Martin Midstream Partners (MMLP) 10-Q 26 Jul 21 2021 Q2 Quarterly report Financial data

Cover Page

Cover Page - shares	6 Months Ended
	Jun. 30, 2021	Jul. 26, 2021
Cover [Abstract]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Jun. 30, 2021
Document Transition Report	false
Entity File Number	000-50056
Entity Registrant Name	MARTIN MIDSTREAM PARTNERS L.P.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	05-0527861
Entity Address, Address Line One	4200 Stone Road
Entity Address, City or Town	Kilgore
Entity Address, State or Province	TX
Entity Address, Postal Zip Code	75662
City Area Code	903
Local Phone Number	983-6200
Title of each class	Common Units representing limited partnership interests
Trading Symbol(s)	MMLP
Name of each exchange on which registered	NASDAQ
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding (in shares)		38,802,750
Entity Central Index Key	0001176334
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2021
Document Fiscal Period Focus	Q2
Amendment Flag	false

CONSOLIDATED AND CONDENSED BALA

CONSOLIDATED AND CONDENSED BALANCE SHEETS - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Assets
Cash	$ 681	$ 4,958
Accounts and other receivables, less allowance for doubtful accounts of $225 and $261, respectively	55,051	52,748
Inventories	71,358	54,122
Due from affiliates	20,619	14,807
Other current assets	6,913	8,991
Total current assets	154,622	135,626
Property, plant and equipment, at cost	891,746	889,108
Accumulated depreciation	(530,624)	(509,237)
Property, plant and equipment, net	361,122	379,871
Goodwill	16,823	16,823
Right-of-use assets	19,955	22,260
Deferred income taxes, net	21,495	22,253
Other assets, net	2,862	2,805
Total assets	576,879	579,638
Liabilities and Partners’ Capital (Deficit)
Current installments of long-term debt and finance lease obligations	236	31,497
Trade and other accounts payable	55,453	51,900
Product exchange payables	700	373
Due to affiliates	1,939	435
Income taxes payable	308	556
Fair value of derivatives	412	207
Other accrued liabilities	29,394	34,407
Total current liabilities	88,442	119,375
Long-term debt, net	517,311	484,597
Finance lease obligations	169	289
Operating lease liabilities	13,423	15,181
Other long-term obligations	8,631	7,067
Total liabilities	627,976	626,509
Commitments and contingencies
Partners’ capital (deficit)	(51,097)	(46,871)
Total partners’ capital (deficit)	(51,097)	(46,871)
Total liabilities and partners' capital (deficit)	$ 576,879	$ 579,638

CONSOLIDATED AND CONDENSED BA_2

CONSOLIDATED AND CONDENSED BALANCE SHEETS (Parenthetical) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Statement of Financial Position [Abstract]
Allowance for doubtful accounts	$ 225	$ 261

CONSOLIDATED AND CONDENSED STAT

CONSOLIDATED AND CONDENSED STATEMENTS OF OPERATIONS - USD ($) $ in Thousands		3 Months Ended		6 Months Ended
		Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Revenues:
Revenues		$ 184,293	$ 140,638	$ 385,267	$ 339,521
Cost of products sold: (excluding depreciation and amortization)
Cost of products sold		105,993	63,290	220,844	172,100
Expenses:
Operating expenses	[1]	47,313	44,202	91,947	95,484
Selling, general and administrative	[1]	8,960	9,858	19,569	20,320
Depreciation and amortization		14,483	15,343	28,917	30,582
Total costs and expenses		176,749	132,693	361,277	318,486
Other operating income (loss), net		89	15	(671)	2,525
Operating income		7,633	7,960	23,319	23,560
Other income (expense):
Interest expense, net		(13,309)	(9,377)	(26,262)	(19,302)
Gain on retirement of senior unsecured notes		0	0	0	3,484
Other, net		(1)	4	(1)	7
Total other expense		(13,310)	(9,373)	(26,263)	(15,811)
Net income (loss) before taxes		(5,677)	(1,413)	(2,944)	7,749
Income tax expense		(935)	(790)	(1,157)	(1,137)
Net income (loss)		(6,612)	(2,203)	(4,101)	6,612
Less general partner's interest in net (income) loss		132	44	82	(132)
Less (income) loss allocable to unvested restricted units		20	10	10	(45)
Limited partners' interest in net income (loss)		$ (6,460)	$ (2,149)	$ (4,009)	$ 6,435
Net income (loss) per unit attributable to limited partners - basic (in dollars per share)		$ (0.17)	$ (0.06)	$ (0.10)	$ 0.17
Net income (loss) per unit attributable to limited partners - diluted (in dollars per share)		$ (0.17)	$ (0.06)	$ (0.10)	$ 0.17
Weighted average limited partner units - basic (in shares)		38,687,874	38,661,852	38,690,228	38,651,357
Weighted average limited partner units - diluted (in shares)		38,687,874	38,661,852	38,690,228	38,651,897
Terminalling and storage
Revenues:
Revenues	[1]	$ 18,702	$ 19,908	$ 37,080	$ 40,382
Transportation
Revenues:
Revenues	[1]	34,926	31,485	64,741	70,426
Sulfur services
Revenues:
Revenues		2,949	2,914	5,899	5,829
Product sales
Revenues:
Revenues	[1]	127,716	86,331	277,547	222,884
Natural gas liquids
Revenues:
Revenues	[1]	67,232	30,299	165,317	112,510
Cost of products sold: (excluding depreciation and amortization)
Cost of products sold	[1]	61,590	24,293	140,725	94,128
Sulfur services
Revenues:
Revenues	[1]	35,337	30,506	67,222	55,914
Cost of products sold: (excluding depreciation and amortization)
Cost of products sold	[1]	24,177	17,559	45,391	32,854
Terminalling and storage
Revenues:
Revenues	[1]	25,147	25,526	45,008	54,460
Cost of products sold: (excluding depreciation and amortization)
Cost of products sold	[1]	$ 20,226	$ 21,438	$ 34,728	$ 45,118
[1]	Related Party Transactions Included Above Three Months Ended Six Months Ended June 30, June 30, 2021 2020 2021 2020 Revenues:* Terminalling and storage $ 15,569 $ 15,942 $ 30,875 $ 31,816 Transportation 4,889 5,393 8,899 11,287 Product Sales 71 38 185 130 Costs and expenses:* Cost of products sold: (excluding depreciation and amortization) Sulfur services 2,403 2,554 4,938 5,321 Terminalling and storage 7,036 4,249 11,604 10,026 Expenses: Operating expenses 19,590 19,440 37,958 41,211 Selling, general and administrative 7,285 8,055 15,965 16,367

CONSOLIDATED AND CONDENSED ST_2

CONSOLIDATED AND CONDENSED STATEMENTS OF OPERATIONS - Related Party Transactions (Parentheticals) - USD ($) $ in Thousands		3 Months Ended		6 Months Ended
		Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Revenues:
Revenues		$ 184,293	$ 140,638	$ 385,267	$ 339,521
Cost of products sold: (excluding depreciation and amortization)
Cost of products sold		105,993	63,290	220,844	172,100
Expenses:
Operating expenses		19,590	19,440	37,958	41,211
Selling, general and administrative		7,285	8,055	15,965	16,367
Terminalling and storage
Revenues:
Revenues	[1]	18,702	19,908	37,080	40,382
Transportation
Revenues:
Revenues	[1]	34,926	31,485	64,741	70,426
Product Sales
Revenues:
Revenues	[1]	127,716	86,331	277,547	222,884
Sulfur services
Revenues:
Revenues	[1]	35,337	30,506	67,222	55,914
Cost of products sold: (excluding depreciation and amortization)
Cost of products sold	[1]	24,177	17,559	45,391	32,854
Terminalling and storage
Revenues:
Revenues	[1]	25,147	25,526	45,008	54,460
Cost of products sold: (excluding depreciation and amortization)
Cost of products sold	[1]	20,226	21,438	34,728	45,118
Related Party
Expenses:
Operating expenses		19,590	19,440	37,958	41,211
Related Party | Terminalling and storage
Revenues:
Revenues		15,569	15,942	30,875	31,816
Expenses:
Operating expenses		4,127	4,417	8,229	8,992
Related Party | Transportation
Revenues:
Revenues		4,889	5,393	8,899	11,287
Expenses:
Operating expenses		13,644	13,388	26,703	28,941
Related Party | Product Sales
Revenues:
Revenues		71	38	185	130
Related Party | Sulfur services
Cost of products sold: (excluding depreciation and amortization)
Cost of products sold		2,403	2,554	4,938	5,321
Expenses:
Operating expenses		1,306	1,137	2,049	2,283
Related Party | Terminalling and storage
Cost of products sold: (excluding depreciation and amortization)
Cost of products sold		$ 7,036	$ 4,249	$ 11,604	$ 10,026
[1]	Related Party Transactions Included Above Three Months Ended Six Months Ended June 30, June 30, 2021 2020 2021 2020 Revenues:* Terminalling and storage $ 15,569 $ 15,942 $ 30,875 $ 31,816 Transportation 4,889 5,393 8,899 11,287 Product Sales 71 38 185 130 Costs and expenses:* Cost of products sold: (excluding depreciation and amortization) Sulfur services 2,403 2,554 4,938 5,321 Terminalling and storage 7,036 4,249 11,604 10,026 Expenses: Operating expenses 19,590 19,440 37,958 41,211 Selling, general and administrative 7,285 8,055 15,965 16,367

CONSOLIDATED AND CONDENSED ST_3

CONSOLIDATED AND CONDENSED STATEMENTS OF CAPITAL (DEFICIT) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Increase (Decrease) in Partners' Capital
Beginning balance			$ (46,871)	$ (36,196)
Net income (loss)	$ (6,612)	$ (2,203)	(4,101)	6,612
Cash distributions			(396)	(4,923)
Unit-based compensation			288	709
Purchase of treasury units			(17)	(9)
Ending balance	(51,097)	(33,807)	(51,097)	(33,807)
Common Limited | Common
Increase (Decrease) in Partners' Capital
Beginning balance			$ (48,776)	$ (38,342)
Beginning balance (in shares)			38,851,174	38,863,389
Net income (loss)			$ (4,019)	$ 6,480
Issuance of restricted units (in shares)			42,168	81,000
Forfeiture of restricted units (in shares)			(83,436)	(84,134)
Cash distributions			$ (388)	$ (4,825)
Unit-based compensation			288	709
Purchase of treasury units			$ (17)	$ (9)
Purchase of treasury units (in shares)			(7,156)	(7,748)
Ending balance	$ (52,912)	$ (35,987)	$ (52,912)	$ (35,987)
Ending balance (in shares)	38,802,750	38,852,507	38,802,750	38,852,507
General Partner Amount
Increase (Decrease) in Partners' Capital
Beginning balance			$ 1,905	$ 2,146
Net income (loss)			(82)	132
Cash distributions			(8)	(98)
Ending balance	$ 1,815	$ 2,180	$ 1,815	$ 2,180

CONSOLIDATED AND CONDENSED ST_4

CONSOLIDATED AND CONDENSED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020
Cash flows from operating activities:
Net income (loss)	$ (4,101)	$ 6,612
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	28,917	30,582
Amortization of deferred debt issuance costs	1,521	991
Amortization of premium on notes payable	0	(153)
Deferred income tax expense	758	1,018
Loss on sale of property, plant and equipment, net	671	175
Gain on retirement of senior unsecured notes	0	(3,484)
Derivative (income) loss	884	(1,463)
Net cash received (paid) for commodity derivatives	(679)	796
Unit-based compensation	288	709
Change in current assets and liabilities, excluding effects of acquisitions and dispositions:
Accounts and other receivables	(2,303)	37,180
Inventories	(17,572)	(3,128)
Due from affiliates	(5,812)	(1,060)
Other current assets	1,435	(5,547)
Trade and other accounts payable	3,335	(16,502)
Product exchange payables	327	811
Due to affiliates	1,504	(1,026)
Income taxes payable	(248)	26
Other accrued liabilities	(3,053)	(2,452)
Change in other non-current assets and liabilities	213	541
Net cash provided by operating activities	6,085	44,626
Cash flows from investing activities:
Payments for property, plant and equipment	(8,200)	(19,053)
Payments for plant turnaround costs	(1,694)	(231)
Proceeds from involuntary conversion of property, plant and equipment	0	4,369
Proceeds from sale of property, plant and equipment	133	1,768
Net cash used in investing activities	(9,761)	(13,147)
Cash flows from financing activities:
Payments of long-term debt	(144,790)	(156,860)
Payments under finance lease obligations	(2,591)	(3,222)
Proceeds from long-term debt	147,500	131,000
Purchase of treasury units	(17)	(9)
Payment of debt issuance costs	(307)	(269)
Cash distributions paid	(396)	(4,923)
Net cash used in financing activities	(601)	(34,283)
Net decrease in cash	(4,277)	(2,804)
Cash at beginning of period	4,958	2,856
Cash at end of period	681	52
Non-cash additions to property, plant and equipment	$ 686	$ 1,276

Nature of Operations and Basis

Nature of Operations and Basis of Presentation	6 Months Ended
	Jun. 30, 2021
Accounting Policies [Abstract]
Nature of Operations and Basis of Presentation	NATURE OF OPERATIONS AND BASIS OF PRESENTATION Martin Midstream Partners L.P. (the "Partnership") is a publicly traded limited partnership with a diverse set of operations focused primarily in the United States ("U.S.") Gulf Coast region. Its four primary business lines include: terminalling, processing, storage and packaging services for petroleum products and by-products including the refining of naphthenic crude oil; land and marine transportation services for petroleum products and by-products, chemicals, and specialty products; sulfur and sulfur-based products processing, manufacturing, marketing and distribution; and natural gas liquids marketing, distribution, and transportation services. The Partnership’s unaudited consolidated and condensed financial statements have been prepared in accordance with the requirements of Form 10-Q and U.S. Generally Accepted Accounting Principles ("U.S. GAAP") for interim financial reporting. Accordingly, these financial statements have been condensed and do not include all of the information and footnotes required by U.S. GAAP for annual audited financial statements of the type contained in the Partnership’s annual reports on Form 10-K. In the opinion of the management of the Partnership’s general partner, all adjustments and elimination of significant intercompany balances necessary for a fair presentation of the Partnership’s financial position, results of operations, and cash flows for the periods shown have been made. All such adjustments are of a normal recurring nature. Results for such interim periods are not necessarily indicative of the results of operations for the full year. These financial statements should be read in conjunction with the Partnership’s audited consolidated financial statements and notes thereto included in the Partnership’s annual report on Form 10-K for the year ended December 31, 2020, filed with the SEC on March 3, 2021. Management has made a number of estimates and assumptions relating to the reporting of assets and liabilities and the disclosure of contingent assets and liabilities to prepare these consolidated and condensed financial statements in conformity with U.S. GAAP. Actual results could differ from those estimates.

New Accounting Pronouncements

New Accounting Pronouncements	6 Months Ended
	Jun. 30, 2021
Accounting Changes and Error Corrections [Abstract]
New Accounting Pronouncements	NEW ACCOUNTING PRONOUNCEMENTS On January 1, 2021, the Partnership adopted Financial Accounting Standards Board ("FASB") Accounting Standards Update ("ASU") 2019-12, Income Taxes (Accounting Standards Codification ("ASC") Topic 740): Simplifying the Accounting for Income Taxes , which removes certain exceptions to general principles in ASC 740 and clarifies and amends existing guidance within U.S. GAAP. Adoption of the new standard did not have a material impact on the Partnership’s consolidated financial statements.

