Alliance Resource Partners (ARLP) 10-K 23 Feb 24 2023 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($)	12 Months Ended
	Dec. 31, 2023	Feb. 23, 2024	Jun. 30, 2023
Document and Entity Information
Document Type	10-K
Document Annual Report	true
Document Transition Report	false
Document Period End Date	Dec. 31, 2023
Entity File Number	0-26823
Entity Registrant Name	ALLIANCE RESOURCE PARTNERS LP
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	73-1564280
Entity Address, Address Line One	1717 South Boulder Avenue, Suite 400
Entity Address, City or Town	Tulsa
Entity Address, State or Province	OK
Entity Address, Postal Zip Code	74119
City Area Code	918
Local Phone Number	295-7600
Title of 12(b) Security	Common Units
Trading Symbol	ARLP
Security Exchange Name	NASDAQ
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
ICFR Auditor Attestation Flag	true
Entity Shell Company	false
Document Financial Statement Error Correction [Flag]	false
Entity Common Units Outstanding		128,061,981
Entity Public Float			$ 1,948,772,132
Auditor Name	GRANT THORNTON LLP
Auditor Firm ID	248
Auditor Location	Tulsa, Oklahoma
Entity Central Index Key	0001086600
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2023
Document Fiscal Period Focus	FY
Amendment Flag	false

CONSOLIDATED BALANCE SHEETS

CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
CURRENT ASSETS:
Cash and cash equivalents	$ 59,813	$ 296,023
Trade receivables	282,622	241,412
Other receivables	9,678	8,601
Inventories, net	127,556	77,326
Advance royalties	7,780	7,556
Prepaid expenses and other assets	28,672	26,675
Total current assets	516,121	657,593
PROPERTY, PLANT AND EQUIPMENT:
Property, plant and equipment, at cost	4,172,544	3,931,422
Less accumulated depreciation, depletion and amortization	(2,149,881)	(2,050,754)
Total property, plant and equipment, net	2,022,663	1,880,668
OTHER ASSETS:
Advance royalties	71,125	67,713
Equity method investments	46,503	49,371
Equity securities	92,541	42,000
Operating lease right-of-use assets	16,569	14,950
Other long-term assets	22,904	15,726
Total other assets	249,642	189,760
TOTAL ASSETS	2,788,426	2,728,021
CURRENT LIABILITIES:
Accounts payable	108,269	95,122
Accrued taxes other than income taxes	21,007	22,967
Accrued payroll and related expenses	29,884	39,623
Accrued interest	3,558	5,000
Workers' compensation and pneumoconiosis benefits	15,913	14,099
Due to affiliates	28,498	53,790
Current maturities, long-term debt, net	20,338	24,970
Total current liabilities	227,467	255,571
LONG-TERM LIABILITIES:
Long-term debt, excluding current maturities, net	316,821	397,203
Pneumoconiosis benefits	127,249	100,089
Accrued pension benefit	8,618	12,553
Workers' compensation	37,257	39,551
Asset retirement obligations	146,925	142,254
Long-term operating lease obligations	13,661	12,132
Deferred income tax liabilities	33,450	35,814
Other liabilities	18,381	24,828
Total long-term liabilities	702,362	764,424
Total liabilities	929,829	1,019,995
COMMITMENTS AND CONTINGENCIES - (Note 21)
ARLP Partners' Capital:
Limited Partners - Common Unitholders 127,125,437 and 127,195,219 units outstanding, respectively	1,896,027	1,656,025
General Partner's interest		66,548
Accumulated other comprehensive loss	(61,525)	(41,054)
Total Partners' Capital	1,834,502	1,681,519
Noncontrolling interest	24,095	26,507
Total Partners' Capital	1,858,597	1,708,026
TOTAL LIABILITIES AND PARTNERS' CAPITAL	$ 2,788,426	$ 2,728,021

CONSOLIDATED BALANCE SHEETS (Pa

CONSOLIDATED BALANCE SHEETS (Parenthetical) - shares	Dec. 31, 2023	Dec. 31, 2022
CONSOLIDATED BALANCE SHEETS
Common units outstanding	127,125,437	127,195,219

CONSOLIDATED STATEMENTS OF INCO

CONSOLIDATED STATEMENTS OF INCOME - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
SALES AND OPERATING REVENUES:
Revenues	$ 2,566,701	$ 2,419,967	$ 1,579,230
EXPENSES:
Outside coal purchases	36,149	151	6,372
General and administrative	79,096	80,425	70,275
Depreciation, depletion and amortization	267,982	276,670	264,794
Settlement gain		(6,664)
Total operating expenses	1,894,304	1,752,524	1,355,467
INCOME FROM OPERATIONS	672,397	667,443	223,763
Interest expense (net of interest capitalized of $6,706, $922 and $396, respectively)	(36,091)	(37,331)	(39,229)
Interest income	9,394	2,035	88
Equity method investment income (loss)	(1,468)	5,634	2,130
Other income (expense)	218	4,355	(2,966)
INCOME BEFORE INCOME TAXES	644,450	642,136	183,786
INCOME TAX EXPENSE	8,280	53,978	417
NET INCOME	636,170	588,158	183,369
LESS: NET INCOME ATTRIBUTABLE TO NONCONTROLLING INTEREST	(6,052)	(1,958)	(598)
NET INCOME ATTRIBUTABLE TO ARLP	630,118	586,200	182,771
NET INCOME ATTRIBUTABLE TO ARLP
GENERAL PARTNER	1,384	9,010	4,614
LIMITED PARTNERS	$ 628,734	$ 577,190	$ 178,157
EARNINGS PER LIMITED PARTNER UNIT - BASIC (in dollars per unit)	$ 4.81	$ 4.39	$ 1.36
EARNINGS PER LIMITED PARTNER UNIT - DILUTED (in dollars per unit)	$ 4.81	$ 4.39	$ 1.36
WEIGHTED-AVERAGE NUMBER OF UNITS OUTSTANDING - BASIC (in units)	127,180,312	127,195,219	127,195,219
WEIGHTED-AVERAGE NUMBER OF UNITS OUTSTANDING - DILUTED (in units)	127,180,000	127,195,000	127,195,000
Product
EXPENSES:
Operating expenses (excluding depreciation, depletion and amortization)	$ 1,368,787	$ 1,288,082	$ 944,419
Coal sales
SALES AND OPERATING REVENUES:
Revenues	2,210,210	2,102,229	1,386,923
Oil & gas royalties
SALES AND OPERATING REVENUES:
Revenues	137,751	151,060	84,183
Transportation
SALES AND OPERATING REVENUES:
Revenues	142,290	113,860	69,607
EXPENSES:
Operating expenses (excluding depreciation, depletion and amortization)	142,290	113,860	69,607
Other revenues
SALES AND OPERATING REVENUES:
Revenues	$ 76,450	$ 52,818	$ 38,517

CONSOLIDATED STATEMENTS OF IN_2

CONSOLIDATED STATEMENTS OF INCOME (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
CONSOLIDATED STATEMENTS OF INCOME
Interest expense, interest capitalized	$ 6,706	$ 922	$ 396

CONSOLIDATED STATEMENTS OF COMP

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
NET INCOME	$ 636,170	$ 588,158	$ 183,369
OTHER COMPREHENSIVE INCOME (LOSS):
Total recognized in accumulated other comprehensive loss	(20,471)	23,175	23,445
OTHER COMPREHENSIVE INCOME (LOSS)	(20,471)	23,175	23,445
COMPREHENSIVE INCOME	615,699	611,333	206,814
Less: Comprehensive income attributable to noncontrolling interest	(6,052)	(1,958)	(598)
COMPREHENSIVE INCOME ATTRIBUTABLE TO ARLP	609,647	609,375	206,216
Defined benefit pension plan
OTHER COMPREHENSIVE INCOME (LOSS):
Amortization of prior service cost (1)	186	186	186
Net actuarial gain	2,894	10,148	14,921
Amortization of net actuarial loss (1)	682	1,963	4,327
Total recognized in accumulated other comprehensive loss	3,762	12,297	19,434
Pneumoconiosis benefits
OTHER COMPREHENSIVE INCOME (LOSS):
Net actuarial gain	(25,615)	9,840	(161)
Amortization of net actuarial loss (1)	1,382	1,038	4,172
Total recognized in accumulated other comprehensive loss	$ (24,233)	$ 10,878	$ 4,011

CONSOLIDATED STATEMENTS OF CASH

CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income	$ (636,170)	$ (588,158)	$ (183,369)
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation, depletion and amortization	267,982	276,670	264,794
Non-cash compensation expense	12,864	11,029	5,709
Coal inventory adjustment to market	33,296	364	70
Equity method investment loss (income)	1,468	(5,634)	(2,130)
Distributions from equity method investments	2,567	5,634	2,130
Net gain on sale of property, plant and equipment	(3,230)	(3,665)	(6,592)
Change in deferred income tax	(8,973)	34,775	349
Other	11,259	5,313	3,900
Changes in operating assets and liabilities:
Trade receivables	(41,210)	(108,893)	(25,931)
Other receivables	(1,077)	(7,921)	3,109
Inventories, net	(78,004)	(20,138)	(4,673)
Prepaid expenses and other assets	(2,940)	(9,179)	211
Advance royalties	(3,636)	(6,787)	(7,523)
Accounts payable	17,842	14,580	19,481
Accrued taxes other than income taxes	(1,960)	5,180	(7,267)
Accrued payroll and related benefits	(9,739)	2,818	8,281
Pneumoconiosis benefits	3,924	3,849	6,832
Workers' compensation	(1,477)	(3,996)	(1,292)
Other	(4,484)	20,192	(10,654)
Total net adjustments	194,472	214,191	248,804
Net cash provided by operating activities	830,642	802,349	432,173
Property, plant and equipment:
Capital expenditures	(379,338)	(286,394)	(122,984)
Change in accounts payable and accrued liabilities	(29,695)	35,956	2,594
Proceeds from sale of property, plant and equipment	3,710	7,468	7,719
Contributions to equity method investments	(2,518)	(24,087)
Purchase of equity securities	(49,560)	(42,000)
JC Resources acquisition	(64,999)
Oil & gas reserve business combinations	(14,459)	(92,618)
Oil & gas reserve asset acquisitions	(24,225)		(30,960)
Other	1,351	(1,663)	943
Net cash used in investing activities	(559,733)	(403,338)	(142,688)
CASH FLOWS FROM FINANCING ACTIVITIES:
Borrowings under securitization facility		27,500	35,000
Payments under securitization facility		(27,500)	(90,900)
Payments on equipment financings	(24,970)	(16,071)	(17,299)
Borrowings under revolving credit facilities			15,000
Payments under revolving credit facilities			(102,500)
Borrowings from line of credit			5,340
Payment on line of credit			(5,340)
Borrowing under long-term debt	75,000
Payments on long-term debt	(129,455)
Payment of debt issuance costs	(12,376)		(113)
Payments for purchases of units under unit repurchase program	(19,432)
Payments for tax withholdings related to settlements under deferred compensation plans	(10,334)		(1,090)
Excess purchase price over the contributed basis from JC Resources acquisition	(7,251)
Cash retained by JC Resources in acquisition	(2,933)	(10,537)	(6,971)
Distributions paid to Partners	(364,579)	(196,347)	(52,158)
Other	(10,789)	(2,436)	(1,625)
Net cash used in financing activities	(507,119)	(225,391)	(222,656)
NET CHANGE IN CASH AND CASH EQUIVALENTS	(236,210)	173,620	66,829
CASH AND CASH EQUIVALENTS AT BEGINNING OF PERIOD	296,023	122,403	55,574
CASH AND CASH EQUIVALENTS AT END OF PERIOD	$ 59,813	$ 296,023	$ 122,403

CONSOLIDATED STATEMENT OF PARTN

CONSOLIDATED STATEMENT OF PARTNERS' CAPITAL - USD ($)	Limited Partners' Capital	General Partners' Capital	Accumulated Other Comprehensive Income (Loss)	Noncontrolling Interest	Total
Balance at beginning of period at Dec. 31, 2020	$ 1,148,565,000	$ 70,432,000	$ (87,674,000)	$ 11,376,000	$ 1,142,699,000
Balance at beginning of period (in units) at Dec. 31, 2020	127,195,219
Comprehensive income (loss):
Net income	$ 178,157,000	4,614,000		598,000	183,369,000
Actuarially determined long-term liability adjustments			23,445,000		23,445,000
Total comprehensive income					206,814,000
Settlement of deferred common unit- based compensation plans	$ (1,090,000)				(1,090,000)
Settlement of deferred common unit- based compensation plans (in units)	0
Common unit-based compensation	$ 5,709,000				5,709,000
Distributions on deferred common unit-based compensation	(1,280,000)				(1,280,000)
Distributions from consolidated company to noncontrolling interest				(859,000)	(859,000)
Cash retained by JC Resources in acquisition		(6,971,000)			(6,971,000)
Distributions to Partners	(50,878,000)				(50,878,000)
Balance at end of period at Dec. 31, 2021	$ 1,279,183,000	68,075,000	(64,229,000)	11,115,000	1,294,144,000
Balance at end of period (in units) at Dec. 31, 2021	127,195,219
Comprehensive income (loss):
Net income	$ 577,190,000	9,010,000		1,958,000	588,158,000
Actuarially determined long-term liability adjustments			23,175,000		23,175,000
Total comprehensive income					611,333,000
Common unit-based compensation	11,029,000				11,029,000
Distributions on deferred common unit-based compensation	(5,553,000)				(5,553,000)
Distributions from consolidated company to noncontrolling interest	0	0	0	(1,596,000)	(1,596,000)
Profits interest adjustment for noncontrolling interest	(15,030,000)			15,030,000
Cash retained by JC Resources in acquisition		(10,537,000)			(10,537,000)
Distributions to Partners	(190,794,000)				(190,794,000)
Balance at end of period at Dec. 31, 2022	$ 1,656,025,000	66,548,000	(41,054,000)	26,507,000	$ 1,708,026,000
Balance at end of period (in units) at Dec. 31, 2022	127,195,219				127,195,219
Comprehensive income (loss):
Net income	$ 628,734,000	1,384,000		6,052,000	$ 636,170,000
Actuarially determined long-term liability adjustments			(20,471,000)		(20,471,000)
Total comprehensive income					615,699,000
Settlement of deferred common unit- based compensation plans	$ (10,334,000)				(10,334,000)
Settlement of deferred common unit- based compensation plans (in units)	860,060
Purchase of units under unit repurchase program	$ (19,432,000)				(19,432,000)
Purchase of units under unit repurchase program (in units)	(929,842)
Common unit-based compensation	$ 12,864,000				12,864,000
Distributions on deferred common unit-based compensation	(8,530,000)				(8,530,000)
Distributions from consolidated company to noncontrolling interest				(8,464,000)	(8,464,000)
JC Resources acquisition	(7,251,000)	(64,999,000)			(72,250,000)
Cash retained by JC Resources in acquisition		$ (2,933,000)			(2,933,000)
Distributions to Partners	(356,049,000)				(356,049,000)
Balance at end of period at Dec. 31, 2023	$ 1,896,027,000		$ (61,525,000)	$ 24,095,000	$ 1,858,597,000
Balance at end of period (in units) at Dec. 31, 2023	127,125,437				127,125,437

ORGANIZATION AND PRESENTATION

ORGANIZATION AND PRESENTATION	12 Months Ended
	Dec. 31, 2023
ORGANIZATION AND PRESENTATION
ORGANIZATION AND PRESENTATION	1. ORGANIZATION AND PRESENTATION ​ Significant Relationships Referenced in Notes to Consolidated Financial Statements ​ ● References to "we," "us," "our" or "ARLP Partnership" mean the business and operations of Alliance Resource Partners, L.P., the parent company, as well as its consolidated subsidiaries. ● References to "ARLP" mean Alliance Resource Partners, L.P., individually as the parent company, and not on a consolidated basis. ● References to "MGP" mean Alliance Resource Management GP, LLC, ARLP's general partner. ● References to "Mr. Craft" mean Joseph W. Craft III, the Chairman, President and Chief Executive Officer of MGP. ● References to "Intermediate Partnership" mean Alliance Resource Operating Partners, L.P., the intermediate partnership of Alliance Resource Partners, L.P. ● References to "Alliance Coal" mean Alliance Coal, LLC, an indirect wholly owned subsidiary of ARLP. ● References to "Alliance Minerals" mean Alliance Minerals, LLC, an indirect wholly owned subsidiary of ARLP. ● References to "Alliance Resource Properties" mean Alliance Resource Properties, LLC, an indirect wholly owned subsidiary of ARLP . ​ Organization ​ ARLP is a Delaware limited partnership listed on the NASDAQ Global Select Market under the ticker symbol "ARLP." ARLP was formed in May 1999 and completed its initial public offering on August 19, 1999 when it acquired substantially all of the coal production and marketing assets of Alliance Resource Holdings, Inc., a Delaware corporation ("ARH"), and its subsidiaries. We are managed by our general partner, MGP, a Delaware limited liability company, which holds a non-economic general partner interest in ARLP. Alliance GP, LLC ("AGP"), which is indirectly wholly owned by Mr. Craft, is the direct owner of MGP. ​ Oil & Gas Acquisitions ​ Boulders ​ On October 13, 2021, we acquired approximately 1,480 oil & gas net royalty acres in the Delaware Basin from Boulders Royalty Corp. ("Boulders") for a purchase price of $31.0 million (the "Boulders Acquisition"). ​ Belvedere ​ On September 9, 2022, we acquired approximately 394 oil & gas net royalty acres in the Delaware Basin from Belvedere Operating, LLC ("Belvedere") for a purchase price of $11.4 million (the "Belvedere Acquisition"). ​ Jase ​ On October 26, 2022, we acquired approximately 3,928 oil & gas net royalty acres in the Midland and Delaware Basins from Jase Minerals, LP ("Jase") for a purchase price of $81.2 million (the "Jase Acquisition"). ​ JC Resources ​ On February 22, 2023, we acquired approximately 2,682 oil & gas net royalty acres in the Delaware Basin from JC Resources LP ("JC Resources"), an entity owned by Mr. Craft, for $72.3 million, which was funded with cash on hand ("JC Resources Acquisition"). Because JC Resources is owned by Mr. Craft, the JC Resources Acquisition is accounted for as a reorganization of entities under common control, whereby the assets and liabilities acquired from JC Resources are combined with the ARLP Partnership at their historical amounts for all periods presented. Recasting for the JC Resources Acquisition increased revenues by $13.5 million and $9.3 million for the years ended December 31, 2022 and 2021, respectively, and increased income from operations, net income and comprehensive income by $9.0 million and $4.6 million for the years ended December 31, 2022 and 2021, respectively. We did not recast historical earnings per limited partner unit as pre-acquisition earnings from the JC Resources Acquisition were allocated to our general partner. ​ Skyland ​ On December 7, 2023, we acquired approximately 2,372 oil & gas net royalty acres in the Anadarko, Williston and Delaware Basins from Skyland Minerals, L.P. ("Skyland") and Haymaker Minerals & Royalties II, LLC ("Haymaker") for a purchase price of $14.5 million which was funded with cash on hand ("Skyland Acquisition"). ​ The Boulders, Belvedere, Jase, JC Resources and Skyland Acquisitions enhanced our ownership position in various basins and furthered our business strategy to grow our Oil & Gas Royalties segment through accretive acquisitions. See Note 3 – Acquisitions for more information. We now hold approximately 67,700 net royalty acres in premier oil & gas resource plays including previous acquisitions and our investment in AllDale Minerals III, LP ("AllDale III"). ​ Growth Investments and Opportunities ​ Francis ​ On April 5, 2022, we invested $20 million in Francis Renewable Energy, LLC ("Francis"), in the form of a convertible note. Our convertible note matured on April 1, 2023 and was converted into a preferred equity interest in Francis. Francis currently is active in the installation, management and operation of metered-for-fee, public-access electric vehicle ("EV") charging stations. Francis also develops and constructs EV charging stations for third-party customers. For more information on this investment, please see Note 11 – Variable Interest Entities. ​ Infinitum ​ During 2022, we purchased $42.0 million of Series D Preferred Stock in Infinitum Electric, Inc. ("Infinitum"), a Texas-based startup developer and manufacturer of electric motors featuring printed circuit board stators which have the potential to result in motors that are smaller, lighter, quieter, more efficient and capable of operating at a fraction of the carbon footprint of conventional electric motors. On September 8, 2023, we purchased $24.6 million of Series E Preferred Stock ("Series E Preferred Stock" and, together with the "Series D Preferred Stock," the "Infinitum Preferred Stock") in Infinitum. The Infinitum Preferred Stock provides for non-cumulative dividends when and if declared by Infinitum's board of directors. Each share of Infinitum Preferred Stock is convertible, at any time, at our option, into shares of common stock of Infinitum. For more information on this investment, please see Note 12 – Equity Investments. ​ NGP ET IV ​ On June 2, 2022, we committed to purchase $25.0 million of limited partner interests in NGP Energy Transition, L.P. ("NGP ET IV"), a private equity fund sponsored by NGP Energy Capital Management, LLC ("NGP"). NGP ET IV focuses on investments that are part of the global transition toward a lower carbon economy by partnering with top-tier management teams and investing growth equity in companies that drive or enable the growth of renewable energy, the electrification of our economy or the efficient use of energy. For more information on this investment, please see Note 11 – Variable Interest Entities. ​ Ascend ​ On August 22, 2023, we purchased $25.0 million of Series D Preferred Stock (the "Ascend Preferred Stock") in Ascend Elements, Inc. ("Ascend"), a U.S.-based manufacturer and recycler of sustainable, engineered battery materials for electric vehicles. The Ascend Preferred Stock provides for non-cumulative dividends when and if declared by Ascend's board of directors. Each share is convertible, at any time, at our option, into shares of common stock of Ascend. For more information on this investment please see Note 12 – Equity Investments. ​ The Francis, Infinitum, NGP ET IV and Ascend investments further our business strategy to pursue opportunities that support the advancement of energy and related infrastructure and leverage our core competencies and build platforms for future lines of business with long-term growth and cash flow generation. ​ Change in Tax Status ​ On March 15, 2022, Alliance Minerals changed its federal income tax status from a pass-through entity to a taxable entity via a "check the box" election (the "Tax Election"), which became effective January 1, 2022. This election for Alliance Minerals reduced the total income tax burden on our oil & gas royalties, as Alliance Minerals now pays entity-level taxes at corporate tax rates which are favorable to our unitholders. For more information on the Tax Election please see Note 7 – Income Taxes. ​ Presentation ​ The consolidated financial statements include the accounts and operations of the ARLP Partnership and present our financial position as of December 31, 2023 and 2022, and results of our operations, comprehensive income, cash flows and changes in partners' capital for each of the three years in the period ended December 31, 2023. All of our intercompany transactions and accounts have been eliminated.

