,163 Income from discontinued operations — — — 7 For the Nine Months Ended September 30, 2020 Revenues $ 95,490 $ 5,200 $ — $ 100,690 Gain on asset sales and disposals 465 — — 465 Operating and maintenance expenses 19,059 141 — 19,200 Depreciation, depletion and amortization 6,185 — — 6,185 General and administrative expenses — — 11,168 11,168 Asset impairments 133,217 — — 133,217 Other expenses, net 56 — 30,835 30,891 Net income (loss) from continuing operations (62,562) 5,059 (42,003) (99,506) For the Nine Months Ended September 30, 2019 Revenues $ 168,777 $ 36,833 $ — $ 205,610 Gain on asset sales and disposals 6,609 — — 6,609 Operating and maintenance expenses 26,590 223 — 26,813 Depreciation, depletion and amortization 11,746 — — 11,746 General and administrative expenses — — 12,799 12,799 Asset impairments 484 — — 484 Other expenses, net — — 66,343 66,343 Net income (loss) from continuing operations 136,566 36,610 (79,142) 94,034 Income from discontinued operations — — — 206

Equity Investment

Equity Investment	9 Months Ended
	Sep. 30, 2020
Equity Method Investments and Joint Ventures [Abstract]
Equity Investment	Equity Investment The Partnership accounts for its 49% investment in Ciner Wyoming using the equity method of accounting. Activity related to this investment is as follows: For the Three Months Ended For the Nine Months Ended September 30, (In thousands) 2020 2019 2020 2019 Balance at beginning of period $ 252,420 $ 251,135 $ 263,080 $ 247,051 Income allocation to NRP’s equity interests 3,004 15,068 8,450 40,511 Amortization of basis difference (1,018) (1,250) (3,250) (3,678) Other comprehensive income (loss) 2,428 (520) 2,764 (341) Distribution — (6,370) (14,210) (25,480) Balance at end of period $ 256,834 $ 258,063 $ 256,834 $ 258,063 The following table represents summarized financial information for Ciner Wyoming as derived from their respective unaudited financial statements for the three and nine months ended September 30, 2020 and 2019: For the Three Months Ended For the Nine Months Ended September 30, (In thousands) 2020 2019 2020 2019 Net sales $ 98,197 $ 137,148 $ 288,804 $ 397,378 Gross profit 11,704 36,747 35,363 103,382 Net income 6,130 30,750 17,245 82,675

Mineral Rights, Net

Mineral Rights, Net	9 Months Ended
	Sep. 30, 2020
Extractive Industries [Abstract]
Mineral Rights, Net	Mineral Rights, Net The Partnership’s mineral rights consist of the following: September 30, 2020 December 31, 2019 (In thousands) Carrying Value Accumulated Depletion Net Book Value Carrying Value Accumulated Depletion Net Book Value Coal properties $ 798,870 $ (354,843) $ 444,027 $ 981,352 $ (420,448) $ 560,904 Aggregates properties 9,102 (2,741) 6,361 41,486 (13,357) 28,129 Oil and gas royalty properties 12,354 (8,416) 3,938 12,395 (7,887) 4,508 Other 13,156 (1,612) 11,544 13,156 (1,601) 11,555 Total mineral rights, net $ 833,482 $ (367,612) $ 465,870 $ 1,048,389 $ (443,293) $ 605,096 Depletion expense related to the Partnership’s mineral rights is included in depreciation, depletion and amortization on its Consolidated Statements of Comprehensive Income (Loss) and totaled $2.1 million and $2.8 million for the three months ended September 30, 2020 and 2019, respectively, and $6.0 million and $9.5 million for the nine months ended September 30, 2020 and 2019, respectively. The Partnership recorded $0.9 million and $133.2 million of expense to fully impair certain properties during the three and nine months ended September 30, 2020, respectively, primarily related to weakened coal markets that resulted in termination of certain coal leases, changes to lessee mine plans resulting in permanent moves off certain of our coal properties and decreased oil and gas drilling activity which negatively impacted the outlook for NRP's frac sand properties. The Partnership has developed procedures to evaluate its long-lived assets for possible impairment periodically or whenever events or changes in circumstances indicate an asset's net book value may not be recoverable. Potential events or circumstances include, but are not limited to, specific events such as a reduction in economically recoverable reserves or production ceasing on a property for an extended period. This analysis is based on historic, current and future performance and considers both quantitative and qualitative information. While the Partnership's impairment evaluation as of September 30, 2020 incorporated an estimated impact of the global COVID-19 pandemic, there is significant uncertainty as to the severity and duration of this disruption. If the impact is worse than we currently estimate, an additional impairment charge may be recognized in future periods.

Debt, Net

Debt, Net	9 Months Ended
	Sep. 30, 2020
Debt Disclosure [Abstract]
Debt, Net	Debt, Net The Partnership's debt consists of the following: September 30, December 31, (In thousands) 2020 2019 NRP LP debt: 9.125% senior notes, with semi-annual interest payments in June and December, due June 2025, issued at par ("2025 Senior Notes") $ 300,000 $ 300,000 Opco debt: Revolving credit facility $ — $ — Senior Notes 5.05% with semi-annual interest payments in January and July, with annual principal payments in July, due July 2020 $ — $ 6,780 5.55% with semi-annual interest payments in June and December, with annual principal payments in June, due June 2023 7,094 9,458 4.73% with semi-annual interest payments in June and December, with annual principal payments in December, due December 2023 24,016 24,016 5.82% with semi-annual interest payments in March and September, with annual principal payments in March, due March 2024 50,738 63,423 8.92% with semi-annual interest payments in March and September, with annual principal payments in March, due March 2024 16,047 20,059 5.03% with semi-annual interest payments in June and December, with annual principal payments in December, due December 2026 79,945 79,945 5.18% with semi-annual interest payments in June and December, with annual principal payments in December, due December 2026 20,375 20,375 Total Opco Senior Notes $ 198,215 $ 224,056 Total debt at face value $ 498,215 $ 524,056 Net unamortized debt issuance costs (6,742) (7,858) Total debt, net $ 491,473 $ 516,198 Less: current portion of long-term debt (39,072) (45,776) Total long-term debt, net $ 452,401 $ 470,422 NRP LP Debt 2025 Senior Notes The 2025 Senior Notes were issued under an Indenture dated as of April 29, 2019 (the "2025 Indenture"), bear interest at 9.125% per year and mature on June 30, 2025. Interest is payable semi-annually on June 30 and December 30. NRP and NRP Finance have the option to redeem the 2025 Senior Notes, in whole or in part, at any time on or after October 30, 2021, at the redemption prices (expressed as percentages of principal amount) of 104.563% for the 12-month period beginning October 30, 2021, 102.281% for the 12-month period beginning October 30, 2022, and thereafter at 100.000%, together, in each case, with any accrued and unpaid interest to the date of redemption. Furthermore, before October 30, 2021, NRP may on any one or more occasions redeem up to 35% of the aggregate principal amount of the 2025 Senior Notes with the net proceeds of certain public or private equity offerings at a redemption price of 109.125% of the principal amount of 2025 Senior Notes, plus any accrued and unpaid interest, if any, to the date of redemption, if at least 65% of the aggregate principal amount of the 2025 Senior Notes issued under the 2025 Indenture remains outstanding immediately after such redemption and the redemption occurs within 180 days of the closing date of such equity offering. In the event of a change of control, as defined in the 2025 Indenture, the holders of the 2025 Senior Notes may require us to purchase their 2025 Senior Notes at a purchase price equal to 101% of the principal amount of the 2025 Senior Notes, plus accrued and unpaid interest, if any. The 2025 Senior Notes were issued at par. The 2025 Senior Notes are the senior unsecured obligations of NRP and NRP Finance. The 2025 Senior Notes rank equal in right of payment to all existing and future senior unsecured debt of NRP and NRP Finance and senior in right of payment to any of NRP's subordinated debt. The 2025 Senior Notes are effectively subordinated in right of payment to all future secured debt of NRP and NRP Finance to the extent of the value of the collateral securing such indebtedness and are structurally subordinated in right of payment to all existing and future debt and other liabilities of our subsidiaries, including the Opco Credit Facility and each series of Opco’s existing senior notes. None of NRP's subsidiaries guarantee the 2025 Senior Notes. As of September 30, 2020 and December 31, 2019, NRP and NRP Finance were in compliance with the terms of the Indenture relating to their 2025 Senior Notes. 2022 Senior Notes During the second quarter of 2019, the Partnership redeemed the 2022 Senior Notes at a redemption price equal to 105.250% of the principal amount of the 2022 Senior Notes, plus accrued and unpaid interest. In connection with the early redemption, the Partnership paid an $18.1 million call premium and wrote off $10.4 million of unamortized debt issuance costs and debt discount. These expenses are included in loss on extinguishment of debt on the Partnership's Consolidated Statements of Comprehensive Income (Loss). Opco Debt All of Opco’s debt is guaranteed by its wholly owned subsidiaries and is secured by certain of the assets of Opco and its wholly owned subsidiaries other than NRP Trona LLC. As of September 30, 2020 and December 31, 2019, Opco was in compliance with the terms of the financial covenants contained in its debt agreements. Opco Credit Facility In April 2019, the Partnership entered into the Fourth Amendment (the “Fourth Amendment”) to the Opco Credit Facility (the "Opco Credit Facility"). The Fourth Amendment extended the term of the Opco Credit Facility until April 2023. Lender commitments under the Opco Credit Facility remain at $100.0 million. The Opco Credit Facility contains financial covenants requiring Opco to maintain: • A leverage ratio of consolidated indebtedness to EBITDDA (as defined in the Opco Credit Facility) not to exceed 4.0x; provided, however, that if the Partnership increases its quarterly distribution to its common unitholders above $0.45 per common unit, the maximum leverage ratio under the Opco Credit Facility will permanently decrease from 4.0x to 3.0x; and • a fixed charge coverage ratio of consolidated EBITDDA to consolidated fixed charges (consisting of consolidated interest expense and consolidated lease expense) of not less than 3.5 to 1.0. During the three and nine months ended September 30, 2020 and 2019, the Partnership did not have any borrowings outstanding under the Opco Credit Facility and had $100 million in available borrowing capacity at both September 30, 2020 and December 31, 2019. The Opco Credit Facility is collateralized and secured by liens on certain of Opco’s assets with carrying values of $366.8 million and $399.7 million classified as mineral rights, net and other long-term assets, net on the Partnership’s Consolidated Balance Sheets as of September 30, 2020 and December 31, 2019, respectively. Opco Senior Notes Opco has issued several series of private placement senior notes (the "Opco Senior Notes") with various interest rates and principal due dates. As of September 30, 2020 and December 31, 2019, the Opco Senior Notes had cumulative principal balances of $198.2 million and $224.1 million, respectively. Opco made mandatory principal payments of $25.8 million during the nine months ended September 30, 2020 and $97.1 million during the nine months ended September 30, 2019, which included a $49.3 million pre-payment as a result of the sale of the Partnership's construction aggregates business.