Revenue

Revenue	6 Months Ended
	Jun. 30, 2021
Revenue from Contract with Customer [Abstract]
Revenue	REVENUE The following table disaggregates our revenue by major source: Three Months Ended June 30, Six Months Ended June 30, 2021 2020 2021 2020 Terminalling and storage segment Lubricant product sales $ 25,147 $ 25,526 $ 45,008 $ 54,460 Throughput and storage 18,702 19,908 37,080 40,382 $ 43,849 $ 45,434 $ 82,088 $ 94,842 Natural gas liquids segment Natural gas liquids product sales $ 67,232 $ 30,299 $ 165,317 $ 112,510 $ 67,232 $ 30,299 $ 165,317 $ 112,510 Sulfur services segment Sulfur product sales $ 7,386 $ 6,367 $ 14,454 $ 12,849 Fertilizer product sales 27,951 24,139 52,768 43,065 Sulfur services 2,949 2,914 5,899 5,829 $ 38,286 $ 33,420 $ 73,121 $ 61,743 Transportation segment Land transportation $ 27,486 $ 19,873 $ 50,442 $ 44,107 Inland transportation 6,633 10,611 13,357 24,317 Offshore transportation 807 1,001 942 2,002 $ 34,926 $ 31,485 $ 64,741 $ 70,426 Revenue is measured based on a consideration specified in a contract with a customer and excludes amounts collected on behalf of third parties where the Partnership is acting as an agent. The Partnership recognizes revenue when the Partnership satisfies a performance obligation, which typically occurs when the Partnership transfers control over a product to a customer or as the Partnership delivers a service. The following is a description of the principal activities - separated by reportable segments - from which the Partnership generates revenue. Terminalling and Storage Segment Revenue is recognized for storage contracts based on the contracted monthly tank fixed fee. For throughput contracts, revenue is recognized based on the volume moved through the Partnership’s terminals at the contracted rate. For the Partnership’s tolling agreement, revenue is recognized based on the contracted monthly reservation fee and throughput volumes moved through the facility. When lubricants and drilling fluids are sold by truck or rail, revenue is recognized when title is transferred, which is either upon delivering product to the customer or when the product leaves the Partnership's facility, depending on the specific terms of the contract. Delivery of product is invoiced as the transaction occurs and is generally paid within a month. Throughput and storage revenue in the table above includes non-cancelable revenue arrangements that are under the scope of ASC 842, whereby the Partnership has committed certain Terminalling and Storage assets in exchange for a minimum fee. Natural Gas Liquids Segment Natural Gas Liquids ("NGL") revenue is recognized when product is delivered by truck, rail, or pipeline to the Partnership's NGL customers. Revenue is recognized on title transfer of the product to the customer. Delivery of product is invoiced as the transaction occurs and is generally paid within a month. Sulfur Services Segment Revenue from sulfur and fertilizer product sales is recognized when the customer takes title to the product. Delivery of product is invoiced as the transaction occurs and is generally paid within a month. Revenue from sulfur services is recognized as services are performed during each monthly period. The performance of the service is invoiced as the transaction occurs and is generally paid within a month. Transportation Segment Revenue related to land transportation is recognized for line hauls based on a mileage rate. For contracted trips, revenue is recognized upon completion of the particular trip. The performance of the service is invoiced as the transaction occurs and is generally paid within a month. Revenue related to marine transportation is recognized for time charters based on a per day rate. For contracted trips, revenue is recognized upon completion of the particular trip. The performance of the service is invoiced as the transaction occurs and is generally paid within a month. The table below includes estimated minimum revenue expected to be recognized in the future related to performance obligations that are unsatisfied at the end of the reporting period. The Partnership applies the practical expedient in ASC 606-10-50-14(a) and does not disclose information about remaining performance obligations that have original expected durations of one year or less. 2021 2022 2023 2024 2025 Thereafter Total Terminalling and storage Throughput and storage $ 21,046 $ 40,394 $ 41,605 $ 42,854 $ 44,197 $ 294,141 $ 484,237 Natural Gas Services Natural Gas Liquids 3,288 6,048 5,391 5,405 5,391 3,131 28,654 Sulfur services Sulfur product sales 8,582 16,279 15,233 975 975 — 42,044 Total $ 32,916 $ 62,721 $ 62,229 $ 49,234 $ 50,563 $ 297,272 $ 554,935

Inventories

Inventories	6 Months Ended
	Jun. 30, 2021
Inventory Disclosure [Abstract]
Inventories	INVENTORIES Components of inventories at June 30, 2021 and December 31, 2020 were as follows: June 30, December 31, Natural gas liquids $ 41,805 $ 27,878 Sulfur 71 24 Fertilizer 8,216 10,854 Lubricants 16,701 11,002 Other 4,565 4,364 $ 71,358 $ 54,122

Debt

Debt	6 Months Ended
	Jun. 30, 2021
Debt Disclosure [Abstract]
Debt	DEBT At June 30, 2021 and December 31, 2020, long-term debt consisted of the following: June 30, December 31, $300,000 Revolving credit facility at variable interest rate (5.00% 1 weighted average at June 30, 2021), due August 2023 4 secured by substantially all of the Partnership’s assets, including, without limitation, inventory, accounts receivable, vessels, equipment, fixed assets and the interests in the Partnership’s operating subsidiaries, net of unamortized debt issuance costs of $3,392 and $3,826, respectively 2 $ 176,108 $ 144,174 $400,000 Senior notes, 7.25% interest, net of unamortized debt issuance costs of $— and $—, respectively, including unamortized premium of $— and $—, respectively, issued $250,000 February 2013 and $150,000 April 2014, $26,200 repurchased during 2015, $9,344 repurchased during 2020, $335,666 refinanced as part of the August 2020 Exchange offer, $28,790 repaid at maturity in February 2021, unsecured 2,3,4 — 28,790 $53,750 Senior notes, 10.0% interest, net of unamortized debt issuance costs of $3,005 and $3,577, respectively, due February 2024, secured 2,3 50,745 50,173 $291,970 Senior notes, 11.5% interest, net of unamortized debt issuance costs of $1,512 and $1,720, respectively, due February 2025, secured 2,3 290,458 290,250 Total 517,311 513,387 Less: current portion — (28,790) Total long-term debt, net of current portion $ 517,311 $ 484,597 Current installments of finance lease obligations $ 236 $ 2,707 Finance lease obligations 169 289 Total finance lease obligations $ 405 $ 2,996 1 Interest rate fluctuates based on LIBOR or the base prime rate (set on the date of each advance) plus an applicable margin. The margin is set every three months. All amounts outstanding at December 31, 2020 and June 30, 2021 were at LIBOR plus an applicable margin with LIBOR having a floor of 1.0% per annum. The applicable margin for revolving loans that are LIBOR loans currently ranges from 2.75% to 4.00%, and the applicable margin for revolving loans that are base prime rate loans currently ranges from 1.75% to 3.00%. The applicable margin for LIBOR borrowings at June 30, 2021 is 4.00%. The credit facility contains various covenants that limit the Partnership’s ability to make distributions; make certain investments and acquisitions; enter into certain agreements; incur indebtedness; sell assets; and make certain amendments to the Partnership's omnibus agreement with Martin Resource Management Corporation (the "Omnibus Agreement"). The credit facility was amended on July 16, 2021 to, among other things, reduce the commitments thereunder from $300,000 to $275,000. 2 The Partnership is in compliance with all debt covenants as of June 30, 2021 and December 31, 2020, respectively. 3 The indentures for each of the outstanding series of senior notes restrict the Partnership’s ability to sell assets; pay distributions or repurchase units or redeem or repurchase subordinated debt; make investments; incur or guarantee additional indebtedness or issue preferred units; and consolidate, merge or transfer all or substantially all of its assets. 4 On February 15, 2021, the 2021 Notes matured and the Partnership retired the outstanding balance of $28,790 using funds borrowed under its revolving credit facility.

Leases

Leases	6 Months Ended
	Jun. 30, 2021
Leases [Abstract]
Leases	LEASES The Partnership has numerous operating leases primarily for terminal facilities and transportation and other equipment. The leases generally provide that all expenses related to the equipment are to be paid by the lessee. Operating lease Right-of-Use assets and operating lease liabilities are recognized based on the present value of lease payments over the lease term at commencement date. Because most of the Partnership's leases do not provide an implicit rate of return, the Partnership uses its imputed collateralized rate based on the information available at commencement date in determining the present value of lease payments. The estimated rate is based on a risk-free rate plus a risk-adjusted margin. Our leases have remaining lease terms of 1 year to 15 years, some of which include options to extend the leases for up to 5 years, and some of which include options to terminate the leases within 1 year. The Partnership includes extension periods and excludes termination periods from its lease term if, at commencement, it is reasonably likely that the Partnership will exercise the option. The components of lease expense for the three and six months ended June 30, 2021 and 2020 were as follows: Three Months Ended June 30, Six Months Ended June 30, 2021 2020 2021 2020 Operating lease cost $ 2,199 $ 2,767 $ 4,501 $ 5,611 Finance lease cost: Amortization of right-of-use assets $ 25 526 $ 115 1,115 Interest on lease liabilities $ 6 86 $ 16 196 Short-term lease cost $ 2,473 3,492 $ 5,581 6,915 Variable lease cost $ 26 $ 22 $ 59 $ 50 Total lease cost $ 4,729 $ 6,893 $ 10,272 $ 13,887 Supplemental balance sheet information related to leases at June 30, 2021 and December 31, 2020 was as follows: June 30, December 31, 2020 Operating Leases Operating lease right-of-use assets $ 19,955 $ 22,260 Current portion of operating lease liabilities included in "Other accrued liabilities" $ 6,961 $ 7,529 Operating lease liabilities $ 13,423 15,181 Total operating lease liabilities $ 20,384 $ 22,710 Finance Leases Property, plant and equipment, at cost $ 1,071 $ 10,352 Accumulated depreciation $ (315) (3,703) Property, plant and equipment, net $ 756 $ 6,649 Current installments of finance lease obligations $ 236 $ 2,707 Finance lease obligations $ 169 289 Total finance lease obligations $ 405 $ 2,996 The Partnership’s future minimum lease obligations as of June 30, 2021 consist of the following: Operating Leases Finance Leases Year 1 $ 7,769 $ 252 Year 2 5,094 172 Year 3 2,566 — Year 4 1,735 — Year 5 1,053 — Thereafter 5,511 — Total $ 23,728 $ 424 Less amounts representing interest costs (3,344) (19) Total lease liability $ 20,384 $ 405 The Partnership has non-cancelable revenue arrangements that are under the scope of ASC 842 whereby we have committed certain terminalling and storage assets in exchange for a minimum fee. Future minimum revenues the Partnership expects to receive under these non-cancelable arrangements as of June 30, 2021 are as follows: 2021 - $11,559; 2022 - $14,771; 2023 - $14,364; 2024 - $14,364; 2025 - $13,798; subsequent years - $38,539.
Leases	LEASES The Partnership has numerous operating leases primarily for terminal facilities and transportation and other equipment. The leases generally provide that all expenses related to the equipment are to be paid by the lessee. Operating lease Right-of-Use assets and operating lease liabilities are recognized based on the present value of lease payments over the lease term at commencement date. Because most of the Partnership's leases do not provide an implicit rate of return, the Partnership uses its imputed collateralized rate based on the information available at commencement date in determining the present value of lease payments. The estimated rate is based on a risk-free rate plus a risk-adjusted margin. Our leases have remaining lease terms of 1 year to 15 years, some of which include options to extend the leases for up to 5 years, and some of which include options to terminate the leases within 1 year. The Partnership includes extension periods and excludes termination periods from its lease term if, at commencement, it is reasonably likely that the Partnership will exercise the option. The components of lease expense for the three and six months ended June 30, 2021 and 2020 were as follows: Three Months Ended June 30, Six Months Ended June 30, 2021 2020 2021 2020 Operating lease cost $ 2,199 $ 2,767 $ 4,501 $ 5,611 Finance lease cost: Amortization of right-of-use assets $ 25 526 $ 115 1,115 Interest on lease liabilities $ 6 86 $ 16 196 Short-term lease cost $ 2,473 3,492 $ 5,581 6,915 Variable lease cost $ 26 $ 22 $ 59 $ 50 Total lease cost $ 4,729 $ 6,893 $ 10,272 $ 13,887 Supplemental balance sheet information related to leases at June 30, 2021 and December 31, 2020 was as follows: June 30, December 31, 2020 Operating Leases Operating lease right-of-use assets $ 19,955 $ 22,260 Current portion of operating lease liabilities included in "Other accrued liabilities" $ 6,961 $ 7,529 Operating lease liabilities $ 13,423 15,181 Total operating lease liabilities $ 20,384 $ 22,710 Finance Leases Property, plant and equipment, at cost $ 1,071 $ 10,352 Accumulated depreciation $ (315) (3,703) Property, plant and equipment, net $ 756 $ 6,649 Current installments of finance lease obligations $ 236 $ 2,707 Finance lease obligations $ 169 289 Total finance lease obligations $ 405 $ 2,996 The Partnership’s future minimum lease obligations as of June 30, 2021 consist of the following: Operating Leases Finance Leases Year 1 $ 7,769 $ 252 Year 2 5,094 172 Year 3 2,566 — Year 4 1,735 — Year 5 1,053 — Thereafter 5,511 — Total $ 23,728 $ 424 Less amounts representing interest costs (3,344) (19) Total lease liability $ 20,384 $ 405 The Partnership has non-cancelable revenue arrangements that are under the scope of ASC 842 whereby we have committed certain terminalling and storage assets in exchange for a minimum fee. Future minimum revenues the Partnership expects to receive under these non-cancelable arrangements as of June 30, 2021 are as follows: 2021 - $11,559; 2022 - $14,771; 2023 - $14,364; 2024 - $14,364; 2025 - $13,798; subsequent years - $38,539.

Supplemental Balance Sheet Info

Supplemental Balance Sheet Information	6 Months Ended
	Jun. 30, 2021
Balance Sheet Related Disclosures [Abstract]
Supplemental Balance Sheet Information	SUPPLEMENTAL BALANCE SHEET INFORMATION Components of "Other accrued liabilities" were as follows: June 30, December 31, 2020 Accrued interest $ 14,851 $ 16,104 Asset retirement obligations 300 1,692 Property and other taxes payable 3,765 4,869 Accrued payroll 2,940 3,244 Operating lease liabilities 6,961 7,529 Other 577 969 $ 29,394 $ 34,407 The schedule below summarizes the changes in our asset retirement obligations: June 30, 2021 Beginning asset retirement obligations $ 8,759 Additions to asset retirement obligations — Accretion expense 194 Liabilities settled (22) Ending asset retirement obligations 8,931 Current portion of asset retirement obligations 1 (300) Long-term portion of asset retirement obligations 2 $ 8,631 1 The current portion of asset retirement obligations is included in "Other accrued liabilities" on the Partnership's Consolidated and Condensed Balance Sheets. 2 The non-current portion of asset retirement obligations is included in "Other long-term obligations" on the Partnership's Consolidated and Condensed Balance Sheets.