SUMMARY OF SIGNIFICANT ACCOUNTI

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES	12 Months Ended
	Dec. 31, 2023
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES	2. SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES ​ Variable Interest Entity ("VIE") ​ VIEs are primarily entities that lack sufficient equity to finance their activities without additional financial support from other parties or whose equity holders, as a group, lack one or more of the following characteristics: (a) direct or indirect ability to make decisions, (b) obligation to absorb expected losses or (c) right to receive expected residual returns. A VIE must be evaluated quantitatively and qualitatively to determine the primary beneficiary, which is the reporting entity that has (a) the power to direct activities of a VIE that most significantly impact the VIE's economic performance and (b) the obligation to absorb losses of the VIE that could potentially be significant to the VIE or the right to receive benefits from the VIE that could potentially be significant to the VIE. The primary beneficiary is required to consolidate the VIE for financial reporting purposes. ​ To determine a VIE's primary beneficiary, we perform a qualitative assessment to determine which party, if any, has the power to direct activities of the VIE and the obligation to absorb losses and/or receive its benefits. This assessment involves identifying the activities that most significantly impact the VIE's economic performance and determine whether it, or another party, has the power to direct those activities. When evaluating whether we are the primary beneficiary of a VIE, we perform a qualitative analysis that considers the design of the VIE, the nature of our involvement and the variable interests held by other parties. ​ Business Combinations ​ A business consists of inputs and processes applied to those inputs that have the ability to contribute to the creation of outputs. We account for the acquisition of a business as a business combination, where we record the assets acquired, including identified intangible assets and liabilities assumed at their fair value, which in many instances involves estimates based on third-party valuations, such as appraisals, or internal valuations based on discounted cash flow analyses or other valuation techniques. However, if substantially all the fair value of the assets acquired is concentrated in a single identifiable asset or a group of similar identifiable assets with the same risk profile, the acquisition is accounted for as an asset acquisition and recorded at cost. ​ Estimates ​ The preparation of consolidated financial statements in conformity with generally accepted accounting principles of the United States ("GAAP") requires management to make estimates and assumptions that affect the reported amounts and disclosures in the consolidated financial statements. Actual results could differ from those estimates. Significant estimates and assumptions include: ​ ● Asset retirement obligations; ● Pension valuation variables; ● Workers' compensation and pneumoconiosis valuation variables; ● Acquisition related purchase price allocations; ● Life of mine assumptions; ● Oil & gas reserve quantities and carrying amounts; and ● Determination of oil & gas revenue accruals ​ Fair Value Measurements ​ We apply fair value measurements to certain assets and liabilities. Fair value is defined as the price that would be received to sell an asset or paid to transfer a liability (an exit price) in an orderly transaction between market participants at the measurement date. Fair value is based on assumptions that market participants would use when pricing an asset or liability, including assumptions about risk and risks inherent in valuation techniques and inputs to valuations. Fair value measurements assume that the transaction occurs in the principal market for the asset or liability or, in the absence of a principal market, the most advantageous market for the asset or liability (the market for which the reporting entity would be able to maximize the amount received or minimize the amount paid). Valuation techniques used in our fair value measurements are based on observable and unobservable inputs. Observable inputs reflect market data obtained from independent sources, while unobservable inputs reflect our own market assumptions. ​ We use the following fair value hierarchy, which prioritizes the inputs to valuation techniques used to measure fair value into three broad levels: ​ ● Level 1 – Quoted prices for identical assets and liabilities in active markets that we have the ability to access at the measurement date. ​ ● Level 2 – Quoted prices for similar instruments in active markets; quoted prices for identical or similar instruments in markets that are not active; and model derived valuations whose inputs are observable or whose significant value drivers are observable. ​ ● Level 3 – Unobservable inputs for the asset or liability including situations where there is little, if any, market activity for the asset or liability. ​ The fair value hierarchy gives the highest priority to quoted prices in active markets (Level 1) and the lowest priority to unobservable data (Level 3). In some cases, the inputs used to measure fair value might fall into different levels of the fair value hierarchy. The lowest level input that is significant to a fair value measurement determines the applicable level in the fair value hierarchy. Assessing the significance of a particular input to the fair value measurement requires judgment, considering factors specific to the asset or liability. Significant fair value measurements are used in our significant estimates and are discussed throughout these notes. ​ Cash and Cash Equivalents ​ Cash and cash equivalents include cash on hand and on deposit, including highly liquid investments with maturities of three months or less. At times the ARLP Partnership maintains deposits in federally insured financial institutions in excess of stated federally insured limits. Management monitors the credit ratings and concentration of risk with these financial institutions on a continuing basis to safeguard cash deposits. Based on this monitoring and other diligence, including discussions with representatives of the financial institutions, we have no reason to believe that any of the financial institutions in which we have deposits in excess of stated federally insured limits are facing financial difficulties, defaults or limited liquidity situations that would cause us to be unable to access our deposits. ​ Cash Management ​ The cash flows from operating activities section of our consolidated statements of cash flows reflects an adjustment for $6.7 million representing book overdrafts at December 31, 2023. We did not have material book overdrafts at December 31, 2022 and 2021. ​ Inventories ​ Coal inventories are stated at the lower of cost or net realizable value on a first-in, first-out basis. Supply inventories are stated at an average cost basis, less a reserve for obsolete and surplus items. ​ Advance Royalties ​ Rights to coal mineral leases are often acquired and/or maintained through advance royalty payments. Where royalty payments represent prepayments recoupable against future production, they are recorded as an asset, with amounts expected to be recouped within one year classified as a current asset. As mining occurs on these leases, the royalty prepayments are charged to operating expenses. We assess the recoverability of royalty prepayments based on estimated future production. Royalty prepayments estimated to be nonrecoverable are expensed. Our advance royalties are summarized as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, ​ ​ 2023 2022 ​ ​ ​ (in thousands) ​ ​ ​ ​ ​ ​ ​ ​ ​ Advance royalties, affiliates (see Note 20 – Related-Party Transactions) ​ $ 64,599 ​ $ 60,608 ​ Advance royalties, third-parties ​ 14,306 ​ 14,661 ​ Total advance royalties ​ $ 78,905 ​ $ 75,269 ​ ​ Property, Plant and Equipment ​ Expenditures which extend the useful lives of existing plant and equipment assets are capitalized. Interest costs associated with major asset additions are capitalized during the construction period. Maintenance and repairs that do not extend the useful life or increase productivity of the asset are charged to operating expense as incurred. Exploration expenditures are charged to operating expense as incurred, including costs related to drilling and study costs incurred to convert or upgrade mineral resources to reserves. Processing facilities and mineral rights, assuming current production estimates, are depreciated or depleted using the units-of-production method. Mining equipment and other plant and equipment assets are depreciated principally using the straight-line method over the remaining estimated life of each mine. Buildings, office equipment and improvements are amortized straight line over their estimated useful lives. Gains or losses arising from retirements are included in operating expenses. Depletion of coal mineral rights is provided on the basis of tonnage mined in relation to estimated recoverable tonnage, which equals estimated proven and probable coal mineral reserves. Therefore, our coal mineral rights are depleted based on only proven and probable coal mineral reserves. See Oil & Gas Reserve Quantities and Carrying Amounts ​ Mine Development Costs ​ Mine development costs are capitalized until production, other than production incidental to the mine development process, commences and are amortized on a units of production method based on the estimated proven and probable coal mineral reserves. Mine development costs represent costs incurred in establishing access to coal mineral reserves and include costs associated with sinking or driving shafts and underground drifts, permanent excavations, roads and tunnels. The end of the development phase and the beginning of the production phase takes place when construction of the mine for economic extraction is substantially complete. Coal extracted during the development phase is incidental to the mine's production capacity and is not considered to shift the mine into the production phase. ​ Oil & Gas Reserve Quantities and Carrying Amounts ​ We are wholly dependent on third-party operators to explore, develop, produce and operate the properties associated with our mineral interests. We follow the successful efforts method of accounting for our oil & gas mineral interests. Under this method, costs to acquire mineral interests in oil & gas properties are capitalized when incurred. The costs of mineral interests in unproved properties are capitalized pending the results of exploration and leasing efforts by operators. As mineral interests in unproved properties are determined to be proved, the related costs are transferred to proved oil & gas properties. ​ Mineral interests in oil & gas properties are grouped using a reasonable aggregation of properties with a common geological structural feature or stratigraphic condition, which we may also refer to as a depletable group. Mineral interests in proved oil & gas properties are depleted based on the units-of-production method. Proved reserves are quantities of oil & gas that can be estimated with reasonable certainty to be recoverable in the future from a given date forward, from known reservoirs, under existing economic conditions, operating methods, and government regulations. Proved developed resources are the quantities expected to be recovered through the Operators' existing wells with existing equipment, infrastructure and operating methods. ​ We evaluate impairment of our oil & gas mineral interests in proved properties whenever events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable. This evaluation is performed on a depletable group basis. We compare the undiscounted projected future cash flows expected in connection with a depletable group to its unamortized carrying amount to determine recoverability. When the carrying amount of a depletable group exceeds its estimated undiscounted future cash flows, the carrying amount is written down to its fair value, which is measured as the present value of the projected future cash flows of such properties. The factors used to determine fair value include estimates of proved reserves, future commodity prices, timing of future production, future expenditures, and a risk-adjusted discount rate. ​ Our oil & gas mineral interests in unproved properties are also assessed for impairment periodically but at least annually when facts and circumstances indicate that the unproved property will not be transferred to proved properties. Impairment of individual unproved properties whose acquisition costs are relatively significant are assessed on a property-by-property basis, and an impairment loss is recognized if we determine that the unproved property will not be transferred to proved properties. Impairment of unproved properties whose acquisition costs are not individually significant are assessed on a group basis. Any amount of loss to be recognized and the amount of a valuation allowance needed to provide for impairment of those properties is determined by amortizing those properties in the aggregate on the basis of historical experience and other relevant information, such as the relative proportion of such properties on which proved reserves have been found in the past. ​ Upon the sale of a complete depletable group, the book value thereof, less proceeds or salvage value, are charged to income. Upon the sale or retirement of an aggregation of interests which make up less than a complete depletable group, the proceeds are credited to accumulated depreciation, depletion and amortization, unless doing so would significantly alter the depreciation, depletion and amortization rate of the depletable group, in which case a gain or loss would be recorded. ​ Equity Investments ​ Our investments and ownership interests in equity securities without readily determinable fair values in entities in which we do not have a controlling financial interest or significant influence are accounted for using a measurement alternative other than fair value which is historical cost minus impairment, if any, plus or minus changes resulting from observable price changes in orderly transactions for identical or similar investments of the same entity. Distributions received on those investments are recorded as income unless those distributions are considered a return on investment, in which case the historical cost is reduced. We account for our ownership interests in Infinitum and Ascend as equity securities without readily determinable fair values. See Note 12 – Equity Investments for further discussion of these investments. ​ Our investments and ownership interests in entities in which we do not have a controlling financial interest are accounted for under the equity method of accounting if we have the ability to exercise significant influence over the entity. Investments accounted for under the equity method are initially recorded at cost, and the difference between the basis of our investment and the underlying equity in the net assets of the joint venture at the investment date, if any, is amortized over the lives of the related assets that gave rise to the difference. ​ In the event our ownership requires a disproportionate sharing of income or loss, we use the hypothetical liquidation at book value ("HLBV") method to determine the appropriate allocation of income or loss. Under the HLBV method, income or loss of the investee is allocated based on hypothetical amounts that each investor would be entitled to receive if the net assets held were liquidated at book value at the end of each period, adjusted for any contributions made and distributions received during the period. ​ We hold equity method investments in AllDale III, Francis and NGP ET IV. See Note 11 – Variable Interest Entities and Note 12 – Equity Investments for further discussion of our equity method investments. ​ We review our investments for impairment whenever events or changes in circumstances indicate a loss in the value of the investment may be other-than-temporary. ​ Leases ​ We lease buildings and equipment under operating lease agreements that provide for the payment of minimum rentals. We also have noncancelable lease agreements with third parties for land and equipment under finance lease obligations. Some of our arrangements within these agreements have both lease and non-lease components, which are generally accounted for separately. We have elected a practical expedient to account for lease and non-lease components as a single lease component for leases of buildings and office equipment. Our leases have approximate lease terms of 1 to 19 years, some of which include automatic renewals up to ten years, which are likely to be exercised and some of which include options to terminate the lease within one year. We also hold numerous mineral reserve leases with both related parties as well as third parties, none of which are accounted for as an operating lease or as a finance lease. ​ We review each agreement to determine if an arrangement within the agreement contains a lease at the inception of an arrangement. Once an arrangement is determined to contain an operating or finance lease with a term greater than 12 months, we recognize a lease liability for the obligation to make lease payments and a right-of-use asset for the right to use the underlying asset for the lease term based on the present value of lease payments over the lease term. The lease term includes all noncancelable periods defined in the lease as well as periods covered by options to extend the lease that we are reasonably certain to exercise. As an implicit borrowing rate cannot be determined under most of our leases, we use our incremental borrowing rate based on the information available at commencement date in determining the present value of lease payments. ​ Expenses related to leases determined to be operating leases will be recognized on a straight-line basis over the lease term including any reasonably assured renewal periods, while those determined to be finance leases will be recognized following a front-loaded expense profile in which interest and amortization are presented separately in the income statement. The determination of whether a lease is accounted for as a finance lease or an operating lease requires management to make estimates primarily about the fair value of the asset and its estimated economic useful life. ​ Common Unit-Based Compensation ​ We maintain the Long-Term Incentive Plan ("LTIP") for certain key employees and executive officers. Pursuant to the LTIP, unit awards of non-vested "phantom" or notional units, also referred to as "restricted units," may be granted, which, upon satisfaction of time and performance-based vesting requirements, entitle the LTIP participant to receive ARLP common units. Certain awards may also contain a minimum-value guarantee payable in ARLP common units or cash that would be paid regardless of whether or not the awards vest, as long as service requirements are met. Annual grant levels, vesting provisions and minimum-value guarantees of restricted units for designated participants are recommended by Mr. Craft, subject to review and approval by the compensation committee of our general partner ("Compensation Committee"). The vesting of all restricted units is subject to the satisfaction of certain financial tests. If it is not probable that the financial tests will be achieved for a particular grant of restricted units, any previously expensed amounts for that grant are reversed, and no future expense will be recognized for that grant. Assuming the financial tests are met, restricted units issued to LTIP participants generally cliff vest on January 1st of the third year following the issuance of such restricted units. We expect to settle restricted unit grants by issuing ARLP common units, except for the portion of the restricted units that will satisfy our tax withholding obligations. We account for forfeitures of non-vested restricted unit grants as they occur. As provided under the distribution equivalent rights ("DERs") provisions of the LTIP and the terms of the restricted unit awards, all currently outstanding non-vested restricted units include contingent rights to receive quarterly distributions in cash or, at the discretion of the Compensation Committee, phantom units in lieu of cash credited to a bookkeeping account with a value equal to the cash distributions we make to unitholders during the vesting period. If it is not probable the financial tests for a particular grant of restricted units will be met, any previously paid DER amounts for that grant are reversed from Partners' Capital and recorded as compensation expense and any future DERs, for that grant, if any, will be recognized as compensation expense when paid. ​ We have utilized the Supplemental Executive Retirement Plan ("SERP") to provide deferred compensation benefits for certain executive officers. All allocations made to participants under the SERP have been made in the form of "phantom" ARLP units. We intend to settle any distributions from the SERP in the form of ARLP common units. The SERP has been administered by the Compensation Committee. ​ Our directors participate in the MGP Amended and Restated Deferred Compensation Plan for Directors ("Directors' Deferred Compensation Plan"). Pursuant to the Directors' Deferred Compensation Plan, for amounts deferred either automatically or at the election of the director, a notional account is established and credited with notional common units of ARLP, described in the Directors' Deferred Compensation Plan as "phantom" units. We intend to settle any distributions from the Directors' Deferred Compensation Plan in the form of ARLP common units. ​ For both the SERP and Directors' Deferred Compensation Plan, when quarterly cash distributions are made with respect to ARLP common units, an amount equal to such quarterly distribution is credited to each participant's notional account as additional phantom units and recorded as compensation expense. All grants of phantom units under the SERP and Directors' Deferred Compensation Plan vest immediately. ​ On December 14, 2023, the Compensation Committee and the Board of Directors approved the termination of the SERP and Directors' Deferred Compensation Plan, and authorized distribution of accounts on December 15, 2024 or as soon thereafter as practical. The accounts will continue to accrue benefits in accordance with plan terms until distributed. ​ The fair value of restricted common unit grants under the LTIP, SERP and the Directors' Deferred Compensation Plan are determined on the grant date of the award and recognized as compensation expense on a pro rata basis for LTIP and SERP awards, as appropriate, over the requisite service period. Compensation expense is fully recognized on the grant date for quarterly distributions credited to SERP accounts and Directors' Deferred Compensation Plan awards. The corresponding liability is classified as equity and included in limited partners' capital in the consolidated financial statements. ​ Workers ' Compensation and Pneumoconiosis (Black Lung) Benefits ​ We are liable for workers' compensation benefits for traumatic injuries and benefits for black lung disease (or pneumoconiosis). Both traumatic claims and pneumoconiosis benefits are covered through our self-insured programs. ​ We provide income replacement and medical treatment for work-related traumatic injury claims as required by applicable state laws. Workers' compensation laws also compensate survivors of workers who suffer employment related deaths. Our liability for traumatic injury claims is the estimated present value of current workers' compensation benefits, based on our actuarial estimates. Our actuarial calculations are based on a blend of actuarial projection methods and numerous assumptions including claim development patterns, mortality, medical costs and interest rates. ​ Our pneumoconiosis benefits liability is calculated using the service cost method based on the actuarial present value of the estimated pneumoconiosis obligation. Our actuarial calculations are based on numerous assumptions including claim development patterns, medical costs and mortality. Actuarial gains or losses are amortized over the remaining service period of active miners. ​ Pension Benefits ​ The funded status of our pension benefit plan is recognized separately in our consolidated balance sheets as either an asset or liability. The funded status is the difference between the fair value of plan assets and the plan's benefit obligation. Pension obligations and net periodic benefit costs are actuarially determined and impacted by various assumptions and estimates including expected return on assets, discount rates, mortality assumptions, employee turnover rates and retirement dates. We evaluate our assumptions periodically and make adjustments to these assumptions and the recorded liability as necessary. ​ The discount rate is determined for our pension benefit plan based on an approach specific to our plan. The year end discount rate is determined considering a yield curve comprised of high-quality corporate bonds and the timing of the expected benefit cash flows. ​ The expected long-term rate of return on plan assets is determined based on broad equity and bond indices, the investment goals and objectives, the target investment allocation and on the average annual total return for each asset class. ​ Unrecognized actuarial gains and losses and unrecognized prior service costs and credits are deferred and recorded in accumulated other comprehensive loss until amortized as a component of net periodic benefit cost. Unrecognized actuarial gains and losses in excess of 10% of the greater of the benefit obligation or the market-related value of plan assets are amortized over the participants' average remaining future years of service. ​ Asset Retirement Obligations ​ Our coal mining operations are governed by various state statutes and the Federal Surface Mining Control and Reclamation Act of 1977, which establish reclamation and mine closing standards. These regulations require, among other things, restoration of property in accordance with specified standards and an approved reclamation plan. We record a liability for the fair value of the estimated cost of future mine asset retirement and closing procedures, escalated for inflation then discounted, on a present value basis in the period incurred or acquired and a corresponding amount is capitalized by increasing the carrying amount of the related long-lived asset. Those costs relate to permanently sealing portals at underground mines and to reclaiming the final pits and support surface acreage for both our underground mines and past surface mines. Examples of these types of costs, common to both types of mining, include, but are not limited to, removing or covering refuse piles and settling ponds, water treatment obligations, and dismantling preparation plants, other facilities and roadway infrastructure. Accounting for asset retirement obligations also requires depreciation of the capitalized asset retirement cost and accretion of the asset retirement obligation over time. Depreciation is generally determined on a units-of-production basis and accretion is generally recognized over the life of the producing assets. As changes in estimates occur (such as mine plan revisions, changes in estimated costs or changes in anticipated timing of reclamation activities), the revisions to the obligation and asset are recognized at the appropriate credit-adjusted, risk-free interest rate. Federal and state laws require bonds to secure our obligations to reclaim lands used for mining and are typically renewed on an annual basis. ​ Coal Revenue Recognition ​ Revenues from coal supply contracts with customers, which primarily relate to sales of thermal coal, are recognized at the point in time when control of the coal passes to the customer. We have determined that each ton of coal represents a separate and distinct performance obligation. Our coal supply contracts and other revenue contracts vary in length from short-term to long-term sales contracts and do not typically have significant financing components. Transportation revenues represent the fulfillment costs incurred for the services provided to customers through third-party carriers and for which we are directly reimbursed. Other revenues primarily consist of transloading fees, administrative service revenues from our affiliates, mine safety services and products, other coal contract fees and other handling and service fees. Performance obligations under these contracts are typically satisfied upon transfer of control of the goods or services to our customer which is determined by the contract and could be upon shipment or upon delivery. ​ The estimated transaction price from each of our contracts is based on the total amount of consideration we expect to be entitled to under the contract. Included in the transaction price for certain coal supply contracts is the impact of variable consideration, including quality price adjustments, handling services, government imposition claims, per ton price fluctuations based on certain coal sales price indices and anticipated payments in lieu of shipments. We have constrained the expected value of variable consideration in our estimation of transaction price and only included this consideration to the extent that it is probable that a significant revenue reversal will not occur. The estimated transaction price for each contract is allocated to our performance obligations based on relative standalone selling prices determined at contract inception. Variable consideration is allocated to a specific part of the contract in many instances, such as if the variable consideration is based on production activities for coal delivered during a certain period or the outcome of a customer's ability to accept coal shipments over a certain period. ​ Contract assets are recorded as trade receivables and reported separately in our consolidated balance sheet from other contract assets as title passes to the customer and our right to consideration becomes unconditional. Payments for coal shipments are typically due within two four weeks ​ Oil & Gas Revenue Recognition ​ Oil & gas royalty revenues are recognized at the point in time when control of the product is transferred to the purchaser by the lessee and collectability of the sales price is reasonably assured. Oil & gas are priced on the delivery date based on prevailing market prices with certain adjustments related to oil quality and physical location. The royalty we receive is tied to a market index, with certain adjustments based on, among other factors, whether a well connects to a gathering or transmission line, quality and heat content of the product, and prevailing supply and demand conditions. ​ We also periodically earn revenue from lease bonuses. We recognize lease bonus revenue when we execute a lease of our mineral interests to exploration and production companies. A lease agreement represents our contract with an operator, which is generally an exploration and production company. The contract will (a) generally transfer the rights to any oil or gas discovered, (b) grant us a right to a specified royalty interest from the operator, and (c) require the operator to commence drilling and complete operations within a specified time period. Control of the minerals transfers to the operator when the lease agreement is executed. At the time we execute the lease agreement, we expect to receive the lease bonus payment within a reasonable time, though in no case more than one year, such that we do not adjust the expected amount of consideration for the effects of any significant financing component. ​ As a non-operator, we have limited visibility into the timing of when new wells start producing. In addition, production statements may not be received for 30 to 90 days or more after the date production is delivered. As a result, we are required to estimate the amount of production delivered to the purchaser and the price that will be received for the sale of the product. The expected sales volumes and prices from our properties are estimated and recorded within the Trade receivables ​ Income Taxes ​ We are not a taxable entity for federal or state income tax purposes; the tax effect of our activities accrues to our unitholders. Although publicly traded partnerships as a general rule are taxed as corporations,

ACQUISITIONS

ACQUISITIONS	12 Months Ended
	Dec. 31, 2023
ACQUISITIONS
ACQUISITIONS	3. ACQUISITION S ​ Boulders ​ On October 13, 2021, we acquired approximately 1,480 oil & gas net royalty acres in the Delaware Basin from Boulders for a purchase price of $31.0 million, which was funded with cash on hand. This acquisition gives us increased exposure to a prolific area of the Delaware Basin and is within close proximity to reserves acquired in previous acquisitions. The acreage acquired in the Boulders Acquisition was mostly undeveloped. Because more than 90% of the mineral interests acquired in the acquisition represent undeveloped properties with a similar risk profile, including proved undeveloped, we have determined that the Boulders Acquisition should be accounted for as an asset acquisition. ​ The following table summarizes the purchase price allocation of the assets acquired in the Boulders Acquisition: ​ ​ ​ ​ ​ ​ ​ ​ (in thousands) ​ ​ ​ ​ ​ Mineral interests in proved properties ​ $ 12,542 ​ Mineral interests in unproved properties ​ ​ 18,418 ​ ​ ​ $ 30,960 ​ ​ Belvedere ​ On September 9, 2022 (the "Belvedere Acquisition Date"), we acquired approximately 394 oil & gas net royalty acres in the Delaware Basin from Belvedere for a cash purchase price of $11.4 million, which was funded with cash on hand. This acquisition gives us additional exposure to a productive area of the Delaware Basin and is within close proximity to reserves that we currently own. Because the mineral interests acquired in the Belvedere Acquisition include royalty interests in both developed properties and undeveloped properties with different risk profiles, we have determined that the acquisition should be accounted for as a business combination and the underlying assets should be recorded at fair value as of the Belvedere Acquisition Date on our consolidated balance sheet. ​ The following table summarizes the fair value allocation of assets acquired as of the Belvedere Acquisition Date: ​ ​ ​ ​ ​ ​ ​ ​ (in thousands) ​ ​ ​ ​ ​ Mineral interests in proved properties ​ $ 7,724 ​ Mineral interests in unproved properties ​ ​ 3,667 ​ ​ ​ $ 11,391 ​ ​ The fair value of the mineral interests was determined using an income approach consisting of a discounted cash flow model. The assumptions used in the discounted cash flow model included estimated production, projected cash flows, forward oil & gas prices and risk adjusted discount rates. Certain assumptions used are not observable in active markets; therefore, the fair value measurements represent Level 3 fair value measurements. ​ The amounts of revenue and earnings from the mineral interests acquired in the Belvedere Acquisition included in our consolidated statements of income from the Belvedere Acquisition Date through December 31, 2022 are as follows: ​ ​ ​ ​ ​ ​ Year Ended ​ ​ December 31, ​ ​ 2022 ​ (in thousands) ​ ​ ​ ​ Revenue $ 722 ​ Net income 488 ​ ​ The following represents our supplemental pro forma consolidated revenues and net income for the years ended December 31, 2022 and 2021 as if the mineral interests acquired in the Belvedere Acquisition had been included in our consolidated results since January 1, 2021. These amounts have been calculated after applying our accounting policies. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended ​ ​ ​ December 31, ​ ​ 2022 2021 ​ ​ ​ (in thousands) ​ ​ ​ (unaudited) ​ Revenues ​ $ 2,420,824 ​ $ 1,580,373 ​ Net income ​ ​ 588,916 ​ ​ 184,361 ​ ​ Jase ​ On October 26, 2022 (the "Jase Acquisition Date"), we acquired approximately 3,928 oil & gas net royalty acres in the Midland and Delaware Basins from Jase for a cash purchase price of $81.2 million which was funded with cash on hand. This acquisition further enhanced our ownership position in the Permian Basin. Because the mineral interests acquired in the Jase Acquisition include royalty interests in both developed properties and undeveloped properties with different risk profiles, we have determined that the acquisition should be accounted for as a business combination and the underlying assets should be recorded at fair value as of the Jase Acquisition Date on our consolidated balance sheet. ​ The following table summarizes the fair value allocation of assets acquired as of the Jase Acquisition Date: ​ ​ ​ ​ ​ ​ ​ ​ (in thousands) ​ ​ ​ ​ ​ Mineral interests in proved properties ​ $ 35,918 ​ Mineral interests in unproved properties ​ ​ 43,740 ​ Receivables ​ ​ 1,569 ​ Net assets acquired ​ $ 81,227 ​ ​ The fair value of the mineral interests was determined using an income approach consisting of a discounted cash flow model. The assumptions used in the discounted cash flow model included estimated production, projected cash flows, forward oil & gas prices and risk adjusted discount rates. The fair value of the receivables was determined using estimated production during the period between the Jase Acquisition Date and the effective date of the agreement and observable sales prices during the period. Certain assumptions used are not observable in active markets; therefore, the fair value measurements represent Level 3 fair value measurements. ​ The amounts of revenue and earnings from the mineral interests acquired in the Jase Acquisition included in our consolidated statements of income from the Jase Acquisition Date through December 31, 2022 are as follows: ​ ​ ​ ​ ​ ​ Year Ended ​ ​ December 31, ​ ​ 2022 ​ (in thousands) ​ ​ ​ ​ Revenue $ 1,689 ​ Net income 854 ​ ​ The following represents our supplemental pro forma consolidated revenues and net income for the years ended December 31, 2022 and 2021 as if the mineral interests acquired in the Jase Acquisition had been included in our consolidated results since January 1, 2021. These amounts have been calculated after applying our accounting policies. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended ​ ​ ​ December 31, ​ ​ 2022 2021 ​ ​ ​ (in thousands) ​ ​ ​ (unaudited) ​ Revenues ​ $ 2,430,734 ​ $ 1,588,914 ​ Net income ​ ​ 596,759 ​ ​ 190,765 ​ ​ JC Resources ​ On February 22, 2023, we completed the JC Resources Acquisition, which gives us increased exposure to a prolific area of the Delaware Basin that is within close proximity to reserves that we currently own. This acquisition was approved by the conflicts committee of MGP's board of directors, which is comprised entirely of independent directors. Because JC Resources is under common control with us, we recorded the acquisition at JC Resources' carrying value for each period presented. The carrying value of the mineral interests as well as related receivables and payables at February 22, 2023 was $65.0 million inclusive of $25.4 million and $37.8 million of mineral interests in proved and unproved properties, respectively. The JC Resources Acquisition increased revenues included in our consolidated statements of income by $10.6 million for the year ended December 31, 2023. ​ Acquisition Agreement ​ On January 27, 2023, we entered into a one-year collaborative agreement with a third party, effective January 1, 2023, committing up to $35.0 million for the acquisition of oil & gas mineral interests in the Midland and Delaware Basins. Under the agreement, the third party assists us in the identification, evaluation, and acquisition of target oil & gas mineral interests. In exchange for these services, the third party receives a participation share, partially funded by the third party, and is paid a periodic management fee. As of December 31, 2023, we have purchased $6.5 million and $6.7 million of oil & gas mineral interests in proved and unproved properties, respectively, pursuant to this agreement. Management fees paid under this agreement have been immaterial. On February 19, 2024, we renewed this agreement for an additional one-year term, committing up to $25.0 million. ​ Skyland Acquisition ​ On December 7, 2023 (the "Skyland Acquisition Date"), we acquired approximately 2,372 oil & gas net royalty acres in the Anadarko, Williston and Delaware Basins from Skyland and Haymaker for a cash purchase price of $14.5 million which was funded with cash on hand. This acquisition further enhanced our ownership position in these basins. Because the mineral interests acquired in the Skyland Acquisition include royalty interests in both developed properties and undeveloped properties with different risk profiles, we have determined that the acquisition should be accounted for as a business combination and the underlying assets should be recorded at fair value as of the Skyland Acquisition Date on our consolidated balance sheet. ​ The following table summarizes the fair value allocation of assets acquired as of the Skyland Acquisition Date: ​ ​ ​ ​ ​ ​ ​ ​ (in thousands) ​ ​ ​ ​ ​ Mineral interests in proved properties ​ $ 8,694 ​ Mineral interests in unproved properties ​ ​ 5,765 ​ Net assets acquired ​ $ 14,459 ​ ​ The fair value of the mineral interests was determined using an income approach consisting of a discounted cash flow model. The assumptions used in the discounted cash flow model included estimated production, projected cash flows, forward oil & gas prices and risk adjusted discount rates. Certain assumptions used are not observable in active markets; therefore, the fair value measurements represent Level 3 fair value measurements. ​ The amounts of revenue and earnings from the mineral interests acquired in the Skyland Acquisition included in our consolidated statements of income from the Skyland Acquisition Date through December 31, 2023 are immaterial. ​ The following represents our supplemental pro forma consolidated revenues and net income for the years ended December 31, 2023 and 2022 as if the mineral interests acquired in the Skyland Acquisition had been included in our consolidated results since January 1, 2022. These amounts have been calculated after applying our accounting policies. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended ​ ​ ​ December 31, ​ ​ 2023 2022 ​ ​ ​ (in thousands) ​ ​ ​ (unaudited) ​ Revenues ​ $ 2,568,516 ​ $ 2,423,313 ​ Net income ​ ​ 637,757 ​ ​ 591,140 ​ ​ Miscellaneous Acquisitions ​ In addition to the acquisitions discussed above, we purchased $6.8 million and $4.3 million of oil & gas mineral interests in proved and unproved properties, respectively, during the year ended December 31, 2023 and $1.3 million and $0.4 million in proved and unproved properties, respectively, during the year ended December 31, 2022.