Fair Value Measurements

Fair Value Measurements	9 Months Ended
	Sep. 30, 2020
Fair Value Disclosures [Abstract]
Fair Value Measurements	Fair Value Measurements Fair Value of Financial Assets and Liabilities The Partnership’s financial assets and liabilities consist of cash and cash equivalents, a contract receivable and debt. The carrying amounts reported on the Consolidated Balance Sheets for cash and cash equivalents approximate fair value due to their short-term nature. The Partnership uses available market data and valuation methodologies to estimate the fair value of its debt and contract receivable. The following table shows the carrying value and estimated fair value of the Partnership's debt and contract receivable: September 30, 2020 December 31, 2019 (In thousands) Fair Value Hierarchy Level Carrying Estimated Carrying Estimated Debt: NRP 2025 Senior Notes 1 $ 294,891 $ 263,250 $ 294,084 $ 269,250 Opco Senior Notes (1) 3 196,582 173,934 222,114 201,090 Opco Credit Facility 3 — — — — Assets: Contract receivable (current and long-term) (2) 3 $ 35,800 $ 27,255 $ 38,945 $ 33,460 (1) The fair value of the Opco Senior Notes are estimated by management using quotations obtained for the NRP 2025 Senior Notes on the closing trading prices near period end, which were at 88% of par value at September 30, 2020. (2) The fair value of the Partnership's contract receivable is determined based on the present value of future cash flow projections related to the underlying asset at a discount rate of 15% at September 30, 2020. NRP has embedded derivatives in the preferred units related to certain conversion options, redemption features and the change of control provision that are accounted for separately from the preferred units as assets and liabilities at fair value on the Partnership's Consolidated Balance Sheets. Level 3 valuation of the embedded derivatives are based on numerous factors including the likelihood of the event occurring. The embedded derivatives are revalued quarterly and changes in their fair value would be recorded in other expenses, net on the Partnership's Consolidated Statements of Comprehensive Income (Loss). The embedded derivatives had zero value as of September 30, 2020 and December 31, 2019.

Related Party Transactions

Related Party Transactions	9 Months Ended
	Sep. 30, 2020
Related Party Transactions [Abstract]
Related Party Transactions	Related Party Transactions Affiliates of our General Partner The Partnership’s general partner does not receive any management fee or other compensation for its management of NRP. However, in accordance with the partnership agreement, the general partner and its affiliates are reimbursed for services provided to the Partnership and for expenses incurred on the Partnership’s behalf. Employees of Quintana Minerals Corporation ("QMC") and Western Pocahontas Properties Limited Partnership ("WPPLP"), affiliates of the Partnership, provide their services to manage the Partnership's business. QMC and WPPLP charge the Partnership the portion of their employee salary and benefits costs related to their employee services provided to NRP. These QMC and WPPLP employee management service costs are presented as operating and maintenance expenses and general and administrative expenses on the Partnership's Consolidated Statements of Comprehensive Income (Loss). NRP also reimburses overhead costs incurred by its affiliates to manage the Partnership's business. These overhead costs include certain rent, information technology, administration of employee benefits and other corporate services incurred by or on behalf of the Partnership’s general partner and its affiliates and are presented as operating and maintenance expenses and general and administrative expenses on the Partnership's Consolidated Statements of Comprehensive Income (Loss). Direct general and administrative expenses charged to the Partnership by QMC and WPPLP are included on the Partnership's Consolidated Statement of Comprehensive Income (Loss) as follows: For the Three Months Ended For the Nine Months Ended September 30, (In thousands) 2020 2019 2020 2019 Operating and maintenance expenses $ 1,562 $ 1,598 $ 4,729 $ 4,806 General and administrative expenses 878 855 2,657 2,704 The Partnership had accounts payable to QMC of $0.4 million at both September 30, 2020 and December 31, 2019 and $0.2 million and $0.1 million to WPPLP on its Consolidated Balance Sheets at September 30, 2020 and December 31, 2019, respectively. During the three months ended September 30, 2020 and 2019, the Partnership recognized $0.2 million and $0.3 million in operating and maintenance expenses, respectively, on its Consolidated Statements of Comprehensive Income (Loss) related to an overriding royalty agreement with WPPLP. These amounts were $0.3 million and $3.8 million during the nine months ended September 30, 2020 and 2019, respectively. At September 30, 2020, the Partnership had $0.4 million of other long-term assets on its Consolidated Balance Sheet related to a prepaid royalty for this agreement and at December 31, 2019, the Partnership had $0.1 million of accounts payable to WPPLP related to this agreement. Industrial Minerals Group LLC Corbin J. Robertson, III, a Director of GP Natural Resource Partners LLC, owned a minority ownership interest in Industrial Minerals Group LLC (“Industrial Minerals”), which, through its subsidiaries, leases two of NRP's coal royalty properties in Central Appalachia. As of December 31, 2019, Mr. Robertson no longer held an equity interest in Industrial Minerals; accordingly, revenues are no longer classified as related party revenues as of such date. Coal royalty related revenues from Industrial Minerals totaled $0.4 million and $0.9 million for the three and nine months ended September 30, 2019, respectively. The Partnership had accounts receivable from Industrial Minerals of $0.7 million on its Consolidated Balance Sheet as of December 31, 2019. Quinwood Coal Company In May 2017, a subsidiary of Alpha Natural Resources assigned two coal leases with us to Quinwood Coal Company ("Quinwood"), an entity wholly owned by Corbin J. Robertson III. Coal related revenues from Quinwood totaled $0.0 million and $0.2 million for the three and nine months ended September 30, 2019, respectively.

Major Customers

Major Customers	9 Months Ended
	Sep. 30, 2020
Risks and Uncertainties [Abstract]
Major Customers	Major Customers Revenues from customers that exceeded 10 percent of total revenues for any of the periods presented below are as follows: For the Three Months Ended September 30, For the Nine Months Ended September 30, 2020 2019 2020 2019 (In thousands) Revenues Percent Revenues Percent Revenues Percent Revenues Percent Foresight Energy (1) (2) $ 8,592 29 % $ 12,375 21 % $ 27,052 27 % $ 44,604 22 % Contura Energy (1) 7,143 24 % 9,190 16 % 23,164 23 % 32,915 16 % (1) Revenues from Foresight Energy and Contura Energy are included within the Partnership's Coal Royalty and Other segment. (2) In June 2020, the Partnership entered into lease amendments with Foresight Energy pursuant to which Foresight agreed to pay NRP fixed cash payments to satisfy all obligations arising out of the existing various coal mining leases and transportation infrastructure fee agreements between the Partnership and Foresight Energy for calendar years 2020 and 2021.

Commitments and Contingencies

Commitments and Contingencies	9 Months Ended
	Sep. 30, 2020
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies NRP is involved, from time to time, in various legal proceedings arising in the ordinary course of business. While the ultimate results of these proceedings cannot be predicted with certainty, Partnership management believes these ordinary course matters will not have a material effect on the Partnership’s financial position, liquidity or operations.

Unit-Based Compensation

Unit-Based Compensation	9 Months Ended
	Sep. 30, 2020
Unit-Based Compensation [Abstract]
Unit-Based Compensation	Unit-Based Compensation The Partnership's unit-based awards granted in 2020 and 2019 were valued using the closing price of NRP's units as of the grant date. The grant date fair value of these awards granted during the nine months ended September 30, 2020 and 2019 were $3.5 million and $5.4 million, respectively. Total unit-based compensation expense associated with these awards was $0.9 million and $0.5 million for the three months ended September 30, 2020 and 2019, respectively, and $2.6 million and $1.8 million for the nine months ended September 30, 2020 and 2019, respectively, and is included in general and administrative expenses and operating and maintenance expenses on the Partnership's Consolidated Statements of Comprehensive Income (Loss). The unamortized cost associated with unvested outstanding awards as of September 30, 2020 is $4.4 million, which is to be recognized over a weighted average period of 1.8 years. The unamortized cost associated with unvested outstanding awards as of December 31, 2019 was $3.5 million. A summary of the unit activity in the outstanding grants during 2020 is as follows: (In thousands) Common Units Weighted Average Exercise Price Outstanding at January 1, 2020 157 $ 37.48 Granted 203 $ 17.20 Fully vested and issued — $ — Forfeitures (5) $ 17.20 Outstanding at September 30, 2020 355 $ 26.20

Credit Losses

Credit Losses	9 Months Ended
	Sep. 30, 2020
Credit Losses [Abstract]
Credit Losses	Credit Losses The Partnership is exposed to credit losses through collection of its trade receivables resulting from contracts with customers and a long-term receivable resulting from a financing transaction with a customer. The Partnership records an allowance for current expected credit losses on these receivables based on the loss-rate method. NRP assessed the likelihood of collection of its receivables utilizing historical loss rates, current market conditions that included the estimated impact of the global COVID-19 pandemic, industry and macroeconomic factors, reasonable and supportable forecasts and facts or circumstances of individual customers and properties. Examples of these facts or circumstances include, but are not limited to, contract disputes or renegotiations with the customer and evaluation of short and long-term economic viability of the contracted property. For its long-term contract receivable, management reverts to the historical loss experience immediately after the reasonable and supportable forecast period ends. As of September 30, 2020, NRP recorded the following current expected credit loss (“CECL”) related to its receivables and long-term contract receivable: (In thousands) Gross CECL Allowance Net Receivables $ 24,172 $ (2,324) $ 21,848 Long-term contract receivable 35,370 (1,579) 33,791 Total $ 59,542 $ (3,903) $ 55,639 NRP recorded $0.3 million and $0.0 million in operating and maintenance expenses on its Consolidated Statement of Comprehensive Income (Loss) related to the change in CECL allowance during the three and nine months ended September 30, 2020, respectively. In addition, the Partnership recorded $0.0 million and $3.9 million of bad debt expense due to balances deemed to be non-collectible in the three and nine months ended September 30, 2020, respectively. NRP has procedures in place to monitor its ongoing credit exposure through timely review of counterparty balances against contract terms and due dates, account and financing receivable reconciliations, bankruptcy monitoring, lessee audits and dispute resolution. The Partnership may employ legal counsel or collection specialists to pursue recovery of defaulted receivables.