Derivative Instruments and Hedg

Derivative Instruments and Hedging Activities	6 Months Ended
	Jun. 30, 2021
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivative Instruments and Hedging Activities	DERIVATIVE INSTRUMENTS AND HEDGING ACTIVITIES The Partnership’s results of operations could be materially impacted by changes in commodity prices and interest rates. In an effort to manage its exposure to these risks, the Partnership periodically enters into various derivative instruments, including commodity and interest rate hedges. All derivatives and hedging instruments are non-hedge derivatives and are included on the balance sheet as an asset or a liability measured at fair value, and changes in fair value are recognized as gains and losses in the earnings of the periods in which they occur. (a) Commodity Derivative Instruments The Partnership from time to time has used derivatives to manage the risk of commodity price fluctuation. Commodity risk is the adverse effect on the value of a liability or future purchase that results from a change in commodity price. The Partnership has established a hedging policy and monitors and manages the commodity market risk associated with potential commodity risk exposure. In addition, the Partnership has focused on utilizing counterparties for these transactions whose financial condition is appropriate for the credit risk involved in each specific transaction. The Partnership has entered into hedging transactions as of June 30, 2021, to protect a portion of its commodity price risk exposure. These hedging arrangements are in the form of swaps for NGLs. At June 30, 2021, the Partnership had instruments totaling a gross notional quantity of 390,000 barrels settling during the period from July 31, 2021 through December 31, 2021. At December 31, 2020, the Partnership had instruments totaling a gross notional quantity of 137,000 barrels settling during the period from January 31, 2021 through February 28, 2021. These instruments settle against the applicable pricing source for each grade and location. For information regarding gains and losses on interest rate derivative instruments, see "Tabular Presentation of Gains and Losses on Derivative Instruments" below. (b) Tabular Presentation of Gains and Losses on Derivative Instruments The following table summarizes the fair value and classification of the Partnership’s derivative instruments in its Consolidated and Condensed Balance Sheets: Fair Values of Derivative Instruments in the Consolidated and Condensed Balance Sheets Derivative Assets Derivative Liabilities Fair Values Fair Values Balance Sheet Location June 30, 2021 December 31, 2020 Balance Sheet Location June 30, 2021 December 31, 2020 Derivatives not designated as hedging instruments: Current: Commodity contracts Fair value of derivatives $ — $ — Fair value of derivatives $ 412 $ 207 Total derivatives not designated as hedging instruments $ — $ — $ 412 $ 207 Effect of Derivative Instruments on the Consolidated and Condensed Statements of Operations For the Three Months Ended June 30, 2021 and 2020 Location of Gain (Loss) Amount of Gain (Loss) Recognized in 2021 2020 Derivatives not designated as hedging instruments: Commodity contracts Cost of products sold $ 552 $ (162) Total effect of derivatives not designated as hedging instruments $ 552 $ (162) Effect of Derivative Instruments on the Consolidated and Condensed Statements of Operations For the Six Months Ended June 30, 2021 and 2020 Location of Gain (Loss) Amount of Gain (Loss) Recognized in 2021 2020 Derivatives not designated as hedging instruments: Commodity contracts Cost of products sold $ (884) $ (129) Total effect of derivatives not designated as hedging instruments $ (884) $ (129)

Partners' Capital

Partners' Capital	6 Months Ended
	Jun. 30, 2021
Partners' Capital Notes [Abstract]
Partners' Capital	PARTNERS' CAPITAL As of June 30, 2021, Partners’ capital consisted of 38,802,750 common limited partner units, representing a 98% partnership interest, and a 2% general partner interest. Martin Resource Management Corporation, through subsidiaries, owns 6,114,532 of the Partnership's common limited partner units representing approximately 15.8% of the Partnership's outstanding common limited partner units. Martin Midstream GP LLC ("MMGP"), the Partnership's general partner, owns the 2% general partnership interest. Martin Resource Management Corporation controls the Partnership's general partner, by virtue of its 51% voting interest in MMGP Holdings, LLC ("Holdings"), the sole member of the Partnership's general partner. The partnership agreement of the Partnership (the "Partnership Agreement") contains specific provisions for the allocation of net income and losses to each of the partners for purposes of maintaining their respective partner capital accounts. Impact on Partners' Capital (Deficit) Related to Transactions Between Entities Under Common Control Under ASC 805, assets and liabilities transferred between entities under common control are accounted for at the historical cost of those entities' ultimate parent, in a manner similar to a pooling of interests. Any difference in the amount paid by the transferee versus the historical cost of the assets transferred is recorded as an adjustment to equity (contribution or distribution) by the transferee. This is in contrast with a business combination between unrelated parties, where assets and liabilities are recorded at their fair values at the acquisition date, with any excess of amounts paid over the fair value representing goodwill. From time to time, the most recent being in 2019, the Partnership has entered into common control acquisitions from Martin Resource Management Corporation. The consideration transferred totaling $550,773 exceeds the historical cost of the net assets received. This excess of the purchase price over the historical cost of the net assets received has resulted in cumulative distributions of $287,734 reflected as reductions to Partners' capital. Incentive Distribution Rights MMGP holds a 2% general partner interest and certain incentive distribution rights ("IDRs") in the Partnership. IDRs are a separate class of non-voting limited partner interest that may be transferred or sold by the general partner under the terms of the Partnership Agreement, and represent the right to receive an increasing percentage of cash distributions after the minimum quarterly distribution and any cumulative arrearages on common units once certain target distribution levels have been achieved. The Partnership is required to distribute all of its available cash from operating surplus, as defined in the Partnership Agreement. The general partner was allocated no incentive distributions during the six months ended June 30, 2021 and 2020. The target distribution levels entitle the general partner to receive 2% of quarterly cash distributions from the minimum of $0.50 per unit up to $0.55 per unit, 15% of quarterly cash distributions in excess of $0.55 per unit until all unitholders have received $0.625 per unit, 25% of quarterly cash distributions in excess of $0.625 per unit until all unitholders have received $0.75 per unit and 50% of quarterly cash distributions in excess of $0.75 per unit. Distributions of Available Cash The Partnership distributes all of its available cash (as defined in the Partnership Agreement) within 45 days after the end of each quarter to unitholders of record and to the general partner. Available cash is generally defined as all cash and cash equivalents of the Partnership on hand at the end of each quarter less the amount of cash reserves its general partner determines in its reasonable discretion is necessary or appropriate to: (i) provide for the proper conduct of the Partnership’s business; (ii) comply with applicable law, any debt instruments or other agreements; or (iii) provide funds for distributions to unitholders and the general partner for any one or more of the next four quarters, plus all cash on the date of determination of available cash for the quarter resulting from working capital borrowings made after the end of the quarter. Net Income per Unit The Partnership follows the provisions of the FASB ASC 260-10 related to earnings per share, which addresses the application of the two-class method in determining income per unit for master limited partnerships having multiple classes of securities that may participate in partnership distributions accounted for as equity distributions. Undistributed earnings are allocated to the general partner and limited partners utilizing the contractual terms of the Partnership Agreement. Distributions to the general partner pursuant to the IDRs are limited to available cash that will be distributed as defined in the Partnership Agreement. Accordingly, the Partnership does not allocate undistributed earnings to the general partner for the IDRs because the general partner's share of available cash is the maximum amount that the general partner would be contractually entitled to receive if all earnings for the period were distributed. When current period distributions are in excess of earnings, the excess distributions for the period are to be allocated to the general partner and limited partners based on their respective sharing of income and losses specified in the Partnership Agreement. Additionally, as required under FASB ASC 260-10-45-61A, unvested share-based payments that entitle employees to receive non-forfeitable distributions are considered participating securities, as defined in FASB ASC 260-10-20, for earnings per unit calculations. For purposes of computing diluted net income per unit, the Partnership uses the more dilutive of the two-class and if-converted methods. Under the if-converted method, the weighted-average number of subordinated units outstanding for the period is added to the weighted-average number of common units outstanding for purposes of computing basic net income per unit and the resulting amount is compared to the diluted net income per unit computed using the two-class method. The following is a reconciliation of net income allocated to the general partner and limited partners for purposes of calculating net income attributable to limited partners per unit: Three Months Ended June 30, Six Months Ended June 30, 2021 2020 2021 2020 Net income (loss) $ (6,612) $ (2,203) $ (4,101) $ 6,612 Less general partner’s interest in net income (loss): Distributions payable on behalf of general partner interest 4 4 8 53 General partner interest in undistributed income (loss) (136) (48) (90) 79 Less income (loss) allocable to unvested restricted units (20) (10) (10) 45 Limited partners’ interest in net income (loss) $ (6,460) $ (2,149) $ (4,009) $ 6,435 The following are the unit amounts used to compute the basic and diluted earnings per limited partner unit for the periods presented: Three Months Ended June 30, Six Months Ended June 30, 2021 2020 2021 2020 Basic weighted average limited partner units outstanding 38,687,874 38,661,852 38,690,228 38,651,357 Dilutive effect of restricted units issued — — — 540 Total weighted average limited partner diluted units outstanding 38,687,874 38,661,852 38,690,228 38,651,897 All outstanding units were included in the computation of diluted earnings per unit and weighted based on the number of days such units were outstanding during the periods presented. All common unit equivalents were antidilutive for the three and six months ended June 30, 2021 and the three months ended June 30, 2020 because the limited partners were allocated a net loss in this period.

Unit Based Awards

Unit Based Awards	6 Months Ended
	Jun. 30, 2021
Share-based Payment Arrangement [Abstract]
Unit Based Awards	UNIT BASED AWARDS The Partnership recognizes compensation cost related to unit-based awards to both employees and non-employees in its consolidated and condensed financial statements in accordance with certain provisions of ASC 718. Amounts recognized in selling, general, and administrative expense in the consolidated and condensed financial statements with respect to these plans are as follows: Three Months Ended June 30, Six Months Ended June 30, 2021 2020 2021 2020 Employees $ — $ 301 $ 194 $ 602 Non-employee directors 48 62 94 107 Total unit-based compensation expense $ 48 $ 363 $ 288 $ 709 All of the Partnership's outstanding awards at June 30, 2021 met the criteria to be treated under equity classification. Long-Term Incentive Plans The Partnership's general partner has a long-term incentive plan for employees and directors of the general partner and its affiliates who perform services for the Partnership. On May 26, 2017, the unitholders of the Partnership approved the Martin Midstream Partners L.P. 2017 Restricted Unit Plan (the "2017 LTIP"). The 2017 LTIP currently permits the grant of awards covering an aggregate of 3,000,000 common units, all of which can be awarded in the form of restricted units. The 2017 LTIP is administered by the compensation committee of the general partner’s board of directors (the "Compensation Committee"). A restricted unit is a unit that is granted to grantees with certain vesting restrictions, which may be time-based and/or performance-based. Once these restrictions lapse, the grantee is entitled to full ownership of the unit without restrictions. The Compensation Committee may determine to make grants under the plan containing such terms as the Compensation Committee shall determine under the plan. With respect to time-based restricted units ("TBRUs"), the Compensation Committee will determine the time period over which restricted units granted to employees and directors will vest. The Compensation Committee may also award a percentage of restricted units with vesting requirements based upon the achievement of specified pre-established performance targets ("Performance Based Restricted Units" or "PBRUs"). The performance targets may include, but are not limited to, the following: revenue and income measures, cash flow measures, net income before interest expense and income tax expense ("EBIT"), net income before interest expense, income tax expense, and depreciation and amortization ("EBITDA"), distribution coverage metrics, expense measures, liquidity measures, market measures, corporate sustainability metrics, and other measures related to acquisitions, dispositions, operational objectives and succession planning objectives. PBRUs are earned only upon our achievement of an objective performance measure for the performance period. PBRUs which vest are payable in common units. Unvested units granted under the 2017 LTIP may or may not participate in cash distributions depending on the terms of each individual award agreement. The performance conditions related to the PBRUs awarded on March 1, 2018 were not achieved and the Partnership treated these units as forfeited at expiration on March 31, 2021. As such, the Partnership did not recognize compensation expense related to these units. The restricted units issued to directors generally vest in equal annual installments over a four-year period. Restricted units issued to employees generally vest in equal annual installments over three years of service. In February 2021, the Partnership issued 14,056 TBRUs to each of the Partnership's three independent directors under the 2017 LTIP. These restricted common units vest in equal installments of 3,514 units on January 24, 2022, 2023, 2024, and 2025. The restricted units are valued at their fair value at the date of grant, which is equal to the market value of common units on such date. A summary of the restricted unit activity for the six months ended June 30, 2021 is provided below: Number of Units Weighted Average Grant-Date Fair Value Per Unit Non-vested, beginning of period 273,424 $ 10.52 Granted (TBRU) 42,168 $ 2.49 Vested (117,280) $ 11.96 Forfeited (83,436) $ 13.90 Non-Vested, end of period 114,876 $ 3.65 Aggregate intrinsic value, end of period $ 347 A summary of the restricted units’ aggregate intrinsic value (market value at vesting date) and fair value of units vested (market value at date of grant) during the three and six months ended June 30, 2021 and 2020 is provided below: Three Months Ended June 30, Six Months Ended June 30, 2021 2020 2021 2020 Aggregate intrinsic value of units vested $ — $ — $ 257 $ 151 Fair value of units vested — — 1,418 1,427 As of June 30, 2021, there was $344 of unrecognized compensation cost related to non-vested restricted units. That cost is expected to be recognized over a weighted-average period of 2.42 years.