INVENTORIES

INVENTORIES	12 Months Ended
	Dec. 31, 2023
INVENTORIES
INVENTORIES	4. INVENTORIES ​ Inventories consist of the following : ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, ​ ​ ​ 2023 2022 ​ ​ (in thousands) ​ ​ ​ ​ ​ ​ ​ ​ ​ Coal ​ $ 56,549 ​ $ 23,553 ​ Supplies (net of reserve for obsolescence of $8,167 and $6,601, respectively) ​ 71,007 ​ 53,773 ​ Total inventories, net ​ $ 127,556 ​ $ 77,326 ​ ​ The table above includes lower of cost or net realizable value adjustments of $33.3 million. These adjustments are a result of lower coal sale prices and higher cost per ton primarily due to the impact of Mettiki's longwall being idle most of the second half of 2023 due to delayed development of a new longwall district, Hamilton experiencing disruptions in production due to a longwall move, and continuing development of the Henderson County mine at our River View complex.

PROPERTY, PLANT AND EQUIPMENT

PROPERTY, PLANT AND EQUIPMENT	12 Months Ended
	Dec. 31, 2023
PROPERTY, PLANT AND EQUIPMENT
PROPERTY, PLANT AND EQUIPMENT	5. PROPERTY, PLANT AND EQUIPMENT ​ Property, plant and equipment consist of the following: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, ​ ​ 2023 2022 ​ ​ ​ (in thousands) ​ ​ ​ ​ ​ ​ ​ ​ ​ Mining equipment and processing facilities ​ $ 1,989,541 ​ $ 1,927,603 ​ Land and coal mineral rights ​ 504,736 ​ 499,950 ​ Oil & gas mineral interests ​ ​ 853,350 ​ ​ 814,667 ​ Buildings, office equipment, improvements and other miscellaneous equipment ​ 310,876 ​ 300,436 ​ Construction, mine development and other projects in progress ​ 184,895 ​ 99,042 ​ Mine development costs ​ 329,146 ​ 289,724 ​ Property, plant and equipment, at cost ​ 4,172,544 ​ 3,931,422 ​ Less accumulated depreciation, depletion and amortization ​ (2,149,881) ​ (2,050,754) ​ Total property, plant and equipment, net ​ $ 2,022,663 ​ $ 1,880,668 ​ ​ All of our property, plant and equipment have depreciable lives of 1 to 20 years. Depreciation, depletion and amortization expense related to property, plant and equipment was $276.4 million, $273.8 million and $260.3 million for the years ended December 31, 2023, 2022 and 2021, respectively. ​ At December 31, 2023 and 2022, land and coal mineral rights above include $13.4 million and $29.9 million, respectively, of carrying value associated with coal mineral reserves and resources attributable to properties where we or a third party to which we lease coal mineral reserves and resources are not currently engaged in mining operations or leasing to third parties, and therefore, the coal mineral reserves are not currently being depleted. We believe that the carrying value of these coal mineral reserves will be recovered. ​ At December 31, 2023 and 2022, our oil & gas mineral interests noted in the table above include the carrying value of our unproved oil & gas mineral interests totaling $411.6 million and $422.7 million, respectively. We generally do not record depletion expense for our unproved oil & gas mineral interests; however, we do review for impairment as needed throughout the year. ​ During 2023, we incurred $44.4 million in mine development costs, primarily related to Tunnel Ridge and the Henderson County mine at River View Coal, LLC ("River View"). During 2022, we incurred $11.3 million in mine development costs, primarily related to Hamilton and River View mine. All past capitalized mine development costs are associated with other mines that shifted to the production phase in past years and we are amortizing these costs accordingly. We believe that the carrying value of the past development costs will be recovered.

LONG-TERM DEBT

LONG-TERM DEBT	12 Months Ended
	Dec. 31, 2023
LONG-TERM DEBT
LONG-TERM DEBT	6. LONG-TERM DEBT ​ Long-term debt consists of the following: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Unamortized Discount and ​ ​ ​ Principal ​ Debt Issuance Costs ​ ​ ​ December 31, ​ December 31, ​ ​ 2023 2022 2023 2022 ​ ​ (in thousands) ​ Revolving credit facility ​ $ — ​ $ — ​ $ (8,118) ​ $ (2,702) ​ Term loan ​ 60,938 ​ — ​ (1,416) ​ — ​ Senior notes ​ 284,607 ​ 400,000 ​ (891) ​ (2,134) ​ Securitization facility ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ November 2019 equipment financing ​ ​ — ​ ​ 21,072 ​ ​ — ​ ​ — ​ June 2020 equipment financing ​ ​ 2,039 ​ ​ 5,937 ​ ​ — ​ ​ — ​ ​ ​ 347,584 ​ 427,009 ​ (10,425) ​ (4,836) ​ Less current maturities ​ (20,789) ​ (24,970) ​ 451 ​ — ​ Total long-term debt ​ $ 326,795 ​ $ 402,039 ​ $ (9,974) ​ $ (4,836) ​ ​ Credit Facility ​ On January 13, 2023, Alliance Coal, as borrower, entered into a Credit Agreement (the "Credit Agreement") with various financial institutions. The Credit Agreement provides for a $425 million revolving credit facility, which includes a sublimit of $15.0 million for swingline borrowings and permits the issuance of letters of credit up to the full amount of $425 million (the "Revolving Credit Facility"), and for a term loan in an aggregate principal amount of $75 million (the "Term Loan"). The Credit Agreement matures on March 9, 2027, at which time the aggregate outstanding principal amount of all Revolving Credit Facility advances and all Term Loan advances are required to be repaid in full. The Credit Agreement will instead mature on January 30, 2025, if on that date our Senior Notes, as discussed below, are still outstanding and Alliance Coal does not have liquidity of at least $200 million. Interest is payable quarterly, with principal of the Term Loan due in quarterly installments equal to 6.25% of the original principal amount of the Term Loan beginning with the quarter ending June 30, 2023 and the balance payable at maturity. The Revolving Credit Facility replaces the $459.5 million revolving credit facility extended to the Intermediate Partnership under its Fifth Amended and Restated Credit Agreement, dated as of March 9, 2020. We incurred debt issuance costs during the year ended December 31, 2023 of $12.4 million in connection with the Credit Agreement. These debt issuance costs are deferred and amortized as a component of interest expense over the term of the Revolving Credit Facility. ​ The Revolving Credit Facility is underwritten by a syndicate of eighteen financial institutions and the obligations of the lenders are individual obligations, which means the failure of one or more lenders to be able to fund its obligation does not relieve the remaining lenders from funding their obligations. Based on our diligence, including discussions with representatives of certain of these financial institutions, as of December 31, 2023 we have no reason to believe that the banks within our syndicate are facing financial difficulties, defaults or limited liquidity situations that would cause them to be unable to fund their obligations under the Credit Agreement. However, should any of the banks in our syndicate experience conditions in the future that limit their ability to fund their obligations, the amount available under the Revolving Credit Facility could be reduced. ​ The Credit Agreement is guaranteed by ARLP and certain of its subsidiaries, including the Intermediate Partnership and most of the direct and indirect subsidiaries of Alliance Coal (the "Subsidiary Guarantors"). The Credit Agreement also is secured by substantially all of the assets of the Subsidiary Guarantors and Alliance Coal. Borrowings under the Credit Agreement bear interest, at our option, at either (i) an adjusted one-month, three-month or six-month term rate based on the secured overnight financing rate published by the Federal Reserve Bank of New York, plus the applicable margin or (ii) the base rate plus the applicable margin. The base rate is the highest of (i) the Overnight Bank Funding Rate plus 0.50%, (ii) the Administrative Agent's prime rate, and (iii) the Daily Simple Secured Overnight Financing Rate plus 100 basis points. The applicable margin for borrowings under the Credit Agreement are determined by reference to the Consolidated Debt to Consolidated Cash Flow Ratio. For borrowings under the Term Loan, we elected the three-month term rate, with applicable margin, which was 8.50% as of December 31, 2023. At December 31, 2023, we had $41.0 million of letters of credit outstanding with $384.0 million available for borrowing under the Revolving Credit Facility. We incurred an annual commitment fee of 0.50% on the undrawn portion of the Revolving Credit Facility. We utilize the Credit Agreement, as appropriate, for working capital requirements, capital expenditures and investments, scheduled debt payments and distribution payments. ​ The Credit Agreement contains various restrictions affecting Alliance Coal and its subsidiaries, including, among other things, restrictions on incurrence of additional indebtedness and liens, sale of assets, investments, mergers and consolidations and transactions with affiliates. In each case, these restrictions are subject to various exceptions. In addition, restrictions apply to cash distributions by Alliance Coal to the Intermediate Partnership if such distribution would result in exceeding a minimum fixed charge coverage ratio (as determined in the Credit Agreement) or in Alliance Coal having liquidity of less than $200 million. The Credit Agreement requires us to maintain (a) a debt of Alliance Coal to cash flow ratio of not more than 1.5 to 1.0, (b) a consolidated debt of Alliance Coal and the Intermediate Partnership to cash flow ratio of not more than 2.5 to 1.0 and (c) an interest coverage ratio of not less than 3.0 to 1.0, in each case, during the four most recently ended fiscal quarters. The debt of Alliance Coal to cash flow ratio, consolidated debt of Alliance Coal and the Intermediate Partnership to cash flow ratio, and interest coverage ratio were 0.08 to 1.0, 0.46 to 1.0 and 63.86 to 1.0, respectively, for the trailing twelve months ended December 31, 2023. We were in compliance with the covenants of the Credit Agreement as of December 31, 2023 and anticipate remaining in compliance with the covenants. ​ Net restricted assets, as defined by the Securities and Exchange Commission, refers to the amount of our consolidated subsidiaries' net assets for which the ability to transfer funds to ARLP in the form of cash dividends, loans, advances, or transfers is restricted. As a result of the restrictions contained in the Credit Facility and its associated compliance ratios, the amount of our net restricted assets at December 31, 2023 was $797.2 million. ​ Senior Notes ​ On April 24, 2017, the Intermediate Partnership and Alliance Resource Finance Corporation (as co-issuer), a wholly owned subsidiary of the Intermediate Partnership ("Alliance Finance"), issued an aggregate principal amount of $400.0 million of senior unsecured notes due 2025 ("Senior Notes") in a private placement to qualified institutional buyers. The Senior Notes have a term of eight years, maturing on May 1, 2025 and accrue interest at an annual rate of 7.5%. Interest is payable semi-annually in arrears on each May 1 and November 1. The indenture governing the Senior Notes contains customary terms, events of default and covenants relating to, among other things, the incurrence of debt, the payment of distributions or similar restricted payments, undertaking transactions with affiliates and limitations on asset sales. During the year ended December 31, 2023, we repurchased or redeemed $115.4 million of our Senior Notes. The gain on extinguishment of the Senior Notes is immaterial. ​ Accounts Receivable Securitization ​ Certain direct and indirect wholly owned subsidiaries of our Intermediate Partnership were party to a $60.0 million accounts receivable securitization facility ("Securitization Facility"). Under the Securitization Facility, certain subsidiaries sell certain trade receivables on an ongoing basis to our Intermediate Partnership, which then sells the trade receivables to AROP Funding, LLC ("AROP Funding"), a wholly owned bankruptcy-remote special purpose subsidiary of our Intermediate Partnership, which in turn borrows on a revolving basis up to $60.0 million secured by the trade receivables. After the sale, Alliance Coal, as servicer of the assets, collects the receivables on behalf of AROP Funding. The Securitization Facility bears interest based on a short-term bank yield index. On December 31, 2023, we had $11.7 million of letters of credit outstanding with $48.3 million available for borrowing under the Securitization Facility. The agreement governing the Securitization Facility contains customary terms and conditions, including limitations with regards to certain customer credit ratings. In January 2024, we extended the term of the Securitization Facility to January 2025 and increased the borrowing availability under the facility to $90.0 million. The Securitization Facility was previously scheduled to mature in January 2024. At December 31, 2023, we did not have any outstanding borrowings under the Securitization Facility. ​ November 2019 Equipment Financing ​ On November 6, 2019, the Intermediate Partnership entered into an equipment financing arrangement accounted for as debt, wherein the Intermediate Partnership received $53.1 million in exchange for conveying its interest in certain equipment owned indirectly by the Intermediate Partnership and entering into a master lease agreement for that equipment (the "November 2019 Equipment Financing"). The November 2019 Equipment Financing contained customary terms and events of default and an implicit interest rate of 4.75% and matured on November 6, 2023. Upon maturity, the equipment reverted to the Intermediate Partnership. ​ June 2020 Equipment Financing ​ On June 5, 2020, the Intermediate Partnership entered into an equipment financing arrangement accounted for as debt, wherein the Intermediate Partnership received $14.7 million in exchange for conveying its interest in certain equipment owned indirectly by the Intermediate Partnership and entering into a master lease agreement for that equipment (the "June 2020 Equipment Financing"). The June 2020 Equipment Financing contains customary terms and events of default and provides for forty-eight monthly payments with an implicit interest rate of 6.1%, maturing on June 5, 2024. Upon maturity, the equipment will revert to the Intermediate Partnership. ​ Other ​ We also have an agreement with a bank to provide additional letters of credit in an amount of $5.0 million to maintain surety bonds to secure certain asset retirement obligations and our obligations for workers' compensation benefits. At December 31, 2023, we had $5.0 million in letters of credit outstanding under this agreement. ​ Aggregate maturities of long-term debt are payable as follows: ​ ​ ​ ​ ​ ​ Year Ended ​ ​ ​ ​ December 31, (in thousands) 2024 ​ $ 20,789 ​ 2025 ​ 303,357 ​ 2026 ​ 18,750 ​ 2027 ​ 4,688 ​ ​ ​ $ 347,584 ​ ​

INCOME TAXES

INCOME TAXES	12 Months Ended
	Dec. 31, 2023
INCOME TAXES
INCOME TAXES	7. INCOME TAXES ​ Components of income tax expense are as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, ​ 2023 2022 2021 ​ ​ (in thousands) ​ Current: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Federal ​ $ 15,917 ​ $ 17,572 ​ $ (1) ​ State ​ 1,336 ​ 1,605 ​ 70 ​ ​ ​ 17,253 ​ 19,177 ​ 69 ​ Deferred: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Federal ​ (7,235) ​ 33,038 ​ 356 ​ State ​ (1,738) ​ 1,763 ​ (8) ​ ​ ​ (8,973) ​ 34,801 ​ 348 ​ Income tax expense ​ $ 8,280 ​ $ 53,978 ​ $ 417 ​ ​ Alliance Minerals' Tax Election resulted in the recognition of an initial deferred tax liability of $37.3 million with a corresponding increase to income tax expense and reduction of net income for the year ended December 31, 2022. This reduction of net income equates to approximately $0.29 per basic and diluted recognized to step up to fair value the financial reporting basis of the interests we already owned at the time of acquisition. The tax basis of the underlying properties of AllDale I & II did not include the Acquisition Gain. ​ Reconciliations of income taxes at the U.S. federal statutory tax rate to income taxes at our effective tax rate are as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, ​ ​ 2023 2022 2021 ​ ​ ​ (in thousands) ​ Income taxes at statutory rate ​ $ 135,335 ​ $ 134,849 ​ $ 38,595 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Less: Income taxes at statutory rate on Partnership income not subject to income taxes ​ (119,556) ​ (113,925) ​ (37,546) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Increase (decrease) resulting from: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ State taxes, net of federal income tax ​ 864 ​ 1,492 ​ 275 ​ Change in valuation allowance of deferred tax assets ​ — ​ (317) ​ (834) ​ Deferred taxes related to tax election ​ ​ — ​ ​ 37,253 ​ ​ — ​ Tax effect of noncontrolling interest income not subject to income taxes ​ ​ (1,361) ​ ​ (5,399) ​ ​ — ​ Return to accrual adjustments ​ ​ (7,008) ​ ​ 69 ​ ​ (1) ​ Other ​ 6 ​ (44) ​ (72) ​ Income tax expense ​ $ 8,280 ​ $ 53,978 ​ $ 417 ​ ​ The effective income tax rates for our income tax expense for the year ended December 31, 2023 and 2021 are less than the federal statutory rate, primarily due to the portion of income not subject to income taxes. The effective income tax rate for our income tax expense for the year ended December 31, 2022 is less than the federal statutory rate, primarily due to the portion of income not subject to income taxes, partially offset by the effect of the Tax Election previously discussed. ​ Significant components of deferred tax liabilities and deferred tax assets are as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, ​ 2023 2022 ​ ​ (in thousands) ​ Deferred tax liabilities: ​ ​ ​ ​ ​ ​ ​ Property, plant and equipment ​ $ (36,453) ​ $ (38,349) ​ Total deferred tax liabilities ​ ​ (36,453) ​ ​ (38,349) ​ ​ ​ ​ ​ ​ ​ ​ ​ Deferred tax assets: ​ ​ ​ ​ ​ ​ ​ Federal loss carryovers and credits ​ ​ 4,508 ​ ​ 2,139 ​ State loss carryovers and credits ​ ​ 2,126 ​ ​ 951 ​ Capitalized research and development ​ ​ 2,567 ​ ​ — ​ Other ​ 1,098 ​ 133 ​ Total deferred tax assets ​ ​ 10,299 ​ ​ 3,223 ​ ​ ​ ​ ​ ​ ​ ​ ​ Overall net deferred tax liabilities ​ $ (26,154) ​ $ (35,126) ​ ​ ​ Federal and state loss carryovers and credits are primarily due to net operating losses and research and development credits associated with the operations of other subsidiaries that are taxable for federal income tax purposes. ​ Research and development expenses are required to be capitalized and amortized for U.S. tax purposes, resulting in a deferred tax asset. These expenses are primarily associated with the operations of other subsidiaries that are taxable for federal income tax purposes. ​ Our 2020 through 2022 tax years remain open to examination by tax authorities, and lower-tier partnership income tax returns for the tax years ended December 31, 2020 and 2021 are being audited by the Internal Revenue Service.

LEASES

LEASES	12 Months Ended
	Dec. 31, 2023
LEASES
LEASES	8. LEASES ​ The components of lease expense were as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, ​ ​ ​ 2023 ​ 2022 2021 ​ ​ (in thousands) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Finance lease cost: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Amortization of right-of-use assets ​ $ 96 ​ $ 597 ​ $ 597 ​ Interest on lease liabilities ​ 27 ​ 73 ​ 147 ​ Operating lease cost ​ 3,572 ​ 2,884 ​ 2,404 ​ Short-term lease cost ​ ​ — ​ ​ — ​ ​ 200 ​ Variable lease cost ​ 1,680 ​ 1,665 ​ 1,306 ​ Total lease cost ​ $ 5,375 ​ $ 5,219 ​ $ 4,654 ​ ​ Rental expense was $5.7 million, $5.1 million and $3.3 million for the years ended December 31, 2023, 2022 and 2021 respectively. ​ Supplemental cash flow information related to leases was as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, ​ ​ ​ 2023 ​ 2022 2021 ​ ​ (in thousands) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cash paid for amounts included in the measurement of lease liabilities: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Operating cash flows for operating leases ​ $ 3,720 ​ $ 2,880 ​ $ 2,367 ​ Operating cash flows for finance leases ​ $ 27 ​ $ 73 ​ $ 147 ​ Financing cash flows for finance leases ​ $ 363 ​ $ 840 ​ $ 766 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Right-of-use assets obtained in exchange for lease obligations: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Operating leases ​ $ 2,596 ​ $ 1,315 ​ $ 189 ​ ​ Supplemental balance sheet information related to leases was as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, ​ ​ ​ 2023 2022 ​ ​ ​ (in thousands) ​ Finance leases: ​ ​ ​ ​ ​ ​ ​ Property and equipment finance lease assets, gross ​ $ 1,085 ​ $ 5,485 ​ Accumulated depreciation ​ (507) ​ (5,061) ​ Property and equipment finance lease assets, net ​ $ 578 ​ $ 424 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, ​ ​ ​ 2023 2022 ​ Weighted average remaining lease term ​ ​ ​ ​ ​ ​ ​ Operating leases ​ ​ 11.7 years ​ ​ 13.4 years ​ Finance leases ​ ​ 4.0 years ​ ​ 5.0 years ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted average discount rate ​ ​ ​ ​ ​ ​ ​ Operating leases ​ ​ 6.0 % ​ ​ 6.0 % ​ Finance leases ​ 4.8 % ​ ​ 4.8 % ​ ​ Maturities of lease liabilities as of December 31, 2023 were as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Operating leases Finance leases ​ ​ ​ (in thousands) ​ ​ ​ ​ ​ ​ ​ ​ ​ 2024 ​ $ 3,437 ​ $ 140 ​ 2025 ​ ​ 2,403 ​ ​ 140 ​ 2026 ​ ​ 1,923 ​ ​ 140 ​ 2027 ​ ​ 1,930 ​ ​ 140 ​ 2028 ​ ​ 1,646 ​ ​ — ​ Thereafter ​ ​ 12,122 ​ ​ — ​ Total lease payments ​ ​ 23,461 ​ ​ 560 ​ Less imputed interest ​ ​ (6,869) ​ ​ (55) ​ Total ​ $ 16,592 ​ $ 505 ​ ​ The current portion of our operating finance Other current liabilities Other liabilities

FAIR VALUE MEASUREMENTS

FAIR VALUE MEASUREMENTS	12 Months Ended
	Dec. 31, 2023
FAIR VALUE MEASUREMENTS
FAIR VALUE MEASUREMENTS	9. FAIR VALUE MEASUREMENTS ​ The following table summarizes our fair value measurements within the hierarchy not included elsewhere in these notes: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, 2023 ​ December 31, 2022 ​ ​ Level 1 Level 2 Level 3 Level 1 Level 2 Level 3 ​ ​ (in thousands) ​ Long-term debt ​ $ — ​ $ 347,116 ​ $ — ​ $ — ​ $ 424,420 ​ $ — ​ ​ The carrying amounts for cash equivalents, accounts receivable, accounts payable, accrued and other liabilities, approximate fair value due to the short maturity of those instruments. ​ The estimated fair value of our long-term debt, including current maturities, is based on interest rates that we believe are currently available to us in active markets for issuance of debt with similar terms and remaining maturities. See Note 6 – Long-Term Debt for additional information on our long-term debt.

PARTNERS' CAPITAL

PARTNERS' CAPITAL	12 Months Ended
	Dec. 31, 2023
PARTNERS' CAPITAL
PARTNERS' CAPITAL	10. PARTNERS' CAPITAL ​ Distributions ​ Our available cash that is not used for unit repurchases may, at the discretion of our general partner, be distributed within 45 days after the end of each quarter to unitholders of record. Available cash is generally defined in the partnership agreement as all cash and cash equivalents on hand at the end of each quarter less reserves established by MGP in its reasonable discretion for future cash requirements. These reserves are retained to provide for the conduct of our business, the payment of debt principal and interest and to provide funds for future distributions. The following table summarizes the quarterly per unit distribution paid during each quarter of 2021 through 2023: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, ​ 2023 2022 2021 First Quarter ​ $ 0.700 ​ $ 0.250 ​ $ — ​ Second Quarter ​ $ 0.700 ​ $ 0.350 ​ $ 0.100 ​ Third Quarter ​ $ 0.700 ​ $ 0.400 ​ $ 0.100 ​ Fourth Quarter ​ $ 0.700 ​ $ 0.500 ​ $ 0.200 ​ ​ On January 26, 2024, we declared a quarterly distribution of $0.70 per unit, totaling approximately $89.0 million, on all our common units outstanding, which was paid on February 14, 2024 to all unitholders of record on February 7, 2024. ​ Unit Repurchase Program ​ In January 2023, the board of directors of MGP authorized a $93.5 million increase to the unit repurchase program, which had $6.5 million of available capacity as of December 31, 2022. As a result, we were authorized to repurchase up to a total of $100.0 million of ARLP common units. The program has no time limit and we may repurchase units from time to time in the open market or in other privately negotiated transactions. The unit repurchase program authorization does not obligate us to repurchase any dollar amount or number of units. During the year ended December 31, 2023, we repurchased and retired 929,842 units at an average unit price of $20.90 for an aggregate purchase price of $19.4 million, leaving $80.6 million remaining under the current authorization. Since inception of the unit repurchase program, we have repurchased and retired 6,390,446 units at an average unit price of $17.67 for an aggregate purchase price of $112.9 million. ​ Other ​ The noncontrolling interest in our consolidated balance sheets represents Bluegrass Minerals Management, LLC's ("Bluegrass Minerals") ownership interest in Cavalier Minerals JV, LLC ("Cavalier Minerals"). Our accumulated other comprehensive loss consists of unrecognized actuarial gains and losses as well as unrecognized prior service costs related to our pension and pneumoconiosis benefits. See Note 11 – Variable Interest Entities, Note 15 – Employee Benefit Plans and Note 19 – Accrued Workers' Compensation and Pneumoconiosis Benefits for further information.