Financing Transaction

Financing Transaction	9 Months Ended
	Sep. 30, 2020
Financing Transaction [Abstract]
Financing Transaction	Financing Transaction The Partnership owns rail loadout and associated infrastructure at the Sugar Camp mine in the Illinois Basin operated by a subsidiary of Foresight Energy. The infrastructure at the Sugar Camp mine is leased to a subsidiary of Foresight Energy and is accounted for as a financing transaction (the "Sugar Camp lease"). The Sugar Camp lease expires in 2032 with renewal options for up to 80 additional years. Minimum payments are $5.0 million per year through the end of the lease term. The $5.0 million due to the Partnership in 2020 and 2021 is included in the fixed cash payments from Foresight Energy resulting from contract modifications entered into during the second quarter of 2020 as discussed in Note 11. Major Customers . The Partnership is also entitled to variable payments in the form of throughput fees determined based on the amount of coal transported and processed utilizing the Partnership's assets. In the event the Sugar Camp lease is renewed beyond 2032, payments become a fixed $10 thousand per year for the remainder of the renewed term. The following table shows certain amounts related to the Partnership's Sugar Camp lease through 2032: September 30, December 31, (In thousands) 2020 2019 Accounts receivable, net $ — $ 540 Contract receivable, net (current and long-term) 35,800 38,945 Unearned income 19,704 21,889 Projected remaining payments, net $ 55,504 $ 61,374

Leases

Leases	9 Months Ended
	Sep. 30, 2020
Leases [Abstract]
Leases	Leases Lessee Accounting As of September 30, 2020, the Partnership had one operating lease for an office building that is owned by WPPLP. On January 1, 2019, the Partnership entered into a new lease of the building with a five-year base term and five additional five-year renewal options. Upon lease commencement and as of September 30, 2020, the Partnership was reasonably certain to exercise all renewal options included in the lease and capitalized the right-of-use asset and corresponding lease liability on its Consolidated Balance Sheets using the present value of the future lease payments over 30 years. The Partnership's right-of-use asset and lease liability included within other long-term assets, net and other non-current liabilities, respectively, on its Consolidated Balance Sheets totaled $3.5 million at both September 30, 2020 and December 31, 2019. During the three and nine months ended September 30, 2020 and 2019, the Partnership incurred total operating lease expense of $0.1 million and $0.4 million, respectively, included in both operating and maintenance expenses and general and administrative expenses on its Consolidated Statements of Comprehensive Income (Loss). The following table details the maturity analysis of the Partnership's operating lease liability and reconciles the undiscounted cash flows to the operating lease liability included on its Consolidated Balance Sheet: Remaining Annual Lease Payments (In thousands) As of September 30, 2020 2020 $ 121 2021 483 2022 483 2023 483 2024 483 After 2024 11,597 Total lease payments (1) $ 13,650 Less: present value adjustment (2) (10,150) Total operating lease liability $ 3,500 (1) The remaining lease term of the Partnership's operating lease is 28.25 years. (2) The present value of the operating lease liability on the Partnership's Consolidated Balance Sheets was calculated using a 13.5% discount rate which represents the Partnership's estimated incremental borrowing rate under the lease. As the Partnership's lease does not provide an implicit rate, the Partnership estimated the incremental borrowing rate at the time the lease was entered into by utilizing the rate of the Partnership's secured debt and adjusting it for factors that reflect the profile of borrowing over the 30-year expected lease term.
Leases	Leases Lessee Accounting As of September 30, 2020, the Partnership had one operating lease for an office building that is owned by WPPLP. On January 1, 2019, the Partnership entered into a new lease of the building with a five-year base term and five additional five-year renewal options. Upon lease commencement and as of September 30, 2020, the Partnership was reasonably certain to exercise all renewal options included in the lease and capitalized the right-of-use asset and corresponding lease liability on its Consolidated Balance Sheets using the present value of the future lease payments over 30 years. The Partnership's right-of-use asset and lease liability included within other long-term assets, net and other non-current liabilities, respectively, on its Consolidated Balance Sheets totaled $3.5 million at both September 30, 2020 and December 31, 2019. During the three and nine months ended September 30, 2020 and 2019, the Partnership incurred total operating lease expense of $0.1 million and $0.4 million, respectively, included in both operating and maintenance expenses and general and administrative expenses on its Consolidated Statements of Comprehensive Income (Loss). The following table details the maturity analysis of the Partnership's operating lease liability and reconciles the undiscounted cash flows to the operating lease liability included on its Consolidated Balance Sheet: Remaining Annual Lease Payments (In thousands) As of September 30, 2020 2020 $ 121 2021 483 2022 483 2023 483 2024 483 After 2024 11,597 Total lease payments (1) $ 13,650 Less: present value adjustment (2) (10,150) Total operating lease liability $ 3,500 (1) The remaining lease term of the Partnership's operating lease is 28.25 years. (2) The present value of the operating lease liability on the Partnership's Consolidated Balance Sheets was calculated using a 13.5% discount rate which represents the Partnership's estimated incremental borrowing rate under the lease. As the Partnership's lease does not provide an implicit rate, the Partnership estimated the incremental borrowing rate at the time the lease was entered into by utilizing the rate of the Partnership's secured debt and adjusting it for factors that reflect the profile of borrowing over the 30-year expected lease term.

Subsequent Events

Subsequent Events	9 Months Ended
	Sep. 30, 2020
Subsequent Events [Abstract]
Subsequent Events	Subsequent Events The following represents material events that have occurred subsequent to September 30, 2020 through the time of the Partnership’s filing of its Quarterly Report on Form 10-Q with the SEC: Common Unit and Preferred Unit Distributions

Basis of Presentation (Policies

Basis of Presentation (Policies)	9 Months Ended
	Sep. 30, 2020
Accounting Policies [Abstract]
Principles of Consolidation Reporting	Principles of Consolidation and ReportingThe accompanying unaudited Consolidated Financial Statements of the Partnership have been prepared in accordance with generally accepted accounting principles in the United States of America ("GAAP") for interim financial information and with Rule 10-01 of Regulation S-X. Accordingly, they do not include all of the information and footnotes required by GAAP for complete financial statements. These financial statements should be read in conjunction with the financial statements for the year ended December 31, 2019 and notes thereto included in the Partnership's Annual Report on Form 10-K, which was filed with the SEC on February 27, 2020.
Recently Issued Accounting Standards	Recently Adopted Accounting Standards Credit Losses On January 1, 2020, the Partnership adopted ASU No. 2016-13, Financial Instruments—Credit Losses (Topic 326), and all the related amendments ("the new credit loss standard"). The Partnership recognized a $3.9 million cumulative effect of adoption in the opening balance of partners' capital on January 1, 2020 as a result of the adoption of the new credit loss standard. See Note 15. Credit Losses for more information.

Revenue from Contracts with C_2

Revenue from Contracts with Customers (Tables)	3 Months Ended	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2020
Revenue from Contract with Customer [Abstract]
Revenue from Contracts with Customers by Source	The following table presents the Partnership's Coal Royalty and Other segment revenues by major source: For the Three Months Ended For the Nine Months Ended September 30, (In thousands) 2020 2019 2020 2019 Coal royalty revenues (1) $ 10,610 $ 24,727 $ 40,559 $ 87,561 Production lease minimum revenues (1) 4,267 2,752 13,554 21,331 Minimum lease straight-line revenues (1) 3,553 3,982 12,349 11,152 Property tax revenues 1,896 1,606 4,256 4,416 Wheelage revenues 1,680 1,675 5,468 5,035 Coal overriding royalty revenues 1,314 2,189 3,319 10,163 Lease amendment revenues 858 1,535 2,591 6,720 Aggregates royalty revenues 221 954 1,068 3,655 Oil and gas royalty revenues 1,078 374 4,923 2,575 Other revenues 263 125 752 1,429 Coal royalty and other revenues $ 25,740 $ 39,919 $ 88,839 $ 154,037 Transportation and processing services revenues (2) 2,204 3,865 6,651 14,740 Total coal royalty and other segment revenues $ 27,944 $ 43,784 $ 95,490 $ 168,777 (1) Effective January 1, 2020, certain revenues previously classified as coal royalty revenues are classified as production lease minimum revenues or minimum lease straight-line revenues due to contract modifications to certain leases that fixed consideration paid to the Partnership over a two year period. (2) Transportation and processing services revenues from contracts with customers as defined under ASC 606 was $1.2 million and $1.7 million for the three months ended September 30, 2020 and 2019, respectively and $3.7 million and $7.3 million for the nine months ended September 30, 2020 and 2019, respectively. The remaining transportation and processing services revenues of $1.0 million and $2.2 million for the three months ended September 30, 2020 and 2019, respectively, and $2.9 million and $7.5 million for the nine months ended September 30, 2020 and 2019, respectively, related to other NRP-owned infrastructure leased to and operated by third-party operators accounted for under other guidance. See Note 14. Financing Transaction
Schedule of Receivables and Liabilities from Contracts with Customers		The following table details the Partnership's Coal Royalty and Other segment receivables and liabilities resulting from contracts with customers: September 30, December 31, (In thousands) 2020 2019 Receivables Accounts receivable, net $ 15,371 $ 27,915 Other current assets, net (1) 3,696 90 Other long-term assets, net (2) 691 — Contract liabilities Current portion of deferred revenue $ 11,035 $ 4,608 Deferred revenue 50,980 47,213 (1) Other current assets, net includes short-term notes receivables from contracts with customers.
Activity Related to Coal Royalty and Other Segment Deferred Revenue		The following table shows the activity related to the Partnership's Coal Royalty and Other segment deferred revenue: For the Nine Months Ended September 30, (In thousands) 2020 2019 Balance at beginning of period (current and non-current) $ 51,821 $ 52,553 Increase due to minimums and lease amendment fees 38,005 37,315 Recognition of previously deferred revenue (27,811) (41,234) Balance at end of period (current and non-current) $ 62,015 $ 48,634
Schedule of Annual Minimums by Current Remaining Contract Term		The Partnership's non-cancelable annual minimum payments due under the lease terms of its coal and aggregates royalty and overriding royalty leases are as follows as of September 30, 2020 (in thousands): Lease Term (1) Weighted Average Remaining Years Annual Minimum Payments (2) 0 - 5 years 3.7 $ 14,792 5 - 10 years 5.7 7,478 10+ years 13.5 30,922 Total 9.3 $ 53,192 (1) Lease term does not include renewal periods. (2) Annual minimum payments do not include $40.0 million of annual fixed consideration owed to NRP in 2020 and 2021 resulting from contract modifications entered into during the second quarter of 2020. Additionally, $5.0 million of this $40.0 million annual fixed consideration amount relates to a coal infrastructure lease that is accounted for as a financing transaction. See Note 14. Financing Transaction