Related Party Transactions

Related Party Transactions	6 Months Ended
	Jun. 30, 2021
Related Party Transactions [Abstract]
Related Party Transactions	RELATED PARTY TRANSACTIONS As of June 30, 2021, Martin Resource Management Corporation owns 6,114,532 of the Partnership’s common units representing approximately 15.8% of the Partnership’s outstanding limited partner units. Martin Resource Management Corporation controls the Partnership's general partner by virtue of its 51% voting interest in Holdings, the sole member of the Partnership's general partner. The Partnership’s general partner, MMGP, owns a 2% general partner interest in the Partnership and the Partnership’s IDRs. The Partnership’s general partner’s ability, as general partner, to manage and operate the Partnership, and Martin Resource Management Corporation’s ownership as of June 30, 2021, effectively gives Martin Resource Management Corporation the ability to veto some of the Partnership’s actions and to control the Partnership’s management. The following is a description of the Partnership’s material related party agreements and transactions: Omnibus Agreement Omnibus Agreement . The Partnership and its general partner are parties to the Omnibus Agreement dated November 1, 2002, with Martin Resource Management Corporation that governs, among other things, potential competition and indemnification obligations among the parties to the agreement, related party transactions, the provision of general administration and support services by Martin Resource Management Corporation and the Partnership’s use of certain Martin Resource Management Corporation trade names and trademarks. The Omnibus Agreement was amended on November 25, 2009, to include processing crude oil into finished products including naphthenic lubricants, distillates, asphalt and other intermediate cuts. The Omnibus Agreement was amended further on October 1, 2012, to permit the Partnership to provide certain lubricant packaging products and services to Martin Resource Management Corporation. Non-Competition Provisions . Martin Resource Management Corporation has agreed for so long as it controls the general partner of the Partnership, not to engage in the business of: • providing terminalling and storage services for petroleum products and by-products including the refining, blending and packaging of finished lubricants; • providing land and marine transportation of petroleum products, by-products, and chemicals; • distributing NGLs; and • manufacturing and selling sulfur-based fertilizer products and other sulfur-related products. This restriction does not apply to: • the ownership and/or operation on the Partnership’s behalf of any asset or group of assets owned by it or its affiliates; • any business operated by Martin Resource Management Corporation, including the following: ◦ distributing asphalt, marine fuel and other liquids; ◦ providing shore-based marine services in Texas, Louisiana, Mississippi, and Alabama; ◦ operating a crude oil gathering business in Stephens, Arkansas; ◦ providing crude oil gathering and marketing services of base oils, asphalt, and distillate products in Smackover, Arkansas; ◦ providing crude oil marketing and transportation from the well head to the end market; ◦ operating an environmental consulting company; ◦ supplying employees and services for the operation of the Partnership's business; and ◦ operating, solely for the Partnership's account, the asphalt facilities in Omaha, Nebraska, Port Neches, Texas, and South Houston, Texas. • any business that Martin Resource Management Corporation acquires or constructs that has a fair market value of less than $5,000; • any business that Martin Resource Management Corporation acquires or constructs that has a fair market value of $5,000 or more if the Partnership has been offered the opportunity to purchase the business for fair market value and the Partnership declines to do so with the concurrence of the conflicts committee of the board of directors of the general partner of the Partnership (the "Conflicts Committee"); and • any business that Martin Resource Management Corporation acquires or constructs where a portion of such business includes a restricted business and the fair market value of the restricted business is $5,000 or more and represents less than 20% of the aggregate value of the entire business to be acquired or constructed; provided that, following completion of the acquisition or construction, the Partnership will be provided the opportunity to purchase the restricted business. Services. Under the Omnibus Agreement, Martin Resource Management Corporation provides the Partnership with corporate staff, support services, and administrative services necessary to operate the Partnership’s business. The Omnibus Agreement requires the Partnership to reimburse Martin Resource Management Corporation for all direct expenses it incurs or payments it makes on the Partnership’s behalf or in connection with the operation of the Partnership’s business. There is no monetary limitation on the amount the Partnership is required to reimburse Martin Resource Management Corporation for direct expenses. In addition to the direct expenses, under the Omnibus Agreement, the Partnership is required to reimburse Martin Resource Management Corporation for indirect general and administrative and corporate overhead expenses. Effective January 1, 2021, through December 31, 2021, the Conflicts Committee approved an annual reimbursement amount for indirect expenses of $14,386. The Partnership reimbursed Martin Resource Management Corporation for $3,652 and $4,103 of indirect expenses for the three months ended June 30, 2021 and 2020, respectively. The Partnership reimbursed Martin Resource Management Corporation for $7,193 and $8,261 of indirect expenses for the six months ended June 30, 2021 and 2020, respectively. The Conflicts Committee will review and approve future adjustments in the reimbursement amount for indirect expenses, if any, annually. These indirect expenses are intended to cover the centralized corporate functions Martin Resource Management Corporation provides to the Partnership, such as accounting, treasury, clerical, engineering, legal, billing, information technology, administration of insurance, general office expenses and employee benefit plans and other general corporate overhead functions the Partnership shares with Martin Resource Management Corporation retained businesses. The provisions of the Omnibus Agreement regarding Martin Resource Management Corporation’s services will terminate if Martin Resource Management Corporation ceases to control the general partner of the Partnership. Related Party Transactions . The Omnibus Agreement prohibits the Partnership from entering into any material agreement with Martin Resource Management Corporation without the prior approval of the Conflicts Committee. For purposes of the Omnibus Agreement, the term "material agreements" means any agreement between the Partnership and Martin Resource Management Corporation that requires aggregate annual payments in excess of the then-applicable agreed upon reimbursable amount of indirect general and administrative expenses. Please read "Services" above. License Provisions. Under the Omnibus Agreement, Martin Resource Management Corporation has granted the Partnership a nontransferable, nonexclusive, royalty-free right and license to use certain of its trade names and marks, as well as the trade names and marks used by some of its affiliates. Amendment and Termination. The Omnibus Agreement may be amended by written agreement of the parties; provided, however, that it may not be amended without the approval of the Conflicts Committee if such amendment would adversely affect the unitholders. The Omnibus Agreement was first amended on November 25, 2009, to permit the Partnership to provide refining services to Martin Resource Management Corporation. The Omnibus Agreement was amended further on October 1, 2012, to permit the Partnership to provide certain lubricant packaging products and services to Martin Resource Management Corporation. Such amendments were approved by the Conflicts Committee. The Omnibus Agreement, other than the indemnification provisions and the provisions limiting the amount for which the Partnership will reimburse Martin Resource Management Corporation for general and administrative services performed on its behalf, will terminate if the Partnership is no longer an affiliate of Martin Resource Management Corporation. Master Transportation Services Agreement Master Transportation Agreement. Martin Transport, Inc. ("MTI"), a wholly owned subsidiary of the Partnership, is a party to a master transportation services agreement effective January 1, 2019, with certain wholly owned subsidiaries of Martin Resource Management Corporation. Under the agreement, MTI agreed to transport Martin Resource Management Corporation's petroleum products and by-products. Term and Pricing. The agreement will continue unless either party terminates the agreement by giving at least 30 days' written notice to the other party. The rates under the agreement are subject to any adjustments which are mutually agreed upon or in accordance with a price index. Additionally, shipping charges are also subject to fuel surcharges determined on a weekly basis in accordance with the U.S. Department of Energy’s national diesel price list. Indemnification. MTI has agreed to indemnify Martin Resource Management Corporation against all claims arising out of the negligence or willful misconduct of MTI and its officers, employees, agents, representatives and subcontractors. Martin Resource Management Corporation has agreed to indemnify MTI against all claims arising out of the negligence or willful misconduct of Martin Resource Management Corporation and its officers, employees, agents, representatives and subcontractors. In the event a claim is the result of the joint negligence or misconduct of MTI and Martin Resource Management Corporation, indemnification obligations will be shared in proportion to each party’s allocable share of such joint negligence or misconduct. Marine Agreements Marine Transportation Agreement. The Partnership is a party to a marine transportation agreement effective January 1, 2006, as amended, under which the Partnership provides marine transportation services to Martin Resource Management Corporation on a spot-contract basis at applicable market rates. Effective each January 1, this agreement automatically renews for consecutive one year periods unless either party terminates the agreement by giving written notice to the other party at least 60 days prior to the expiration of the then applicable term. The fees the Partnership charges Martin Resource Management Corporation are based on applicable market rates. Marine Fuel. The Partnership is a party to an agreement with Martin Resource Management Corporation dated November 1, 2002, under which Martin Resource Management Corporation provides the Partnership with marine fuel from its locations in the Gulf of Mexico at a fixed rate in excess of the Platt’s U.S. Gulf Coast Index for #2 Fuel Oil. Under this agreement, the Partnership agreed to purchase all of its marine fuel requirements that occur in the areas serviced by Martin Resource Management Corporation. Terminal Services Agreements Diesel Fuel Terminal Services Agreement. Effective January 1, 2016, the Partnership entered into a second amended and restated terminalling services agreement under which the Partnership provides terminal services to Martin Resource Management Corporation for marine fuel distribution. At such time, the per-gallon throughput fee the Partnership charged under this agreement was increased when compared to the previous agreement and may be adjusted annually based on a price index. This agreement was further amended on January 1, 2017, October 1, 2017, April 1, 2019, and January 1, 2020 to modify its minimum throughput requirements and throughput fees. The term of this agreement is currently evergreen and it will continue on a month to month basis until terminated by either party by giving 60 days’ written notice. Miscellaneous Terminal Services Agreements. The Partnership is currently party to several terminal services agreements and from time to time the Partnership may enter into other terminal service agreements for the purpose of providing terminal services to related parties. Individually, each of these agreements is immaterial but when considered in the aggregate they could be deemed material. These agreements are throughput based with a minimum volume commitment. Generally, the fees due under these agreements are adjusted annually based on a price index. Other Agreements Cross Tolling Agreement. The Partnership is a party to an amended and restated tolling agreement with Cross Oil Refining and Marketing, Inc. ("Cross") dated October 28, 2014, under which the Partnership processes crude oil into finished products, including naphthenic lubricants, distillates, asphalt and other intermediate cuts for Cross. The tolling agreement expires November 25, 2031. Under this tolling agreement, Cross agreed to process a minimum of 6,500 barrels per day of crude oil at the facility at a fixed price per barrel. Any additional barrels are processed at a modified price per barrel. In addition, Cross agreed to pay a monthly reservation fee and a periodic fuel surcharge fee based on certain parameters specified in the tolling agreement. Further, certain capital improvements, to the extent requested by Cross, are reimbursed through a capital recovery fee. As of December 31, 2019, the annual capital recovery fee reimbursement of $2,088 expired. An additional $2,586 of capital recovery fee reimbursement expired on December 31, 2020. All of these fees (other than the fuel surcharge and capital recovery fee) are subject to escalation annually based upon the greater of 3% or the increase in the Consumer Price Index for a specified annual perio d . A lso, the Partnership renegotiated a crude transportation contract set to expire in the first half of 2022, resulting in a reduction in revenue of $2,145 annually beginning January 1, 2020. East Texas Mack Leases. MTI leases equipment, including tractors and trailers, from East Texas Mack Sales ("East Texas Mack"). Certain of our directors or officers are owners of East Texas Mack, including entities affiliated with Ruben Martin, who owns approximately 46% of the issued and outstanding stock of East Texas Mack. Amounts paid to East Texas Mack for tractor and trailer lease payments and lease residuals for the three months ended June 30, 2021 and 2020 were $282 and $154, respectively. Amounts paid to East Texas Mack for tractor and trailer lease payments and lease residuals for the six months ended June 30, 2021 and 2020 were $518 and $259, respectively. Other Miscellaneous Agreements. From time to time the Partnership enters into other miscellaneous agreements with Martin Resource Management Corporation for the provision of other services or the purchase of other goods. The tables below summarize the related party transactions that are included in the related financial statement captions on the face of the Partnership’s Consolidated and Condensed Statements of Operations. The revenues, costs and expenses reflected in these tables are tabulations of the related party transactions that are recorded in the corresponding captions of the consolidated and condensed financial statements and do not reflect a statement of profits and losses for related party transactions. The impact of related party revenues from sales of products and services is reflected in the consolidated and condensed financial statements as follows: Three Months Ended June 30, Six Months Ended June 30, 2021 2020 2021 2020 Revenues: Terminalling and storage $ 15,569 $ 15,942 $ 30,875 $ 31,816 Transportation 4,889 5,393 8,899 11,287 Product sales: Sulfur services 29 9 59 28 Terminalling and storage 42 29 126 102 71 38 185 130 $ 20,529 $ 21,373 $ 39,959 $ 43,233 The impact of related party cost of products sold is reflected in the consolidated and condensed financial statements as follows: Three Months Ended June 30, Six Months Ended June 30, 2021 2020 2021 2020 Cost of products sold: Sulfur services $ 2,403 $ 2,554 $ 4,938 $ 5,321 Terminalling and storage 7,036 4,249 11,604 10,026 $ 9,439 $ 6,803 $ 16,542 $ 15,347 The impact of related party operating expenses is reflected in the consolidated and condensed financial statements as follows: Three Months Ended June 30, Six Months Ended June 30, 2021 2020 2021 2020 Operating expenses: Transportation $ 13,644 $ 13,388 $ 26,703 $ 28,941 Natural gas liquids 513 498 977 995 Sulfur services 1,306 1,137 2,049 2,283 Terminalling and storage 4,127 4,417 8,229 8,992 $ 19,590 $ 19,440 $ 37,958 $ 41,211 The impact of related party selling, general and administrative expenses is reflected in the consolidated and condensed financial statements as follows: Three Months Ended June 30, Six Months Ended June 30, 2021 2020 2021 2020 Selling, general and administrative: Transportation $ 1,701 $ 1,817 $ 3,371 $ 3,656 Natural gas liquids 276 533 2,084 1,237 Sulfur services 736 746 1,507 1,489 Terminalling and storage 832 835 1,652 1,673 Indirect, including overhead allocation 3,740 4,124 7,351 8,312 $ 7,285 $ 8,055 $ 15,965 $ 16,367

Business Segments

Business Segments	6 Months Ended
	Jun. 30, 2021
Segment Reporting [Abstract]
Business Segments	BUSINESS SEGMENTS The Partnership has four reportable segments: terminalling and storage, transportation, sulfur services and natural gas liquids. The Partnership’s reportable segments are strategic business units that offer different products and services. The operating income of these segments is reviewed by the chief operating decision maker to assess performance and make business decisions. The accounting policies of the operating segments are the same as those described in Note 2 in the Partnership’s Annual Report on Form 10-K for the year ended December 31, 2020, filed with the SEC on March 3, 2021. The Partnership evaluates the performance of its reportable segments based on operating income. There is no allocation of administrative expenses or interest expense. Three Months Ended June 30, 2021 Operating Revenues Intersegment Revenues Eliminations Operating Revenues after Eliminations Depreciation and Amortization Operating Income (Loss) after Eliminations Capital Expenditures and Plant Turnaround Costs Terminalling and storage 45,524 (1,675) 43,849 6,996 2,576 1,507 Transportation 38,349 (3,423) 34,926 4,331 (2,709) 1,091 Sulfur services 38,286 — 38,286 2,568 8,249 799 Natural gas liquids 67,232 — 67,232 588 3,297 140 Indirect selling, general and administrative — — — — (3,780) — Total $ 189,391 $ (5,098) $ 184,293 $ 14,483 $ 7,633 $ 3,537 Three Months Ended June 30, 2020 Operating Revenues Intersegment Revenues Eliminations Operating Revenues after Eliminations Depreciation and Amortization Operating Income (Loss) after Eliminations Capital Expenditures and Plant Turnaround Costs Terminalling and storage 46,976 (1,542) 45,434 7,272 2,969 3,427 Transportation 35,259 (3,774) 31,485 4,328 (2,078) 772 Sulfur services 33,420 — 33,420 3,131 8,814 1,739 Natural gas liquids 30,300 (1) 30,299 612 2,616 70 Indirect selling, general and administrative — — — — (4,361) — Total $ 145,955 $ (5,317) $ 140,638 $ 15,343 $ 7,960 $ 6,008 Six Months Ended June 30, 2021 Operating Revenues Intersegment Revenues Eliminations Operating Revenues after Eliminations Depreciation and Amortization Operating Income (Loss) after Eliminations Capital Expenditures and Plant Turnaround Costs Terminalling and storage $ 85,358 $ (3,270) $ 82,088 $ 14,101 $ 4,884 $ 4,172 Transportation 72,318 (7,577) 64,741 8,329 (8,212) 1,616 Sulfur services 73,121 — 73,121 5,288 16,602 3,863 Natural gas liquids 165,317 — 165,317 1,199 17,744 461 Indirect selling, general and administrative — — — — (7,699) — Total $ 396,114 $ (10,847) $ 385,267 $ 28,917 $ 23,319 $ 10,112 Six Months Ended June 30, 2020 Operating Revenues Intersegment Revenues Eliminations Operating Revenues after Eliminations Depreciation and Amortization Operating Income (Loss) after Eliminations Capital Expenditures and Plant Turnaround Costs Terminalling and storage $ 98,110 $ (3,268) $ 94,842 $ 14,728 $ 3,727 $ 7,022 Transportation 80,433 (10,007) 70,426 8,608 (7,099) 4,698 Sulfur services 61,756 (13) 61,743 6,025 22,672 4,874 Natural gas liquids 112,515 (5) 112,510 1,221 12,993 175 Indirect selling, general and administrative — — — — (8,733) — Total $ 352,814 $ (13,293) $ 339,521 $ 30,582 $ 23,560 $ 16,769 The Partnership's assets by reportable segment as of June 30, 2021 and December 31, 2020, are as follows: June 30, 2021 December 31, 2020 Total assets: Terminalling and storage $ 254,877 $ 252,794 Transportation 145,709 151,953 Sulfur services 97,750 94,154 Natural gas liquids 78,543 80,737 Total assets $ 576,879 $ 579,638

Commitments and Contingencies

Commitments and Contingencies	6 Months Ended
	Jun. 30, 2021
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	COMMITMENTS AND CONTINGENCIES Contingencies From time to time, the Partnership is subject to various claims and legal actions arising in the ordinary course of business. In the opinion of management, the ultimate disposition of these matters will not have a material adverse effect on the Partnership. On December 31, 2015, the Partnership received a demand from a customer in its lubricants packaging business for defense and indemnity in connection with lawsuits filed against it in various United States District Courts, which generally allege that the customer engaged in unlawful and deceptive business practices in connection with its marketing and advertising of its private label motor oil. The Partnership disputes that it has any obligation to defend or indemnify the customer for its conduct. Accordingly, on January 7, 2016, the Partnership filed a Complaint for Declaratory Judgment in the Chancery Court of Davidson County, Tennessee requesting a judicial determination that the Partnership does not owe the customer the demanded defense and indemnity obligations. The lawsuits against the customer have been transferred to the United States District Court for the Western District of Missouri for consolidated pretrial proceedings. On March 1, 2017, at the request of the parties, the Chancery Court of Davidson County, Tennessee administratively closed the Partnership's lawsuit pending rulings in the United States District Court for the Western District of Missouri. In the event that either party moves the Chancery Court of Davidson County, Tennessee to reopen the case, we expect the Court would grant such motion and reopen the case. Further, the same customer has made a claim under the Partnership’s insurance policy. The insurer has denied the claim. However, in the event that the customer is successful in pursuing the claim, such action would negatively impact the Partnership because the Partnership may have certain reimbursement obligations it would owe the insurance company. If the case is reopened or the insurance claim by the customer is successful, we are currently unable to determine the exposure we may have in this matter, if any.