VARIABLE INTEREST ENTITIES

VARIABLE INTEREST ENTITIES	12 Months Ended
	Dec. 31, 2023
VARIABLE INTEREST ENTITIES
VARIABLE INTEREST ENTITIES	11. VARIABLE INTEREST ENTITIES ​ AllDale I & II and Cavalier Minerals ​ We own the general partner interests and, including the limited partner interests we hold through our ownership in Cavalier Minerals, approximately 97% of the limited partner interests in AllDale I & II. As the general partner of AllDale I & II, we are entitled to receive 20.0% of all distributions from AllDale I & II with the remaining 80.0% allocated to limited partners based upon ownership percentages. ​ Cavalier Minerals owns approximately 72% of the limited partner interests in AllDale I & II. We own the managing member interest and a 96% member interest in Cavalier Minerals. Bluegrass Minerals owns a 4% member interest in Cavalier Minerals and a profits interest which entitles it to receive distributions equal to 25% of all distributions (including in liquidation) after all members have recovered their investment. All members have recovered their investment and Bluegrass Minerals began receiving its profits interest distributions in late 2022. ​ We have concluded that AllDale I, AllDale II and Cavalier Minerals are VIEs which we consolidate as the primary beneficiary because we have the power to direct the activities that most significantly impact the economic performance of AllDale I, AllDale II and Cavalier Minerals in addition to having substantial equity ownership. ​ Our share of Cavalier Minerals' investment in AllDale I & II is eliminated in consolidation and Bluegrass Minerals' investment in Cavalier Minerals is accounted for as noncontrolling ownership interest in our consolidated balance sheets. Additionally, earnings attributable to Bluegrass Minerals are recognized as noncontrolling interest in our consolidated statements of income. ​ The following table presents the carrying amounts and classification of AllDale I & II's assets and liabilities included in our consolidated balance sheets: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, ​ ​ ​ 2023 2022 ​ Assets (liabilities): (in thousands) Cash and cash equivalents ​ $ 4,690 ​ $ 4,698 ​ Trade receivables ​ 16,058 ​ 13,933 ​ Total property, plant and equipment, net ​ 389,767 ​ 406,135 ​ Accounts payable ​ ​ (175) ​ ​ (257) ​ Due to affiliates ​ — ​ ​ (24) ​ Accrued taxes other than income taxes ​ (958) ​ ​ (206) ​ ​ AllDale III ​ AllDale III owns oil & gas mineral interests in areas around the oil & gas mineral interests we own. Alliance Minerals owns a 13.9% limited partner interest in AllDale III. Alliance Minerals' investment in AllDale III is subject to a 25% profits interest for the general partner that is subject to a return hurdle equal to the greater of 125% of cumulative capital contributions and a 10% internal rate of return, and following an 80/20 "catch-up" provision for the general partner. ​ We have concluded that AllDale III is a VIE that we do not consolidate because we are not the primary beneficiary and AllDale III is structured as a limited partnership with the limited partners (1) not having the ability to remove the general partner and (2) not participating significantly in the operational decisions. We are not the primary beneficiary of AllDale III because we do not have the power to direct the activities that most significantly impact AllDale III's economic performance. See Note 12 – Equity Investments for more information about the accounting for our investment in AllDale III. ​ Francis ​ On April 5, 2022, we invested $20 million in Francis, in the form of a convertible note. Our convertible note matured on April 1, 2023 and was converted into a preferred equity interest in Francis. Prior to conversion, we had determined the note more closely represented equity as opposed to debt. Therefore, we accounted for the convertible note as an equity contribution even though we did not participate in Francis' earnings or losses and were not eligible to receive distributions during the term of the note. Subsequent to the conversion on April 1, 2023, we participate in earnings and losses and are eligible to receive distributions. As of December 31, 2023, we held approximately 17.0% of Francis' equity. ​ We have concluded that Francis is a VIE that we do not consolidate because we are not the primary beneficiary and Francis' management structure is similar to a limited partnership with the non-managing members (i) not having the ability to remove the managing member and (ii) not participating significantly in the operational decisions. We are not the primary beneficiary of Francis because we do not have the power to direct the activities that most significantly impact Francis's economic performance. See Note 12 – Equity Investments for more information about the accounting for our investment in Francis. ​ NGP ET IV ​ On June 2, 2022, we committed to purchase $25.0 million of limited partner interests in NGP ET IV, a private equity fund sponsored by NGP and focused on investments that are part of the global transition toward a lower carbon economy. This commitment represents a 3.6% interest in NGP ET IV. As of December 31, 2023, we have funded $6.6 million of this commitment. ​ We have concluded that NGP ET IV is a VIE that we do not consolidate because we are not the primary beneficiary and NGP ET IV is structured as a limited partnership with limited partners (i) not having the ability to remove the general partner and (ii) not participating significantly in the operational decisions. We are not the primary beneficiary of NGP ET IV because we do not have the power to direct the activities that most significantly impact NGP ET IV's economic performance. See Note 12 – Equity Investments for more information about the accounting for our investment in NGP ET IV.

EQUITY INVESTMENTS

EQUITY INVESTMENTS	12 Months Ended
	Dec. 31, 2023
EQUITY INVESTMENTS
EQUITY INVESTMENTS	12. EQUITY INVESTMENTS ​ AllDale III ​ We account for our ownership interest in the income or loss of AllDale III as an equity method investment. We record equity income or loss based on AllDale III's distribution structure. The changes in our equity method investment in AllDale III were as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, ​ ​ 2023 2022 2021 ​ ​ (in thousands) Beginning balance ​ $ 25,284 ​ $ 26,325 ​ $ 27,268 Equity method investment income ​ ​ 2,567 ​ ​ 5,634 ​ ​ 2,130 Distributions received ​ ​ (3,918) ​ ​ (6,675) ​ ​ (3,073) Ending balance ​ $ 23,933 ​ $ 25,284 ​ $ 26,325 ​ Francis ​ We account for our ownership interest in the income or loss of Francis as an equity method investment. Prior to the conversion of our convertible note, we did not participate in Francis' earnings or losses; however, upon conversion on April 1, 2023 we began participating. As a development stage company, Francis depends primarily on capital contributions to meet its operating and debt obligations. We currently believe that the carrying value of our investment is recoverable; however, if Francis is unable to raise sufficient funds to continue its operations and meet its debt obligations, it could have an adverse effect on our investment. The changes in our equity method investment in Francis were as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, ​ ​ ​ 2023 2022 ​ ​ (in thousands) ​ Beginning balance ​ $ 20,000 ​ $ — ​ Contributions ​ ​ — ​ ​ 20,000 ​ Equity method investment loss ​ ​ (3,513) ​ ​ — ​ Ending balance ​ $ 16,487 ​ $ 20,000 ​ ​ NGP ET IV ​ We account for our ownership interest in the income or loss of NGP ET IV as an equity method investment. The changes in our equity method investment in NGP ET IV were as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, ​ ​ ​ 2023 2022 ​ ​ ​ (in thousands) ​ Beginning balance ​ $ 4,087 ​ $ — ​ Contributions ​ ​ 2,518 ​ ​ 4,087 ​ Equity method investment loss ​ ​ (522) ​ ​ — ​ Ending balance ​ $ 6,083 ​ $ 4,087 ​ ​ Infinitum ​ During 2022, we purchased $42.0 million of Series D Preferred Stock in Infinitum, a Texas-based startup developer and manufacturer of electric motors featuring printed circuit board stators. On September 8, 2023, we purchased $24.6 million of Series E Preferred Stock in Infinitum. The Infinitum Preferred Stock provides for non-cumulative dividends when and if declared by Infinitum's board of directors. Each share of Infinitum Preferred Stock is convertible, at any time, at our option, into shares of common stock of Infinitum. We account for our ownership interest in Infinitum as an equity investment without a readily determinable fair value. Absent an observable price change, it is not practicable to estimate the fair value of our investment in Infinitum because of the lack of a quoted market price for our ownership interests. Therefore, we use a measurement alternative other than fair value to account for our investment. ​ Ascend ​ On August 22, 2023, we purchased $25.0 million of Ascend Preferred Stock in Ascend, a U.S.-based manufacturer and recycler of sustainable, engineered battery materials for electric vehicles. The Ascend Preferred Stock provides for non-cumulative dividends when and if declared by Ascend's board of directors. Each share is convertible, at any time, at our option, into shares of common stock of Ascend. We account for our ownership interest in Ascend as an equity investment without a readily determinable fair value. Absent an observable price change, it is not practicable to estimate the fair value of our investment in Ascend because of the lack of a quoted market price for our ownership interests. Therefore, we use a measurement alternative other than fair value to account for our investment.

REVENUE FROM CONTRACTS WITH CUS

REVENUE FROM CONTRACTS WITH CUSTOMERS	12 Months Ended
	Dec. 31, 2023
REVENUE FROM CONTRACTS WITH CUSTOMERS
REVENUE FROM CONTRACTS WITH CUSTOMERS	13. REVENUE FROM CONTRACTS WITH CUSTOMERS ​ The following table illustrates the disaggregation of our revenues by type, including a reconciliation to our segment presentation as presented in Note 23 – Segment Information. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Coal Operations ​ Royalties ​ Other, ​ ​ ​ ​ ​ ​ Illinois ​ ​ ​ ​ Corporate and ​ ​ ​ ​ Basin Appalachia Oil & Gas Coal Elimination Consolidated ​ ​ ​ (in thousands) ​ Year Ended December 31, 2023 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Coal sales ​ $ 1,364,901 ​ $ 845,309 ​ $ — ​ $ — ​ $ — ​ $ 2,210,210 ​ Oil & gas royalties ​ ​ — ​ ​ — ​ ​ 137,751 ​ ​ — ​ ​ — ​ ​ 137,751 ​ Coal royalties ​ ​ — ​ ​ — ​ ​ — ​ ​ 65,572 ​ ​ (65,572) ​ ​ — ​ Transportation revenues ​ ​ 106,150 ​ ​ 36,140 ​ ​ — ​ ​ — ​ ​ — ​ ​ 142,290 ​ Other revenues ​ ​ 10,505 ​ ​ 1,885 ​ ​ 3,774 ​ ​ 42 ​ ​ 60,244 ​ ​ 76,450 ​ Total revenues ​ $ 1,481,556 ​ $ 883,334 ​ $ 141,525 ​ $ 65,614 ​ $ (5,328) ​ $ 2,566,701 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, 2022 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Coal sales ​ $ 1,219,943 ​ $ 882,286 ​ $ — ​ $ — ​ $ — ​ $ 2,102,229 ​ Oil & gas royalties ​ ​ — ​ ​ — ​ ​ 151,060 ​ ​ — ​ ​ — ​ ​ 151,060 ​ Coal royalties ​ ​ — ​ ​ — ​ ​ — ​ ​ 60,624 ​ ​ (60,624) ​ ​ — ​ Transportation revenues ​ ​ 69,540 ​ ​ 44,320 ​ ​ — ​ ​ — ​ ​ — ​ ​ 113,860 ​ Other revenues ​ ​ 6,822 ​ ​ 1,481 ​ ​ 3,837 ​ ​ 56 ​ ​ 40,622 ​ ​ 52,818 ​ Total revenues ​ $ 1,296,305 ​ $ 928,087 ​ $ 154,897 ​ $ 60,680 ​ $ (20,002) ​ $ 2,419,967 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, 2021 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Coal sales ​ $ 873,930 ​ $ 512,993 ​ $ — ​ $ — ​ $ — ​ $ 1,386,923 ​ Oil & gas royalties ​ ​ — ​ ​ — ​ ​ 84,183 ​ ​ — ​ ​ — ​ ​ 84,183 ​ Coal royalties ​ ​ — ​ ​ — ​ ​ — ​ ​ 51,402 ​ ​ (51,402) ​ ​ — ​ Transportation revenues ​ ​ 41,001 ​ ​ 28,606 ​ ​ — ​ ​ — ​ ​ — ​ ​ 69,607 ​ Other revenues ​ ​ 4,666 ​ ​ 3,940 ​ ​ 2,256 ​ ​ 69 ​ ​ 27,586 ​ ​ 38,517 ​ Total revenues ​ $ 919,597 ​ $ 545,539 ​ $ 86,439 ​ $ 51,471 ​ $ (23,816) ​ $ 1,579,230 ​ ​ The following table illustrates the projected revenue for all current coal supply contracts allocated to performance obligations that are unsatisfied or partially unsatisfied as of December 31, 2023 and disaggregated by segment and contract duration. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 2027 and ​ ​ ​ ​ 2024 2025 2026 Thereafter Total ​ ​ (in thousands) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Illinois Basin Coal Operations coal revenues ​ $ 1,291,152 ​ $ 494,386 ​ $ 253,465 ​ $ 238,500 ​ $ 2,277,503 ​ Appalachia Coal Operations coal revenues ​ ​ 754,183 ​ ​ 325,425 ​ ​ 1,600 ​ ​ — ​ ​ 1,081,208 ​ Total coal revenues (1) ​ $ 2,045,335 ​ $ 819,811 ​ $ 255,065 ​ $ 238,500 ​ $ 3,358,711 ​ (1) Coal revenues generally consists of consolidated revenues excluding our Oil & Gas Royalties segment as well as intercompany revenues from our Coal Royalties segment .

EARNINGS PER LIMITED PARTNER UN

EARNINGS PER LIMITED PARTNER UNIT	12 Months Ended
	Dec. 31, 2023
EARNINGS PER LIMITED PARTNER UNIT
EARNINGS PER LIMITED PARTNER UNIT	14. EARNINGS PER LIMITED PARTNER UNIT ​ We utilize the two-class method in calculating basic and diluted earnings per limited partner unit ("EPU"). Subsequent to the JC Resources Acquisition, which is discussed in more detail in Note 1 – Organization and Presentation, net income attributable to ARLP is allocated to limited partners and participating securities with nonforfeitable distributions or distribution equivalents, while net losses attributable to ARLP are allocated only to limited partners but not to participating securities. Prior to the JC Resources Acquisition, in addition to limited partners and participating securities allocations, amounts are also allocated to our general partner for historical earnings from the mineral interests acquired in the JC Resources Acquisition. Our participating securities are outstanding restricted unit awards under our LTIP and phantom units in notional accounts under our SERP and the Directors' Deferred Compensation Plan. ​ The following is a reconciliation of net income attributable to ARLP used for calculating basic and diluted earnings per unit and the weighted-average units used in computing EPU. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, ​ ​ 2023 2022 2021 ​ ​ ​ (in thousands, except per unit data) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net income attributable to ARLP ​ $ 630,118 ​ $ 586,200 ​ $ 182,771 ​ Less: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ General partner's interest in net income attributable to ARLP ​ (1,384) ​ (9,010) ​ (4,614) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Limited partners' interest in net income attributable to ARLP ​ 628,734 ​ 577,190 ​ 178,157 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Less: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Distributions to participating securities ​ (9,688) ​ (8,527) ​ (2,334) ​ Undistributed earnings attributable to participating securities ​ (7,203) ​ (10,576) ​ (2,403) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net income attributable to ARLP available to limited partners ​ $ 611,843 ​ $ 558,087 ​ $ 173,420 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted-average limited partner units outstanding – basic and diluted ​ 127,180 ​ 127,195 ​ 127,195 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Earnings per limited partner unit - basic and diluted (1) ​ $ 4.81 ​ $ 4.39 ​ $ 1.36 ​ (1) Diluted EPU gives effect to all potentially dilutive common units outstanding during the period using the treasury stock method. Diluted EPU excludes all potentially dilutive units calculated under the treasury stock method if their effect is anti-dilutive. For the years ended December 31, 2023, 2022 and 2021, the combined total of LTIP, SERP and Directors' Deferred Compensation Plan units of 2,922,384 , 3,540,385 and 1,967,672 , respectively, were considered anti-dilutive under the treasury stock method.

EMPLOYEE BENEFIT PLANS

EMPLOYEE BENEFIT PLANS	12 Months Ended
	Dec. 31, 2023
COMPONENTS OF PENSION PLAN NET PERIODIC BENEFIT COSTS
EMPLOYEE BENEFIT PLANS	15. EMPLOYEE BENEFIT PLANS ​ Defined Contribution Plans ​ All regular full-time employees are eligible to participate in a defined contribution profit sharing and savings plan ("PSSP") that we sponsor. PSSP participants may elect to make voluntary contributions to this plan up to a specified amount of their compensation. We make matching contributions based on a percent of an employee's eligible compensation and also make an additional non-matching contribution. Our contribution expense for the PSSP was approximately $21.8 million, $19.4 million and $17.7 million for the years ended December 31, 2023, 2022 and 2021, respectively. ​ Defined Benefit Plan ​ Eligible employees and former employees of certain of our mining operations participate in a defined benefit plan (the "Pension Plan") that we sponsor. The Pension Plan is closed to new applicants. Participants in the Pension Plan are no longer receiving benefit accruals for service. The benefit formula for the Pension Plan is a fixed-dollar unit based on years of service. ​ The following sets forth changes in benefit obligations and plan assets for the years ended December 31, 2023 and 2022 and the funded status of the Pension Plan reconciled with the amounts reported in our consolidated financial statements: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, ​ ​ ​ 2023 2022 ​ ​ (dollars in thousands) ​ Change in benefit obligations: ​ ​ ​ ​ ​ ​ ​ Benefit obligations at beginning of year ​ $ 104,682 ​ $ 139,566 ​ Interest cost ​ 5,180 ​ 3,749 ​ Actuarial loss (gain) ​ 2,446 ​ (32,996) ​ Benefits paid ​ (6,438) ​ (5,637) ​ Benefit obligations at end of year ​ 105,870 ​ 104,682 ​ ​ ​ ​ ​ ​ ​ ​ ​ Change in plan assets: ​ ​ ​ ​ ​ ​ ​ Fair value of plan assets at beginning of year ​ 92,129 ​ 113,976 ​ Actual return on plan assets ​ 11,561 ​ (16,210) ​ Benefits paid ​ (6,438) ​ (5,637) ​ Fair value of plan assets at end of year ​ 97,252 ​ 92,129 ​ Funded status at the end of year ​ $ (8,618) ​ $ (12,553) ​ ​ ​ ​ ​ ​ ​ ​ ​ Amounts recognized in balance sheet: ​ ​ ​ ​ ​ ​ ​ Non-current liability ​ $ (8,618) ​ $ (12,553) ​ ​ ​ ​ ​ ​ ​ ​ ​ Amounts recognized in accumulated other comprehensive income consists of: ​ ​ ​ ​ ​ ​ ​ Prior service cost ​ $ (196) ​ $ (382) ​ Net actuarial loss ​ ​ (11,584) ​ ​ (15,160) ​ ​ ​ $ (11,780) ​ $ (15,542) ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted-average assumption to determine benefit obligations as of December 31, ​ ​ ​ ​ ​ ​ ​ Discount rate ​ 4.90% ​ 5.10% ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted-average assumptions used to determine net periodic benefit cost for the year ended December 31, ​ ​ ​ ​ ​ ​ ​ Discount rate ​ 5.10% ​ 2.73% ​ Expected return on plan assets ​ 7.00% ​ 6.00% ​ ​ The actuarial loss component of the change in benefit obligations in 2023 was primarily attributable to a decrease in the discount rate compared to the prior year end. The actuarial gain component of the change in benefit obligations in 2022 was primarily attributable to an increase in the discount rate compared to the prior year end. ​ The expected long-term rate of return used to determine our pension liability is based on an asset allocation assumption of: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Asset allocation ​ As of December 31, 2023 assumption Equity securities ​ 75% ​ Fixed income securities 25% ​ ​ 100% ​ ​ The actual return on plan assets was 12.5% and (14.6)% for the years ended December 31, 2023 and 2022, respectively. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, ​ 2023 2022 2021 ​ ​ ​ (in thousands) Components of net periodic benefit cost (credit): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Interest cost ​ $ 5,180 ​ $ 3,749 ​ $ 3,438 ​ Expected return on plan assets ​ (6,220) ​ (6,638) ​ (6,580) ​ Amortization of prior service cost ​ ​ 186 ​ ​ 186 ​ ​ 186 ​ Amortization of net loss ​ 682 ​ 1,963 ​ 4,327 ​ Net periodic benefit cost (credit) (1) ​ $ (172) ​ $ (740) ​ $ 1,371 ​ (1) Nonservice components of net periodic benefit cost (credit) are included in the Other income (expense) line item within our consolidated statements of income. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, ​ ​ 2023 2022 ​ ​ ​ (in thousands) ​ Other changes in plan assets and benefit obligation recognized in accumulated other comprehensive loss: ​ ​ ​ ​ ​ ​ ​ Net actuarial gain ​ $ 2,894 ​ $ 10,148 ​ Reversal of amortization item: ​ ​ ​ ​ ​ ​ ​ Prior service cost ​ ​ 186 ​ ​ 186 ​ Net actuarial loss ​ 682 ​ 1,963 ​ Total recognized in accumulated other comprehensive loss ​ 3,762 ​ 12,297 ​ Net periodic benefit cost ​ 172 ​ 740 ​ Total recognized in net periodic benefit cost and accumulated other comprehensive loss ​ $ 3,934 ​ $ 13,037 ​ ​ Estimated future benefit payments as of December 31, 2023 are as follows: ​ ​ ​ ​ ​ ​ Year Ended ​ ​ ​ ​ December 31, (in thousands) ​ ​ ​ ​ ​ 2024 ​ $ 6,331 ​ 2025 ​ 6,490 ​ 2026 ​ 6,688 ​ 2027 ​ 6,820 ​ 2028 ​ 6,899 ​ 2029-2033 ​ 35,204 ​ ​ ​ $ 68,432 ​ ​ We do not expect to make material contributions to the Pension Plan during 2024. ​ The Compensation Committee has appointed an investment manager with full investment authority with respect to Pension Plan investments subject to investment guidelines and compliance with Employee Retirement Income Security Act of 1974 or other applicable laws. The investment manager employs an asset allocation strategy through investment in certain investment types such as equity securities and fixed income securities. The asset allocation process provides that the total portfolio allocation will be adjusted as the funded ratio of the plan changes and market conditions warrant, consistent with managing risks in accordance with plan objectives and time horizon. As the funded ratio improves, more assets may be allocated to the core fixed income portfolio to reduce volatility. The objective of the allocation policy is to achieve an average annual return greater than the actuarial discount rate over the specified time horizon. General asset allocation guidelines at December 31, 2023 are as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ Percentage of Total Portfolio ​ Minimum Maximum ​ ​ ​ ​ ​ ​ Equity securities ​ 50% ​ 85% ​ Fixed income securities ​ 15% ​ 50% ​ ​ Equity securities include domestic and international common stocks, convertible notes and bonds, convertible preferred stocks, American Depository Receipts of non-U.S. companies and Real Estate Investment Trusts. Fixed income securities include debt securities issued by the federal government as well as state and local governments, banker's acceptances, repurchase agreements, asset-backed securities, collateralized mortgage-backed securities, corporate debt securities, inflation-index bonds and structured notes. ​ The following information discloses the fair values of our Pension Plan assets by asset category: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, ​ ​ 2023 ​ 2022 ​ ​ ​ Level 1 ​ Level 2 ​ Level 3 ​ Total ​ Level 1 ​ Level 2 ​ Level 3 ​ Total ​ ​ ​ (in thousands) Cash and cash equivalents ​ $ 1,665 ​ $ — ​ $ — ​ $ 1,665 ​ $ 5,422 ​ $ — ​ $ — ​ $ 5,422 ​ Equity investments - Individual securities (a): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Consumer discretionary ​ ​ 2,605 ​ ​ — ​ ​ — ​ ​ 2,605 ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ Consumer durables ​ ​ 2,088 ​ ​ — ​ ​ — ​ ​ 2,088 ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ Energy ​ ​ 952 ​ ​ — ​ ​ — ​ ​ 952 ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ Financials ​ ​ 4,852 ​ ​ — ​ ​ — ​ ​ 4,852 ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ Health Care ​ ​ 4,296 ​ ​ — ​ ​ — ​ ​ 4,296 ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ Industrials & materials ​ ​ 4,507 ​ ​ — ​ ​ — ​ ​ 4,507 ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ Information technology & communication ​ ​ 8,102 ​ ​ — ​ ​ — ​ ​ 8,102 ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ Fixed income investments - Individual securities (b): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Preferred stocks non-convertible ​ ​ 37 ​ ​ — ​ ​ — ​ ​ 37 ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ Equity investments - Mutual funds (c): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Mid-cap stock funds ​ ​ 11,847 ​ ​ — ​ ​ — ​ ​ 11,847 ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ Small-cap stock funds ​ ​ 4,007 ​ ​ — ​ ​ — ​ ​ 4,007 ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ International stock funds ​ ​ 7,849 ​ ​ — ​ ​ — ​ ​ 7,849 ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ Equity investments - Exchange traded funds (d): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Large-cap blend - S&P 500 index ​ ​ 18,044 ​ ​ — ​ ​ — ​ ​ 18,044 ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ International - Developed markets ​ ​ 3,138 ​ ​ — ​ ​ — ​ ​ 3,138 ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ International - Emerging markets ​ ​ 1,894 ​ ​ — ​ ​ — ​ ​ 1,894 ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ Accrued income (e) ​ ​ — ​ ​ 29 ​ ​ — ​ ​ 29 ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ ​ $ 75,883 ​ $ 29 ​ $ — ​ $ 75,912 ​ $ 5,422 ​ $ — ​ $ — ​ $ 5,422 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Commingled investment funds measured at net asset value (f): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Equities - United States ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 36,259 ​ Equities - United States futures ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (697) ​ Equities - International developed markets ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 14,214 ​ Equities - International developed markets futures ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (1,693) ​ Equities - International emerging markets ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 782 ​ Equities - International emerging markets futures ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 3,289 ​ Fixed income - Investment grade ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 21,340 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 13,856 ​ Fixed income - High yield ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 156 ​ Fixed income - Futures ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 8,590 ​ Alternatives ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 11,951 ​ Total ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ $ 97,252 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ $ 92,129 ​ (a) Equity investments - Individual securities include investments in publicly traded common stock and American Depository Receipts. Publicly traded common stocks are traded on a national securities exchange and investments in common stocks are valued using quoted market prices multiplied by the number of shares owned. American Depository Receipts are negotiable securities issued by a bank representing shares in a foreign company and traded on a national securities exchange. (b) Fixed income investments - Individual securities include investments in preferred stock that are traded on a national securities exchange and valued using quoted market prices multiplied by the number of shares owned. (c) Equity investments - Mutual funds are valued daily in actively traded markets. For purposes of calculating the value, portfolio securities and other assets for which market quotes are readily available are valued at market value. Investments initially valued in currencies other than the U.S. dollars are converted to the U.S. dollar using exchange rates obtained from pricing services. (d) Equity investments – Exchange traded funds are funds that own financial assets and trade on exchanges, generally tracking a specific index. Investments in exchange traded funds are valued using a market approach based on the quoted market prices. (e) Accrued income represents dividends or interest declared, but not received, on equity securities owned at December 31, 2023. (f) Investments measured at fair value using the net asset value per share (or its equivalent) have not been classified within the fair value hierarchy. The fair values of all commingled investment funds are determined based on the net asset values per unit of each of the funds. The net asset values per unit represent the aggregate value of the fund's assets at fair value less liabilities, divided by the number of units outstanding .