Common and Preferred Unit Dis_2

Common and Preferred Unit Distributions (Tables)	9 Months Ended
	Sep. 30, 2020
Equity [Abstract]
Distributions declared and paid	The following table shows the cash distributions declared and paid to common and preferred unitholders during the nine months ended September 30, 2020 and 2019, respectively: Common Units Preferred Units Date Paid Period Covered by Distribution Distribution per Unit Total Distribution (1) (In thousands) Distribution per Unit Total Distribution 2020 February 2020 October 1 - December 31, 2019 $ 0.45 $ 5,630 $ 30.00 $ 7,500 May 2020 January 1 - March 31, 2020 — — 15.00 3,750 June 2020 (2) January 1 - March 31, 2020 — — 15.45 3,863 August 2020 April 1 - June 30, 2020 0.45 5,630 30.00 7,500 2019 February 2019 October 1 - December 31, 2018 $ 0.45 $ 5,625 $ 30.00 $ 7,500 May 2019 January 1 - March 31, 2019 0.45 5,630 30.00 7,500 May 2019 (3) Special Distribution 0.85 10,635 — — August 2019 April 1 - June 30, 2019 0.45 5,630 30.00 7,500 (1) Total common unit distribution includes the amount paid to NRP's general partner in accordance with the general partner's 2% general partner interest. (2) Redemption of preferred units paid in kind plus accrued interest. (3) Special distribution was made to cover the common unitholders’ tax liability resulting from the sale of NRP’s construction aggregates business in December 2018.

Net Income Per Common Unit (Tab

Net Income Per Common Unit (Tables)	9 Months Ended
	Sep. 30, 2020
Earnings Per Share [Abstract]
Reconciliation of Net Income to Weighted Average Units Outstanding	The following tables reconcile the numerator and denominator of the basic and diluted net income (loss) per common unit computations and calculates basic and diluted net income (loss) per common unit: For the Three Months Ended For the Nine Months Ended September 30, (In thousands, except per unit data) 2020 2019 2020 2019 Allocation of net income (loss) Net income (loss) from continuing operations $ 7,216 $ 39,163 $ (99,506) $ 94,034 Less: income attributable to preferred unitholders (7,500) (7,500) (22,613) (22,500) Net income (loss) from continuing operations attributable to common unitholders and general partner $ (284) $ 31,663 $ (122,119) $ 71,534 Add (less): net loss (income) from continuing operations attributable to the general partner 5 (634) 2,442 (1,431) Net income (loss) from continuing operations attributable to common unitholders $ (279) $ 31,029 $ (119,677) $ 70,103 Net income from discontinued operations $ — $ 7 $ — $ 206 Less: net income from discontinued operations attributable to the general partner — — — (4) Net income from discontinued operations attributable to common unitholders $ — $ 7 $ — $ 202 Net income (loss) $ 7,216 $ 39,170 $ (99,506) $ 94,240 Less: income attributable to preferred unitholders (7,500) (7,500) (22,613) (22,500) Net income (loss) attributable to common unitholders and general partner $ (284) $ 31,670 $ (122,119) $ 71,740 Add (less): net loss (income) attributable to the general partner 5 (634) 2,442 (1,435) Net income (loss) attributable to common unitholders $ (279) $ 31,036 $ (119,677) $ 70,305 Basic net income (loss) per common unit Weighted average common units—basic 12,261 12,261 12,261 12,259 Basic net income (loss) from continuing operations per common unit $ (0.02) $ 2.53 $ (9.76) $ 5.72 Basic net income from discontinued operations per common unit $ 0.00 $ 0.00 $ 0.00 $ 0.02 Basic net income (loss) per common unit $ (0.02) $ 2.53 $ (9.76) $ 5.73 For the Three Months Ended For the Nine Months Ended September 30, (In thousands, except per unit data) 2020 2019 2020 2019 Diluted income (loss) per common unit Weighted average common units—basic 12,261 12,261 12,261 12,259 Plus: dilutive effect of preferred units — 10,494 — 10,494 Plus: dilutive effect of warrants — 389 — 800 Plus: dilutive effect of unvested unit-based awards — 13 — 31 Weighted average common units—diluted 12,261 23,157 12,261 23,584 Net income (loss) from continuing operations $ 7,216 $ 39,163 $ (99,506) $ 94,034 Less: income attributable to preferred unitholders (7,500) — (22,613) — Diluted net income (loss) from continuing operations attributable to common unitholders and general partner $ (284) $ 39,163 $ (122,119) $ 94,034 Add (less): diluted net loss (income) from continuing operations attributable to the general partner 5 (784) 2,442 (1,881) Diluted net income (loss) from continuing operations attributable to common unitholders $ (279) $ 38,379 $ (119,677) $ 92,153 Diluted net income from discontinued operations attributable to common unitholders $ — $ 7 $ — $ 202 Net income (loss) $ 7,216 $ 39,170 $ (99,506) $ 94,240 Less: income attributable to preferred unitholders (7,500) — (22,613) — Diluted net income (loss) attributable to common unitholders and general partner $ (284) $ 39,170 $ (122,119) $ 94,240 Add (less): diluted net loss (income) attributable to the general partner 5 (784) 2,442 (1,885) Diluted net income (loss) attributable to common unitholders $ (279) $ 38,386 $ (119,677) $ 92,355 Diluted net income (loss) from continuing operations per common unit $ (0.02) $ 1.66 $ (9.76) $ 3.91 Diluted net income from discontinued operations per common unit $ 0.00 $ 0.00 $ 0.00 $ 0.01 Diluted net income (loss) per common unit $ (0.02) $ 1.66 $ (9.76) $ 3.92

Segment Information (Tables)

Segment Information (Tables)	9 Months Ended
	Sep. 30, 2020
Segment Reporting [Abstract]
Schedule of Segment Reporting Information, by Segment	The following table summarizes certain financial information for each of the Partnership's business segments: Operating Segments (In thousands) Coal Royalty and Other Soda Ash Corporate and Financing Total For the Three Months Ended September 30, 2020 Revenues $ 27,944 $ 1,986 $ — $ 29,930 Operating and maintenance expenses 5,685 96 — 5,781 Depreciation, depletion and amortization 2,111 — — 2,111 General and administrative expenses — — 3,634 3,634 Asset impairments 934 — — 934 Other expenses, net 41 — 10,213 10,254 Net income (loss) from continuing operations 19,173 1,890 (13,847) 7,216 For the Three Months Ended September 30, 2019 Revenues $ 43,784 $ 13,818 $ — $ 57,602 Gain on asset sales and disposals 6,107 — — 6,107 Operating and maintenance expenses 5,771 223 — 5,994 Depreciation, depletion and amortization 3,384 — — 3,384 General and administrative expenses — — 4,253 4,253 Asset impairments 484 — — 484 Other expenses, net — — 10,431 10,431 Net income (loss) from continuing operations 40,252 13,595 (14,684) 39,163 Income from discontinued operations — — — 7 For the Nine Months Ended September 30, 2020 Revenues $ 95,490 $ 5,200 $ — $ 100,690 Gain on asset sales and disposals 465 — — 465 Operating and maintenance expenses 19,059 141 — 19,200 Depreciation, depletion and amortization 6,185 — — 6,185 General and administrative expenses — — 11,168 11,168 Asset impairments 133,217 — — 133,217 Other expenses, net 56 — 30,835 30,891 Net income (loss) from continuing operations (62,562) 5,059 (42,003) (99,506) For the Nine Months Ended September 30, 2019 Revenues $ 168,777 $ 36,833 $ — $ 205,610 Gain on asset sales and disposals 6,609 — — 6,609 Operating and maintenance expenses 26,590 223 — 26,813 Depreciation, depletion and amortization 11,746 — — 11,746 General and administrative expenses — — 12,799 12,799 Asset impairments 484 — — 484 Other expenses, net — — 66,343 66,343 Net income (loss) from continuing operations 136,566 36,610 (79,142) 94,034 Income from discontinued operations — — — 206

Equity Investment (Tables)

Equity Investment (Tables)	9 Months Ended
	Sep. 30, 2020
Equity Method Investments and Joint Ventures [Abstract]
Schedule of Summarized Financial Information	Activity related to this investment is as follows: For the Three Months Ended For the Nine Months Ended September 30, (In thousands) 2020 2019 2020 2019 Balance at beginning of period $ 252,420 $ 251,135 $ 263,080 $ 247,051 Income allocation to NRP’s equity interests 3,004 15,068 8,450 40,511 Amortization of basis difference (1,018) (1,250) (3,250) (3,678) Other comprehensive income (loss) 2,428 (520) 2,764 (341) Distribution — (6,370) (14,210) (25,480) Balance at end of period $ 256,834 $ 258,063 $ 256,834 $ 258,063 The following table represents summarized financial information for Ciner Wyoming as derived from their respective unaudited financial statements for the three and nine months ended September 30, 2020 and 2019: For the Three Months Ended For the Nine Months Ended September 30, (In thousands) 2020 2019 2020 2019 Net sales $ 98,197 $ 137,148 $ 288,804 $ 397,378 Gross profit 11,704 36,747 35,363 103,382 Net income 6,130 30,750 17,245 82,675

Mineral Rights, Net (Tables)