Fair Value Measurements

Fair Value Measurements	6 Months Ended
	Jun. 30, 2021
Fair Value Disclosures [Abstract]
Fair Value Measurements	FAIR VALUE MEASUREMENTS The Partnership uses a valuation framework based upon inputs that market participants use in pricing certain assets and liabilities. These inputs are classified into two categories: observable inputs and unobservable inputs. Observable inputs represent market data obtained from independent sources. Unobservable inputs represent the Partnership's own market assumptions. Unobservable inputs are used only if observable inputs are unavailable or not reasonably available without undue cost and effort. The two types of inputs are further prioritized into the following hierarchy: Level 1: Quoted market prices in active markets for identical assets or liabilities. Level 2: Observable market-based inputs or unobservable inputs that are corroborated by market data. Level 3: Unobservable inputs that reflect the entity's own assumptions and are not corroborated by market data. Assets and liabilities measured at fair value on a recurring basis are summarized below: Level 2 June 30, 2021 December 31, 2020 Commodity derivative contracts, net $ (412) $ (207) The Partnership is required to disclose estimated fair values for its financial instruments. Fair value estimates are set forth below for these financial instruments. The following methods and assumptions were used to estimate the fair value of each class of financial instrument: • Accounts and other receivables, trade and other accounts payable, accrued interest payable, other accrued liabilities, income taxes payable and due from/to affiliates: The carrying amounts approximate fair value due to the short maturity and highly liquid nature of these instruments, and as such these have been excluded from the table below. There is negligible credit risk associated with these instruments. • Current and non-current portion of long-term debt: The carrying amount of the revolving credit facility approximates fair value due to the debt having a variable interest rate and is in Level 2. The estimated fair value of the 2021 Notes, 2024 Notes, and 2025 Notes (collectively, the "Senior Notes") is considered Level 1, as the fair value is based on quoted market prices in active markets. June 30, 2021 December 31, 2020 Carrying Fair Carrying Fair 2021 Notes $ — $ — $ 28,790 $ 28,581 2024 Notes $ 50,745 $ 55,314 $ 50,173 $ 55,214 2025 Notes $ 290,458 $ 303,927 $ 290,250 $ 288,692 Total $ 341,203 $ 359,241 $ 369,213 $ 372,487

Condensed Consolidated Financia

Condensed Consolidated Financial Information	6 Months Ended
	Jun. 30, 2021
Consolidating Financial Statements [Abstract]
Condensed Consolidated Financial Information	CONDENSED CONSOLIDATED FINANCIAL INFORMATION    The Partnership's operations are conducted by its operating subsidiaries as it has no independent assets or operations. Martin Operating Partnership L.P. (the "Operating Partnership"), the Partnership’s wholly-owned subsidiary, and the Partnership's other operating subsidiaries have issued in the past, and may issue in the future, unconditional guarantees of senior or subordinated debt securities of the Partnership. The guarantees that have been issued are full, irrevocable and unconditional and joint and several. In addition, the Operating Partnership may also issue senior or subordinated debt securities which, if issued, will be fully, irrevocably and unconditionally guaranteed by the Partnership. Substantially all of the Partnership's operating subsidiaries are subsidiary guarantors of its Senior Notes and any subsidiaries other than the subsidiary guarantors are minor.

Income Taxes

Income Taxes	6 Months Ended
	Jun. 30, 2021
Income Tax Disclosure [Abstract]
Income Taxes	INCOME TAXES Three Months Ended June 30, Six Months Ended June 30, 2021 2020 2021 2020 Provision for income taxes $ 935 $ 790 $ 1,157 $ 1,137 The operations of a partnership are generally not subject to income taxes, except for Texas margin tax, because its income is taxed directly to its partners. MTI, a wholly owned subsidiary of the Partnership, is subject to income taxes due to its corporate structure (the "Taxable Subsidiary"). Total income tax expense of $874 and $590, related to the operation of the Taxable Subsidiary, for the three months ended June 30, 2021 and 2020, resulted in an effective income tax rate ("ETR") of 40.22% and (472.00)%, respectively. Total income tax expense of $977 and $937, related to the operation of the Taxable Subsidiary, for the six months ended June 30, 2021 and 2020, resulted in an ETR of 38.73% and 98.32%, respectively. The increase in the effective income tax rate during the three months ended June 30, 2021 compared to the three months ended June 30, 2020 was primarily due to pretax income recorded for the three months ended June 30, 2021 compared to pretax losses recorded for the similar period in 2020. The decrease in the effective income tax rate during the six months ended June 30, 2021, compared to the six months ended June 30, 2020, was primarily due to a decrease in permanent differences in the current period. The increase in the provision for income taxes for the three and six months ended June 30, 2021, compared to similar periods in 2020, was primarily due to an increase in income before income taxes in the current period. A current federal income tax expense (benefit) of $108 and $(307), related to the operation of the Taxable Subsidiary, was recorded for the three months ended June 30, 2021 and 2020, respectively. A current federal income tax expense (benefit) of $123 and $(174), related to the operation of the Taxable Subsidiary, was recorded for the six months ended June 30, 2021 and 2020, respectively. A current state income tax expense of $83 and $164, related to the operation of the Taxable Subsidiary, was recorded for the three months ended June 30, 2021 and 2020, respectively. A current state income tax expense of $96 and $93, related to the operation of the Taxable Subsidiary, was recorded for the six months ended June 30, 2021 and 2020, respectively. With respect to MTI, income taxes are accounted for under the asset and liability method pursuant to the provisions of ASC 740 related to income taxes. Deferred tax assets and liabilities are recognized for the future tax consequences attributable to differences between the financial statement carrying amounts of existing assets and liabilities and their respective tax basis. Deferred tax assets and liabilities are measured using enacted tax rates expected to apply to taxable income in the years in which those temporary differences are expected to be recovered or settled. The effect on deferred tax assets and liabilities of a change in tax rates is recognized in income in the period that includes the enactment date. A deferred tax expense related to the MTI temporary differences of $683 and $733 was recorded for the three months ended June 30, 2021 and 2020, respectively. A deferred tax expense related to the MTI temporary differences of $758 and $1,018 was recorded for the six months ended June 30, 2021 and 2020, respectively. A net deferred tax asset of $21,495 and $22,253, related to the cumulative book and tax temporary differences, existed at June 30, 2021 and December 31, 2020, respectively. All income tax positions taken for all open years are more likely than not to be sustained based upon their technical merit under applicable tax laws.

Subsequent Events

Subsequent Events	6 Months Ended
	Jun. 30, 2021
Subsequent Events [Abstract]
Subsequent Events	SUBSEQUENT EVENTS Amendment to Revolving Credit Facility. On July 16, 2021, the Partnership amended its revolving credit facility to, among other things, reduce the commitments thereunder from $300,000 to $275,000, and modify the financial covenants. See “Item 2. Management’s Discussion and Analysis of Financial Condition and Results of Operations – Significant Recent Developments – Amendment to Revolving Credit Facility” for more information regarding this amendment. 2021 Phantom Unit Plan. On July 21, 2021, the board of directors of the general partner of the Partnership and the Compensation Committee approved the Martin Midstream Partners L.P. 2021 Phantom Unit Plan (the “Plan”), effective as of the same date. The Plan permits the awards of phantom units and phantom unit appreciation rights to any employee or non-employee director of the Partnership, including its executive officers. The awards may be time-based or performance-based and will be paid, if at all, in cash. See “Part II – Item 5. Other Information” for more information regarding the Plan.

New Accounting Pronouncements (

New Accounting Pronouncements (Policies)	6 Months Ended
	Jun. 30, 2021
Accounting Changes and Error Corrections [Abstract]
New Accounting Pronouncements	NEW ACCOUNTING PRONOUNCEMENTS On January 1, 2021, the Partnership adopted Financial Accounting Standards Board ("FASB") Accounting Standards Update ("ASU") 2019-12, Income Taxes (Accounting Standards Codification ("ASC") Topic 740): Simplifying the Accounting for Income Taxes , which removes certain exceptions to general principles in ASC 740 and clarifies and amends existing guidance within U.S. GAAP. Adoption of the new standard did not have a material impact on the Partnership’s consolidated financial statements.
Fair Value Measurements	The Partnership uses a valuation framework based upon inputs that market participants use in pricing certain assets and liabilities. These inputs are classified into two categories: observable inputs and unobservable inputs. Observable inputs represent market data obtained from independent sources. Unobservable inputs represent the Partnership's own market assumptions. Unobservable inputs are used only if observable inputs are unavailable or not reasonably available without undue cost and effort. The two types of inputs are further prioritized into the following hierarchy: Level 1: Quoted market prices in active markets for identical assets or liabilities. Level 2: Observable market-based inputs or unobservable inputs that are corroborated by market data. Level 3: Unobservable inputs that reflect the entity's own assumptions and are not corroborated by market data.
Fair Value of Financial Instruments	The Partnership is required to disclose estimated fair values for its financial instruments. Fair value estimates are set forth below for these financial instruments. The following methods and assumptions were used to estimate the fair value of each class of financial instrument: • Accounts and other receivables, trade and other accounts payable, accrued interest payable, other accrued liabilities, income taxes payable and due from/to affiliates: The carrying amounts approximate fair value due to the short maturity and highly liquid nature of these instruments, and as such these have been excluded from the table below. There is negligible credit risk associated with these instruments.

Revenue (Tables)

Revenue (Tables)	6 Months Ended
	Jun. 30, 2021
Revenue from Contract with Customer [Abstract]
Disaggregation of Revenue	The following table disaggregates our revenue by major source: Three Months Ended June 30, Six Months Ended June 30, 2021 2020 2021 2020 Terminalling and storage segment Lubricant product sales $ 25,147 $ 25,526 $ 45,008 $ 54,460 Throughput and storage 18,702 19,908 37,080 40,382 $ 43,849 $ 45,434 $ 82,088 $ 94,842 Natural gas liquids segment Natural gas liquids product sales $ 67,232 $ 30,299 $ 165,317 $ 112,510 $ 67,232 $ 30,299 $ 165,317 $ 112,510 Sulfur services segment Sulfur product sales $ 7,386 $ 6,367 $ 14,454 $ 12,849 Fertilizer product sales 27,951 24,139 52,768 43,065 Sulfur services 2,949 2,914 5,899 5,829 $ 38,286 $ 33,420 $ 73,121 $ 61,743 Transportation segment Land transportation $ 27,486 $ 19,873 $ 50,442 $ 44,107 Inland transportation 6,633 10,611 13,357 24,317 Offshore transportation 807 1,001 942 2,002 $ 34,926 $ 31,485 $ 64,741 $ 70,426
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction	The table below includes estimated minimum revenue expected to be recognized in the future related to performance obligations that are unsatisfied at the end of the reporting period. The Partnership applies the practical expedient in ASC 606-10-50-14(a) and does not disclose information about remaining performance obligations that have original expected durations of one year or less. 2021 2022 2023 2024 2025 Thereafter Total Terminalling and storage Throughput and storage $ 21,046 $ 40,394 $ 41,605 $ 42,854 $ 44,197 $ 294,141 $ 484,237 Natural Gas Services Natural Gas Liquids 3,288 6,048 5,391 5,405 5,391 3,131 28,654 Sulfur services Sulfur product sales 8,582 16,279 15,233 975 975 — 42,044 Total $ 32,916 $ 62,721 $ 62,229 $ 49,234 $ 50,563 $ 297,272 $ 554,935

Inventories (Tables)

Inventories (Tables)	6 Months Ended
	Jun. 30, 2021
Inventory Disclosure [Abstract]
Components of Inventories	Components of inventories at June 30, 2021 and December 31, 2020 were as follows: June 30, December 31, Natural gas liquids $ 41,805 $ 27,878 Sulfur 71 24 Fertilizer 8,216 10,854 Lubricants 16,701 11,002 Other 4,565 4,364 $ 71,358 $ 54,122

Debt (Tables)

Debt (Tables)	6 Months Ended
	Jun. 30, 2021
Debt Disclosure [Abstract]
Schedule of Long-Term Debt	At June 30, 2021 and December 31, 2020, long-term debt consisted of the following: June 30, December 31, $300,000 Revolving credit facility at variable interest rate (5.00% 1 weighted average at June 30, 2021), due August 2023 4 secured by substantially all of the Partnership’s assets, including, without limitation, inventory, accounts receivable, vessels, equipment, fixed assets and the interests in the Partnership’s operating subsidiaries, net of unamortized debt issuance costs of $3,392 and $3,826, respectively 2 $ 176,108 $ 144,174 $400,000 Senior notes, 7.25% interest, net of unamortized debt issuance costs of $— and $—, respectively, including unamortized premium of $— and $—, respectively, issued $250,000 February 2013 and $150,000 April 2014, $26,200 repurchased during 2015, $9,344 repurchased during 2020, $335,666 refinanced as part of the August 2020 Exchange offer, $28,790 repaid at maturity in February 2021, unsecured 2,3,4 — 28,790 $53,750 Senior notes, 10.0% interest, net of unamortized debt issuance costs of $3,005 and $3,577, respectively, due February 2024, secured 2,3 50,745 50,173 $291,970 Senior notes, 11.5% interest, net of unamortized debt issuance costs of $1,512 and $1,720, respectively, due February 2025, secured 2,3 290,458 290,250 Total 517,311 513,387 Less: current portion — (28,790) Total long-term debt, net of current portion $ 517,311 $ 484,597 Current installments of finance lease obligations $ 236 $ 2,707 Finance lease obligations 169 289 Total finance lease obligations $ 405 $ 2,996 1 Interest rate fluctuates based on LIBOR or the base prime rate (set on the date of each advance) plus an applicable margin. The margin is set every three months. All amounts outstanding at December 31, 2020 and June 30, 2021 were at LIBOR plus an applicable margin with LIBOR having a floor of 1.0% per annum. The applicable margin for revolving loans that are LIBOR loans currently ranges from 2.75% to 4.00%, and the applicable margin for revolving loans that are base prime rate loans currently ranges from 1.75% to 3.00%. The applicable margin for LIBOR borrowings at June 30, 2021 is 4.00%. The credit facility contains various covenants that limit the Partnership’s ability to make distributions; make certain investments and acquisitions; enter into certain agreements; incur indebtedness; sell assets; and make certain amendments to the Partnership's omnibus agreement with Martin Resource Management Corporation (the "Omnibus Agreement"). The credit facility was amended on July 16, 2021 to, among other things, reduce the commitments thereunder from $300,000 to $275,000. 2 The Partnership is in compliance with all debt covenants as of June 30, 2021 and December 31, 2020, respectively. 3 The indentures for each of the outstanding series of senior notes restrict the Partnership’s ability to sell assets; pay distributions or repurchase units or redeem or repurchase subordinated debt; make investments; incur or guarantee additional indebtedness or issue preferred units; and consolidate, merge or transfer all or substantially all of its assets.