COMMON UNIT-BASED COMPENSATION

COMMON UNIT-BASED COMPENSATION PLANS	12 Months Ended
	Dec. 31, 2023
COMMON UNIT-BASED COMPENSATION PLANS
COMMON UNIT-BASED COMPENSATION PLANS	16. COMMON UNIT-BASED COMPENSATION PLANS ​ Long-Term Incentive Plan ​ A summary of non-vested LTIP grants of restricted units is as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Number of units Weighted average grant date fair value per unit Intrinsic value ​ ​ ​ ​ ​ ​ ​ (in thousands) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Non-vested grants at January 1, 2021 ​ 1,430,489 ​ $ 5.02 ​ $ 6,409 ​ Granted (1) ​ 1,818,190 ​ ​ 6.03 ​ ​ ​ ​ Forfeited ​ (118,204) ​ 5.48 ​ ​ ​ ​ Non-vested grants at December 31, 2021 ​ 3,130,475 ​ ​ 5.59 ​ ​ 39,569 ​ Granted (1) ​ 769,907 ​ ​ 14.65 ​ ​ ​ ​ Forfeited ​ (203,249) ​ 6.93 ​ ​ ​ ​ Non-vested grants at December 31, 2022 ​ 3,697,133 ​ ​ 7.40 ​ ​ 75,126 ​ Granted (1) 450,125 ​ ​ 21.54 ​ ​ ​ ​ Vested (2) (1,291,330) ​ 5.02 ​ ​ ​ ​ Forfeited (145,584) ​ 6.86 ​ ​ ​ ​ Non-vested grants at December 31, 2023 2,710,344 ​ 10.91 ​ ​ 57,405 ​ (1) Restricted units granted have certain minimum-value guarantees per unit, regardless of whether or not the awards vest . (2) During the year ended December 31, 2023, we issued 860,060 unrestricted common units to the LTIP participants. The remaining vested units were settled in cash to satisfy our tax withholding obligations. ​ For the years ended December 31, 2023, 2022 and 2021, our LTIP expense for grants of restricted units was $10.4 million, $9.4 million and $5.4 million, respectively. The total obligation associated with LTIP grants of restricted units as of December 31, 2023 and 2022 was $19.5 million and $16.0 million, respectively, and is included in the partners' capital Limited partners-common unitholders ​ On January 24, 2024, the Compensation Committee authorized additional grants of 440,470 restricted units, of which 425,470 units were granted. These restricted units have certain minimum-value guarantees, regardless of whether or not the awards vest. ​ Supplemental Executive Retirement Plan and Directors' Deferred Compensation Plan ​ A summary of SERP and Directors' Deferred Compensation Plan activity is as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Number of units Weighted average grant date fair value per unit Intrinsic value ​ ​ ​ ​ ​ ​ ​ (in thousands) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Phantom units outstanding as of January 1, 2021 ​ 760,630 ​ $ 22.04 ​ $ 3,408 ​ Granted ​ 46,638 ​ ​ 9.45 ​ ​ ​ ​ Settled (1) ​ (138,570) ​ ​ 25.86 ​ ​ ​ ​ Phantom units outstanding as of December 31, 2021 ​ 668,698 ​ ​ 20.37 ​ ​ 8,452 ​ Granted ​ 73,842 ​ ​ 19.44 ​ ​ ​ ​ Phantom units outstanding as of December 31, 2022 ​ 742,540 ​ ​ 20.28 ​ ​ 15,088 ​ Granted ​ 118,737 ​ ​ 20.46 ​ ​ ​ ​ Settled (1) (49,331) ​ ​ 20.27 ​ ​ ​ ​ Phantom units outstanding as of December 31, 2023 811,946 ​ 20.44 ​ ​ 17,197 ​ (1) During the years ended December 31, 2023 and 2021, we purchased 27,576 ARLP common units and 102,962 ARLP common units on the open market to settle the accounts of participants under the SERP. Units purchased were net of units settled in cash to satisfy tax-withholding obligations. ​ Total SERP and Directors' Deferred Compensation Plan expense was $2.4 million, $1.4 million and $0.4 million for the years ended December 31, 2023, 2022 and 2021, respectively. As of December 31, 2023 and 2022, the total obligation associated with the SERP and Directors' Deferred Compensation Plan was $16.6 million and $15.1 million, respectively, and is included in the partners' capital Limited partners-common unitholders

SUPPLEMENTAL CASH FLOW INFORMAT

SUPPLEMENTAL CASH FLOW INFORMATION	12 Months Ended
	Dec. 31, 2023
SUPPLEMENTAL CASH FLOW INFORMATION
SUPPLEMENTAL CASH FLOW INFORMATION	17. SUPPLEMENTAL CASH FLOW INFORMATION ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, ​ 2023 2022 2021 ​ ​ (in thousands) ​ Cash Paid For: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Interest ​ $ 37,126 ​ $ 34,844 ​ $ 36,402 ​ Income taxes ​ $ 13,615 ​ $ 23,794 ​ $ 11 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Non-Cash Activity: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Accounts payable for purchase of property, plant and equipment ​ $ 14,586 ​ $ 44,281 ​ $ 8,325 ​ Right-of-use assets acquired by operating lease ​ $ 2,596 ​ $ 1,315 ​ $ 189 ​ Market value of common units distributed under deferred compensation plans before tax withholding requirements ​ $ 28,906 ​ $ — ​ $ 1,082 ​ ​

ASSET RETIREMENT OBLIGATIONS

ASSET RETIREMENT OBLIGATIONS	12 Months Ended
	Dec. 31, 2023
ASSET RETIREMENT OBLIGATIONS
ASSET RETIREMENT OBLIGATIONS	18. ASSET RETIREMENT OBLIGATIONS ​ The following table presents the activity affecting the asset retirement and mine closing liability: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, ​ 2023 2022 ​ ​ (in thousands) ​ ​ ​ ​ ​ ​ ​ ​ ​ Beginning balance ​ $ 149,813 ​ $ 131,099 ​ Accretion expense ​ 4,433 ​ 3,731 ​ Payments ​ (2,317) ​ (2,445) ​ Allocation of liability associated with mine development and change in assumptions ​ (1,486) ​ 17,428 ​ Ending balance ​ $ 150,443 ​ $ 149,813 ​ ​ For the year ended December 31, 2023, the allocation of liability associated with mine development and change in assumptions decreased by $1.5 million. The decrease was largely attributable to lower cost assumptions. ​ For the year ended December 31, 2022, the allocation of liability associated with mine development and change in assumptions increased by $17.4 million. The increase was largely attributable to higher cost assumptions as well as the expansion of refuse disposal facilities at certain mines. ​ The impact of discounting our estimated cash flows resulted in reducing the accrual for asset retirement obligations by $116.2 million and $110.4 million at December 31, 2023 and 2022, respectively. Estimated payments of asset retirement obligations as of December 31, 2023 are as follows: ​ ​ ​ ​ ​ ​ Year Ended ​ ​ ​ ​ December 31, (in thousands) ​ ​ ​ ​ ​ 2024 ​ $ 3,518 ​ 2025 ​ 5,557 ​ 2026 ​ 4,063 ​ 2027 ​ 7,038 ​ 2028 ​ 4,291 ​ Thereafter ​ 242,134 ​ Aggregate undiscounted asset retirement obligations ​ 266,601 ​ Less: effect of discounting ​ (116,158) ​ Total asset retirement obligations ​ 150,443 ​ Less: current portion ​ (3,518) ​ Non-current asset retirement obligations ​ $ 146,925 ​ ​ As of December 31, 2023 and 2022, we had approximately $173.5 million and $174.3 million, respectively, in surety bonds outstanding to secure the performance of our reclamation obligations.

ACCRUED WORKERS' COMPENSATION A

ACCRUED WORKERS' COMPENSATION AND PNEUMOCONIOSIS BENEFITS	12 Months Ended
	Dec. 31, 2023
ACCRUED WORKERS' COMPENSATION AND PNEUMOCONIOSIS BENEFITS
ACCRUED WORKERS' COMPENSATION AND PNEUMOCONIOSIS BENEFITS	19. ACCRUED WORKERS' COMPENSATION AND PNEUMOCONIOSIS BENEFITS ​ The following is a reconciliation of the changes in workers' compensation liability (including current and long-term liability balances): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, ​ ​ ​ 2023 2022 ​ ​ ​ ​ ​ ​ ​ ​ ​ Beginning balance ​ $ 49,452 ​ $ 53,448 ​ Changes in accruals ​ 12,155 ​ 7,384 ​ Payments ​ (14,438) ​ (12,708) ​ Interest accretion ​ 2,202 ​ 1,147 ​ Valuation loss (gain) ​ (1,396) ​ 181 ​ Ending balance ​ $ 47,975 ​ $ 49,452 ​ ​ The discount rate used to calculate the estimated present value of future obligations for workers' compensation was 4.66% and 4.87% at December 31, 2023 and 2022, respectively. ​ The valuation gain in 2023 was primarily attributable to a favorable change in claims development partially offset by a decrease in the discount rate used to calculate the estimated present value of the future obligations. The valuation loss in 2022 was primarily attributable to an increase in the discount rate used to calculate the estimated present value of the future obligations being partially offset by unfavorable changes in claims development. ​ As of December 31, 2023 and 2022, we had $99.4 million and $99.8 million, respectively, in surety bonds and letters of credit outstanding to secure workers' compensation obligations. ​ We limit our exposure to traumatic injury claims by purchasing a high deductible insurance policy that starts paying benefits after deductibles for the particular claim year have been met. Our workers' compensation liability above is presented on a gross basis and does not include our expected receivables on our insurance policy. Our receivables for traumatic injury claims under this policy as of December 31, 2023 and 2022 were $4.1 million. Our receivables are included in Other long-term assets ​ The following is a reconciliation of the changes in pneumoconiosis benefit obligations: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, ​ ​ 2023 2022 ​ ​ ​ (in thousands) ​ ​ ​ ​ ​ ​ ​ ​ ​ Benefit obligations at beginning of year ​ $ 104,287 ​ $ 111,316 ​ Service cost ​ 2,698 ​ 3,798 ​ Interest cost ​ 4,951 ​ 2,991 ​ Actuarial loss (gain) ​ 25,615 ​ (9,840) ​ Benefits and expenses paid ​ (5,107) ​ (3,978) ​ Benefit obligations at end of year ​ $ 132,444 ​ $ 104,287 ​ ​ The following is a reconciliation of the changes in the pneumoconiosis benefit obligation recognized in accumulated other comprehensive loss: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, ​ ​ 2023 2022 2021 ​ ​ (in thousands) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net actuarial gain (loss) ​ $ (25,615) ​ $ 9,840 ​ $ (161) ​ Reversal of amortization item: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net actuarial loss ​ 1,382 ​ 1,038 ​ 4,172 ​ Total recognized in accumulated other comprehensive loss ​ $ (24,233) ​ $ 10,878 ​ $ 4,011 ​ ​ The discount rate used to calculate the estimated present value of future obligations for pneumoconiosis benefits was 4.81%, 5.0% and 2.73% at December 31, 2023, 2022 and 2021, respectively. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, ​ ​ 2023 2022 2021 ​ ​ (in thousands) ​ Amount recognized in accumulated other comprehensive loss consists of: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net actuarial loss ​ $ 49,745 ​ $ 25,510 ​ $ 36,388 ​ ​ The actuarial loss component of the change in benefit obligations in 2023 was primarily attributable to a) unfavorable changes in the discount rate, b) unfavorable demographics in the at-risk population, c) unfavorable black lung claims experience, d) unfavorable assumption changes regarding future average medical benefits, and e) unfavorable assumption changes related to Federal and State benefit levels. The actuarial gain component of the change in benefit obligations in 2022 was primarily attributable to favorable assumption changes in the discount rate and demographics in the at-risk population. These components were offset in part by a) unfavorable black lung claims experience, b) unfavorable assumption changes regarding future average medical benefits and legal expense levels, and c) unfavorable assumption changes related to Federal and State benefit levels. ​ Summarized below is information about the amounts recognized in the accompanying consolidated balance sheets for pneumoconiosis and workers' compensation benefits: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, ​ ​ 2023 2022 ​ ​ (in thousands) ​ ​ ​ ​ ​ ​ ​ ​ ​ Workers' compensation claims ​ $ 47,975 ​ $ 49,452 ​ Pneumoconiosis benefit claims ​ ​ 132,444 ​ ​ 104,287 ​ Total obligations ​ 180,419 ​ 153,739 ​ Less current portion ​ (15,913) ​ (14,099) ​ Non-current obligations ​ $ 164,506 ​ $ 139,640 ​ ​ Both the pneumoconiosis benefit and workers' compensation obligations were unfunded at December 31, 2023 and 2022. ​ The pneumoconiosis benefit and workers' compensation expense consists of the following components: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, ​ 2023 2022 2021 ​ ​ ​ (in thousands) ​ Black lung benefits: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Service cost $ 2,698 ​ $ 3,798 ​ $ 4,021 ​ Interest cost (1) ​ 4,951 ​ 2,991 ​ 2,545 ​ Net amortization (1) ​ 1,382 ​ 1,038 ​ 4,172 ​ Total pneumoconiosis expense ​ 9,031 ​ 7,827 ​ 10,738 ​ Workers' compensation expense ​ 15,152 ​ 11,675 ​ 8,339 ​ Net periodic benefit cost ​ $ 24,183 ​ $ 19,502 ​ $ 19,077 ​ ________________________________________ (1) Interest cost and net amortization is included in the Other income line item within our consolidated statements of income .

RELATED-PARTY TRANSACTIONS

RELATED-PARTY TRANSACTIONS	12 Months Ended
	Dec. 31, 2023
RELATED-PARTY TRANSACTIONS
RELATED-PARTY TRANSACTIONS	20. RELATED-PARTY TRANSACTIONS ​ We have continuing related-party transactions with MGP and its affiliates. The Board of Directors and its conflicts committee ("Conflicts Committee") review our related-party transactions that involve a potential conflict of interest between our general partner or its affiliates and ARLP or its subsidiaries or any other partner of ARLP to determine that such transactions are fair and reasonable to ARLP. As a result of these reviews, the Board of Directors and the Conflicts Committee approved each of the transactions described below that had such potential conflict of interest as fair and reasonable to ARLP. ​ Line of Credit ​ On February 19, 2021, we entered into a line of credit arrangement (the "Line of Credit") with a related party for $5.0 million. This Line of Credit was amended on November 4, 2021 to increase the total available under the Line of Credit to $5.5 million. The Line of Credit had a maturity date of February 28, 2023 and accrued interest at an annual rate of 3.5% payable quarterly. During the year ended December 31, 2021 we received proceeds and made payments ​ Affiliate Coal Lease Agreements ​ The following table summarizes advanced royalties outstanding and related payments and recoupments under our affiliate coal lease agreements: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ WKY CoalPlay ​ ​ ​ ​ ​ ​ ​ Towhead ​ Webster ​ Henderson ​ WKY ​ ​ ​ ​ ​ Craft Foundations ​ Coal ​ Coal ​ Coal ​ CoalPlay ​ ​ ​ ​ ​ ​ ​ Henderson ​ ​ ​ ​ ​ Henderson ​ ​ ​ ​ ​ ​ Tunnel ​ & Union ​ Webster ​ Henderson ​ & Union ​ ​ ​ ​ ​ ​ Ridge ​ Counties, KY ​ County, KY ​ County, KY ​ Counties, KY ​ Total ​ ​ ​ Acquired ​ Acquired ​ Acquired ​ Acquired ​ Acquired ​ ​ ​ ​ ​ ​ 2005 ​ 2014 ​ 2014 ​ 2014 ​ 2015 ​ ​ ​ ​ ​ (in thousands) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ As of January 1, 2021 ​ $ 1,500 ​ $ 19,178 ​ $ — ​ $ 15,129 ​ $ 12,582 ​ $ 48,389 ​ Payments ​ ​ 3,000 ​ ​ 3,597 ​ ​ 2,568 ​ ​ 2,521 ​ ​ 2,131 ​ ​ 13,817 ​ Recoupment ​ ​ (3,000) ​ ​ (1,025) ​ ​ — ​ ​ — ​ ​ — ​ ​ (4,025) ​ Unrecoupable ​ ​ — ​ ​ — ​ ​ (2,568) ​ ​ — ​ ​ — ​ ​ (2,568) ​ As of December 31, 2021 ​ ​ 1,500 ​ ​ 21,750 ​ ​ — ​ ​ 17,650 ​ ​ 14,713 ​ ​ 55,613 ​ Payments ​ ​ 3,000 ​ ​ 3,597 ​ ​ — ​ ​ 2,522 ​ ​ 2,131 ​ ​ 11,250 ​ Recoupment ​ ​ (3,000) ​ ​ (3,255) ​ ​ — ​ ​ — ​ ​ — ​ ​ (6,255) ​ Unrecoupable ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ As of December 31, 2022 ​ ​ 1,500 ​ ​ 22,092 ​ ​ — ​ ​ 20,172 ​ ​ 16,844 ​ ​ 60,608 ​ Payments ​ ​ 3,000 ​ ​ 3,597 ​ ​ — ​ ​ 2,521 ​ ​ 2,131 ​ ​ 11,249 ​ Recoupment ​ ​ (3,000) ​ ​ (4,258) ​ ​ — ​ ​ — ​ ​ — ​ ​ (7,258) ​ Unrecoupable ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ As of December 31, 2023 ​ $ 1,500 ​ $ 21,431 ​ $ — ​ $ 22,693 ​ $ 18,975 ​ $ 64,599 ​ ​ Craft Foundations ​ In January 2005, we acquired Tunnel Ridge from ARH. In connection with this acquisition, we assumed a coal lease with Alliance Resource GP, LLC, an entity indirectly wholly owned by Mr. Craft and Kathleen S. Craft until it was dissolved in December 2020. In December 2018, the property subject to the lease was transferred to the Joseph W. Craft III Foundation and the Kathleen S. Craft Foundation, which each hold an undivided one half ​ Tunnel Ridge has a surface land lease with an annual payment of $0.2 million, payable in January of each year with the Craft Foundations. ​ WKY CoalPlay ​ In February 2015, WKY CoalPlay, LLC ("WKY CoalPlay") entered into a coal lease agreement with Alliance Resource Properties regarding coal mineral resources located in Henderson and Union Counties, Kentucky. The lease has an initial term of 20 years and provides for earned royalty payments to WKY CoalPlay of 4.0% of the coal sales price and annual minimum royalty payments of $2.1 million. All annual minimum royalty payments are recoupable from future earned royalties. ​ In December 2014, WKY CoalPlay's subsidiaries, Towhead Coal Reserves, LLC and Henderson Coal Reserves, LLC entered into coal lease agreements with Alliance Resource Properties. The leases have initial terms of 20 years and provide for earned royalty payments of 4.0% of the coal sales price and annual minimum royalty payments of $3.6 million and $2.5 million, respectively. All annual minimum royalty payments under each agreement are recoupable from future earned royalties payable under that agreement. ​ In December 2014, WKY CoalPlay's subsidiary, Webster Coal Reserves, LLC entered into a coal lease agreement with Alliance Resource Properties. The lease had a term of 7 years and provided for earned royalty payments of 4.0% of the coal sales price and annual minimum royalty payments of $2.6 million. This lease expired in December 2021.

COMMITMENTS AND CONTINGENCIES

COMMITMENTS AND CONTINGENCIES	12 Months Ended
	Dec. 31, 2023
COMMITMENTS AND CONTINGENCIES
COMMITMENTS AND CONTINGENCIES	21. COMMITMENTS AND CONTINGENCIES ​ Commitments ​ We lease buildings and equipment under operating lease agreements that provide for the payment of both minimum and contingent rentals. We also have noncancelable coal mineral reserve and resource leases as discussed in Note 20 – Related-Party Transactions. ​ Contractual Commitments ​ In connection with planned capital projects, we have contractual commitments of approximately $201.9 million at December 31, 2023. As of December 31, 2023, we had $22.3 million in commitments to purchase coal from external production sources in 2024 and thereafter. ​ General Litigation ​ Certain of our subsidiaries are party to litigation in which the plaintiffs allege violations of the Fair Labor Standards Act and state law due to alleged failure to compensate for time "donning" and "doffing" equipment and to account for certain bonuses in the calculation of overtime rates and pay. The plaintiffs seek class and collective action certification, which we oppose, and the courts have not yet made definitive final rulings on those issues. We believe our ultimate exposure, if any, will not be material to our results of operations or financial position; however, if our current belief as to the merit of the claims is not upheld, it is reasonably possible that the ultimate resolution of these matters could result in a potential loss that may be material to our results of operations. ​ We also have various other lawsuits, claims and regulatory proceedings incidental to our business that are pending against the ARLP Partnership. We record an accrual for a potential loss related to these matters when, in management's opinion, such loss is probable and reasonably estimable. Based on known facts and circumstances, we believe the ultimate outcome of these outstanding lawsuits, claims and regulatory proceedings will not have a material adverse effect on our financial condition, results of operations or liquidity. However, if the results of these matters are different from management's current expectations, such matters could have a material adverse effect on our business and operations. ​ Other ​ Effective October 1, 2023, we renewed our property and casualty insurance program through September 30, 2024. Our property insurance was procured from our wholly owned captive insurance company, Wildcat Insurance, LLC ("Wildcat Insurance"). Wildcat Insurance charged certain of our subsidiaries for the premiums on this program and in return purchased reinsurance for the program in the standard market. The maximum limit in the commercial property program is $100.0 million per occurrence, excluding a $1.5 million deductible for property damage, a 75 or 90 day waiting period for underground business interruption depending on the mining complex and an additional $25.0 million overall aggregate deductible. We retained a 7.25% participating interest in our current commercial property insurance program. We can make no assurances that we will not experience significant insurance claims in the future that could have a material adverse effect on our business, financial condition, results of operations and ability to purchase property insurance in the future. Also, exposures exist for which no insurance may be available and for which we have not reserved. In addition, the insurance industry has been subject to efforts by environmental activists to restrict coverages available for fossil-fuel companies.

CONCENTRATION OF CREDIT RISK AN

CONCENTRATION OF CREDIT RISK AND MAJOR CUSTOMERS	12 Months Ended
	Dec. 31, 2023
CONCENTRATION OF CREDIT RISK AND MAJOR CUSTOMERS
CONCENTRATION OF CREDIT RISK AND MAJOR CUSTOMERS	22. CONCENTRATION OF CREDIT RISK AND MAJOR CUSTOMERS ​ The international coal market has been a part of our business with indirect sales to end-users in Europe, Africa, Asia, North America and South America. Our sales into the international coal market are considered exports and are made through brokered transactions. During the years ended December 31, 2023, 2022 and 2021, export tons represented approximately 15.7%, 12.5% and 12.5% of tons sold, respectively. ​ Because title to our export shipments typically transfers to our brokerage customers at a point that does not necessarily reflect the end-usage point, we attribute export tons to the country with the end-usage point, if known. No individual country was attributed greater than 10% of total domestic and export tons sold during the years ended December 31, 2023, 2022 and 2021. ​ We have significant long-term coal supply agreements, some of which contain prospective price adjustment provisions designed to reflect changes in market conditions, labor and other production costs and, in the infrequent circumstance when the coal is sold other than free on board the mine, changes in transportation rates. A major customer is defined as a customer from which we derive at least ten percent of our total revenues, including transportation revenues. Total revenues from major customers are as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, ​ Segment 2023 ​ 2022 ​ 2021 ​ ​ ​ ​ (in thousands) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Customer A Illinois Basin/Appalachia ​ $ 332,500 ​ $ — ​ $ — ​ Customer B ​ Illinois Basin ​ ​ 253,573 ​ ​ 260,146 ​ ​ — ​ Customer C ​ Illinois Basin ​ ​ — ​ ​ 328,406 ​ ​ 239,482 ​ Customer D Illinois Basin/Appalachia ​ — ​ ​ 228,480 ​ — ​ ​ Trade accounts receivable from major customers totaled approximately $54.3 million and $63.6 million at December 31, 2023 and 2022, respectively. Our credit loss experience has historically been insignificant. Financial conditions of our customers could result in a material change to our credit loss expense in future periods. The coal supply agreements with Customers A and B expire in 2025 and 2029, respectively.

SEGMENT INFORMATION

SEGMENT INFORMATION	12 Months Ended
	Dec. 31, 2023
SEGMENT INFORMATION
SEGMENT INFORMATION	23. SEGMENT INFORMATION ​ We operate in the United States as a diversified natural resource company that generates operating and royalty income from the production and marketing of coal to major domestic and international utilities and industrial users as well as royalty income from oil & gas mineral interests. We aggregate multiple operating segments into four reportable segments, Illinois Basin Coal Operations, Appalachia Coal Operations, Oil & Gas Royalties and Coal Royalties. We also have an "all other" category referred to as Other, Corporate and Elimination. Our two coal operations reportable segments correspond to major coal producing regions in the eastern United States with similar economic characteristics including coal quality, geology, coal marketing opportunities, mining and transportation methods and regulatory issues. The two coal operations reportable segments include seven mining complexes operating in Illinois, Indiana, Kentucky, Maryland, Pennsylvania, and West Virginia and a coal loading terminal in Indiana on the Ohio River. Our Oil & Gas Royalties reportable segment includes our oil & gas mineral interests which are located primarily in the Permian (Delaware and Midland), Anadarko (SCOOP/STACK) and Williston (Bakken) basins. The operations within our Oil & Gas Royalties reportable segment primarily include receiving royalties and lease bonuses for our oil & gas mineral interests. Our Coal Royalties reportable segment includes coal mineral reserves and resources owned or leased by Alliance Resource Properties, which are either (a) leased to our mining complexes or (b) near our coal mining operations but not yet leased. ​ The Illinois Basin Coal Operations reportable segment includes (a) the Gibson County Coal, LLC's ("Gibson ") mining complex, (b) the Warrior Coal, LLC ("Warrior") mining complex, (c) the River View mining complex and (d) the Hamilton mining complex. The segment also includes our Mt. Vernon Transfer Terminal, LLC ("Mt. Vernon") coal loading terminal in Indiana which operates on the Ohio River, Mid-America Carbonates, LLC ("MAC") and other support services, and our non-operating mining complexes. ​ The Appalachia Coal Operations reportable segment includes (a) the Mettiki mining complex, (b) the Tunnel Ridge mining complex and (c) the MC Mining, LLC ("MC Mining") mining complex. ​ The Oil & Gas Royalties reportable segment includes oil & gas mineral interests held by Alliance Minerals' through its consolidated subsidiaries as well as equity interests held in AllDale III (Note 12 – Equity Investments). ​ Coal Royalties reportable segment includes coal mineral reserves and resources owned or leased by Alliance Resource Properties that are (a) leased to certain of our mining complexes in both the Illinois Basin Coal Operations and Appalachia Coal Operations reportable segments or (b) located near our operations and external mining operations. Approximately 60% of the coal sold by our coal operations' mines was leased from our Coal Royalties entities. ​ Other, Corporate and Elimination includes marketing and administrative activities, Matrix Design Group, LLC, its subsidiaries, and Alliance Design Group, LLC (collectively referred to as the "Matrix Group"), our investments in Francis, Infinitum, NGP ET IV and Ascend (see Note 12 – Equity Investments), Wildcat Insurance, which assists the ARLP Partnership with its insurance requirements, AROP Funding and Alliance Finance (both discussed in Note 6 – Long-Term Debt) and other miscellaneous activities. The eliminations included in Other, Corporate and Elimination primarily represent the intercompany coal royalty transactions described above between our Coal Royalties reportable segment and our coal operations' mines. ​ Reportable segment results are presented below. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Coal Operations ​ Royalties ​ Other, ​ ​ ​ ​ ​ Illinois ​ ​ ​ ​ ​ Corporate and ​ ​ ​ ​ Basin Appalachia Oil & Gas Coal ​ Elimination Consolidated ​ ​ (in thousands) Year Ended December 31, 2023 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Revenues - Outside (1) ​ $ 1,481,556 ​ $ 883,334 ​ $ 141,525 ​ $ 42 ​ $ 60,244 ​ $ 2,566,701 ​ Revenues - Intercompany ​ ​ — ​ ​ — ​ ​ — ​ ​ 65,572 ​ ​ (65,572) ​ ​ — ​ Total revenues (1) ​ ​ 1,481,556 ​ ​ 883,334 ​ ​ 141,525 ​ ​ 65,614 ​ ​ (5,328) ​ ​ 2,566,701 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Segment Adjusted EBITDA Expense (2) ​ 861,288 ​ ​ 516,471 ​ ​ 16,532 ​ ​ 24,451 ​ ​ (14,024) ​ 1,404,718 ​ Segment Adjusted EBITDA (3) ​ 514,118 ​ ​ 330,723 ​ ​ 121,508 ​ ​ 41,163 ​ ​ 4,661 ​ 1,012,173 ​ Total assets ​ 966,102 ​ ​ 488,427 ​ ​ 781,184 ​ ​ 315,592 ​ ​ 237,121 ​ 2,788,426 ​ Capital expenditures (4) ​ 257,885 ​ ​ 116,217 ​ ​ — ​ ​ 400 ​ ​ 4,836 ​ 379,338 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, 2022 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Revenues - Outside (1) ​ $ 1,296,305 ​ $ 928,087 ​ $ 154,897 ​ $ 56 ​ $ 40,622 ​ $ 2,419,967 ​ Revenues - Intercompany ​ ​ — ​ ​ — ​ ​ — ​ ​ 60,624 ​ ​ (60,624) ​ ​ — ​ Total revenues (1) ​ ​ 1,296,305 ​ ​ 928,087 ​ ​ 154,897 ​ ​ 60,680 ​ ​ (20,002) ​ ​ 2,419,967 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Segment Adjusted EBITDA Expense (2) ​ 806,080 ​ ​ 464,029 ​ ​ 15,395 ​ ​ 21,871 ​ ​ (23,497) ​ 1,283,878 ​ Segment Adjusted EBITDA (3) ​ 420,684 ​ ​ 426,402 ​ ​ 143,179 ​ ​ 38,809 ​ ​ 3,495 ​ 1,032,569 ​ Total assets ​ 779,018 ​ ​ 431,913 ​ ​ 778,465 ​ ​ 321,587 ​ ​ 417,038 ​ 2,728,021 ​ Capital expenditures (4) ​ 158,624 ​ ​ 76,603 ​ ​ — ​ ​ 38,276 ​ ​ 12,891 ​ 286,394 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, 2021 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Revenues - Outside (1) ​ $ 919,597 ​ $ 545,539 ​ $ 86,439 ​ $ 69 ​ $ 27,586 ​ $ 1,579,230 ​ Revenues - Intercompany ​ ​ — ​ ​ — ​ ​ — ​ ​ 51,402 ​ ​ (51,402) ​ ​ — ​ Total revenues (1) ​ ​ 919,597 ​ ​ 545,539 ​ ​ 86,439 ​ ​ 51,471 ​ ​ (23,816) ​ ​ 1,579,230 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Segment Adjusted EBITDA Expense (2) ​ 613,303 ​ 344,332 ​ 11,051 ​ 18,269 ​ ​ (33,198) ​ 953,757 ​ Segment Adjusted EBITDA (3) ​ 265,292 ​ 172,601 ​ 76,920 ​ 33,202 ​ ​ 9,383 ​ 557,398 ​ Total assets ​ 676,091 ​ 420,144 ​ 698,702 ​ 285,943 ​ ​ 146,601 ​ 2,227,481 ​ Capital expenditures (4) ​ 60,166 ​ 47,577 ​ — ​ 45 ​ ​ 15,196 ​ 122,984 ​ (1) Revenues included in the Other, Corporate and Elimination column are attributable to intercompany eliminations, which are primarily intercompany coal royalties eliminations, outside revenues at the Matrix Group and other outside miscellaneous sales and revenue activities. ​ (2) Segment Adjusted EBITDA Expense includes operating expenses, coal purchases and other income. Transportation expenses are excluded as transportation revenues are recognized in an amount equal to transportation expenses when title passes to the customer. ​ The following is a reconciliation of Operating expenses (excluding depreciation, depletion and amortization) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, ​ 2023 2022 2021 ​ ​ (in thousands) ​ Operating expenses (excluding depreciation, depletion and amortization) ​ $ 1,368,787 ​ $ 1,288,082 ​ $ 944,419 ​ Outside coal purchases ​ 36,149 ​ 151 ​ 6,372 ​ Other expense (income) ​ (218) ​ (4,355) ​ 2,966 ​ Segment Adjusted EBITDA Expense ​ $ 1,404,718 ​ $ 1,283,878 ​ $ 953,757 ​ ​ (3) Segment Adjusted EBITDA is defined as net income attributable to ARLP before net interest expense, income taxes, depreciation, depletion and amortization and general and administrative expense. Management therefore is able to focus solely on the evaluation of segment operating profitability as it relates to our revenues and operating expenses, which are primarily controlled by our segments. Net income , the most comparable GAAP financial measure, is reconciled to consolidated Segment Adjusted EBITDA: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, ​ 2023 2022 2021 ​ ​ (in thousands) ​ Net income ​ $ 636,170 ​ $ 588,158 ​ $ 183,369 ​ Noncontrolling interest ​ ​ (6,052) ​ ​ (1,958) ​ ​ (598) ​ Net income attributable to ARLP ​ $ 630,118 ​ $ 586,200 ​ $ 182,771 ​ General and administrative ​ 79,096 ​ 80,425 ​ 70,275 ​ Depreciation, depletion and amortization ​ 267,982 ​ 276,670 ​ 264,794 ​ Interest expense, net ​ 26,697 ​ 35,296 ​ 39,141 ​ Income tax expense ​ 8,280 ​ 53,978 ​ 417 ​ Consolidated Segment Adjusted EBITDA ​ $ 1,012,173 ​ $ 1,032,569 $ 557,398 ​ ​ (4) Capital expenditures shown exclude $110.9 million, $92.6 million and $31.0 million paid for oil & gas acquisitions in 2023, 2022 and 2021, respectively. See Note 3 – Acquisitions for more information.