Mineral Rights, Net (Tables)	9 Months Ended
	Sep. 30, 2020
Extractive Industries [Abstract]
Mineral Rights	The Partnership’s mineral rights consist of the following: September 30, 2020 December 31, 2019 (In thousands) Carrying Value Accumulated Depletion Net Book Value Carrying Value Accumulated Depletion Net Book Value Coal properties $ 798,870 $ (354,843) $ 444,027 $ 981,352 $ (420,448) $ 560,904 Aggregates properties 9,102 (2,741) 6,361 41,486 (13,357) 28,129 Oil and gas royalty properties 12,354 (8,416) 3,938 12,395 (7,887) 4,508 Other 13,156 (1,612) 11,544 13,156 (1,601) 11,555 Total mineral rights, net $ 833,482 $ (367,612) $ 465,870 $ 1,048,389 $ (443,293) $ 605,096

Debt, Net (Tables)

Debt, Net (Tables)	9 Months Ended
	Sep. 30, 2020
Debt Disclosure [Abstract]
Total Debt	The Partnership's debt consists of the following: September 30, December 31, (In thousands) 2020 2019 NRP LP debt: 9.125% senior notes, with semi-annual interest payments in June and December, due June 2025, issued at par ("2025 Senior Notes") $ 300,000 $ 300,000 Opco debt: Revolving credit facility $ — $ — Senior Notes 5.05% with semi-annual interest payments in January and July, with annual principal payments in July, due July 2020 $ — $ 6,780 5.55% with semi-annual interest payments in June and December, with annual principal payments in June, due June 2023 7,094 9,458 4.73% with semi-annual interest payments in June and December, with annual principal payments in December, due December 2023 24,016 24,016 5.82% with semi-annual interest payments in March and September, with annual principal payments in March, due March 2024 50,738 63,423 8.92% with semi-annual interest payments in March and September, with annual principal payments in March, due March 2024 16,047 20,059 5.03% with semi-annual interest payments in June and December, with annual principal payments in December, due December 2026 79,945 79,945 5.18% with semi-annual interest payments in June and December, with annual principal payments in December, due December 2026 20,375 20,375 Total Opco Senior Notes $ 198,215 $ 224,056 Total debt at face value $ 498,215 $ 524,056 Net unamortized debt issuance costs (6,742) (7,858) Total debt, net $ 491,473 $ 516,198 Less: current portion of long-term debt (39,072) (45,776) Total long-term debt, net $ 452,401 $ 470,422

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	9 Months Ended
	Sep. 30, 2020
Fair Value Disclosures [Abstract]
Debt and Contracts Receivable	The following table shows the carrying value and estimated fair value of the Partnership's debt and contract receivable: September 30, 2020 December 31, 2019 (In thousands) Fair Value Hierarchy Level Carrying Estimated Carrying Estimated Debt: NRP 2025 Senior Notes 1 $ 294,891 $ 263,250 $ 294,084 $ 269,250 Opco Senior Notes (1) 3 196,582 173,934 222,114 201,090 Opco Credit Facility 3 — — — — Assets: Contract receivable (current and long-term) (2) 3 $ 35,800 $ 27,255 $ 38,945 $ 33,460 (1) The fair value of the Opco Senior Notes are estimated by management using quotations obtained for the NRP 2025 Senior Notes on the closing trading prices near period end, which were at 88% of par value at September 30, 2020.

Related Party Transactions (Tab

Related Party Transactions (Tables)	9 Months Ended
	Sep. 30, 2020
Related Party Transactions [Abstract]
Summary of Reimbursements	Direct general and administrative expenses charged to the Partnership by QMC and WPPLP are included on the Partnership's Consolidated Statement of Comprehensive Income (Loss) as follows: For the Three Months Ended For the Nine Months Ended September 30, (In thousands) 2020 2019 2020 2019 Operating and maintenance expenses $ 1,562 $ 1,598 $ 4,729 $ 4,806 General and administrative expenses 878 855 2,657 2,704

Major Customers (Tables)

Major Customers (Tables)	9 Months Ended
	Sep. 30, 2020
Risks and Uncertainties [Abstract]
Major customers	Revenues from customers that exceeded 10 percent of total revenues for any of the periods presented below are as follows: For the Three Months Ended September 30, For the Nine Months Ended September 30, 2020 2019 2020 2019 (In thousands) Revenues Percent Revenues Percent Revenues Percent Revenues Percent Foresight Energy (1) (2) $ 8,592 29 % $ 12,375 21 % $ 27,052 27 % $ 44,604 22 % Contura Energy (1) 7,143 24 % 9,190 16 % 23,164 23 % 32,915 16 % (1) Revenues from Foresight Energy and Contura Energy are included within the Partnership's Coal Royalty and Other segment. (2) In June 2020, the Partnership entered into lease amendments with Foresight Energy pursuant to which Foresight agreed to pay NRP fixed cash payments to satisfy all obligations arising out of the existing various coal mining leases and transportation infrastructure fee agreements between the Partnership and Foresight Energy for calendar years 2020 and 2021.

Unit-Based Compensation (Tables

Unit-Based Compensation (Tables)	9 Months Ended
	Sep. 30, 2020
Unit-Based Compensation [Abstract]
Summary of Activity in Awards	A summary of the unit activity in the outstanding grants during 2020 is as follows: (In thousands) Common Units Weighted Average Exercise Price Outstanding at January 1, 2020 157 $ 37.48 Granted 203 $ 17.20 Fully vested and issued — $ — Forfeitures (5) $ 17.20 Outstanding at September 30, 2020 355 $ 26.20

Credit Losses (Tables)

Credit Losses (Tables)	9 Months Ended
	Sep. 30, 2020
Credit Losses [Abstract]
Accounts Receivable, Allowance for Credit Loss	(In thousands) Gross CECL Allowance Net Receivables $ 24,172 $ (2,324) $ 21,848 Long-term contract receivable 35,370 (1,579) 33,791 Total $ 59,542 $ (3,903) $ 55,639

Financing Transaction (Tables)

Financing Transaction (Tables)	9 Months Ended
	Sep. 30, 2020
Financing Transaction [Abstract]
Financing Receivable, after Allowance for Credit Loss	The following table shows certain amounts related to the Partnership's Sugar Camp lease through 2032: September 30, December 31, (In thousands) 2020 2019 Accounts receivable, net $ — $ 540 Contract receivable, net (current and long-term) 35,800 38,945 Unearned income 19,704 21,889 Projected remaining payments, net $ 55,504 $ 61,374

Leases (Tables)

Leases (Tables)	9 Months Ended
	Sep. 30, 2020
Leases [Abstract]
Lessee, Operating Lease, Liability, Maturity	The following table details the maturity analysis of the Partnership's operating lease liability and reconciles the undiscounted cash flows to the operating lease liability included on its Consolidated Balance Sheet: Remaining Annual Lease Payments (In thousands) As of September 30, 2020 2020 $ 121 2021 483 2022 483 2023 483 2024 483 After 2024 11,597 Total lease payments (1) $ 13,650 Less: present value adjustment (2) (10,150) Total operating lease liability $ 3,500 (1) The remaining lease term of the Partnership's operating lease is 28.25 years. (2) The present value of the operating lease liability on the Partnership's Consolidated Balance Sheets was calculated using a 13.5% discount rate which represents the Partnership's estimated incremental borrowing rate under the lease. As the Partnership's lease does not provide an implicit rate, the Partnership estimated the incremental borrowing rate at the time the lease was entered into by utilizing the rate of the Partnership's secured debt and adjusting it for factors that reflect the profile of borrowing over the 30-year expected lease term.

Basis of Presentation - Narrati

Basis of Presentation - Narrative (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2020USD ($)segment	Jun. 30, 2020USD ($)	Mar. 31, 2020USD ($)	Jan. 01, 2020USD ($)	Dec. 31, 2019USD ($)	Sep. 30, 2019USD ($)	Jun. 30, 2019USD ($)	Mar. 31, 2019USD ($)	Dec. 31, 2018USD ($)
Restricted Cash and Cash Equivalents Items [Line Items]
Number of operating segments | segment	2
Partners' Capital, Including Portion Attributable to Noncontrolling Interest	$ 201,959	$ 204,621	$ 337,416		$ 336,028	$ 466,254	$ 440,261	$ 445,040	$ 420,546
Cumulative Effect, Period of Adoption, Adjustment
Restricted Cash and Cash Equivalents Items [Line Items]
Partners' Capital, Including Portion Attributable to Noncontrolling Interest				$ (3,911)
Ciner Wyoming
Restricted Cash and Cash Equivalents Items [Line Items]
Percentage of partnership interest owned (percent)	49.00%

Revenue from Contracts with C_3

Revenue from Contracts with Customers - Schedule of Partnerships' Coal Royalty and Other Segment Revenues from Contracts with Customers (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Disaggregation of Revenue [Line Items]
Total coal royalty and other segment revenues	$ 27,944	$ 43,784	$ 95,490	$ 168,777
Revenues	29,930	57,602	100,690	205,610
Coal Royalty and Other
Disaggregation of Revenue [Line Items]
Total coal royalty and other segment revenues	25,740	39,919	88,839	154,037
Revenues	25,740	39,919	88,839	154,037
Coal Royalty and Other | Coal royalty revenues
Disaggregation of Revenue [Line Items]
Total coal royalty and other segment revenues	10,610	24,727	40,559	87,561
Coal Royalty and Other | Production lease minimum revenues
Disaggregation of Revenue [Line Items]
Total coal royalty and other segment revenues	4,267	2,752	13,554	21,331
Coal Royalty and Other | Minimum lease straight-line revenues
Disaggregation of Revenue [Line Items]
Total coal royalty and other segment revenues	3,553	3,982	12,349	11,152
Coal Royalty and Other | Property tax revenues
Disaggregation of Revenue [Line Items]
Total coal royalty and other segment revenues	1,896	1,606	4,256	4,416
Coal Royalty and Other | Wheelage revenues
Disaggregation of Revenue [Line Items]
Total coal royalty and other segment revenues	1,680	1,675	5,468	5,035
Coal Royalty and Other | Coal overriding royalty revenues
Disaggregation of Revenue [Line Items]
Total coal royalty and other segment revenues	1,314	2,189	3,319	10,163
Coal Royalty and Other | Lease amendment revenues
Disaggregation of Revenue [Line Items]
Total coal royalty and other segment revenues	858	1,535	2,591	6,720
Coal Royalty and Other | Aggregates royalty revenues
Disaggregation of Revenue [Line Items]
Total coal royalty and other segment revenues	221	954	1,068	3,655
Coal Royalty and Other | Oil and gas royalty revenues
Disaggregation of Revenue [Line Items]
Total coal royalty and other segment revenues	1,078	374	4,923	2,575
Coal Royalty and Other | Other revenues
Disaggregation of Revenue [Line Items]
Total coal royalty and other segment revenues	263	125	752	1,429
Coal Royalty and Other | Transportation and processing services revenues
Disaggregation of Revenue [Line Items]
Total coal royalty and other segment revenues	1,200	1,700	3,700	7,300
Revenues	2,204	3,865	6,651	14,740
Lease revenue	$ 1,000	$ 2,200	$ 2,900	$ 7,500