Leases (Tables)

Leases (Tables)	6 Months Ended
	Jun. 30, 2021
Leases [Abstract]
Components of Lease Expense	The components of lease expense for the three and six months ended June 30, 2021 and 2020 were as follows: Three Months Ended June 30, Six Months Ended June 30, 2021 2020 2021 2020 Operating lease cost $ 2,199 $ 2,767 $ 4,501 $ 5,611 Finance lease cost: Amortization of right-of-use assets $ 25 526 $ 115 1,115 Interest on lease liabilities $ 6 86 $ 16 196 Short-term lease cost $ 2,473 3,492 $ 5,581 6,915 Variable lease cost $ 26 $ 22 $ 59 $ 50 Total lease cost $ 4,729 $ 6,893 $ 10,272 $ 13,887
Schedule of Supplemental Balance Sheet Information	Supplemental balance sheet information related to leases at June 30, 2021 and December 31, 2020 was as follows: June 30, December 31, 2020 Operating Leases Operating lease right-of-use assets $ 19,955 $ 22,260 Current portion of operating lease liabilities included in "Other accrued liabilities" $ 6,961 $ 7,529 Operating lease liabilities $ 13,423 15,181 Total operating lease liabilities $ 20,384 $ 22,710 Finance Leases Property, plant and equipment, at cost $ 1,071 $ 10,352 Accumulated depreciation $ (315) (3,703) Property, plant and equipment, net $ 756 $ 6,649 Current installments of finance lease obligations $ 236 $ 2,707 Finance lease obligations $ 169 289 Total finance lease obligations $ 405 $ 2,996
Schedule of Future Minimum Lease Obligations, Finance Lease	The Partnership’s future minimum lease obligations as of June 30, 2021 consist of the following: Operating Leases Finance Leases Year 1 $ 7,769 $ 252 Year 2 5,094 172 Year 3 2,566 — Year 4 1,735 — Year 5 1,053 — Thereafter 5,511 — Total $ 23,728 $ 424 Less amounts representing interest costs (3,344) (19) Total lease liability $ 20,384 $ 405
Schedule of Future Minimum Lease Obligations, Operating Leases	The Partnership’s future minimum lease obligations as of June 30, 2021 consist of the following: Operating Leases Finance Leases Year 1 $ 7,769 $ 252 Year 2 5,094 172 Year 3 2,566 — Year 4 1,735 — Year 5 1,053 — Thereafter 5,511 — Total $ 23,728 $ 424 Less amounts representing interest costs (3,344) (19) Total lease liability $ 20,384 $ 405

Supplemental Balance Sheet In_2

Supplemental Balance Sheet Information (Tables)	6 Months Ended
	Jun. 30, 2021
Balance Sheet Related Disclosures [Abstract]
Schedule of Other Accrued Liabilities	Components of "Other accrued liabilities" were as follows: June 30, December 31, 2020 Accrued interest $ 14,851 $ 16,104 Asset retirement obligations 300 1,692 Property and other taxes payable 3,765 4,869 Accrued payroll 2,940 3,244 Operating lease liabilities 6,961 7,529 Other 577 969 $ 29,394 $ 34,407
Schedule of Asset Retirement Obligations	The schedule below summarizes the changes in our asset retirement obligations: June 30, 2021 Beginning asset retirement obligations $ 8,759 Additions to asset retirement obligations — Accretion expense 194 Liabilities settled (22) Ending asset retirement obligations 8,931 Current portion of asset retirement obligations 1 (300) Long-term portion of asset retirement obligations 2 $ 8,631 1 The current portion of asset retirement obligations is included in "Other accrued liabilities" on the Partnership's Consolidated and Condensed Balance Sheets. 2 The non-current portion of asset retirement obligations is included in "Other long-term obligations" on the Partnership's Consolidated and Condensed Balance Sheets.

Derivative Instruments and He_2

Derivative Instruments and Hedging Activities (Tables)	6 Months Ended
	Jun. 30, 2021
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Effect of Derivative Instruments on the Consolidated Balance Sheets	The following table summarizes the fair value and classification of the Partnership’s derivative instruments in its Consolidated and Condensed Balance Sheets: Fair Values of Derivative Instruments in the Consolidated and Condensed Balance Sheets Derivative Assets Derivative Liabilities Fair Values Fair Values Balance Sheet Location June 30, 2021 December 31, 2020 Balance Sheet Location June 30, 2021 December 31, 2020 Derivatives not designated as hedging instruments: Current: Commodity contracts Fair value of derivatives $ — $ — Fair value of derivatives $ 412 $ 207 Total derivatives not designated as hedging instruments $ — $ — $ 412 $ 207
Effect of Derivative Instruments on the Consolidated Statement of Operations	Effect of Derivative Instruments on the Consolidated and Condensed Statements of Operations For the Three Months Ended June 30, 2021 and 2020 Location of Gain (Loss) Amount of Gain (Loss) Recognized in 2021 2020 Derivatives not designated as hedging instruments: Commodity contracts Cost of products sold $ 552 $ (162) Total effect of derivatives not designated as hedging instruments $ 552 $ (162) Effect of Derivative Instruments on the Consolidated and Condensed Statements of Operations For the Six Months Ended June 30, 2021 and 2020 Location of Gain (Loss) Amount of Gain (Loss) Recognized in 2021 2020 Derivatives not designated as hedging instruments: Commodity contracts Cost of products sold $ (884) $ (129) Total effect of derivatives not designated as hedging instruments $ (884) $ (129)

Partners' Capital (Tables)

Partners' Capital (Tables)	6 Months Ended
	Jun. 30, 2021
Partners' Capital Notes [Abstract]
Reconciliation of Net Income to Partners Interest in Net Income	The following is a reconciliation of net income allocated to the general partner and limited partners for purposes of calculating net income attributable to limited partners per unit: Three Months Ended June 30, Six Months Ended June 30, 2021 2020 2021 2020 Net income (loss) $ (6,612) $ (2,203) $ (4,101) $ 6,612 Less general partner’s interest in net income (loss): Distributions payable on behalf of general partner interest 4 4 8 53 General partner interest in undistributed income (loss) (136) (48) (90) 79 Less income (loss) allocable to unvested restricted units (20) (10) (10) 45 Limited partners’ interest in net income (loss) $ (6,460) $ (2,149) $ (4,009) $ 6,435 Three Months Ended June 30, Six Months Ended June 30, 2021 2020 2021 2020 Basic weighted average limited partner units outstanding 38,687,874 38,661,852 38,690,228 38,651,357 Dilutive effect of restricted units issued — — — 540 Total weighted average limited partner diluted units outstanding 38,687,874 38,661,852 38,690,228 38,651,897

Unit Based Awards (Tables)

Unit Based Awards (Tables)	6 Months Ended
	Jun. 30, 2021
Share-based Payment Arrangement [Abstract]
Schedule of Compensation Costs Related to Unit Based Plan	Amounts recognized in selling, general, and administrative expense in the consolidated and condensed financial statements with respect to these plans are as follows: Three Months Ended June 30, Six Months Ended June 30, 2021 2020 2021 2020 Employees $ — $ 301 $ 194 $ 602 Non-employee directors 48 62 94 107 Total unit-based compensation expense $ 48 $ 363 $ 288 $ 709
Summary of Restricted Unit Activity	A summary of the restricted unit activity for the six months ended June 30, 2021 is provided below: Number of Units Weighted Average Grant-Date Fair Value Per Unit Non-vested, beginning of period 273,424 $ 10.52 Granted (TBRU) 42,168 $ 2.49 Vested (117,280) $ 11.96 Forfeited (83,436) $ 13.90 Non-Vested, end of period 114,876 $ 3.65 Aggregate intrinsic value, end of period $ 347
Summary of Aggregate Intrinsic Value and Fair Value of Units Vested	A summary of the restricted units’ aggregate intrinsic value (market value at vesting date) and fair value of units vested (market value at date of grant) during the three and six months ended June 30, 2021 and 2020 is provided below: Three Months Ended June 30, Six Months Ended June 30, 2021 2020 2021 2020 Aggregate intrinsic value of units vested $ — $ — $ 257 $ 151 Fair value of units vested — — 1,418 1,427

Related Party Transactions (Tab

Related Party Transactions (Tables)	6 Months Ended
	Jun. 30, 2021
Related Party Transactions [Abstract]
The Impact of Related Party Transactions	The impact of related party revenues from sales of products and services is reflected in the consolidated and condensed financial statements as follows: Three Months Ended June 30, Six Months Ended June 30, 2021 2020 2021 2020 Revenues: Terminalling and storage $ 15,569 $ 15,942 $ 30,875 $ 31,816 Transportation 4,889 5,393 8,899 11,287 Product sales: Sulfur services 29 9 59 28 Terminalling and storage 42 29 126 102 71 38 185 130 $ 20,529 $ 21,373 $ 39,959 $ 43,233 The impact of related party cost of products sold is reflected in the consolidated and condensed financial statements as follows: Three Months Ended June 30, Six Months Ended June 30, 2021 2020 2021 2020 Cost of products sold: Sulfur services $ 2,403 $ 2,554 $ 4,938 $ 5,321 Terminalling and storage 7,036 4,249 11,604 10,026 $ 9,439 $ 6,803 $ 16,542 $ 15,347 The impact of related party operating expenses is reflected in the consolidated and condensed financial statements as follows: Three Months Ended June 30, Six Months Ended June 30, 2021 2020 2021 2020 Operating expenses: Transportation $ 13,644 $ 13,388 $ 26,703 $ 28,941 Natural gas liquids 513 498 977 995 Sulfur services 1,306 1,137 2,049 2,283 Terminalling and storage 4,127 4,417 8,229 8,992 $ 19,590 $ 19,440 $ 37,958 $ 41,211 The impact of related party selling, general and administrative expenses is reflected in the consolidated and condensed financial statements as follows: Three Months Ended June 30, Six Months Ended June 30, 2021 2020 2021 2020 Selling, general and administrative: Transportation $ 1,701 $ 1,817 $ 3,371 $ 3,656 Natural gas liquids 276 533 2,084 1,237 Sulfur services 736 746 1,507 1,489 Terminalling and storage 832 835 1,652 1,673 Indirect, including overhead allocation 3,740 4,124 7,351 8,312 $ 7,285 $ 8,055 $ 15,965 $ 16,367

Business Segments (Tables)

Business Segments (Tables)	6 Months Ended
	Jun. 30, 2021
Segment Reporting [Abstract]
Segment Reporting by Segment	Three Months Ended June 30, 2021 Operating Revenues Intersegment Revenues Eliminations Operating Revenues after Eliminations Depreciation and Amortization Operating Income (Loss) after Eliminations Capital Expenditures and Plant Turnaround Costs Terminalling and storage 45,524 (1,675) 43,849 6,996 2,576 1,507 Transportation 38,349 (3,423) 34,926 4,331 (2,709) 1,091 Sulfur services 38,286 — 38,286 2,568 8,249 799 Natural gas liquids 67,232 — 67,232 588 3,297 140 Indirect selling, general and administrative — — — — (3,780) — Total $ 189,391 $ (5,098) $ 184,293 $ 14,483 $ 7,633 $ 3,537 Three Months Ended June 30, 2020 Operating Revenues Intersegment Revenues Eliminations Operating Revenues after Eliminations Depreciation and Amortization Operating Income (Loss) after Eliminations Capital Expenditures and Plant Turnaround Costs Terminalling and storage 46,976 (1,542) 45,434 7,272 2,969 3,427 Transportation 35,259 (3,774) 31,485 4,328 (2,078) 772 Sulfur services 33,420 — 33,420 3,131 8,814 1,739 Natural gas liquids 30,300 (1) 30,299 612 2,616 70 Indirect selling, general and administrative — — — — (4,361) — Total $ 145,955 $ (5,317) $ 140,638 $ 15,343 $ 7,960 $ 6,008 Six Months Ended June 30, 2021 Operating Revenues Intersegment Revenues Eliminations Operating Revenues after Eliminations Depreciation and Amortization Operating Income (Loss) after Eliminations Capital Expenditures and Plant Turnaround Costs Terminalling and storage $ 85,358 $ (3,270) $ 82,088 $ 14,101 $ 4,884 $ 4,172 Transportation 72,318 (7,577) 64,741 8,329 (8,212) 1,616 Sulfur services 73,121 — 73,121 5,288 16,602 3,863 Natural gas liquids 165,317 — 165,317 1,199 17,744 461 Indirect selling, general and administrative — — — — (7,699) — Total $ 396,114 $ (10,847) $ 385,267 $ 28,917 $ 23,319 $ 10,112 Six Months Ended June 30, 2020 Operating Revenues Intersegment Revenues Eliminations Operating Revenues after Eliminations Depreciation and Amortization Operating Income (Loss) after Eliminations Capital Expenditures and Plant Turnaround Costs Terminalling and storage $ 98,110 $ (3,268) $ 94,842 $ 14,728 $ 3,727 $ 7,022 Transportation 80,433 (10,007) 70,426 8,608 (7,099) 4,698 Sulfur services 61,756 (13) 61,743 6,025 22,672 4,874 Natural gas liquids 112,515 (5) 112,510 1,221 12,993 175 Indirect selling, general and administrative — — — — (8,733) — Total $ 352,814 $ (13,293) $ 339,521 $ 30,582 $ 23,560 $ 16,769
Assets by Segment	The Partnership's assets by reportable segment as of June 30, 2021 and December 31, 2020, are as follows: June 30, 2021 December 31, 2020 Total assets: Terminalling and storage $ 254,877 $ 252,794 Transportation 145,709 151,953 Sulfur services 97,750 94,154 Natural gas liquids 78,543 80,737 Total assets $ 576,879 $ 579,638

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	6 Months Ended
	Jun. 30, 2021
Fair Value Disclosures [Abstract]
Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis	Assets and liabilities measured at fair value on a recurring basis are summarized below: Level 2 June 30, 2021 December 31, 2020 Commodity derivative contracts, net $ (412) $ (207) June 30, 2021 December 31, 2020 Carrying Fair Carrying Fair 2021 Notes $ — $ — $ 28,790 $ 28,581 2024 Notes $ 50,745 $ 55,314 $ 50,173 $ 55,214 2025 Notes $ 290,458 $ 303,927 $ 290,250 $ 288,692 Total $ 341,203 $ 359,241 $ 369,213 $ 372,487

Income Taxes (Tables)

Income Taxes (Tables)	6 Months Ended
	Jun. 30, 2021
Income Tax Disclosure [Abstract]
Schedule of Income Tax Expense	Three Months Ended June 30, Six Months Ended June 30, 2021 2020 2021 2020 Provision for income taxes $ 935 $ 790 $ 1,157 $ 1,137

Nature of Operations and Basi_2

Nature of Operations and Basis of Presentation (Details)	6 Months Ended
	Jun. 30, 2021segment
Accounting Policies [Abstract]
Number of primary business lines	4

Revenue - Disaggregation of Rev

Revenue - Disaggregation of Revenue (Details) - USD ($) $ in Thousands		3 Months Ended		6 Months Ended
		Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Disaggregation of Revenue
Revenues		$ 184,293	$ 140,638	$ 385,267	$ 339,521
Lubricant product sales
Disaggregation of Revenue
Revenues	[1]	25,147	25,526	45,008	54,460
Throughput and storage
Disaggregation of Revenue
Revenues	[1]	18,702	19,908	37,080	40,382
Natural gas liquids
Disaggregation of Revenue
Revenues	[1]	67,232	30,299	165,317	112,510
Sulfur services
Disaggregation of Revenue
Revenues		2,949	2,914	5,899	5,829
Terminalling and storage segment
Disaggregation of Revenue
Revenues		43,849	45,434	82,088	94,842
Terminalling and storage segment | Lubricant product sales
Disaggregation of Revenue
Revenues		25,147	25,526	45,008	54,460
Terminalling and storage segment | Throughput and storage
Disaggregation of Revenue
Revenues		18,702	19,908	37,080	40,382
Natural gas liquids segment
Disaggregation of Revenue
Revenues		67,232	30,299	165,317	112,510
Natural gas liquids segment | Natural gas liquids
Disaggregation of Revenue
Revenues		67,232	30,299	165,317	112,510
Sulfur services segment
Disaggregation of Revenue
Revenues		38,286	33,420	73,121	61,743
Sulfur services segment | Sulfur product sales
Disaggregation of Revenue
Revenues		7,386	6,367	14,454	12,849
Sulfur services segment | Fertilizer product sales
Disaggregation of Revenue
Revenues		27,951	24,139	52,768	43,065
Sulfur services segment | Sulfur services
Disaggregation of Revenue
Revenues		2,949	2,914	5,899	5,829
Transportation segment
Disaggregation of Revenue
Revenues		34,926	31,485	64,741	70,426
Transportation segment | Land transportation
Disaggregation of Revenue
Revenues		27,486	19,873	50,442	44,107
Transportation segment | Inland transportation
Disaggregation of Revenue
Revenues		6,633	10,611	13,357	24,317
Transportation segment | Offshore transportation
Disaggregation of Revenue
Revenues		$ 807	$ 1,001	$ 942	$ 2,002
[1]	Related Party Transactions Included Above Three Months Ended Six Months Ended June 30, June 30, 2021 2020 2021 2020 Revenues:* Terminalling and storage $ 15,569 $ 15,942 $ 30,875 $ 31,816 Transportation 4,889 5,393 8,899 11,287 Product Sales 71 38 185 130 Costs and expenses:* Cost of products sold: (excluding depreciation and amortization) Sulfur services 2,403 2,554 4,938 5,321 Terminalling and storage 7,036 4,249 11,604 10,026 Expenses: Operating expenses 19,590 19,440 37,958 41,211 Selling, general and administrative 7,285 8,055 15,965 16,367