SCHEDULE I CONDENSED FINANCIAL

SCHEDULE I CONDENSED FINANCIAL INFORMATION OF REGISTRANT	12 Months Ended
	Dec. 31, 2023
CONDENSED FINANCIAL INFORMATION OF REGISTRANT
CONDENSED FINANCIAL INFORMATION OF REGISTRANT	SCHEDULE I – CONDENSED FINANCIAL INFORMATION OF REGISTRANT ALLIANCE RESOURCE PARTNERS, L.P. ​ CONDENSED BALANCE SHEETS (PARENT) DECEMBER 31, 2023 AND 2022 (In thousands, except unit data) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, ​ ​ ​ 2023 2022* ​ ASSETS ​ ​ ​ ​ ​ CURRENT ASSETS: ​ ​ ​ ​ ​ ​ ​ Cash and cash equivalents ​ $ 2,043 ​ $ 2,174 ​ Total current assets ​ 2,043 ​ 2,174 ​ OTHER ASSETS: ​ ​ ​ ​ ​ ​ ​ Investments in consolidated subsidiaries ​ 1,894,158 ​ 1,720,499 ​ Total other assets ​ 1,894,158 ​ 1,720,499 ​ TOTAL ASSETS ​ $ 1,896,201 ​ $ 1,722,673 ​ ​ ​ ​ ​ ​ ​ ​ ​ LIABILITIES AND PARTNERS' CAPITAL ​ ​ ​ ​ ​ ​ ​ CURRENT LIABILITIES: ​ ​ ​ ​ ​ ​ ​ Accrued taxes other than income taxes ​ $ 174 ​ $ 100 ​ Total current liabilities ​ 174 ​ 100 ​ Total liabilities ​ 174 ​ 100 ​ ​ ​ ​ ​ ​ ​ ​ ​ PARTNERS' CAPITAL: ​ ​ ​ ​ ​ ​ ​ Limited Partners - Common Unitholders 127,125,437 and 127,195,219 units outstanding, respectively ​ 1,896,027 ​ 1,656,025 ​ General Partner's interest ​ — ​ 66,548 ​ Total Partners' Capital ​ ​ 1,896,027 ​ ​ 1,722,573 ​ TOTAL LIABILITIES AND PARTNERS' CAPITAL ​ $ 1,896,201 ​ $ 1,722,673 ​ * See accompanying notes. ​ CONDENSED STATEMENTS OF OPERATIONS (PARENT) FOR THE YEARS ENDED DECEMBER 31, 2023, 2022 AND 2021 (In thousands, except unit and per unit data) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, ​ 2023 2022* 2021* EXPENSES: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ General and administrative ​ $ 151 ​ $ — ​ $ — ​ Total operating expenses ​ 151 ​ — ​ — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ LOSS FROM OPERATIONS ​ (151) ​ — ​ — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Interest income ​ ​ 57 ​ ​ — ​ ​ — ​ Equity in earnings of consolidated subsidiaries ​ 630,212 ​ 586,200 ​ 182,771 ​ NET INCOME ATTRIBUTABLE TO ARLP ​ $ 630,118 ​ $ 586,200 ​ $ 182,771 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ NET INCOME ATTRIBUTABLE TO ARLP ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ GENERAL PARTNER ​ $ 1,384 ​ $ 9,010 ​ $ 4,614 ​ LIMITED PARTNERS ​ $ 628,734 ​ $ 577,190 ​ $ 178,157 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ EARNINGS PER LIMITED PARTNER UNIT - BASIC AND DILUTED ​ $ 4.81 ​ $ 4.39 ​ $ 1.36 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ WEIGHTED-AVERAGE NUMBER OF UNITS OUTSTANDING – BASIC AND DILUTED ​ 127,180,312 ​ 127,195,219 ​ 127,195,219 ​ * See accompanying notes. ​ CONDENSED STATEMENTS OF CASH FLOWS (PARENT) FOR THE YEARS ENDED DECEMBER 31, 2023, 2022 AND 2021 (In thousands) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, ​ ​ 2023 2022* 2021* ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ CASH FLOWS FROM OPERATING ACTIVITIES: ​ $ 364,448 ​ $ 196,348 ​ $ 52,157 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ CASH FLOWS FROM FINANCING ACTIVITIES: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Distributions paid to Partners ​ ​ (364,579) ​ (196,347) ​ (52,158) ​ Net cash used in financing activities ​ (364,579) ​ (196,347) ​ (52,158) ​ NET CHANGE IN CASH AND CASH EQUIVALENTS ​ (131) ​ 1 ​ (1) ​ CASH AND CASH EQUIVALENTS AT BEGINNING OF PERIOD ​ 2,174 ​ 2,173 ​ 2,174 ​ CASH AND CASH EQUIVALENTS AT END OF PERIOD ​ $ 2,043 ​ $ 2,174 ​ $ 2,173 ​ * Recast as discussed in "Item 8. Financial Statements and Supplementary Data—Note 1 – Organization and Presentation" of this Annual Report on Form 10-K. See accompanying notes. ​ ​ NOTES TO FINANCIAL INFORMATION (PARENT) ​ 1. BASIS OF PRESENTATION ​ In these parent-company-only financial statements, our investment in consolidated subsidiaries is stated at cost plus equity in undistributed earnings of subsidiaries and reduced by distributions received from subsidiaries since the date of acquisition. These parent-company-only financial statements have been recast as a result of the JC Resources Acquisition as discussed in "Item 8. Financial Statements and Supplementary Data—Note 1 – Organization and Presentation" of this Annual Report on Form 10-K. These parent-company-only financial statements should be read in conjunction with our consolidated financial statements in "Item 8. Financial Statements and Supplementary Data" of this Annual Report on Form 10-K. ​ 2. GUARANTEES ​ As the parent of Alliance Coal and the Intermediate Partnership, ARLP is a guarantor of the Credit Facility and the Senior Notes discussed in "Item 8. Financial Statements and Supplementary Data—Note 6 – Long-Term Debt" of this Annual Report on Form 10-K. In addition to these guarantees, ARLP has provided guarantees on surety indemnity agreements and financially guaranteed certain coal supply agreements. The duration of these guarantees varies. The maximum undiscounted potential future payment obligation for our guarantees of certain coal supply agreements as of December 31, 2023 is approximately $75.1 million. These guarantees provide for compensation to customers based on additional cost to the customer to replace any contracted tons that our subsidiaries fail to deliver. We do not expect to make any payments under these guarantees. ​ 3. CASH DISTRIBUTIONS RECEIVED ​ We received distributions of $364.6 million, $196.3 million and $52.2 million from our consolidated subsidiaries during the years ended December 31, 2023, 2022, and 2021, respectively.

SUMMARY OF SIGNIFICANT ACCOUN_2

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Policies)	12 Months Ended
	Dec. 31, 2023
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES
Variable Interest Entity ("VIE")	Variable Interest Entity ("VIE") ​ VIEs are primarily entities that lack sufficient equity to finance their activities without additional financial support from other parties or whose equity holders, as a group, lack one or more of the following characteristics: (a) direct or indirect ability to make decisions, (b) obligation to absorb expected losses or (c) right to receive expected residual returns. A VIE must be evaluated quantitatively and qualitatively to determine the primary beneficiary, which is the reporting entity that has (a) the power to direct activities of a VIE that most significantly impact the VIE's economic performance and (b) the obligation to absorb losses of the VIE that could potentially be significant to the VIE or the right to receive benefits from the VIE that could potentially be significant to the VIE. The primary beneficiary is required to consolidate the VIE for financial reporting purposes. ​ To determine a VIE's primary beneficiary, we perform a qualitative assessment to determine which party, if any, has the power to direct activities of the VIE and the obligation to absorb losses and/or receive its benefits. This assessment involves identifying the activities that most significantly impact the VIE's economic performance and determine whether it, or another party, has the power to direct those activities. When evaluating whether we are the primary beneficiary of a VIE, we perform a qualitative analysis that considers the design of the VIE, the nature of our involvement and the variable interests held by other parties.
Business Combinations	Business Combinations ​ A business consists of inputs and processes applied to those inputs that have the ability to contribute to the creation of outputs. We account for the acquisition of a business as a business combination, where we record the assets acquired, including identified intangible assets and liabilities assumed at their fair value, which in many instances involves estimates based on third-party valuations, such as appraisals, or internal valuations based on discounted cash flow analyses or other valuation techniques. However, if substantially all the fair value of the assets acquired is concentrated in a single identifiable asset or a group of similar identifiable assets with the same risk profile, the acquisition is accounted for as an asset acquisition and recorded at cost.
Estimates	Estimates ​ The preparation of consolidated financial statements in conformity with generally accepted accounting principles of the United States ("GAAP") requires management to make estimates and assumptions that affect the reported amounts and disclosures in the consolidated financial statements. Actual results could differ from those estimates. Significant estimates and assumptions include: ​ ● Asset retirement obligations; ● Pension valuation variables; ● Workers' compensation and pneumoconiosis valuation variables; ● Acquisition related purchase price allocations; ● Life of mine assumptions; ● Oil & gas reserve quantities and carrying amounts; and ● Determination of oil & gas revenue accruals
Fair Value Measurements	Fair Value Measurements ​ We apply fair value measurements to certain assets and liabilities. Fair value is defined as the price that would be received to sell an asset or paid to transfer a liability (an exit price) in an orderly transaction between market participants at the measurement date. Fair value is based on assumptions that market participants would use when pricing an asset or liability, including assumptions about risk and risks inherent in valuation techniques and inputs to valuations. Fair value measurements assume that the transaction occurs in the principal market for the asset or liability or, in the absence of a principal market, the most advantageous market for the asset or liability (the market for which the reporting entity would be able to maximize the amount received or minimize the amount paid). Valuation techniques used in our fair value measurements are based on observable and unobservable inputs. Observable inputs reflect market data obtained from independent sources, while unobservable inputs reflect our own market assumptions. ​ We use the following fair value hierarchy, which prioritizes the inputs to valuation techniques used to measure fair value into three broad levels: ​ ● Level 1 – Quoted prices for identical assets and liabilities in active markets that we have the ability to access at the measurement date. ​ ● Level 2 – Quoted prices for similar instruments in active markets; quoted prices for identical or similar instruments in markets that are not active; and model derived valuations whose inputs are observable or whose significant value drivers are observable. ​ ● Level 3 – Unobservable inputs for the asset or liability including situations where there is little, if any, market activity for the asset or liability. ​ The fair value hierarchy gives the highest priority to quoted prices in active markets (Level 1) and the lowest priority to unobservable data (Level 3). In some cases, the inputs used to measure fair value might fall into different levels of the fair value hierarchy. The lowest level input that is significant to a fair value measurement determines the applicable level in the fair value hierarchy. Assessing the significance of a particular input to the fair value measurement requires judgment, considering factors specific to the asset or liability. Significant fair value measurements are used in our significant estimates and are discussed throughout these notes.
Cash and Cash Equivalents	Cash and Cash Equivalents ​ Cash and cash equivalents include cash on hand and on deposit, including highly liquid investments with maturities of three months or less. At times the ARLP Partnership maintains deposits in federally insured financial institutions in excess of stated federally insured limits. Management monitors the credit ratings and concentration of risk with these financial institutions on a continuing basis to safeguard cash deposits. Based on this monitoring and other diligence, including discussions with representatives of the financial institutions, we have no reason to believe that any of the financial institutions in which we have deposits in excess of stated federally insured limits are facing financial difficulties, defaults or limited liquidity situations that would cause us to be unable to access our deposits.
Cash Management	Cash Management ​ The cash flows from operating activities section of our consolidated statements of cash flows reflects an adjustment for $6.7 million representing book overdrafts at December 31, 2023. We did not have material book overdrafts at December 31, 2022 and 2021.
Inventories	Inventories ​ Coal inventories are stated at the lower of cost or net realizable value on a first-in, first-out basis. Supply inventories are stated at an average cost basis, less a reserve for obsolete and surplus items.
Advance Royalties	Advance Royalties ​ Rights to coal mineral leases are often acquired and/or maintained through advance royalty payments. Where royalty payments represent prepayments recoupable against future production, they are recorded as an asset, with amounts expected to be recouped within one year classified as a current asset. As mining occurs on these leases, the royalty prepayments are charged to operating expenses. We assess the recoverability of royalty prepayments based on estimated future production. Royalty prepayments estimated to be nonrecoverable are expensed. Our advance royalties are summarized as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, ​ ​ 2023 2022 ​ ​ ​ (in thousands) ​ ​ ​ ​ ​ ​ ​ ​ ​ Advance royalties, affiliates (see Note 20 – Related-Party Transactions) ​ $ 64,599 ​ $ 60,608 ​ Advance royalties, third-parties ​ 14,306 ​ 14,661 ​ Total advance royalties ​ $ 78,905 ​ $ 75,269 ​
Property, Plant and Equipment	Property, Plant and Equipment ​ Expenditures which extend the useful lives of existing plant and equipment assets are capitalized. Interest costs associated with major asset additions are capitalized during the construction period. Maintenance and repairs that do not extend the useful life or increase productivity of the asset are charged to operating expense as incurred. Exploration expenditures are charged to operating expense as incurred, including costs related to drilling and study costs incurred to convert or upgrade mineral resources to reserves. Processing facilities and mineral rights, assuming current production estimates, are depreciated or depleted using the units-of-production method. Mining equipment and other plant and equipment assets are depreciated principally using the straight-line method over the remaining estimated life of each mine. Buildings, office equipment and improvements are amortized straight line over their estimated useful lives. Gains or losses arising from retirements are included in operating expenses. Depletion of coal mineral rights is provided on the basis of tonnage mined in relation to estimated recoverable tonnage, which equals estimated proven and probable coal mineral reserves. Therefore, our coal mineral rights are depleted based on only proven and probable coal mineral reserves. See Oil & Gas Reserve Quantities and Carrying Amounts
Mine Development Costs	Mine Development Costs ​ Mine development costs are capitalized until production, other than production incidental to the mine development process, commences and are amortized on a units of production method based on the estimated proven and probable coal mineral reserves. Mine development costs represent costs incurred in establishing access to coal mineral reserves and include costs associated with sinking or driving shafts and underground drifts, permanent excavations, roads and tunnels. The end of the development phase and the beginning of the production phase takes place when construction of the mine for economic extraction is substantially complete. Coal extracted during the development phase is incidental to the mine's production capacity and is not considered to shift the mine into the production phase.
Oil & Gas Reserve Quantities and Carrying Amounts	Oil & Gas Reserve Quantities and Carrying Amounts ​ We are wholly dependent on third-party operators to explore, develop, produce and operate the properties associated with our mineral interests. We follow the successful efforts method of accounting for our oil & gas mineral interests. Under this method, costs to acquire mineral interests in oil & gas properties are capitalized when incurred. The costs of mineral interests in unproved properties are capitalized pending the results of exploration and leasing efforts by operators. As mineral interests in unproved properties are determined to be proved, the related costs are transferred to proved oil & gas properties. ​ Mineral interests in oil & gas properties are grouped using a reasonable aggregation of properties with a common geological structural feature or stratigraphic condition, which we may also refer to as a depletable group. Mineral interests in proved oil & gas properties are depleted based on the units-of-production method. Proved reserves are quantities of oil & gas that can be estimated with reasonable certainty to be recoverable in the future from a given date forward, from known reservoirs, under existing economic conditions, operating methods, and government regulations. Proved developed resources are the quantities expected to be recovered through the Operators' existing wells with existing equipment, infrastructure and operating methods. ​ We evaluate impairment of our oil & gas mineral interests in proved properties whenever events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable. This evaluation is performed on a depletable group basis. We compare the undiscounted projected future cash flows expected in connection with a depletable group to its unamortized carrying amount to determine recoverability. When the carrying amount of a depletable group exceeds its estimated undiscounted future cash flows, the carrying amount is written down to its fair value, which is measured as the present value of the projected future cash flows of such properties. The factors used to determine fair value include estimates of proved reserves, future commodity prices, timing of future production, future expenditures, and a risk-adjusted discount rate. ​ Our oil & gas mineral interests in unproved properties are also assessed for impairment periodically but at least annually when facts and circumstances indicate that the unproved property will not be transferred to proved properties. Impairment of individual unproved properties whose acquisition costs are relatively significant are assessed on a property-by-property basis, and an impairment loss is recognized if we determine that the unproved property will not be transferred to proved properties. Impairment of unproved properties whose acquisition costs are not individually significant are assessed on a group basis. Any amount of loss to be recognized and the amount of a valuation allowance needed to provide for impairment of those properties is determined by amortizing those properties in the aggregate on the basis of historical experience and other relevant information, such as the relative proportion of such properties on which proved reserves have been found in the past. ​ Upon the sale of a complete depletable group, the book value thereof, less proceeds or salvage value, are charged to income. Upon the sale or retirement of an aggregation of interests which make up less than a complete depletable group, the proceeds are credited to accumulated depreciation, depletion and amortization, unless doing so would significantly alter the depreciation, depletion and amortization rate of the depletable group, in which case a gain or loss would be recorded.
Equity Investments	​ Equity Investments ​ Our investments and ownership interests in equity securities without readily determinable fair values in entities in which we do not have a controlling financial interest or significant influence are accounted for using a measurement alternative other than fair value which is historical cost minus impairment, if any, plus or minus changes resulting from observable price changes in orderly transactions for identical or similar investments of the same entity. Distributions received on those investments are recorded as income unless those distributions are considered a return on investment, in which case the historical cost is reduced. We account for our ownership interests in Infinitum and Ascend as equity securities without readily determinable fair values. See Note 12 – Equity Investments for further discussion of these investments. ​ Our investments and ownership interests in entities in which we do not have a controlling financial interest are accounted for under the equity method of accounting if we have the ability to exercise significant influence over the entity. Investments accounted for under the equity method are initially recorded at cost, and the difference between the basis of our investment and the underlying equity in the net assets of the joint venture at the investment date, if any, is amortized over the lives of the related assets that gave rise to the difference. ​ In the event our ownership requires a disproportionate sharing of income or loss, we use the hypothetical liquidation at book value ("HLBV") method to determine the appropriate allocation of income or loss. Under the HLBV method, income or loss of the investee is allocated based on hypothetical amounts that each investor would be entitled to receive if the net assets held were liquidated at book value at the end of each period, adjusted for any contributions made and distributions received during the period. ​ We hold equity method investments in AllDale III, Francis and NGP ET IV. See Note 11 – Variable Interest Entities and Note 12 – Equity Investments for further discussion of our equity method investments. ​ We review our investments for impairment whenever events or changes in circumstances indicate a loss in the value of the investment may be other-than-temporary.
Leases	Leases ​ We lease buildings and equipment under operating lease agreements that provide for the payment of minimum rentals. We also have noncancelable lease agreements with third parties for land and equipment under finance lease obligations. Some of our arrangements within these agreements have both lease and non-lease components, which are generally accounted for separately. We have elected a practical expedient to account for lease and non-lease components as a single lease component for leases of buildings and office equipment. Our leases have approximate lease terms of 1 to 19 years, some of which include automatic renewals up to ten years, which are likely to be exercised and some of which include options to terminate the lease within one year. We also hold numerous mineral reserve leases with both related parties as well as third parties, none of which are accounted for as an operating lease or as a finance lease. ​ We review each agreement to determine if an arrangement within the agreement contains a lease at the inception of an arrangement. Once an arrangement is determined to contain an operating or finance lease with a term greater than 12 months, we recognize a lease liability for the obligation to make lease payments and a right-of-use asset for the right to use the underlying asset for the lease term based on the present value of lease payments over the lease term. The lease term includes all noncancelable periods defined in the lease as well as periods covered by options to extend the lease that we are reasonably certain to exercise. As an implicit borrowing rate cannot be determined under most of our leases, we use our incremental borrowing rate based on the information available at commencement date in determining the present value of lease payments. ​ Expenses related to leases determined to be operating leases will be recognized on a straight-line basis over the lease term including any reasonably assured renewal periods, while those determined to be finance leases will be recognized following a front-loaded expense profile in which interest and amortization are presented separately in the income statement. The determination of whether a lease is accounted for as a finance lease or an operating lease requires management to make estimates primarily about the fair value of the asset and its estimated economic useful life.
Common Unit-Based Compensation	Common Unit-Based Compensation ​ We maintain the Long-Term Incentive Plan ("LTIP") for certain key employees and executive officers. Pursuant to the LTIP, unit awards of non-vested "phantom" or notional units, also referred to as "restricted units," may be granted, which, upon satisfaction of time and performance-based vesting requirements, entitle the LTIP participant to receive ARLP common units. Certain awards may also contain a minimum-value guarantee payable in ARLP common units or cash that would be paid regardless of whether or not the awards vest, as long as service requirements are met. Annual grant levels, vesting provisions and minimum-value guarantees of restricted units for designated participants are recommended by Mr. Craft, subject to review and approval by the compensation committee of our general partner ("Compensation Committee"). The vesting of all restricted units is subject to the satisfaction of certain financial tests. If it is not probable that the financial tests will be achieved for a particular grant of restricted units, any previously expensed amounts for that grant are reversed, and no future expense will be recognized for that grant. Assuming the financial tests are met, restricted units issued to LTIP participants generally cliff vest on January 1st of the third year following the issuance of such restricted units. We expect to settle restricted unit grants by issuing ARLP common units, except for the portion of the restricted units that will satisfy our tax withholding obligations. We account for forfeitures of non-vested restricted unit grants as they occur. As provided under the distribution equivalent rights ("DERs") provisions of the LTIP and the terms of the restricted unit awards, all currently outstanding non-vested restricted units include contingent rights to receive quarterly distributions in cash or, at the discretion of the Compensation Committee, phantom units in lieu of cash credited to a bookkeeping account with a value equal to the cash distributions we make to unitholders during the vesting period. If it is not probable the financial tests for a particular grant of restricted units will be met, any previously paid DER amounts for that grant are reversed from Partners' Capital and recorded as compensation expense and any future DERs, for that grant, if any, will be recognized as compensation expense when paid. ​ We have utilized the Supplemental Executive Retirement Plan ("SERP") to provide deferred compensation benefits for certain executive officers. All allocations made to participants under the SERP have been made in the form of "phantom" ARLP units. We intend to settle any distributions from the SERP in the form of ARLP common units. The SERP has been administered by the Compensation Committee. ​ Our directors participate in the MGP Amended and Restated Deferred Compensation Plan for Directors ("Directors' Deferred Compensation Plan"). Pursuant to the Directors' Deferred Compensation Plan, for amounts deferred either automatically or at the election of the director, a notional account is established and credited with notional common units of ARLP, described in the Directors' Deferred Compensation Plan as "phantom" units. We intend to settle any distributions from the Directors' Deferred Compensation Plan in the form of ARLP common units. ​ For both the SERP and Directors' Deferred Compensation Plan, when quarterly cash distributions are made with respect to ARLP common units, an amount equal to such quarterly distribution is credited to each participant's notional account as additional phantom units and recorded as compensation expense. All grants of phantom units under the SERP and Directors' Deferred Compensation Plan vest immediately. ​ On December 14, 2023, the Compensation Committee and the Board of Directors approved the termination of the SERP and Directors' Deferred Compensation Plan, and authorized distribution of accounts on December 15, 2024 or as soon thereafter as practical. The accounts will continue to accrue benefits in accordance with plan terms until distributed. ​ The fair value of restricted common unit grants under the LTIP, SERP and the Directors' Deferred Compensation Plan are determined on the grant date of the award and recognized as compensation expense on a pro rata basis for LTIP and SERP awards, as appropriate, over the requisite service period. Compensation expense is fully recognized on the grant date for quarterly distributions credited to SERP accounts and Directors' Deferred Compensation Plan awards. The corresponding liability is classified as equity and included in limited partners' capital in the consolidated financial statements.
Workers' Compensation and Pneumoconiosis (Black Lung) Benefits	Workers ' Compensation and Pneumoconiosis (Black Lung) Benefits ​ We are liable for workers' compensation benefits for traumatic injuries and benefits for black lung disease (or pneumoconiosis). Both traumatic claims and pneumoconiosis benefits are covered through our self-insured programs. ​ We provide income replacement and medical treatment for work-related traumatic injury claims as required by applicable state laws. Workers' compensation laws also compensate survivors of workers who suffer employment related deaths. Our liability for traumatic injury claims is the estimated present value of current workers' compensation benefits, based on our actuarial estimates. Our actuarial calculations are based on a blend of actuarial projection methods and numerous assumptions including claim development patterns, mortality, medical costs and interest rates. ​ Our pneumoconiosis benefits liability is calculated using the service cost method based on the actuarial present value of the estimated pneumoconiosis obligation. Our actuarial calculations are based on numerous assumptions including claim development patterns, medical costs and mortality. Actuarial gains or losses are amortized over the remaining service period of active miners.
Pension Benefits	Pension Benefits ​ The funded status of our pension benefit plan is recognized separately in our consolidated balance sheets as either an asset or liability. The funded status is the difference between the fair value of plan assets and the plan's benefit obligation. Pension obligations and net periodic benefit costs are actuarially determined and impacted by various assumptions and estimates including expected return on assets, discount rates, mortality assumptions, employee turnover rates and retirement dates. We evaluate our assumptions periodically and make adjustments to these assumptions and the recorded liability as necessary. ​ The discount rate is determined for our pension benefit plan based on an approach specific to our plan. The year end discount rate is determined considering a yield curve comprised of high-quality corporate bonds and the timing of the expected benefit cash flows. ​ The expected long-term rate of return on plan assets is determined based on broad equity and bond indices, the investment goals and objectives, the target investment allocation and on the average annual total return for each asset class. ​ Unrecognized actuarial gains and losses and unrecognized prior service costs and credits are deferred and recorded in accumulated other comprehensive loss until amortized as a component of net periodic benefit cost. Unrecognized actuarial gains and losses in excess of 10% of the greater of the benefit obligation or the market-related value of plan assets are amortized over the participants' average remaining future years of service.
Asset Retirement Obligations	Asset Retirement Obligations ​ Our coal mining operations are governed by various state statutes and the Federal Surface Mining Control and Reclamation Act of 1977, which establish reclamation and mine closing standards. These regulations require, among other things, restoration of property in accordance with specified standards and an approved reclamation plan. We record a liability for the fair value of the estimated cost of future mine asset retirement and closing procedures, escalated for inflation then discounted, on a present value basis in the period incurred or acquired and a corresponding amount is capitalized by increasing the carrying amount of the related long-lived asset. Those costs relate to permanently sealing portals at underground mines and to reclaiming the final pits and support surface acreage for both our underground mines and past surface mines. Examples of these types of costs, common to both types of mining, include, but are not limited to, removing or covering refuse piles and settling ponds, water treatment obligations, and dismantling preparation plants, other facilities and roadway infrastructure. Accounting for asset retirement obligations also requires depreciation of the capitalized asset retirement cost and accretion of the asset retirement obligation over time. Depreciation is generally determined on a units-of-production basis and accretion is generally recognized over the life of the producing assets. As changes in estimates occur (such as mine plan revisions, changes in estimated costs or changes in anticipated timing of reclamation activities), the revisions to the obligation and asset are recognized at the appropriate credit-adjusted, risk-free interest rate. Federal and state laws require bonds to secure our obligations to reclaim lands used for mining and are typically renewed on an annual basis.
Revenue Recognition	Coal Revenue Recognition ​ Revenues from coal supply contracts with customers, which primarily relate to sales of thermal coal, are recognized at the point in time when control of the coal passes to the customer. We have determined that each ton of coal represents a separate and distinct performance obligation. Our coal supply contracts and other revenue contracts vary in length from short-term to long-term sales contracts and do not typically have significant financing components. Transportation revenues represent the fulfillment costs incurred for the services provided to customers through third-party carriers and for which we are directly reimbursed. Other revenues primarily consist of transloading fees, administrative service revenues from our affiliates, mine safety services and products, other coal contract fees and other handling and service fees. Performance obligations under these contracts are typically satisfied upon transfer of control of the goods or services to our customer which is determined by the contract and could be upon shipment or upon delivery. ​ The estimated transaction price from each of our contracts is based on the total amount of consideration we expect to be entitled to under the contract. Included in the transaction price for certain coal supply contracts is the impact of variable consideration, including quality price adjustments, handling services, government imposition claims, per ton price fluctuations based on certain coal sales price indices and anticipated payments in lieu of shipments. We have constrained the expected value of variable consideration in our estimation of transaction price and only included this consideration to the extent that it is probable that a significant revenue reversal will not occur. The estimated transaction price for each contract is allocated to our performance obligations based on relative standalone selling prices determined at contract inception. Variable consideration is allocated to a specific part of the contract in many instances, such as if the variable consideration is based on production activities for coal delivered during a certain period or the outcome of a customer's ability to accept coal shipments over a certain period. ​ Contract assets are recorded as trade receivables and reported separately in our consolidated balance sheet from other contract assets as title passes to the customer and our right to consideration becomes unconditional. Payments for coal shipments are typically due within two four weeks ​ Oil & Gas Revenue Recognition ​ Oil & gas royalty revenues are recognized at the point in time when control of the product is transferred to the purchaser by the lessee and collectability of the sales price is reasonably assured. Oil & gas are priced on the delivery date based on prevailing market prices with certain adjustments related to oil quality and physical location. The royalty we receive is tied to a market index, with certain adjustments based on, among other factors, whether a well connects to a gathering or transmission line, quality and heat content of the product, and prevailing supply and demand conditions. ​ We also periodically earn revenue from lease bonuses. We recognize lease bonus revenue when we execute a lease of our mineral interests to exploration and production companies. A lease agreement represents our contract with an operator, which is generally an exploration and production company. The contract will (a) generally transfer the rights to any oil or gas discovered, (b) grant us a right to a specified royalty interest from the operator, and (c) require the operator to commence drilling and complete operations within a specified time period. Control of the minerals transfers to the operator when the lease agreement is executed. At the time we execute the lease agreement, we expect to receive the lease bonus payment within a reasonable time, though in no case more than one year, such that we do not adjust the expected amount of consideration for the effects of any significant financing component. ​ As a non-operator, we have limited visibility into the timing of when new wells start producing. In addition, production statements may not be received for 30 to 90 days or more after the date production is delivered. As a result, we are required to estimate the amount of production delivered to the purchaser and the price that will be received for the sale of the product. The expected sales volumes and prices from our properties are estimated and recorded within the Trade receivables
Income Taxes	Income Taxes ​ We are not a taxable entity for federal or state income tax purposes; the tax effect of our activities accrues to our unitholders. Although publicly traded partnerships as a general rule are taxed as corporations, we qualify for an exemption because at least 90% of our income consists of qualifying income, as defined in Section 7704(c) of the Internal Revenue Code. Net income for financial statement purposes may differ significantly from taxable income reportable to unitholders as a result of differences between the tax basis and financial reporting basis of assets and liabilities and the taxable income allocation requirements under our partnership agreement. Individual unitholders have different investment bases depending upon the timing and price of acquisition of their partnership units. Furthermore, each unitholder's tax accounting, which is partially dependent upon the unitholder's tax position, differs from the accounting followed in our consolidated financial statements. Accordingly, the aggregate difference in the basis of our net assets for financial and tax reporting purposes cannot be readily determined because information regarding each unitholder's tax attributes in our partnership is not available to us. ​ Our subsidiary Alliance Minerals within our Oil & Gas Royalties segment and certain other subsidiaries within our Other, Corporate and Elimination category are subject to federal and state income taxes. We use the liability method of accounting for income taxes, under which deferred tax assets and liabilities are recognized for the future tax consequences of (i) temporary differences between the financial statement carrying amounts and the tax basis of existing assets and liabilities and (ii) operating losses and tax credit carryforwards. Deferred income tax assets and liabilities are based on enacted rates applicable to the future period when those temporary differences are expected to be recovered or settled. The effect of a change in tax status or a change in tax rates on deferred tax assets and liabilities is recognized in the period the change in status is elected or rate change is enacted. A valuation allowance is provided for deferred tax assets when it is more likely than not the deferred tax assets will not be realized.
New Accounting Standards Issued and Adopted	New Accounting Standards Issued and Not Yet Adopted ​ In November 2023, the Financial Accounting Standards Board ("FASB") issued Accounting Standards Update ("ASU") 2023-07, Segment Reporting (Topic 280): Improvements to Reportable Segment Disclosures ​ In December 2023, the FASB issued ASU 2023-09, Income Taxes (Topic 740): Improvements to Income Tax Disclosures (loss) from continuing operations before income tax (benefit) disaggregated between domestic and foreign. ASU 2023-09 is effective for fiscal years beginning after December 15, 2024, with early adoption permitted. We are currently evaluating the impact of adopting ASU 2023-09, but do not expect it to have a material effect on our consolidated financial statements.