Revenue from Contracts with C_4

Revenue from Contracts with Customers - Schedule of Receivables and Liabilities from Contracts with Customers (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Segment Reporting Information [Line Items]
Other long-term assets, net	$ 7,447	$ 6,989
Current portion of deferred revenue	11,035	4,608
Deferred revenue	50,980	47,213
Coal Royalty
Segment Reporting Information [Line Items]
Accounts receivable, net	15,371	27,915
Other current assets, net	3,696	90
Other long-term assets, net	691	0
Current portion of deferred revenue	11,035	4,608
Deferred revenue	$ 50,980	$ 47,213

Revenue from Contracts with C_5

Revenue from Contracts with Customers Revenue Recognition Deferred Revenue Rollforward (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019
Movement in Deferred Revenue [Roll Forward]
Balance at beginning of period (current and non-current)	$ 51,821	$ 52,553
Increase due to minimums and lease amendment fees	38,005	37,315
Recognition of previously deferred revenue	(27,811)	(41,234)
Balance at end of period (current and non-current)	$ 62,015	$ 48,634

Revenue from Contracts with C_6

Revenue from Contracts with Customers - Schedule of Annual Minimums by Current Remaining Contract Term (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2020	Dec. 31, 2021	Dec. 31, 2020
Revenue from Contract with Customer [Abstract]
Payments for (Proceeds from) Loans Receivable, Annual Minimum Payment	$ 5,000
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Annual minimum payments	53,192
Payments from coal lease accounted for as financing transaction	5,000
Forecast
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Annual fixed consideration after contract modifications		$ 40,000	$ 40,000
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2020-10-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Annual minimum payments	$ 14,792
Average Remaining Contract Term	3 years 8 months 12 days
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2025-10-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Annual minimum payments	$ 7,478
Average Remaining Contract Term	5 years 8 months 12 days
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2030-10-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Annual minimum payments	$ 30,922
Average Remaining Contract Term	9 years 3 months 18 days

Common and Preferred Unit Dis_3

Common and Preferred Unit Distributions Narrative (Details) - USD ($) $ in Thousands	3 Months Ended						9 Months Ended
	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Sep. 30, 2020	Sep. 30, 2019
Temporary Equity [Line Items]
Income attributable to preferred unitholders	$ (7,500)	$ (7,600)	$ (7,500)	$ (7,500)	$ (7,500)	$ (7,500)	$ (22,613)	$ (22,500)
Natural Resource Partners L.P. | General Partner
Temporary Equity [Line Items]
General partner's general partner distribution							2.00%

Common and Preferred Unit Dis_4

Common and Preferred Unit Distributions Distributions declared and paid (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended						9 Months Ended
	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Sep. 30, 2020
Natural Resource Partners L.P. | General Partner
Class of Stock [Line Items]
General partner's general partner distribution							2.00%
Common unitholders and general partner
Class of Stock [Line Items]
Distribution per Unit	$ 0.45	$ 0	$ 0.45		$ 0.45	$ 0.45
Total distributions, common units			$ 5,630	$ 5,630	$ 16,265	$ 5,625
Preferred Partner
Class of Stock [Line Items]
Total distributions, common units	$ 5,630	$ 7,613	7,500	7,500	7,500	7,500
Preferred Partner | General Partner
Class of Stock [Line Items]
Total distributions, common units	$ 150	$ 152	$ 150	$ 150	$ 150	$ 150
Preferred Partner | Preferred Stock
Class of Stock [Line Items]
Distribution per Unit	$ 30	$ 15	$ 30		$ 30	$ 30
Total distributions, preferred units	$ 7,500	$ 3,750	$ 7,500		$ 7,500	$ 7,500
Cash Distribution | Common unitholders and general partner
Class of Stock [Line Items]
Total distributions, common units	$ 5,630	$ 0	$ 5,630		$ 5,630	$ 5,625
Special Tax Distribution | Common unitholders and general partner
Class of Stock [Line Items]
Distribution per Unit					$ 0.85
Total distributions, common units					$ 10,635
Redemption of preferred units paid in kind | Preferred Partner | Preferred Stock
Class of Stock [Line Items]
Distribution per Unit		$ 15.45
Total distributions, preferred units		$ 3,863

Net Income Per Common Unit (Det

Net Income Per Common Unit (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended										9 Months Ended
	Sep. 30, 2020	Jun. 30, 2020		Mar. 31, 2020		Sep. 30, 2019	Jun. 30, 2019		Mar. 31, 2019		Sep. 30, 2020	Sep. 30, 2019
Allocation of net income (loss)
Net income (loss) from continuing operations	$ 7,216					$ 39,163					$ (99,506)	$ 94,034
Less: income attributable to preferred unitholders						0						0
Net income (loss) from continuing operations attributable to common unitholders and general partner	(284)					31,663					(122,119)	71,534
Add (less): net loss (income) from continuing operations attributable to the general partner	5					(634)					2,442	(1,431)
Net income (loss) from continuing operations attributable to common unitholders	(279)					31,029					(119,677)	70,103
Net income from discontinued operations	0					7					0	206
Less: net income from discontinued operations attributable to the general partner	0					0					0	(4)
Net income from discontinued operations attributable to common unitholders	0					7					0	202
Net income (loss)	7,216	$ (125,501)	[1]	$ 18,779	[2]	39,170	$ 19,351	[3]	$ 35,719	[3]	(99,506)	94,240
Net income (loss) attributable to common unitholders and general partner	(284)					31,670					(122,119)	71,740
Net income (loss) attributable to the general partner	5					(634)					2,442	(1,435)
Net income (loss) attributable to common unitholders	$ (279)					$ 31,036					$ (119,677)	$ 70,305
Basic Income (Loss) per Unit:
Weighted average common units (in shares)	12,261					12,261					12,261	12,259
Basic net income (loss) from continuing operations per common unit	$ (0.02)					$ 2.53					$ (9.76)	$ 5.72
Basic net income from discontinued operations per common unit	0					0					0	0.02
Basic net income (loss) per common unit	$ (0.02)					$ 2.53					$ (9.76)	$ 5.73
Diluted income (loss) per common unit
Dilutive effect of Preferred Units (in shares)	0					10,494					0	10,494
Dilutive effect of Warrants (in shares)	0					389					0	800
Dilutive effect of unvested unit-based awards (in shares)						13						31
Weighted average common units—diluted (in shares)	12,261					23,157					12,261	23,584
Less: income attributable to preferred unitholders	$ (7,500)	$ (7,600)		$ (7,500)		$ (7,500)	$ (7,500)		$ (7,500)		$ (22,613)	$ (22,500)
Diluted net income (loss) from continuing operations attributable to common unitholders and general partner	(284)					39,163					(122,119)	94,034
Add (less): diluted net loss (income) from continuing operations attributable to the general partner	5					(784)					2,442	(1,881)
Diluted net income (loss) from continuing operations attributable to common unitholders	(279)					38,379					(119,677)	92,153
Diluted net income from discontinued operations attributable to common unitholders	0					7					0	202
Diluted net income (loss) attributable to common unitholders and general partner	284					(39,170)					122,119	(94,240)
Add (less): diluted net loss (income) attributable to the general partner	5					(784)					2,442	(1,885)
Diluted net income (loss) attributable to common unitholders	$ (279)					$ 38,386					$ (119,677)	$ 92,355
Diluted net income per common unit from continuing operations (in dollars per share)	$ (0.02)					$ 1.66					$ (9.76)	$ 3.91
Diluted net income (loss) from discontinued operations per common unit (in dollars per share)	0					0					0	0.01
Diluted net income per common unit (in dollars per share)	$ (0.02)					$ 1.66					$ (9.76)	$ 3.92
Warrant Holders | Warrants at $22.81 Strike
Class of Warrant or Right, Warrants Issued	1,750					1,750					1,750	1,750
Class of Warrant or Right, Exercise Price of Warrants or Rights	$ 22.81					$ 22.81					$ 22.81	$ 22.81
Warrant Holders | Warrants at $34.00 Strike
Class of Warrant or Right, Warrants Issued	2,250					2,250					2,250	2,250
Class of Warrant or Right, Exercise Price of Warrants or Rights	$ 34					$ 34					$ 34	$ 34
[1]	Net loss includes $7.6 million attributable to preferred unitholders that accumulated during the period, of which $7.46 million is allocated to the common unitholders and $0.15 million is allocated to the general partner.
[2]	Net income includes $7.5 million attributable to preferred unitholders that accumulated during the period, of which $7.35 million is allocated to the common unitholders and $0.15 million is allocated to the general partner.
[3]	Net income includes $7.5 million attributable to preferred unitholders that accumulated during the period, of which $7.35 million is allocated to the common unitholders and $0.15 million is allocated to the general partner.