Revenue - Estimated Revenue Exp

Revenue - Estimated Revenue Expected to be Recognized in Future (Details) $ in Thousands	Jun. 30, 2021USD ($)
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction
Revenue, remaining performance obligation	$ 554,935
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2021-07-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction
Revenue, remaining performance obligation	$ 32,916
Revenue, remaining performance obligation, expected timing of satisfaction, period	6 months
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2022-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction
Revenue, remaining performance obligation	$ 62,721
Revenue, remaining performance obligation, expected timing of satisfaction, period	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2023-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction
Revenue, remaining performance obligation	$ 62,229
Revenue, remaining performance obligation, expected timing of satisfaction, period	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2024-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction
Revenue, remaining performance obligation	$ 49,234
Revenue, remaining performance obligation, expected timing of satisfaction, period	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2025-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction
Revenue, remaining performance obligation	$ 50,563
Revenue, remaining performance obligation, expected timing of satisfaction, period	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2026-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction
Revenue, remaining performance obligation	$ 297,272
Revenue, remaining performance obligation, expected timing of satisfaction, period
Terminalling and storage segment | Terminalling and storage
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction
Revenue, remaining performance obligation	$ 484,237
Terminalling and storage segment | Terminalling and storage | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2021-07-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction
Revenue, remaining performance obligation	$ 21,046
Revenue, remaining performance obligation, expected timing of satisfaction, period	6 months
Terminalling and storage segment | Terminalling and storage | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2022-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction
Revenue, remaining performance obligation	$ 40,394
Revenue, remaining performance obligation, expected timing of satisfaction, period	1 year
Terminalling and storage segment | Terminalling and storage | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2023-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction
Revenue, remaining performance obligation	$ 41,605
Revenue, remaining performance obligation, expected timing of satisfaction, period	1 year
Terminalling and storage segment | Terminalling and storage | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2024-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction
Revenue, remaining performance obligation	$ 42,854
Revenue, remaining performance obligation, expected timing of satisfaction, period	1 year
Terminalling and storage segment | Terminalling and storage | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2025-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction
Revenue, remaining performance obligation	$ 44,197
Revenue, remaining performance obligation, expected timing of satisfaction, period	1 year
Terminalling and storage segment | Terminalling and storage | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2026-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction
Revenue, remaining performance obligation	$ 294,141
Revenue, remaining performance obligation, expected timing of satisfaction, period
Natural gas liquids | Natural gas liquids
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction
Revenue, remaining performance obligation	$ 28,654
Natural gas liquids | Natural gas liquids | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2021-07-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction
Revenue, remaining performance obligation	$ 3,288
Revenue, remaining performance obligation, expected timing of satisfaction, period	6 months
Natural gas liquids | Natural gas liquids | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2022-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction
Revenue, remaining performance obligation	$ 6,048
Revenue, remaining performance obligation, expected timing of satisfaction, period	1 year
Natural gas liquids | Natural gas liquids | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2023-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction
Revenue, remaining performance obligation	$ 5,391
Revenue, remaining performance obligation, expected timing of satisfaction, period	1 year
Natural gas liquids | Natural gas liquids | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2024-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction
Revenue, remaining performance obligation	$ 5,405
Revenue, remaining performance obligation, expected timing of satisfaction, period	1 year
Natural gas liquids | Natural gas liquids | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2025-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction
Revenue, remaining performance obligation	$ 5,391
Revenue, remaining performance obligation, expected timing of satisfaction, period	1 year
Natural gas liquids | Natural gas liquids | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2026-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction
Revenue, remaining performance obligation	$ 3,131
Revenue, remaining performance obligation, expected timing of satisfaction, period
Sulfur services segment | Sulfur services
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction
Revenue, remaining performance obligation	$ 42,044
Sulfur services segment | Sulfur services | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2021-07-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction
Revenue, remaining performance obligation	$ 8,582
Revenue, remaining performance obligation, expected timing of satisfaction, period	6 months
Sulfur services segment | Sulfur services | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2022-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction
Revenue, remaining performance obligation	$ 16,279
Revenue, remaining performance obligation, expected timing of satisfaction, period	1 year
Sulfur services segment | Sulfur services | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2023-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction
Revenue, remaining performance obligation	$ 15,233
Revenue, remaining performance obligation, expected timing of satisfaction, period	1 year
Sulfur services segment | Sulfur services | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2024-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction
Revenue, remaining performance obligation	$ 975
Revenue, remaining performance obligation, expected timing of satisfaction, period	1 year
Sulfur services segment | Sulfur services | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2025-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction
Revenue, remaining performance obligation	$ 975
Revenue, remaining performance obligation, expected timing of satisfaction, period	1 year
Sulfur services segment | Sulfur services | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2026-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction
Revenue, remaining performance obligation	$ 0
Revenue, remaining performance obligation, expected timing of satisfaction, period

Inventories (Details)

Inventories (Details) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Inventory Disclosure [Abstract]
Natural gas liquids	$ 41,805	$ 27,878
Sulfur	71	24
Fertilizer	8,216	10,854
Lubricants	16,701	11,002
Other	4,565	4,364
Inventories	$ 71,358	$ 54,122

Debt (Details)

Debt (Details) - USD ($)	1 Months Ended		6 Months Ended
	Feb. 28, 2021	Aug. 31, 2020	Jun. 30, 2021	Jun. 30, 2020	Feb. 15, 2021	Dec. 31, 2020	Dec. 31, 2015	Apr. 30, 2014	Feb. 28, 2013
Debt Instrument
Total long-term debt			$ 517,311,000			$ 513,387,000
Less: current portion			0			(28,790,000)
Total long-term debt, net of current portion			517,311,000			484,597,000
Current installments of finance lease obligations			236,000			2,707,000
Finance lease obligations			169,000			289,000
Total lease liability			405,000			2,996,000
Payment of long term debt			144,790,000	$ 156,860,000
Revolving Loan Facility
Debt Instrument
Total long-term debt			176,108,000			144,174,000
Maximum borrowing capacity			$ 300,000,000
Weighted average interest rate (percent)			5.00%
Unamortized debt issuance costs			$ 3,392,000			3,826,000
Revolving Loan Facility | LIBOR
Debt Instrument
Interest rate floor (percent)			1.00%
Applicable margins (percent)			4.00%
Revolving Loan Facility | LIBOR | Minimum
Debt Instrument
Applicable margins (percent)			2.75%
Revolving Loan Facility | LIBOR | Maximum
Debt Instrument
Applicable margins (percent)			4.00%
Revolving Loan Facility | Prime Rate | Minimum
Debt Instrument
Applicable margins (percent)			1.75%
Revolving Loan Facility | Prime Rate | Maximum
Debt Instrument
Applicable margins (percent)			3.00%
Senior Notes | Senior Notes 7.25%
Debt Instrument
Total long-term debt			$ 0		$ 28,790,000	28,790,000
Unamortized debt issuance costs						0
Face amount						$ 400,000,000		$ 150,000,000	$ 250,000,000
Stated interest rate (percent)						7.25%
Unamortized premium						$ 0
Repurchase amount						9,344,000	$ 26,200,000
Debt refinanced		$ 335,666,000
Payment of long term debt	$ 28,790,000
Senior Notes | Senior Notes 10.0%
Debt Instrument
Total long-term debt			50,745,000			50,173,000
Unamortized debt issuance costs			3,005,000			3,577,000
Face amount			$ 53,750,000
Stated interest rate (percent)			10.00%
Senior Notes | Senior Note 11.5%
Debt Instrument
Total long-term debt			$ 290,458,000			290,250,000
Unamortized debt issuance costs			1,512,000			$ 1,720,000
Face amount			$ 291,970,000
Stated interest rate (percent)			11.50%

Debt - Narratives (Details)

Debt - Narratives (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Debt Disclosure [Abstract]
Cash paid for interest	$ 2,648	$ 2,376	$ 25,995	$ 19,113
Capitalized interest	$ 0	$ 6	$ 0	$ 9

Leases - Narrative (Details)

Leases - Narrative (Details) $ in Thousands	6 Months Ended
	Jun. 30, 2021USD ($)
New Accounting Pronouncements or Change in Accounting Principle
Lease termination term	1 year
Non-cancelable revenue arrangements, future minimum revenues, 2021	$ 11,559
Non-cancelable revenue arrangements, future minimum revenues, 2022	14,771
Non-cancelable revenue arrangements, future minimum revenues, 2023	14,364
Non-cancelable revenue arrangements, future minimum revenues, 2024	14,364
Non-cancelable revenue arrangements, future minimum revenues, 2025	13,798
Non-cancelable revenue arrangements, future minimum revenues, subsequent years	$ 38,539
Minimum
New Accounting Pronouncements or Change in Accounting Principle
Remaining lease term (years)	1 year
Maximum
New Accounting Pronouncements or Change in Accounting Principle
Remaining lease term (years)	15 years
Lease renewal term (years)	5 years

Leases - Lease Costs (Details)

Leases - Lease Costs (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Leases [Abstract]
Operating lease cost	$ 2,199	$ 2,767	$ 4,501	$ 5,611
Finance lease cost:
Amortization of right-of-use assets	25	526	115	1,115
Interest on lease liabilities	6	86	16	196
Short-term lease cost	2,473	3,492	5,581	6,915
Variable lease cost	26	22	59	50
Total lease cost	$ 4,729	$ 6,893	$ 10,272	$ 13,887

Leases - Balance Sheet Informat

Leases - Balance Sheet Information (Details) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Operating Leases
Operating lease right-of-use assets	$ 19,955	$ 22,260
Current portion of operating lease liabilities included in "Other accrued liabilities"	6,961	7,529
Operating lease liabilities	13,423	15,181
Total operating lease liabilities	$ 20,384	$ 22,710
Operating Lease, Liability, Current, Statement of Financial Position [Extensible List]	Other accrued liabilities	Other accrued liabilities
Finance Leases
Property, plant and equipment, at cost	$ 1,071	$ 10,352
Accumulated depreciation	(315)	(3,703)
Property, plant and equipment, net	756	6,649
Current installments of finance lease obligations	236	2,707
Finance lease obligations	169	289
Total finance lease obligations	$ 405	$ 2,996

Leases - Future Minimum Lease O

Leases - Future Minimum Lease Obligations (Details) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Operating Leases
Year 1	$ 7,769
Year 2	5,094
Year 3	2,566
Year 4	1,735
Year 5	1,053
Thereafter	5,511
Total	23,728
Less amounts representing interest costs	(3,344)
Total lease liability	20,384	$ 22,710
Finance Leases
Year 1	252
Year 2	172
Year 3	0
Year 4	0
Year 5	0
Thereafter	0
Total	424
Less amounts representing interest costs	(19)
Total lease liability	$ 405	$ 2,996

Supplemental Balance Sheet In_3

Supplemental Balance Sheet Information - Other Accrued Liabilities (Details) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Balance Sheet Related Disclosures [Abstract]
Accrued interest	$ 14,851	$ 16,104
Asset retirement obligations	300	1,692
Property and other taxes payable	3,765	4,869
Accrued payroll	2,940	3,244
Operating lease liabilities	6,961	7,529
Other	577	969
Total other accrued liabilities	$ 29,394	$ 34,407

Supplemental Balance Sheet In_4

Supplemental Balance Sheet Information - Asset Retirement Obligations (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2021	Dec. 31, 2020
Asset Retirement Obligation, Roll Forward Analysis
Beginning asset retirement obligations	$ 8,759
Additions to asset retirement obligations	0
Accretion expense	194
Liabilities settled	(22)
Ending asset retirement obligations	8,931
Current portion of asset retirement obligations	(300)	$ (1,692)
Long-term portion of asset retirement obligations	$ 8,631

Derivative Instruments and He_3

Derivative Instruments and Hedging Activities - Narrative (Details) - bbl bbl in Thousands	6 Months Ended	12 Months Ended
	Jun. 30, 2021	Dec. 31, 2020
Commodity contracts
Derivatives, Fair Value
Notional quantity (in bbl)	390	137

Derivative Instruments and He_4

Derivative Instruments and Hedging Activities - Balance Sheet Derivatives (Details) - Derivatives not designated as hedging instruments - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Derivatives, Fair Value
Derivative Assets	$ 0	$ 0
Derivative Liabilities	412	207
Commodity contracts | Fair value of derivatives
Derivatives, Fair Value
Derivative Assets	0	0
Derivative Liabilities	$ 412	$ 207

Derivative Instruments and He_5

Derivative Instruments and Hedging Activities - Statement of Operations Derivatives (Details) - Derivatives not designated as hedging instruments - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Derivative Instruments, Gain (Loss)
Amount of Gain (Loss) Recognized in Income on Derivatives	$ 552	$ (162)	$ (884)	$ (129)
Commodity contracts | Cost of products sold
Derivative Instruments, Gain (Loss)
Amount of Gain (Loss) Recognized in Income on Derivatives	$ 552	$ (162)	$ (884)	$ (129)

Partners' Capital - Narrative (

Partners' Capital - Narrative (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2019
Limited Partners' Capital Account
Common limited partner units (in shares)	38,802,750
Cash distributions	$ 396	$ 4,923
Martin Resource Management Corporation | Martin Resource Management
Limited Partners' Capital Account
Voting interest percentage	51.00%
Martin Resource Management
Limited Partners' Capital Account
Common limited partner units (in shares)	6,114,532
Voting interest percentage	15.80%
Martin Resource Management Corporation
Limited Partners' Capital Account
Ownership interest (percentage)	98.00%
Martin Resource Management Corporation | Martin Resource Management Corporation
Limited Partners' Capital Account
Purchase price			$ 550,773
Cash distributions			$ 287,734
MMGP LLC
Limited Partners' Capital Account
General partner interest percentage	2.00%
MMGP LLC | Martin Resource Management
Limited Partners' Capital Account
Ownership interest (percentage)	15.80%
General partner interest percentage	2.00%

Partners' Capital - Incentive D

Partners' Capital - Incentive Distribution Rights and Distributions of Available Cash (Details) - USD ($)	6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020
Limited Partners' Capital Account
Distribution period	45 days
MMGP
Limited Partners' Capital Account
Incentive distribution	$ 0	$ 0
MMGP | Target Level 1
Limited Partners' Capital Account
Target cash distribution, percent	2.00%
MMGP | Target Level 2
Limited Partners' Capital Account
Target cash distribution, percent	15.00%
Target cash distribution (USD per share)	$ 0.625
MMGP | Target Level 3
Limited Partners' Capital Account
Target cash distribution, percent	25.00%
Target cash distribution (USD per share)	$ 0.75
MMGP | Target Level 4
Limited Partners' Capital Account
Target cash distribution, percent	50.00%
MMGP | Minimum | Target Level 1
Limited Partners' Capital Account
Target cash distribution (USD per share)	$ 0.50
MMGP | Minimum | Target Level 2
Limited Partners' Capital Account
Target cash distribution (USD per share)	0.55
MMGP | Minimum | Target Level 3
Limited Partners' Capital Account
Target cash distribution (USD per share)	0.625
MMGP | Minimum | Target Level 4
Limited Partners' Capital Account
Target cash distribution (USD per share)	0.75
MMGP | Maximum | Target Level 1
Limited Partners' Capital Account
Target cash distribution (USD per share)	$ 0.55
MMGP LLC
Limited Partners' Capital Account
General partner interest percentage	2.00%
MMGP LLC | MMGP
Limited Partners' Capital Account
General partner interest percentage	2.00%