SUMMARY OF SIGNIFICANT ACCOUN_3

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Tables)	12 Months Ended
	Dec. 31, 2023
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES
Summary of advance royalties	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, ​ ​ 2023 2022 ​ ​ ​ (in thousands) ​ ​ ​ ​ ​ ​ ​ ​ ​ Advance royalties, affiliates (see Note 20 – Related-Party Transactions) ​ $ 64,599 ​ $ 60,608 ​ Advance royalties, third-parties ​ 14,306 ​ 14,661 ​ Total advance royalties ​ $ 78,905 ​ $ 75,269 ​

ACQUISITIONS (Tables)

ACQUISITIONS (Tables)	12 Months Ended
	Dec. 31, 2023
Acquisition
Schedule of asset acquisition	​ ​ ​ ​ ​ ​ ​ ​ (in thousands) ​ ​ ​ ​ ​ Mineral interests in proved properties ​ $ 12,542 ​ Mineral interests in unproved properties ​ ​ 18,418 ​ ​ ​ $ 30,960 ​
Belvedere
Acquisition
Summary of assets acquired and liabilities assumed	​ ​ ​ ​ ​ ​ ​ ​ (in thousands) ​ ​ ​ ​ ​ Mineral interests in proved properties ​ $ 7,724 ​ Mineral interests in unproved properties ​ ​ 3,667 ​ ​ ​ $ 11,391 ​
Schedule of pro forma income statement	​ ​ ​ ​ ​ ​ Year Ended ​ ​ December 31, ​ ​ 2022 ​ (in thousands) ​ ​ ​ ​ Revenue $ 722 ​ Net income 488 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended ​ ​ ​ December 31, ​ ​ 2022 2021 ​ ​ ​ (in thousands) ​ ​ ​ (unaudited) ​ Revenues ​ $ 2,420,824 ​ $ 1,580,373 ​ Net income ​ ​ 588,916 ​ ​ 184,361 ​
Jase
Acquisition
Summary of assets acquired and liabilities assumed	​ ​ ​ ​ ​ ​ ​ ​ (in thousands) ​ ​ ​ ​ ​ Mineral interests in proved properties ​ $ 35,918 ​ Mineral interests in unproved properties ​ ​ 43,740 ​ Receivables ​ ​ 1,569 ​ Net assets acquired ​ $ 81,227 ​
Schedule of pro forma income statement	​ ​ ​ ​ ​ ​ Year Ended ​ ​ December 31, ​ ​ 2022 ​ (in thousands) ​ ​ ​ ​ Revenue $ 1,689 ​ Net income 854 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended ​ ​ ​ December 31, ​ ​ 2022 2021 ​ ​ ​ (in thousands) ​ ​ ​ (unaudited) ​ Revenues ​ $ 2,430,734 ​ $ 1,588,914 ​ Net income ​ ​ 596,759 ​ ​ 190,765 ​
Skyland
Acquisition
Summary of assets acquired and liabilities assumed	​ ​ ​ ​ ​ ​ ​ ​ (in thousands) ​ ​ ​ ​ ​ Mineral interests in proved properties ​ $ 8,694 ​ Mineral interests in unproved properties ​ ​ 5,765 ​ Net assets acquired ​ $ 14,459 ​
Schedule of pro forma income statement	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended ​ ​ ​ December 31, ​ ​ 2023 2022 ​ ​ ​ (in thousands) ​ ​ ​ (unaudited) ​ Revenues ​ $ 2,568,516 ​ $ 2,423,313 ​ Net income ​ ​ 637,757 ​ ​ 591,140 ​

INVENTORIES (Tables)

INVENTORIES (Tables)	12 Months Ended
	Dec. 31, 2023
INVENTORIES
Schedule of inventories	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, ​ ​ ​ 2023 2022 ​ ​ (in thousands) ​ ​ ​ ​ ​ ​ ​ ​ ​ Coal ​ $ 56,549 ​ $ 23,553 ​ Supplies (net of reserve for obsolescence of $8,167 and $6,601, respectively) ​ 71,007 ​ 53,773 ​ Total inventories, net ​ $ 127,556 ​ $ 77,326 ​

PROPERTY, PLANT AND EQUIPMENT (

PROPERTY, PLANT AND EQUIPMENT (Tables)	12 Months Ended
	Dec. 31, 2023
PROPERTY, PLANT AND EQUIPMENT
Schedule of property, plant and equipment	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, ​ ​ 2023 2022 ​ ​ ​ (in thousands) ​ ​ ​ ​ ​ ​ ​ ​ ​ Mining equipment and processing facilities ​ $ 1,989,541 ​ $ 1,927,603 ​ Land and coal mineral rights ​ 504,736 ​ 499,950 ​ Oil & gas mineral interests ​ ​ 853,350 ​ ​ 814,667 ​ Buildings, office equipment, improvements and other miscellaneous equipment ​ 310,876 ​ 300,436 ​ Construction, mine development and other projects in progress ​ 184,895 ​ 99,042 ​ Mine development costs ​ 329,146 ​ 289,724 ​ Property, plant and equipment, at cost ​ 4,172,544 ​ 3,931,422 ​ Less accumulated depreciation, depletion and amortization ​ (2,149,881) ​ (2,050,754) ​ Total property, plant and equipment, net ​ $ 2,022,663 ​ $ 1,880,668 ​

LONG-TERM DEBT (Tables)

LONG-TERM DEBT (Tables)	12 Months Ended
	Dec. 31, 2023
LONG-TERM DEBT
Schedule of long-term debt	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Unamortized Discount and ​ ​ ​ Principal ​ Debt Issuance Costs ​ ​ ​ December 31, ​ December 31, ​ ​ 2023 2022 2023 2022 ​ ​ (in thousands) ​ Revolving credit facility ​ $ — ​ $ — ​ $ (8,118) ​ $ (2,702) ​ Term loan ​ 60,938 ​ — ​ (1,416) ​ — ​ Senior notes ​ 284,607 ​ 400,000 ​ (891) ​ (2,134) ​ Securitization facility ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ November 2019 equipment financing ​ ​ — ​ ​ 21,072 ​ ​ — ​ ​ — ​ June 2020 equipment financing ​ ​ 2,039 ​ ​ 5,937 ​ ​ — ​ ​ — ​ ​ ​ 347,584 ​ 427,009 ​ (10,425) ​ (4,836) ​ Less current maturities ​ (20,789) ​ (24,970) ​ 451 ​ — ​ Total long-term debt ​ $ 326,795 ​ $ 402,039 ​ $ (9,974) ​ $ (4,836) ​
Schedule of aggregate maturities of long-term debt	​ ​ ​ ​ ​ ​ Year Ended ​ ​ ​ ​ December 31, (in thousands) 2024 ​ $ 20,789 ​ 2025 ​ 303,357 ​ 2026 ​ 18,750 ​ 2027 ​ 4,688 ​ ​ ​ $ 347,584 ​ ​

INCOME TAXES (Tables)

INCOME TAXES (Tables)	12 Months Ended
	Dec. 31, 2023
INCOME TAXES
Components of income tax expense	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, ​ 2023 2022 2021 ​ ​ (in thousands) ​ Current: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Federal ​ $ 15,917 ​ $ 17,572 ​ $ (1) ​ State ​ 1,336 ​ 1,605 ​ 70 ​ ​ ​ 17,253 ​ 19,177 ​ 69 ​ Deferred: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Federal ​ (7,235) ​ 33,038 ​ 356 ​ State ​ (1,738) ​ 1,763 ​ (8) ​ ​ ​ (8,973) ​ 34,801 ​ 348 ​ Income tax expense ​ $ 8,280 ​ $ 53,978 ​ $ 417 ​
Reconciliation from provision for income taxes at U.S. federal statutory rate to effective tax rate	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, ​ ​ 2023 2022 2021 ​ ​ ​ (in thousands) ​ Income taxes at statutory rate ​ $ 135,335 ​ $ 134,849 ​ $ 38,595 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Less: Income taxes at statutory rate on Partnership income not subject to income taxes ​ (119,556) ​ (113,925) ​ (37,546) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Increase (decrease) resulting from: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ State taxes, net of federal income tax ​ 864 ​ 1,492 ​ 275 ​ Change in valuation allowance of deferred tax assets ​ — ​ (317) ​ (834) ​ Deferred taxes related to tax election ​ ​ — ​ ​ 37,253 ​ ​ — ​ Tax effect of noncontrolling interest income not subject to income taxes ​ ​ (1,361) ​ ​ (5,399) ​ ​ — ​ Return to accrual adjustments ​ ​ (7,008) ​ ​ 69 ​ ​ (1) ​ Other ​ 6 ​ (44) ​ (72) ​ Income tax expense ​ $ 8,280 ​ $ 53,978 ​ $ 417 ​
Components of deferred tax liabilities and deferred tax assets	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, ​ 2023 2022 ​ ​ (in thousands) ​ Deferred tax liabilities: ​ ​ ​ ​ ​ ​ ​ Property, plant and equipment ​ $ (36,453) ​ $ (38,349) ​ Total deferred tax liabilities ​ ​ (36,453) ​ ​ (38,349) ​ ​ ​ ​ ​ ​ ​ ​ ​ Deferred tax assets: ​ ​ ​ ​ ​ ​ ​ Federal loss carryovers and credits ​ ​ 4,508 ​ ​ 2,139 ​ State loss carryovers and credits ​ ​ 2,126 ​ ​ 951 ​ Capitalized research and development ​ ​ 2,567 ​ ​ — ​ Other ​ 1,098 ​ 133 ​ Total deferred tax assets ​ ​ 10,299 ​ ​ 3,223 ​ ​ ​ ​ ​ ​ ​ ​ ​ Overall net deferred tax liabilities ​ $ (26,154) ​ $ (35,126) ​

LEASES (Tables)

LEASES (Tables)	12 Months Ended
	Dec. 31, 2023
LEASES
Schedule of lease cost and other information	The components of lease expense were as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, ​ ​ ​ 2023 ​ 2022 2021 ​ ​ (in thousands) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Finance lease cost: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Amortization of right-of-use assets ​ $ 96 ​ $ 597 ​ $ 597 ​ Interest on lease liabilities ​ 27 ​ 73 ​ 147 ​ Operating lease cost ​ 3,572 ​ 2,884 ​ 2,404 ​ Short-term lease cost ​ ​ — ​ ​ — ​ ​ 200 ​ Variable lease cost ​ 1,680 ​ 1,665 ​ 1,306 ​ Total lease cost ​ $ 5,375 ​ $ 5,219 ​ $ 4,654 ​ Supplemental cash flow information related to leases was as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, ​ ​ ​ 2023 ​ 2022 2021 ​ ​ (in thousands) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cash paid for amounts included in the measurement of lease liabilities: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Operating cash flows for operating leases ​ $ 3,720 ​ $ 2,880 ​ $ 2,367 ​ Operating cash flows for finance leases ​ $ 27 ​ $ 73 ​ $ 147 ​ Financing cash flows for finance leases ​ $ 363 ​ $ 840 ​ $ 766 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Right-of-use assets obtained in exchange for lease obligations: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Operating leases ​ $ 2,596 ​ $ 1,315 ​ $ 189 ​ ​ Supplemental balance sheet information related to leases was as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, ​ ​ ​ 2023 2022 ​ ​ ​ (in thousands) ​ Finance leases: ​ ​ ​ ​ ​ ​ ​ Property and equipment finance lease assets, gross ​ $ 1,085 ​ $ 5,485 ​ Accumulated depreciation ​ (507) ​ (5,061) ​ Property and equipment finance lease assets, net ​ $ 578 ​ $ 424 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, ​ ​ ​ 2023 2022 ​ Weighted average remaining lease term ​ ​ ​ ​ ​ ​ ​ Operating leases ​ ​ 11.7 years ​ ​ 13.4 years ​ Finance leases ​ ​ 4.0 years ​ ​ 5.0 years ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted average discount rate ​ ​ ​ ​ ​ ​ ​ Operating leases ​ ​ 6.0 % ​ ​ 6.0 % ​ Finance leases ​ 4.8 % ​ ​ 4.8 % ​
Schedule of maturities of operating lease liabilities	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Operating leases Finance leases ​ ​ ​ (in thousands) ​ ​ ​ ​ ​ ​ ​ ​ ​ 2024 ​ $ 3,437 ​ $ 140 ​ 2025 ​ ​ 2,403 ​ ​ 140 ​ 2026 ​ ​ 1,923 ​ ​ 140 ​ 2027 ​ ​ 1,930 ​ ​ 140 ​ 2028 ​ ​ 1,646 ​ ​ — ​ Thereafter ​ ​ 12,122 ​ ​ — ​ Total lease payments ​ ​ 23,461 ​ ​ 560 ​ Less imputed interest ​ ​ (6,869) ​ ​ (55) ​ Total ​ $ 16,592 ​ $ 505 ​
Schedule of maturities of finance lease liabilities	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Operating leases Finance leases ​ ​ ​ (in thousands) ​ ​ ​ ​ ​ ​ ​ ​ ​ 2024 ​ $ 3,437 ​ $ 140 ​ 2025 ​ ​ 2,403 ​ ​ 140 ​ 2026 ​ ​ 1,923 ​ ​ 140 ​ 2027 ​ ​ 1,930 ​ ​ 140 ​ 2028 ​ ​ 1,646 ​ ​ — ​ Thereafter ​ ​ 12,122 ​ ​ — ​ Total lease payments ​ ​ 23,461 ​ ​ 560 ​ Less imputed interest ​ ​ (6,869) ​ ​ (55) ​ Total ​ $ 16,592 ​ $ 505 ​ ​

FAIR VALUE MEASUREMENTS (Tables

FAIR VALUE MEASUREMENTS (Tables)	12 Months Ended
	Dec. 31, 2023
FAIR VALUE MEASUREMENTS
Summary of fair value measurements within the hierarchy	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, 2023 ​ December 31, 2022 ​ ​ Level 1 Level 2 Level 3 Level 1 Level 2 Level 3 ​ ​ (in thousands) ​ Long-term debt ​ $ — ​ $ 347,116 ​ $ — ​ $ — ​ $ 424,420 ​ $ — ​

PARTNERS' CAPITAL (Tables)

PARTNERS' CAPITAL (Tables)	12 Months Ended
	Dec. 31, 2023
PARTNERS' CAPITAL
Summary of quarterly per unit distribution paid	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, ​ 2023 2022 2021 First Quarter ​ $ 0.700 ​ $ 0.250 ​ $ — ​ Second Quarter ​ $ 0.700 ​ $ 0.350 ​ $ 0.100 ​ Third Quarter ​ $ 0.700 ​ $ 0.400 ​ $ 0.100 ​ Fourth Quarter ​ $ 0.700 ​ $ 0.500 ​ $ 0.200 ​

VARIABLE INTEREST ENTITIES (Tab

VARIABLE INTEREST ENTITIES (Tables)	12 Months Ended
	Dec. 31, 2023
VARIABLE INTEREST ENTITIES
Schedule of assets and liabilities	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, ​ ​ ​ 2023 2022 ​ Assets (liabilities): (in thousands) Cash and cash equivalents ​ $ 4,690 ​ $ 4,698 ​ Trade receivables ​ 16,058 ​ 13,933 ​ Total property, plant and equipment, net ​ 389,767 ​ 406,135 ​ Accounts payable ​ ​ (175) ​ ​ (257) ​ Due to affiliates ​ — ​ ​ (24) ​ Accrued taxes other than income taxes ​ (958) ​ ​ (206) ​

EQUITY INVESTMENTS (Tables)

EQUITY INVESTMENTS (Tables)	12 Months Ended
	Dec. 31, 2023
All Dale Minerals III
Investments
Schedule of changes in equity method investments	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, ​ ​ 2023 2022 2021 ​ ​ (in thousands) Beginning balance ​ $ 25,284 ​ $ 26,325 ​ $ 27,268 Equity method investment income ​ ​ 2,567 ​ ​ 5,634 ​ ​ 2,130 Distributions received ​ ​ (3,918) ​ ​ (6,675) ​ ​ (3,073) Ending balance ​ $ 23,933 ​ $ 25,284 ​ $ 26,325
Francis Renewable Energy
Investments
Schedule of changes in equity method investments	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, ​ ​ ​ 2023 2022 ​ ​ (in thousands) ​ Beginning balance ​ $ 20,000 ​ $ — ​ Contributions ​ ​ — ​ ​ 20,000 ​ Equity method investment loss ​ ​ (3,513) ​ ​ — ​ Ending balance ​ $ 16,487 ​ $ 20,000 ​
NGP ET IV
Investments
Schedule of changes in equity method investments	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, ​ ​ ​ 2023 2022 ​ ​ ​ (in thousands) ​ Beginning balance ​ $ 4,087 ​ $ — ​ Contributions ​ ​ 2,518 ​ ​ 4,087 ​ Equity method investment loss ​ ​ (522) ​ ​ — ​ Ending balance ​ $ 6,083 ​ $ 4,087 ​

REVENUE FROM CONTRACTS WITH C_2

REVENUE FROM CONTRACTS WITH CUSTOMERS (Tables)	12 Months Ended
	Dec. 31, 2023
REVENUE FROM CONTRACTS WITH CUSTOMERS
Schedule of disaggregation of revenues by type	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Coal Operations ​ Royalties ​ Other, ​ ​ ​ ​ ​ ​ Illinois ​ ​ ​ ​ Corporate and ​ ​ ​ ​ Basin Appalachia Oil & Gas Coal Elimination Consolidated ​ ​ ​ (in thousands) ​ Year Ended December 31, 2023 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Coal sales ​ $ 1,364,901 ​ $ 845,309 ​ $ — ​ $ — ​ $ — ​ $ 2,210,210 ​ Oil & gas royalties ​ ​ — ​ ​ — ​ ​ 137,751 ​ ​ — ​ ​ — ​ ​ 137,751 ​ Coal royalties ​ ​ — ​ ​ — ​ ​ — ​ ​ 65,572 ​ ​ (65,572) ​ ​ — ​ Transportation revenues ​ ​ 106,150 ​ ​ 36,140 ​ ​ — ​ ​ — ​ ​ — ​ ​ 142,290 ​ Other revenues ​ ​ 10,505 ​ ​ 1,885 ​ ​ 3,774 ​ ​ 42 ​ ​ 60,244 ​ ​ 76,450 ​ Total revenues ​ $ 1,481,556 ​ $ 883,334 ​ $ 141,525 ​ $ 65,614 ​ $ (5,328) ​ $ 2,566,701 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, 2022 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Coal sales ​ $ 1,219,943 ​ $ 882,286 ​ $ — ​ $ — ​ $ — ​ $ 2,102,229 ​ Oil & gas royalties ​ ​ — ​ ​ — ​ ​ 151,060 ​ ​ — ​ ​ — ​ ​ 151,060 ​ Coal royalties ​ ​ — ​ ​ — ​ ​ — ​ ​ 60,624 ​ ​ (60,624) ​ ​ — ​ Transportation revenues ​ ​ 69,540 ​ ​ 44,320 ​ ​ — ​ ​ — ​ ​ — ​ ​ 113,860 ​ Other revenues ​ ​ 6,822 ​ ​ 1,481 ​ ​ 3,837 ​ ​ 56 ​ ​ 40,622 ​ ​ 52,818 ​ Total revenues ​ $ 1,296,305 ​ $ 928,087 ​ $ 154,897 ​ $ 60,680 ​ $ (20,002) ​ $ 2,419,967 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, 2021 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Coal sales ​ $ 873,930 ​ $ 512,993 ​ $ — ​ $ — ​ $ — ​ $ 1,386,923 ​ Oil & gas royalties ​ ​ — ​ ​ — ​ ​ 84,183 ​ ​ — ​ ​ — ​ ​ 84,183 ​ Coal royalties ​ ​ — ​ ​ — ​ ​ — ​ ​ 51,402 ​ ​ (51,402) ​ ​ — ​ Transportation revenues ​ ​ 41,001 ​ ​ 28,606 ​ ​ — ​ ​ — ​ ​ — ​ ​ 69,607 ​ Other revenues ​ ​ 4,666 ​ ​ 3,940 ​ ​ 2,256 ​ ​ 69 ​ ​ 27,586 ​ ​ 38,517 ​ Total revenues ​ $ 919,597 ​ $ 545,539 ​ $ 86,439 ​ $ 51,471 ​ $ (23,816) ​ $ 1,579,230 ​
Schedule of current coal supply contracts allocated to performance obligations that are unsatisfied or partially unsatisfied	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 2027 and ​ ​ ​ ​ 2024 2025 2026 Thereafter Total ​ ​ (in thousands) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Illinois Basin Coal Operations coal revenues ​ $ 1,291,152 ​ $ 494,386 ​ $ 253,465 ​ $ 238,500 ​ $ 2,277,503 ​ Appalachia Coal Operations coal revenues ​ ​ 754,183 ​ ​ 325,425 ​ ​ 1,600 ​ ​ — ​ ​ 1,081,208 ​ Total coal revenues (1) ​ $ 2,045,335 ​ $ 819,811 ​ $ 255,065 ​ $ 238,500 ​ $ 3,358,711 ​ (1) Coal revenues generally consists of consolidated revenues excluding our Oil & Gas Royalties segment as well as intercompany revenues from our Coal Royalties segment .