Segment Information - Additiona

Segment Information - Additional Information (Details)	9 Months Ended
	Sep. 30, 2020segment
Segment Reporting Information [Line Items]
Number of operating segments	2
Ciner Wyoming
Segment Reporting Information [Line Items]
Percentage of partnership interest owned (percent)	49.00%

Segment Information - Schedule

Segment Information - Schedule of Segment Reporting Information, by Segment (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Segment Reporting Information [Line Items]
Revenues	$ 29,930	$ 57,602	$ 100,690	$ 205,610
Gain on asset sales and disposals	0	6,107	465	6,609
Operating and maintenance expenses	5,781	5,994	19,200	26,813
Depreciation, depletion and amortization	2,111	3,384	6,185	11,746
General and administrative expenses	3,634	4,253	11,168	12,799
Asset impairments	934	484	133,217	484
Other expenses, net	10,254	10,431	30,891	66,343
Net income (loss) from continuing operations	7,216	39,163	(99,506)	94,034
Net income from discontinued operations	0	7	0	206
Corporate and Financing
Segment Reporting Information [Line Items]
Revenues	0	0	0	0
Gain on asset sales and disposals		0	0	0
Operating and maintenance expenses	0	0	0	0
Depreciation, depletion and amortization	0	0	0	0
General and administrative expenses	3,634	4,253	11,168	12,799
Asset impairments		0	0	0
Other expenses, net	10,213	10,431	30,835	66,343
Net income (loss) from continuing operations	(13,847)	(14,684)	(42,003)	(79,142)
Net income from discontinued operations		0		0
Coal Royalty and Other
Segment Reporting Information [Line Items]
Revenues	25,740	39,919	88,839	154,037
Coal Royalty and Other | Operating Segments
Segment Reporting Information [Line Items]
Revenues	27,944	43,784	95,490	168,777
Gain on asset sales and disposals		6,107	465	6,609
Operating and maintenance expenses	5,685	5,771	19,059	26,590
Depreciation, depletion and amortization	2,111	3,384	6,185	11,746
General and administrative expenses	0	0	0	0
Asset impairments	934	484	133,217	484
Other expenses, net	41	0	56	0
Net income (loss) from continuing operations	19,173	40,252	(62,562)	136,566
Net income from discontinued operations		0		0
Soda Ash
Segment Reporting Information [Line Items]
Revenues	1,986	13,818	5,200	36,833
Soda Ash | Operating Segments
Segment Reporting Information [Line Items]
Revenues	1,986	13,818	5,200	36,833
Gain on asset sales and disposals		0	0	0
Operating and maintenance expenses	96	223	141	223
Depreciation, depletion and amortization	0	0	0	0
General and administrative expenses	0	0	0	0
Asset impairments			0	0
Other expenses, net	0	0	0	0
Net income (loss) from continuing operations	$ 1,890	13,595	$ 5,059	36,610
Net income from discontinued operations		$ 0		$ 0

Equity Investment - Additional

Equity Investment - Additional Information (Detail)	Sep. 30, 2020
Ciner Wyoming
Schedule of Equity Method Investments [Line Items]
Percentage of partnership interest owned (percent)	49.00%

Equity Investment Summary of Ac

Equity Investment Summary of Activity in Equity Method Investment (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Equity Method Investments [Roll Forward]
Balance at beginning of period			$ 263,080
Other comprehensive income (loss)	$ 9,644	$ 38,650	(96,742)	$ 93,900
Balance at end of period	256,834		256,834
Ciner Wyoming
Equity Method Investments [Roll Forward]
Balance at beginning of period	252,420	251,135	263,080	247,051
Income allocation to NRP’s equity interests	3,004	15,068	8,450	40,511
Amortization of basis difference	(1,018)	(1,250)	(3,250)	(3,678)
Other comprehensive income (loss)	2,428	(520)	2,764	(341)
Distribution	0	(6,370)	(14,210)	(25,480)
Balance at end of period	$ 256,834	$ 258,063	$ 256,834	$ 258,063

Equity Investment - Schedule of

Equity Investment - Schedule of Summarized Financial Information of Unaudited Financial Statements (Detail) - USD ($) $ in Thousands	3 Months Ended										9 Months Ended
	Sep. 30, 2020	Jun. 30, 2020	[1]	Mar. 31, 2020	[2]	Sep. 30, 2019	Jun. 30, 2019	[3]	Mar. 31, 2019	[3]	Sep. 30, 2020	Sep. 30, 2019
Schedule of Equity Method Investments [Line Items]
Revenues	$ 29,930					$ 57,602					$ 100,690	$ 205,610
Net income (loss)	7,216	$ (125,501)		$ 18,779		39,170	$ 19,351		$ 35,719		(99,506)	94,240
Ciner Wyoming | Ciner Wyoming
Schedule of Equity Method Investments [Line Items]
Revenues	98,197					137,148					288,804	397,378
Gross Profit	11,704					36,747					35,363	103,382
Net income (loss)	$ 6,130					$ 30,750					$ 17,245	$ 82,675
[1]	Net loss includes $7.6 million attributable to preferred unitholders that accumulated during the period, of which $7.46 million is allocated to the common unitholders and $0.15 million is allocated to the general partner.
[2]	Net income includes $7.5 million attributable to preferred unitholders that accumulated during the period, of which $7.35 million is allocated to the common unitholders and $0.15 million is allocated to the general partner.
[3]	Net income includes $7.5 million attributable to preferred unitholders that accumulated during the period, of which $7.35 million is allocated to the common unitholders and $0.15 million is allocated to the general partner.

Mineral Rights, Net - Mineral R

Mineral Rights, Net - Mineral Rights (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Costs Incurred, Oil and Gas Property Acquisition, Exploration, and Development Activities [Line Items]
Carrying Value	$ 833,482		$ 833,482		$ 1,048,389
Accumulated Depletion	(367,612)		(367,612)		(443,293)
Net Book Value	465,870		465,870		605,096
Asset impairments	934	$ 484	133,217	$ 484
Coal Mineral Rights
Costs Incurred, Oil and Gas Property Acquisition, Exploration, and Development Activities [Line Items]
Carrying Value	798,870		798,870		981,352
Accumulated Depletion	(354,843)		(354,843)		(420,448)
Net Book Value	444,027		444,027		560,904
Aggregates Mineral Rights
Costs Incurred, Oil and Gas Property Acquisition, Exploration, and Development Activities [Line Items]
Carrying Value	9,102		9,102		41,486
Accumulated Depletion	(2,741)		(2,741)		(13,357)
Net Book Value	6,361		6,361		28,129
Oil And Gas Mineral Rights
Costs Incurred, Oil and Gas Property Acquisition, Exploration, and Development Activities [Line Items]
Carrying Value	12,354		12,354		12,395
Accumulated Depletion	(8,416)		(8,416)		(7,887)
Net Book Value	3,938		3,938		4,508
Other Mineral Rights
Costs Incurred, Oil and Gas Property Acquisition, Exploration, and Development Activities [Line Items]
Carrying Value	13,156		13,156		13,156
Accumulated Depletion	(1,612)		(1,612)		(1,601)
Net Book Value	$ 11,544		$ 11,544		$ 11,555

Mineral Rights, Net - Additiona

Mineral Rights, Net - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Extractive Industries [Abstract]
Depletion and amortization expense on coal and other mineral rights	$ 2,100	$ 2,800	$ 6,000	$ 9,500
Asset impairments	$ 934	$ 484	$ 133,217	$ 484

Debt, Net - Debt (Detail)

Debt, Net - Debt (Detail) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Debt Instrument [Line Items]
Principal balance	$ 498,215	$ 524,056
Net unamortized debt issuance costs	(6,742)	(7,858)
Total debt, net	491,473	516,198
Less - current portion of long term debt	(39,072)	(45,776)
Total long-term debt, net	452,401	470,422
NRP LP | 9.125% senior notes, with semi-annual interest payments in June and December, maturing June 2025
Debt Instrument [Line Items]
Principal balance	$ 300,000	300,000
Rate of senior notes	9.125%
Opco | Floating Rate Revolving Credit Facility Due April Two Thousand Twenty Three
Debt Instrument [Line Items]
Line of Credit Facility, Remaining Borrowing Capacity	$ 100,000
Principal balance	0	0
Opco | 5.05% senior notes, with semi-annual interest payments in January and July, with annual principal payments in July, maturing in July 2020
Debt Instrument [Line Items]
Principal balance	$ 0	6,780
Rate of senior notes	5.05%
Opco | 5.55% senior notes, with semi-annual interest payments in June and December, with annual principal payments in June, maturing in June 2023
Debt Instrument [Line Items]
Principal balance	$ 7,094	9,458
Rate of senior notes	5.55%
Opco | 4.73% senior notes, with semi-annual interest payments in June and December, with scheduled principal payments beginning December 2014, maturing in December 2023
Debt Instrument [Line Items]
Principal balance	$ 24,016	24,016
Rate of senior notes	4.73%
Opco | 5.82% senior notes, with semi-annual interest payments in March and September, with annual principal payments in March, maturing in March 2024
Debt Instrument [Line Items]
Principal balance	$ 50,738	63,423
Rate of senior notes	5.82%
Opco | 8.92% senior notes, with semi-annual interest payments in March and September, with scheduled principal payments beginning March 2014, maturing in March 2024
Debt Instrument [Line Items]
Principal balance	$ 16,047	20,059
Rate of senior notes	8.92%
Opco | 5.03% senior notes, with semi-annual interest payments in June and December, with scheduled principal payments beginning December 2014, maturing in December 2026
Debt Instrument [Line Items]
Principal balance	$ 79,945	79,945
Rate of senior notes	5.03%
Opco | 5.18% senior notes, with semi-annual interest payments in June and December, with scheduled principal payments beginning December 2014, maturing in December 2026
Debt Instrument [Line Items]
Principal balance	$ 20,375	20,375
Rate of senior notes	5.18%
Opco | Senior Notes
Debt Instrument [Line Items]
Principal balance	$ 198,215	$ 224,056