Partners' Capital - Net Income

Partners' Capital - Net Income Per Unit (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Partners' Capital Notes [Abstract]
Net income (loss)	$ (6,612)	$ (2,203)	$ (4,101)	$ 6,612
Less general partner’s interest in net income (loss):
Distributions payable on behalf of general partner interest	4	4	8	53
General partner interest in undistributed income (loss)	(136)	(48)	(90)	79
Less income (loss) allocable to unvested restricted units	(20)	(10)	(10)	45
Limited partners' interest in net income (loss)	$ (6,460)	$ (2,149)	$ (4,009)	$ 6,435
Basic weighted average limited partner units outstanding (in shares)	38,687,874	38,661,852	38,690,228	38,651,357
Dilutive effect of restricted units issued (in shares)	0	0	0	540
Total weighted average limited partner diluted units outstanding (in shares)	38,687,874	38,661,852	38,690,228	38,651,897

Unit Based Awards - Schedule of

Unit Based Awards - Schedule of Compensation Costs (Details) - Selling, General and Administrative Expenses - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Share-based Compensation Arrangement by Share-based Payment Award
Total unit-based compensation expense	$ 48	$ 363	$ 288	$ 709
Employees
Share-based Compensation Arrangement by Share-based Payment Award
Total unit-based compensation expense	0	301	194	602
Non-employee directors
Share-based Compensation Arrangement by Share-based Payment Award
Total unit-based compensation expense	$ 48	$ 62	$ 94	$ 107

Unit Based Awards - Narrative (

Unit Based Awards - Narrative (Details) $ in Thousands	Jan. 24, 2025shares	Jan. 24, 2024shares	Jan. 24, 2023shares	Jan. 24, 2022shares	Feb. 28, 2021directorshares	Jun. 30, 2021USD ($)shares	May 26, 2017shares
Share-based Compensation Arrangement by Share-based Payment Award
Number of shares authorized (in shares)							3,000,000
Restricted Units
Share-based Compensation Arrangement by Share-based Payment Award
Vested, number of units (in shares)						117,280
Unrecognized compensation cost related to non-vested restricted units | $						$ 344
Weighted average period for recognition (in years)						2 years 5 months 1 day
Restricted Units | Non-employee directors
Share-based Compensation Arrangement by Share-based Payment Award
Vesting period (in years)						4 years
Restricted Units | Employees
Share-based Compensation Arrangement by Share-based Payment Award
Vesting period (in years)						3 years
Time Based Restricted Units
Share-based Compensation Arrangement by Share-based Payment Award
Granted, number of units (in shares)						42,168
Number of independent directors receiving grants | director					3
Time Based Restricted Units | Non-employee directors
Share-based Compensation Arrangement by Share-based Payment Award
Granted, number of units (in shares)					14,056
Scenario, Forecast | Time Based Restricted Units | Non-employee directors
Share-based Compensation Arrangement by Share-based Payment Award
Vested, number of units (in shares)	3,514	3,514	3,514	3,514

Unit Based Awards - Restricted

Unit Based Awards - Restricted Unit Activity (Details) $ / shares in Units, $ in Thousands	6 Months Ended
	Jun. 30, 2021USD ($)$ / sharesshares
Restricted Units
Number of Units
Non-vested, beginning of period (in shares) | shares	273,424
Vested (in shares) | shares	(117,280)
Forfeited (in shares) | shares	(83,436)
Non-vested, end of period (in shares) | shares	114,876
Weighted Average Grant-Date Fair Value Per Unit
Non-vested, beginning of period (USD per share) | $ / shares	$ 10.52
Vested (USD per share) | $ / shares	11.96
Forfeited (USD per share) | $ / shares	13.90
Non-vested, end of period (USD per share) | $ / shares	$ 3.65
Aggregate intrinsic value, end of period | $	$ 347
Time Based Restricted Units
Number of Units
Granted (in shares) | shares	42,168
Weighted Average Grant-Date Fair Value Per Unit
Granted (USD per share) | $ / shares	$ 2.49

Unit Based Awards - Intrinsic a

Unit Based Awards - Intrinsic and Fair Value (Details) - Restricted Units - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Share-based Compensation Arrangement by Share-based Payment Award
Aggregate intrinsic value of units vested	$ 0	$ 0	$ 257	$ 151
Fair value of units vested	$ 0	$ 0	$ 1,418	$ 1,427

Related Party Transactions - Na

Related Party Transactions - Narrative (Details)	6 Months Ended
	Jun. 30, 2021shares
MMGP LLC
Related Party Transaction
General partner interest percentage	2.00%
Martin Resource Management
Related Party Transaction
Common limited partner units (in shares)	6,114,532
Voting interest percentage	15.80%
Martin Resource Management | Martin Resource Management | MMGP Holdings, LLC
Related Party Transaction
General partner interest percentage	51.00%
Martin Resource Management | MMGP LLC
Related Party Transaction
General partner interest percentage	2.00%

Related Party Transactions - Om

Related Party Transactions - Omnibus Agreement (Details) - Omnibus Agreement - Martin Resource Management - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020	Jan. 01, 2021
Related Party Transaction
Non-compete restriction threshold	$ 5,000,000		$ 5,000,000
Non-compete restriction ownership option opportunity threshold minimum	5,000,000		5,000,000
Non-compete restriction ownership option opportunity threshold minimum with equity limitation	$ 5,000,000		$ 5,000,000
Equity limitation on ownership restriction percentage	20.00%		20.00%
Approved annual reimbursements for indirect expenses					$ 14,386,000
Indirect expenses reimbursed	$ 3,652,000	$ 4,103,000	$ 7,193,000	$ 8,261,000

Related Party Transactions - Ma

Related Party Transactions - Master Transportation Services Agreement (Details)	6 Months Ended
	Jun. 30, 2021
Master Transportation Services Agreement | Martin Resource Management
Related Party Transaction
Termination written notice, minimum (in days)	30 days

Related Party Transactions - _2

Related Party Transactions - Marine Agreements (Details) - Marine Transportation Agreement - Martin Resource Management	6 Months Ended
	Jun. 30, 2021
Related Party Transaction
Automatic consecutive term renewal period (in years)	1 year
Termination written notice, minimum (in days)	60 days

Related Party Transactions - Te

Related Party Transactions - Terminal Services Agreements (Details)	6 Months Ended
	Jun. 30, 2021
Terminal Services Agreements | Martin Resource Management
Related Party Transaction
Termination written notice, minimum (in days)	60 days

Related Party Transactions - Ot

Related Party Transactions - Other Agreements (Details) - Martin Resource Management $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021USD ($)bbl	Jun. 30, 2020USD ($)	Jun. 30, 2022USD ($)	Jun. 30, 2021USD ($)bbl	Jun. 30, 2020USD ($)	Dec. 31, 2020USD ($)	Dec. 31, 2019USD ($)
East Texas Mack Leases
Related Party Transaction
Ownership interest (percent)	46.00%			46.00%
Operating cash flows from operating leases	$ 282	$ 154		$ 518	$ 259
Cross Tolling Agreement
Related Party Transaction
Production minimum per day (in bbl) | bbl	6,500			6,500
Capital recovery fee reimbursement, expired						$ 2,586	$ 2,088
Annual escalation benchmark percentage	3.00%			3.00%
Cross Tolling Agreement | Scenario, Forecast
Related Party Transaction
Annual revenue decrease from contract expiration			$ 2,145

Related Party Transactions - Sc

Related Party Transactions - Schedule of the Impact of Related Party Transactions (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Operating expenses:
Operating expenses	$ 19,590	$ 19,440	$ 37,958	$ 41,211
Related Party
Revenues:
Revenue from related parties	20,529	21,373	39,959	43,233
Cost of products sold:
Cost of products sold	9,439	6,803	16,542	15,347
Operating expenses:
Operating expenses	19,590	19,440	37,958	41,211
Selling, general and administrative:
Selling, general and administrative	7,285	8,055	15,965	16,367
Related Party | Indirect, including overhead allocation
Selling, general and administrative:
Selling, general and administrative	3,740	4,124	7,351	8,312
Related Party | Terminalling and storage
Revenues:
Revenue from related parties	15,569	15,942	30,875	31,816
Operating expenses:
Operating expenses	4,127	4,417	8,229	8,992
Selling, general and administrative:
Selling, general and administrative	832	835	1,652	1,673
Related Party | Transportation
Revenues:
Revenue from related parties	4,889	5,393	8,899	11,287
Operating expenses:
Operating expenses	13,644	13,388	26,703	28,941
Selling, general and administrative:
Selling, general and administrative	1,701	1,817	3,371	3,656
Related Party | Natural gas liquids
Operating expenses:
Operating expenses	513	498	977	995
Selling, general and administrative:
Selling, general and administrative	276	533	2,084	1,237
Related Party | Product sales
Revenues:
Revenue from related parties	71	38	185	130
Related Party | Sulfur services
Revenues:
Revenue from related parties	29	9	59	28
Cost of products sold:
Cost of products sold	2,403	2,554	4,938	5,321
Operating expenses:
Operating expenses	1,306	1,137	2,049	2,283
Selling, general and administrative:
Selling, general and administrative	736	746	1,507	1,489
Related Party | Terminalling and storage
Revenues:
Revenue from related parties	42	29	126	102
Cost of products sold:
Cost of products sold	$ 7,036	$ 4,249	$ 11,604	$ 10,026

Business Segments - Narratives

Business Segments - Narratives (Details)	6 Months Ended
	Jun. 30, 2021segment
Segment Reporting [Abstract]
Number of reportable segments	4

Business Segments - Income Stat

Business Segments - Income Statement (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Segment Reporting Information
Total revenue	$ 184,293	$ 140,638	$ 385,267	$ 339,521
Depreciation and Amortization	14,483	15,343	28,917	30,582
Operating Income (Loss) after Eliminations	7,633	7,960	23,319	23,560
Capital Expenditures and Plant Turnaround Costs	3,537	6,008	10,112	16,769
Terminalling and storage
Segment Reporting Information
Total revenue	43,849	45,434	82,088	94,842
Depreciation and Amortization	6,996	7,272	14,101	14,728
Operating Income (Loss) after Eliminations	2,576	2,969	4,884	3,727
Capital Expenditures and Plant Turnaround Costs	1,507	3,427	4,172	7,022
Transportation
Segment Reporting Information
Total revenue	34,926	31,485	64,741	70,426
Depreciation and Amortization	4,331	4,328	8,329	8,608
Operating Income (Loss) after Eliminations	(2,709)	(2,078)	(8,212)	(7,099)
Capital Expenditures and Plant Turnaround Costs	1,091	772	1,616	4,698
Sulfur services
Segment Reporting Information
Total revenue	38,286	33,420	73,121	61,743
Depreciation and Amortization	2,568	3,131	5,288	6,025
Operating Income (Loss) after Eliminations	8,249	8,814	16,602	22,672
Capital Expenditures and Plant Turnaround Costs	799	1,739	3,863	4,874
Natural gas liquids
Segment Reporting Information
Total revenue	67,232	30,299	165,317	112,510
Depreciation and Amortization	588	612	1,199	1,221
Operating Income (Loss) after Eliminations	3,297	2,616	17,744	12,993
Capital Expenditures and Plant Turnaround Costs	140	70	461	175
Operating Revenues
Segment Reporting Information
Total revenue	189,391	145,955	396,114	352,814
Operating Revenues | Terminalling and storage
Segment Reporting Information
Total revenue	45,524	46,976	85,358	98,110
Operating Revenues | Transportation
Segment Reporting Information
Total revenue	38,349	35,259	72,318	80,433
Operating Revenues | Sulfur services
Segment Reporting Information
Total revenue	38,286	33,420	73,121	61,756
Operating Revenues | Natural gas liquids
Segment Reporting Information
Total revenue	67,232	30,300	165,317	112,515
Intersegment Revenues Eliminations
Segment Reporting Information
Total revenue	(5,098)	(5,317)	(10,847)	(13,293)
Intersegment Revenues Eliminations | Terminalling and storage
Segment Reporting Information
Total revenue	(1,675)	(1,542)	(3,270)	(3,268)
Intersegment Revenues Eliminations | Transportation
Segment Reporting Information
Total revenue	(3,423)	(3,774)	(7,577)	(10,007)
Intersegment Revenues Eliminations | Sulfur services
Segment Reporting Information
Total revenue	0	0	0	(13)
Intersegment Revenues Eliminations | Natural gas liquids
Segment Reporting Information
Total revenue	0	(1)	0	(5)
Indirect selling, general and administrative
Segment Reporting Information
Depreciation and Amortization	0	0	0	0
Operating Income (Loss) after Eliminations	(3,780)	(4,361)	(7,699)	(8,733)
Capital Expenditures and Plant Turnaround Costs	$ 0	$ 0	$ 0	$ 0

Business Segments - Balance She

Business Segments - Balance Sheet (Details) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Total assets:
Total assets	$ 576,879	$ 579,638
Terminalling and storage
Total assets:
Total assets	254,877	252,794
Transportation
Total assets:
Total assets	145,709	151,953
Sulfur services
Total assets:
Total assets	97,750	94,154
Natural gas liquids
Total assets:
Total assets	$ 78,543	$ 80,737

Fair Value Measurements (Detail

Fair Value Measurements (Details) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Recurring | Level 2 | Commodity Contracts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Commodity derivative contracts, net	$ (412)	$ (207)
Nonrecurring | Carrying Value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Notes payable	341,203	369,213
Nonrecurring | Fair Value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Notes payable	359,241	372,487
Nonrecurring | 2021 Notes | Carrying Value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Notes payable	0	28,790
Nonrecurring | 2021 Notes | Fair Value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Notes payable	0	28,581
Nonrecurring | 2024 Notes | Carrying Value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Notes payable	50,745	50,173
Nonrecurring | 2024 Notes | Fair Value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Notes payable	55,314	55,214
Nonrecurring | 2025 Notes | Carrying Value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Notes payable	290,458	290,250
Nonrecurring | 2025 Notes | Fair Value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Notes payable	$ 303,927	$ 288,692

Income Taxes - Income Tax Expen

Income Taxes - Income Tax Expense (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Income Tax Disclosure [Abstract]
Provision for income taxes	$ 935	$ 790	$ 1,157	$ 1,137

Income Taxes - Narrative (Detai

Income Taxes - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020	Dec. 31, 2020
Income Tax Contingency
Income tax expense	$ 935	$ 790	$ 1,157	$ 1,137
Deferred income tax expense			758	1,018
MTI
Income Tax Contingency
Income tax expense	$ 874	$ 590	$ 977	$ 937
Effective income tax rate (percentage)	40.22%	(472.00%)	38.73%	98.32%
Current federal income tax expense (benefit)	$ 108	$ (307)	$ 123	$ (174)
State income tax expense (benefit)	83	164	96	93
Deferred income tax expense	683	$ 733	758	$ 1,018
Deferred tax asset	$ 21,495		$ 21,495		$ 22,253

Subsequent Events (Details)

Subsequent Events (Details) - USD ($)	Jul. 22, 2021	Jul. 16, 2021	Jun. 30, 2021
Revolving Loan Facility
Subsequent Event
Maximum borrowing capacity			$ 300,000,000
Subsequent Event
Subsequent Event
Dividends declared (USD per share)	$ 0.005
Estimated annualized dividends (USD per share)	$ 0.020
Subsequent Event | Revolving Loan Facility
Subsequent Event
Maximum borrowing capacity		$ 275,000,000