Debt, Net - Additional Informat

Debt, Net - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands	Apr. 29, 2019	Jun. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Debt Instrument [Line Items]
Call premium		$ 18,100
Amortized debt issuance costs and debt discount		$ 10,400
Principal balance			$ 498,215		$ 524,056
9.125% senior notes, with semi-annual interest payments in June and December, maturing June 2025 | Senior Notes
Debt Instrument [Line Items]
Rate of senior notes			9.125%
Percentage of principal eligible for redemption			35.00%
Redemption price percentage of principal remaining after redemption			65.00%
Redemption price at change of control event as percentage of principal amount			101.00%
NRP LP | 9.125% senior notes, with semi-annual interest payments in June and December, maturing June 2025
Debt Instrument [Line Items]
Rate of senior notes			9.125%
Principal balance			$ 300,000		300,000
Opco | Floating Rate Revolving Credit Facility Due April Two Thousand Twenty Three
Debt Instrument [Line Items]
Line of Credit Facility, Remaining Borrowing Capacity			$ 100,000
Distribution per share (in dollars per share)			$ 0.45
Ratio Of Ebitda to consolidated fixed charges			3.5
Collateral carrying amount			$ 366,800		399,700
Principal balance			$ 0		0
Opco | 8.92% senior notes, with semi-annual interest payments in March and September, with scheduled principal payments beginning March 2014, maturing in March 2024
Debt Instrument [Line Items]
Rate of senior notes			8.92%
Principal balance			$ 16,047		20,059
Opco | Senior Notes
Debt Instrument [Line Items]
Principal balance			198,215		$ 224,056
Principal payments on its senior notes			$ 25,800	$ 97,100
Pre-payment of Senior Notes				$ 49,300
Partnership leverage ratio			3.75
Additional interest accrue			2.00%
Dividend at or Below $0.45 per Share | Opco | Floating Rate Revolving Credit Facility Due April Two Thousand Twenty Three
Debt Instrument [Line Items]
Maximum leverage ratio			4
Dividend Above $0.45 per Share | Opco | Floating Rate Revolving Credit Facility Due April Two Thousand Twenty Three
Debt Instrument [Line Items]
Maximum leverage ratio			3
Debt Instrument, Redemption, Period Two | 9.125% senior notes, with semi-annual interest payments in June and December, maturing June 2025 | Senior Notes
Debt Instrument [Line Items]
Redemption percentage of principal			104.563%
Debt Instrument, Redemption, Period Two | 10.5% senior notes, with semi-annual interest payments in March and September, maturing March 2022 [Member] | Senior Notes
Debt Instrument [Line Items]
Redemption percentage of principal	105.25%
Debt Instrument, Redemption, Period Three | 9.125% senior notes, with semi-annual interest payments in June and December, maturing June 2025 | Senior Notes
Debt Instrument [Line Items]
Redemption percentage of principal			102.281%
Debt Instrument, Redemption, Period Four | 9.125% senior notes, with semi-annual interest payments in June and December, maturing June 2025 | Senior Notes
Debt Instrument [Line Items]
Redemption percentage of principal			100.00%
Debt Instrument, Redemption, Period One | 9.125% senior notes, with semi-annual interest payments in June and December, maturing June 2025 | Senior Notes
Debt Instrument [Line Items]
Redemption percentage of principal			109.125%

Fair Value Measurements - Contr

Fair Value Measurements - Contracts Receivable and Debt (Detail) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2020	Dec. 31, 2019
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Carrying Value	$ 491,473	$ 516,198
Contracts receivable (current and long-term)	$ 35,800	38,945
Fair value, percentage of par	88.00%
Discount Rate	15.00%
Fair Value, Inputs, Level 3
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Contracts receivable (current and long-term)	$ 27,255	33,460
Senior Notes due 2025
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Carrying Value	294,891	294,084
Senior Notes due 2025 | Fair Value, Inputs, Level 1
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Estimated Fair Value	263,250	269,250
Opco Senior Notes
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Carrying Value	196,582	222,114
Opco Senior Notes | Fair Value, Inputs, Level 3
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Estimated Fair Value	173,934	201,090
Opco Revolving Credit Facility
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Carrying Value	0	0
Opco Revolving Credit Facility | Fair Value, Inputs, Level 3
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Estimated Fair Value	$ 0	$ 0

Fair Value Measurements - Embed

Fair Value Measurements - Embedded Derivatives (Detail) - USD ($)	Sep. 30, 2020	Dec. 31, 2019
Equity [Abstract]
Fair value of embedded derivatives	$ 0	$ 0

Related Party Transactions - Su

Related Party Transactions - Summary of Reimbursements (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Related Party Transaction [Line Items]
General and administrative expenses	$ 3,634	$ 4,253	$ 11,168	$ 12,799
Western Pocahontas Properties and Quintana Minerals Corporation | Affiliated Entity
Related Party Transaction [Line Items]
Operating and maintenance expenses	1,562	1,598	4,729	4,806
General and administrative expenses	$ 878	$ 855	$ 2,657	$ 2,704

Related Party Transactions - Na

Related Party Transactions - Narrative (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Quintana Minerals | Affiliated Entity
Related Party Transaction [Line Items]
Accounts payable to related parties	$ 0.4		$ 0.4		$ 0.4
Western Pocahontas Properties Limited Partnership | Affiliated Entity
Related Party Transaction [Line Items]
Accounts payable to related parties	0.2		0.2		0.1
Operating and maintenance expenses	$ 0.2	$ 0.3	$ 0.3	$ 3.8
Industrial Minerals Group
Related Party Transaction [Line Items]
Revenue from related parties		0.4		0.9
Accounts receivable from related parties					$ 0.7
Quinwood Coal Company
Related Party Transaction [Line Items]
Revenue from related parties		$ 0		$ 0.2

Major Customers (Detail)

Major Customers (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Concentration Risk [Line Items]
Revenues	$ 29,930	$ 57,602	$ 100,690	$ 205,610
Foresight Energy Lp
Concentration Risk [Line Items]
Revenues	8,592	12,375	27,052	44,604
Contura Energy
Concentration Risk [Line Items]
Revenues	$ 7,143	$ 9,190	$ 23,164	$ 32,915
Sales Revenue | Customer Concentration Risk | Foresight Energy Lp
Concentration Risk [Line Items]
Percent	29.00%	21.00%	27.00%	22.00%
Sales Revenue | Customer Concentration Risk | Contura Energy
Concentration Risk [Line Items]
Percent	24.00%	16.00%	23.00%	16.00%

Unit-Based Compensation (Detail

Unit-Based Compensation (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Fair value of awards granted			$ 3.5	$ 5.4
Weighted average remaining term vesting recognized			1 year 9 months 18 days
Unamortized cost associated with unvested outstanding awards	$ 4.4		$ 4.4		$ 3.5
General and administrative expense and operating and maintenance expense
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unit based compensation expense	$ 0.9	$ 0.5	$ 2.6	$ 1.8

Unit-Based Compensation Summary

Unit-Based Compensation Summary of unit based activity (Details) shares in Thousands	9 Months Ended
	Sep. 30, 2020$ / sharesshares
Common Units
Outstanding at beginning of period | shares	157
Granted | shares	203
Fully vested and issued | shares	0
Forfeitures | shares	(5)
Outstanding at the end of period | shares	355
Weighted Average Exercise Price
Outstanding at beginning of period | $ / shares	$ 26.20
Granted | $ / shares	17.20
Fully vested and issued | $ / shares	0
Forfeitures | $ / shares	17.20
Outstanding at the end of period | $ / shares	$ 37.48

Credit Losses (Details)

Credit Losses (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2020	Sep. 30, 2019
Financing Receivable, Allowance for Credit Loss [Line Items]
Short-term Receivables	$ 24,172	$ 24,172
CECL Allowance - Short Term	(2,324)	(2,324)
Short-term receivables, net of CECL	21,848	21,848
Long-term Investments and Receivables, Gross	35,370	35,370
CECL Allowance - Long term	(1,579)	(1,579)
Long-term contract receivable, net	33,791	33,791
Total receivables, Gross	59,542	59,542
CECL Allowance - total	(3,903)	(3,903)
Total receivables, net of CECL	55,639	55,639
Credit Loss, Expense (Reversal)	300	0
Bad debt expense		3,915	$ 6,842
Direct write-offs excluding CECL
Financing Receivable, Allowance for Credit Loss [Line Items]
Bad debt expense	$ 0	$ 3,900

Financing Transaction (Details)

Financing Transaction (Details) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2020	Dec. 31, 2032
Accounts, Notes, Loans and Financing Receivable [Line Items]
Lessor, Operating Lease, Renewal Term	80 years
Payments from coal lease accounted for as financing transaction	$ 5,000
Forecast
Accounts, Notes, Loans and Financing Receivable [Line Items]
Annual rent amount after lease completion		$ 10

Financing Transaction Financing

Financing Transaction Financing Receivable, after Allowance for Credit Loss (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts receivable, net	$ 17,462	$ 30,869
Foresight Energy Lp
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts receivable, net	0	540
Contract receivable, net (current and long-term)	35,800	38,945
Unearned income	(19,704)	(21,889)
Projected remaining payments, net	$ 55,504	$ 61,374

Leases Lessee accounting under

Leases Lessee accounting under ASC 842 - narrative (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Lessor, Lease, Description [Line Items]
Number of options to extend			five
Length of renewal term	5 years		5 years
Operating lease, right-of-use asset	$ 3.5		$ 3.5
Operating lease expenses	$ 0.1	$ 0.1	$ 0.4	$ 0.4
Minimum
Lessor, Lease, Description [Line Items]
Base term on lease (in years)	5 years		5 years

Leases Operating lease maturity

Leases Operating lease maturity schedule (Details) $ in Thousands	Sep. 30, 2020USD ($)
Lessee, Operating Lease, Liability, Payment, Due [Abstract]
2020	$ 121
2021	483
2022	483
2023	483
2024	483
After 2024	11,597
Total lease payments	13,650
Less: present value adjustment	(10,150)
Total operating lease liability	$ 3,500
Remaining lease term of operating lease	28 years 3 months
Discount rate	13.50%
Maximum
Lessee, Operating Lease, Liability, Payment, Due [Abstract]
Expected lease term	30 years

Subsequent Events - Additional

Subsequent Events - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands	Nov. 04, 2020	Sep. 30, 2020	Dec. 31, 2019
Subsequent Event [Line Items]
Preferred units, issued		250,000	250,000
Subsequent Event
Subsequent Event [Line Items]
Distribution per Unit	$ 0.45
Dividends, Preferred Stock	$ 3,750
Preferred units, issued	3,750

Uncategorized Items - nrp-20200

Label	Element	Value
Cumulative Effect, Period of Adoption, Adjustment [Member] | General Partner [Member]
Partners' Capital, Including Portion Attributable to Noncontrolling Interest	us-gaap_PartnersCapitalIncludingPortionAttributableToNoncontrollingInterest	$ (78,000)
Cumulative Effect, Period of Adoption, Adjustment [Member] | Common Stock [Member] | Common unitholders [Member]
Partners' Capital, Including Portion Attributable to Noncontrolling Interest	us-gaap_PartnersCapitalIncludingPortionAttributableToNoncontrollingInterest	$ (3,833,000)