EARNINGS PER LIMITED PARTNER _2

EARNINGS PER LIMITED PARTNER UNIT (Tables)	12 Months Ended
	Dec. 31, 2023
EARNINGS PER LIMITED PARTNER UNIT
Reconciliation of net income (loss) and EPU calculations	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, ​ ​ 2023 2022 2021 ​ ​ ​ (in thousands, except per unit data) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net income attributable to ARLP ​ $ 630,118 ​ $ 586,200 ​ $ 182,771 ​ Less: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ General partner's interest in net income attributable to ARLP ​ (1,384) ​ (9,010) ​ (4,614) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Limited partners' interest in net income attributable to ARLP ​ 628,734 ​ 577,190 ​ 178,157 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Less: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Distributions to participating securities ​ (9,688) ​ (8,527) ​ (2,334) ​ Undistributed earnings attributable to participating securities ​ (7,203) ​ (10,576) ​ (2,403) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net income attributable to ARLP available to limited partners ​ $ 611,843 ​ $ 558,087 ​ $ 173,420 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted-average limited partner units outstanding – basic and diluted ​ 127,180 ​ 127,195 ​ 127,195 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Earnings per limited partner unit - basic and diluted (1) ​ $ 4.81 ​ $ 4.39 ​ $ 1.36 ​ (1) Diluted EPU gives effect to all potentially dilutive common units outstanding during the period using the treasury stock method. Diluted EPU excludes all potentially dilutive units calculated under the treasury stock method if their effect is anti-dilutive. For the years ended December 31, 2023, 2022 and 2021, the combined total of LTIP, SERP and Directors' Deferred Compensation Plan units of 2,922,384 , 3,540,385 and 1,967,672 , respectively, were considered anti-dilutive under the treasury stock method.

EMPLOYEE BENEFIT PLANS (Tables)

EMPLOYEE BENEFIT PLANS (Tables) - Defined benefit pension plan	12 Months Ended
	Dec. 31, 2023
Employee Benefit Plans
Summary of benefit plans for employees	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, ​ ​ ​ 2023 2022 ​ ​ (dollars in thousands) ​ Change in benefit obligations: ​ ​ ​ ​ ​ ​ ​ Benefit obligations at beginning of year ​ $ 104,682 ​ $ 139,566 ​ Interest cost ​ 5,180 ​ 3,749 ​ Actuarial loss (gain) ​ 2,446 ​ (32,996) ​ Benefits paid ​ (6,438) ​ (5,637) ​ Benefit obligations at end of year ​ 105,870 ​ 104,682 ​ ​ ​ ​ ​ ​ ​ ​ ​ Change in plan assets: ​ ​ ​ ​ ​ ​ ​ Fair value of plan assets at beginning of year ​ 92,129 ​ 113,976 ​ Actual return on plan assets ​ 11,561 ​ (16,210) ​ Benefits paid ​ (6,438) ​ (5,637) ​ Fair value of plan assets at end of year ​ 97,252 ​ 92,129 ​ Funded status at the end of year ​ $ (8,618) ​ $ (12,553) ​ ​ ​ ​ ​ ​ ​ ​ ​ Amounts recognized in balance sheet: ​ ​ ​ ​ ​ ​ ​ Non-current liability ​ $ (8,618) ​ $ (12,553) ​ ​ ​ ​ ​ ​ ​ ​ ​ Amounts recognized in accumulated other comprehensive income consists of: ​ ​ ​ ​ ​ ​ ​ Prior service cost ​ $ (196) ​ $ (382) ​ Net actuarial loss ​ ​ (11,584) ​ ​ (15,160) ​ ​ ​ $ (11,780) ​ $ (15,542) ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted-average assumption to determine benefit obligations as of December 31, ​ ​ ​ ​ ​ ​ ​ Discount rate ​ 4.90% ​ 5.10% ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted-average assumptions used to determine net periodic benefit cost for the year ended December 31, ​ ​ ​ ​ ​ ​ ​ Discount rate ​ 5.10% ​ 2.73% ​ Expected return on plan assets ​ 7.00% ​ 6.00% ​
Schedule of long-term rate of return assumptions	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Asset allocation ​ As of December 31, 2023 assumption Equity securities ​ 75% ​ Fixed income securities 25% ​ ​ 100% ​
Components of net periodic benefit cost	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, ​ 2023 2022 2021 ​ ​ ​ (in thousands) Components of net periodic benefit cost (credit): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Interest cost ​ $ 5,180 ​ $ 3,749 ​ $ 3,438 ​ Expected return on plan assets ​ (6,220) ​ (6,638) ​ (6,580) ​ Amortization of prior service cost ​ ​ 186 ​ ​ 186 ​ ​ 186 ​ Amortization of net loss ​ 682 ​ 1,963 ​ 4,327 ​ Net periodic benefit cost (credit) (1) ​ $ (172) ​ $ (740) ​ $ 1,371 ​ (1) Nonservice components of net periodic benefit cost (credit) are included in the Other income (expense) line item within our consolidated statements of income.
Schedule of other changes in plan assets and benefit obligation recognized in accumulated other comprehensive income	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, ​ ​ 2023 2022 ​ ​ ​ (in thousands) ​ Other changes in plan assets and benefit obligation recognized in accumulated other comprehensive loss: ​ ​ ​ ​ ​ ​ ​ Net actuarial gain ​ $ 2,894 ​ $ 10,148 ​ Reversal of amortization item: ​ ​ ​ ​ ​ ​ ​ Prior service cost ​ ​ 186 ​ ​ 186 ​ Net actuarial loss ​ 682 ​ 1,963 ​ Total recognized in accumulated other comprehensive loss ​ 3,762 ​ 12,297 ​ Net periodic benefit cost ​ 172 ​ 740 ​ Total recognized in net periodic benefit cost and accumulated other comprehensive loss ​ $ 3,934 ​ $ 13,037 ​
Schedule of estimated future benefit payments	​ ​ ​ ​ ​ ​ Year Ended ​ ​ ​ ​ December 31, (in thousands) ​ ​ ​ ​ ​ 2024 ​ $ 6,331 ​ 2025 ​ 6,490 ​ 2026 ​ 6,688 ​ 2027 ​ 6,820 ​ 2028 ​ 6,899 ​ 2029-2033 ​ 35,204 ​ ​ ​ $ 68,432 ​
Schedule of asset allocation guidelines, actual asset allocations and fair value of Pension Plan assets	​ ​ ​ ​ ​ ​ ​ ​ ​ Percentage of Total Portfolio ​ Minimum Maximum ​ ​ ​ ​ ​ ​ Equity securities ​ 50% ​ 85% ​ Fixed income securities ​ 15% ​ 50% ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, ​ ​ 2023 ​ 2022 ​ ​ ​ Level 1 ​ Level 2 ​ Level 3 ​ Total ​ Level 1 ​ Level 2 ​ Level 3 ​ Total ​ ​ ​ (in thousands) Cash and cash equivalents ​ $ 1,665 ​ $ — ​ $ — ​ $ 1,665 ​ $ 5,422 ​ $ — ​ $ — ​ $ 5,422 ​ Equity investments - Individual securities (a): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Consumer discretionary ​ ​ 2,605 ​ ​ — ​ ​ — ​ ​ 2,605 ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ Consumer durables ​ ​ 2,088 ​ ​ — ​ ​ — ​ ​ 2,088 ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ Energy ​ ​ 952 ​ ​ — ​ ​ — ​ ​ 952 ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ Financials ​ ​ 4,852 ​ ​ — ​ ​ — ​ ​ 4,852 ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ Health Care ​ ​ 4,296 ​ ​ — ​ ​ — ​ ​ 4,296 ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ Industrials & materials ​ ​ 4,507 ​ ​ — ​ ​ — ​ ​ 4,507 ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ Information technology & communication ​ ​ 8,102 ​ ​ — ​ ​ — ​ ​ 8,102 ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ Fixed income investments - Individual securities (b): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Preferred stocks non-convertible ​ ​ 37 ​ ​ — ​ ​ — ​ ​ 37 ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ Equity investments - Mutual funds (c): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Mid-cap stock funds ​ ​ 11,847 ​ ​ — ​ ​ — ​ ​ 11,847 ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ Small-cap stock funds ​ ​ 4,007 ​ ​ — ​ ​ — ​ ​ 4,007 ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ International stock funds ​ ​ 7,849 ​ ​ — ​ ​ — ​ ​ 7,849 ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ Equity investments - Exchange traded funds (d): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Large-cap blend - S&P 500 index ​ ​ 18,044 ​ ​ — ​ ​ — ​ ​ 18,044 ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ International - Developed markets ​ ​ 3,138 ​ ​ — ​ ​ — ​ ​ 3,138 ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ International - Emerging markets ​ ​ 1,894 ​ ​ — ​ ​ — ​ ​ 1,894 ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ Accrued income (e) ​ ​ — ​ ​ 29 ​ ​ — ​ ​ 29 ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ ​ $ 75,883 ​ $ 29 ​ $ — ​ $ 75,912 ​ $ 5,422 ​ $ — ​ $ — ​ $ 5,422 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Commingled investment funds measured at net asset value (f): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Equities - United States ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 36,259 ​ Equities - United States futures ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (697) ​ Equities - International developed markets ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 14,214 ​ Equities - International developed markets futures ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (1,693) ​ Equities - International emerging markets ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 782 ​ Equities - International emerging markets futures ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 3,289 ​ Fixed income - Investment grade ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 21,340 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 13,856 ​ Fixed income - High yield ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 156 ​ Fixed income - Futures ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 8,590 ​ Alternatives ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 11,951 ​ Total ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ $ 97,252 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ $ 92,129 ​ (a) Equity investments - Individual securities include investments in publicly traded common stock and American Depository Receipts. Publicly traded common stocks are traded on a national securities exchange and investments in common stocks are valued using quoted market prices multiplied by the number of shares owned. American Depository Receipts are negotiable securities issued by a bank representing shares in a foreign company and traded on a national securities exchange. (b) Fixed income investments - Individual securities include investments in preferred stock that are traded on a national securities exchange and valued using quoted market prices multiplied by the number of shares owned. (c) Equity investments - Mutual funds are valued daily in actively traded markets. For purposes of calculating the value, portfolio securities and other assets for which market quotes are readily available are valued at market value. Investments initially valued in currencies other than the U.S. dollars are converted to the U.S. dollar using exchange rates obtained from pricing services. (d) Equity investments – Exchange traded funds are funds that own financial assets and trade on exchanges, generally tracking a specific index. Investments in exchange traded funds are valued using a market approach based on the quoted market prices. (e) Accrued income represents dividends or interest declared, but not received, on equity securities owned at December 31, 2023. (f) Investments measured at fair value using the net asset value per share (or its equivalent) have not been classified within the fair value hierarchy. The fair values of all commingled investment funds are determined based on the net asset values per unit of each of the funds. The net asset values per unit represent the aggregate value of the fund's assets at fair value less liabilities, divided by the number of units outstanding .

COMMON UNIT-BASED COMPENSATIO_2

COMMON UNIT-BASED COMPENSATION PLANS (Tables)	12 Months Ended
	Dec. 31, 2023
ARLP LTIP
COMMON UNIT-BASED COMPENSATION PLANS
Summary of activity in share-based plans	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Number of units Weighted average grant date fair value per unit Intrinsic value ​ ​ ​ ​ ​ ​ ​ (in thousands) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Non-vested grants at January 1, 2021 ​ 1,430,489 ​ $ 5.02 ​ $ 6,409 ​ Granted (1) ​ 1,818,190 ​ ​ 6.03 ​ ​ ​ ​ Forfeited ​ (118,204) ​ 5.48 ​ ​ ​ ​ Non-vested grants at December 31, 2021 ​ 3,130,475 ​ ​ 5.59 ​ ​ 39,569 ​ Granted (1) ​ 769,907 ​ ​ 14.65 ​ ​ ​ ​ Forfeited ​ (203,249) ​ 6.93 ​ ​ ​ ​ Non-vested grants at December 31, 2022 ​ 3,697,133 ​ ​ 7.40 ​ ​ 75,126 ​ Granted (1) 450,125 ​ ​ 21.54 ​ ​ ​ ​ Vested (2) (1,291,330) ​ 5.02 ​ ​ ​ ​ Forfeited (145,584) ​ 6.86 ​ ​ ​ ​ Non-vested grants at December 31, 2023 2,710,344 ​ 10.91 ​ ​ 57,405 ​ (1) Restricted units granted have certain minimum-value guarantees per unit, regardless of whether or not the awards vest . (2) During the year ended December 31, 2023, we issued 860,060 unrestricted common units to the LTIP participants. The remaining vested units were settled in cash to satisfy our tax withholding obligations.
SERP and Deferred Compensation Plans
COMMON UNIT-BASED COMPENSATION PLANS
Summary of activity in share-based plans	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Number of units Weighted average grant date fair value per unit Intrinsic value ​ ​ ​ ​ ​ ​ ​ (in thousands) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Phantom units outstanding as of January 1, 2021 ​ 760,630 ​ $ 22.04 ​ $ 3,408 ​ Granted ​ 46,638 ​ ​ 9.45 ​ ​ ​ ​ Settled (1) ​ (138,570) ​ ​ 25.86 ​ ​ ​ ​ Phantom units outstanding as of December 31, 2021 ​ 668,698 ​ ​ 20.37 ​ ​ 8,452 ​ Granted ​ 73,842 ​ ​ 19.44 ​ ​ ​ ​ Phantom units outstanding as of December 31, 2022 ​ 742,540 ​ ​ 20.28 ​ ​ 15,088 ​ Granted ​ 118,737 ​ ​ 20.46 ​ ​ ​ ​ Settled (1) (49,331) ​ ​ 20.27 ​ ​ ​ ​ Phantom units outstanding as of December 31, 2023 811,946 ​ 20.44 ​ ​ 17,197 ​ (1) During the years ended December 31, 2023 and 2021, we purchased 27,576 ARLP common units and 102,962 ARLP common units on the open market to settle the accounts of participants under the SERP. Units purchased were net of units settled in cash to satisfy tax-withholding obligations.

SUPPLEMENTAL CASH FLOW INFORM_2

SUPPLEMENTAL CASH FLOW INFORMATION (Tables)	12 Months Ended
	Dec. 31, 2023
SUPPLEMENTAL CASH FLOW INFORMATION
Schedule of supplemental cash flow information	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, ​ 2023 2022 2021 ​ ​ (in thousands) ​ Cash Paid For: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Interest ​ $ 37,126 ​ $ 34,844 ​ $ 36,402 ​ Income taxes ​ $ 13,615 ​ $ 23,794 ​ $ 11 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Non-Cash Activity: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Accounts payable for purchase of property, plant and equipment ​ $ 14,586 ​ $ 44,281 ​ $ 8,325 ​ Right-of-use assets acquired by operating lease ​ $ 2,596 ​ $ 1,315 ​ $ 189 ​ Market value of common units distributed under deferred compensation plans before tax withholding requirements ​ $ 28,906 ​ $ — ​ $ 1,082 ​ ​

ASSET RETIREMENT OBLIGATIONS (T

ASSET RETIREMENT OBLIGATIONS (Tables)	12 Months Ended
	Dec. 31, 2023
ASSET RETIREMENT OBLIGATIONS
Schedule of activity affecting the asset retirement and mine closing liability	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, ​ 2023 2022 ​ ​ (in thousands) ​ ​ ​ ​ ​ ​ ​ ​ ​ Beginning balance ​ $ 149,813 ​ $ 131,099 ​ Accretion expense ​ 4,433 ​ 3,731 ​ Payments ​ (2,317) ​ (2,445) ​ Allocation of liability associated with mine development and change in assumptions ​ (1,486) ​ 17,428 ​ Ending balance ​ $ 150,443 ​ $ 149,813 ​
Schedule of estimated payments of asset retirement obligations	​ ​ ​ ​ ​ ​ Year Ended ​ ​ ​ ​ December 31, (in thousands) ​ ​ ​ ​ ​ 2024 ​ $ 3,518 ​ 2025 ​ 5,557 ​ 2026 ​ 4,063 ​ 2027 ​ 7,038 ​ 2028 ​ 4,291 ​ Thereafter ​ 242,134 ​ Aggregate undiscounted asset retirement obligations ​ 266,601 ​ Less: effect of discounting ​ (116,158) ​ Total asset retirement obligations ​ 150,443 ​ Less: current portion ​ (3,518) ​ Non-current asset retirement obligations ​ $ 146,925 ​

ACCRUED WORKERS' COMPENSATION_2

ACCRUED WORKERS' COMPENSATION AND PNEUMOCONIOSIS BENEFITS (Tables)	12 Months Ended
	Dec. 31, 2023
Black lung benefits:
Reconciliation of changes in workers' compensation liability	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, ​ ​ ​ 2023 2022 ​ ​ ​ ​ ​ ​ ​ ​ ​ Beginning balance ​ $ 49,452 ​ $ 53,448 ​ Changes in accruals ​ 12,155 ​ 7,384 ​ Payments ​ (14,438) ​ (12,708) ​ Interest accretion ​ 2,202 ​ 1,147 ​ Valuation loss (gain) ​ (1,396) ​ 181 ​ Ending balance ​ $ 47,975 ​ $ 49,452 ​
Reconciliation of changes in pneumoconiosis benefit obligation	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, ​ ​ 2023 2022 ​ ​ ​ (in thousands) ​ ​ ​ ​ ​ ​ ​ ​ ​ Benefit obligations at beginning of year ​ $ 104,287 ​ $ 111,316 ​ Service cost ​ 2,698 ​ 3,798 ​ Interest cost ​ 4,951 ​ 2,991 ​ Actuarial loss (gain) ​ 25,615 ​ (9,840) ​ Benefits and expenses paid ​ (5,107) ​ (3,978) ​ Benefit obligations at end of year ​ $ 132,444 ​ $ 104,287 ​
Components of pneumoconiosis and workers' compensation expense	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, ​ 2023 2022 2021 ​ ​ ​ (in thousands) ​ Black lung benefits: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Service cost $ 2,698 ​ $ 3,798 ​ $ 4,021 ​ Interest cost (1) ​ 4,951 ​ 2,991 ​ 2,545 ​ Net amortization (1) ​ 1,382 ​ 1,038 ​ 4,172 ​ Total pneumoconiosis expense ​ 9,031 ​ 7,827 ​ 10,738 ​ Workers' compensation expense ​ 15,152 ​ 11,675 ​ 8,339 ​ Net periodic benefit cost ​ $ 24,183 ​ $ 19,502 ​ $ 19,077 ​ ________________________________________ (1) Interest cost and net amortization is included in the Other income line item within our consolidated statements of income .
Pneumoconiosis benefits
Black lung benefits:
Reconciliation of changes in the pneumoconiosis benefit obligation recognized in AOCI	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, ​ ​ 2023 2022 2021 ​ ​ (in thousands) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net actuarial gain (loss) ​ $ (25,615) ​ $ 9,840 ​ $ (161) ​ Reversal of amortization item: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net actuarial loss ​ 1,382 ​ 1,038 ​ 4,172 ​ Total recognized in accumulated other comprehensive loss ​ $ (24,233) ​ $ 10,878 ​ $ 4,011 ​
Schedule of amount recognized in accumulated other comprehensive income	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, ​ ​ 2023 2022 2021 ​ ​ (in thousands) ​ Amount recognized in accumulated other comprehensive loss consists of: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net actuarial loss ​ $ 49,745 ​ $ 25,510 ​ $ 36,388 ​
Summary of information about amounts recognized in the consolidated balance sheets	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, ​ ​ 2023 2022 ​ ​ (in thousands) ​ ​ ​ ​ ​ ​ ​ ​ ​ Workers' compensation claims ​ $ 47,975 ​ $ 49,452 ​ Pneumoconiosis benefit claims ​ ​ 132,444 ​ ​ 104,287 ​ Total obligations ​ 180,419 ​ 153,739 ​ Less current portion ​ (15,913) ​ (14,099) ​ Non-current obligations ​ $ 164,506 ​ $ 139,640 ​

RELATED-PARTY TRANSACTIONS (Tab

RELATED-PARTY TRANSACTIONS (Tables)	12 Months Ended
	Dec. 31, 2023
RELATED-PARTY TRANSACTIONS
Summary of advanced royalties outstanding	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ WKY CoalPlay ​ ​ ​ ​ ​ ​ ​ Towhead ​ Webster ​ Henderson ​ WKY ​ ​ ​ ​ ​ Craft Foundations ​ Coal ​ Coal ​ Coal ​ CoalPlay ​ ​ ​ ​ ​ ​ ​ Henderson ​ ​ ​ ​ ​ Henderson ​ ​ ​ ​ ​ ​ Tunnel ​ & Union ​ Webster ​ Henderson ​ & Union ​ ​ ​ ​ ​ ​ Ridge ​ Counties, KY ​ County, KY ​ County, KY ​ Counties, KY ​ Total ​ ​ ​ Acquired ​ Acquired ​ Acquired ​ Acquired ​ Acquired ​ ​ ​ ​ ​ ​ 2005 ​ 2014 ​ 2014 ​ 2014 ​ 2015 ​ ​ ​ ​ ​ (in thousands) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ As of January 1, 2021 ​ $ 1,500 ​ $ 19,178 ​ $ — ​ $ 15,129 ​ $ 12,582 ​ $ 48,389 ​ Payments ​ ​ 3,000 ​ ​ 3,597 ​ ​ 2,568 ​ ​ 2,521 ​ ​ 2,131 ​ ​ 13,817 ​ Recoupment ​ ​ (3,000) ​ ​ (1,025) ​ ​ — ​ ​ — ​ ​ — ​ ​ (4,025) ​ Unrecoupable ​ ​ — ​ ​ — ​ ​ (2,568) ​ ​ — ​ ​ — ​ ​ (2,568) ​ As of December 31, 2021 ​ ​ 1,500 ​ ​ 21,750 ​ ​ — ​ ​ 17,650 ​ ​ 14,713 ​ ​ 55,613 ​ Payments ​ ​ 3,000 ​ ​ 3,597 ​ ​ — ​ ​ 2,522 ​ ​ 2,131 ​ ​ 11,250 ​ Recoupment ​ ​ (3,000) ​ ​ (3,255) ​ ​ — ​ ​ — ​ ​ — ​ ​ (6,255) ​ Unrecoupable ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ As of December 31, 2022 ​ ​ 1,500 ​ ​ 22,092 ​ ​ — ​ ​ 20,172 ​ ​ 16,844 ​ ​ 60,608 ​ Payments ​ ​ 3,000 ​ ​ 3,597 ​ ​ — ​ ​ 2,521 ​ ​ 2,131 ​ ​ 11,249 ​ Recoupment ​ ​ (3,000) ​ ​ (4,258) ​ ​ — ​ ​ — ​ ​ — ​ ​ (7,258) ​ Unrecoupable ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ As of December 31, 2023 ​ $ 1,500 ​ $ 21,431 ​ $ — ​ $ 22,693 ​ $ 18,975 ​ $ 64,599 ​

CONCENTRATION OF CREDIT RISK _2

CONCENTRATION OF CREDIT RISK AND MAJOR CUSTOMERS (Tables)	12 Months Ended
	Dec. 31, 2023
CONCENTRATION OF CREDIT RISK AND MAJOR CUSTOMERS
Schedule of total revenues from major customers	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, ​ Segment 2023 ​ 2022 ​ 2021 ​ ​ ​ ​ (in thousands) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Customer A Illinois Basin/Appalachia ​ $ 332,500 ​ $ — ​ $ — ​ Customer B ​ Illinois Basin ​ ​ 253,573 ​ ​ 260,146 ​ ​ — ​ Customer C ​ Illinois Basin ​ ​ — ​ ​ 328,406 ​ ​ 239,482 ​ Customer D Illinois Basin/Appalachia ​ — ​ ​ 228,480 ​ — ​

SEGMENT INFORMATION (Tables)

SEGMENT INFORMATION (Tables)	12 Months Ended
	Dec. 31, 2023
SEGMENT INFORMATION
Schedule of reportable segment results	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Coal Operations ​ Royalties ​ Other, ​ ​ ​ ​ ​ Illinois ​ ​ ​ ​ ​ Corporate and ​ ​ ​ ​ Basin Appalachia Oil & Gas Coal ​ Elimination Consolidated ​ ​ (in thousands) Year Ended December 31, 2023 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Revenues - Outside (1) ​ $ 1,481,556 ​ $ 883,334 ​ $ 141,525 ​ $ 42 ​ $ 60,244 ​ $ 2,566,701 ​ Revenues - Intercompany ​ ​ — ​ ​ — ​ ​ — ​ ​ 65,572 ​ ​ (65,572) ​ ​ — ​ Total revenues (1) ​ ​ 1,481,556 ​ ​ 883,334 ​ ​ 141,525 ​ ​ 65,614 ​ ​ (5,328) ​ ​ 2,566,701 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Segment Adjusted EBITDA Expense (2) ​ 861,288 ​ ​ 516,471 ​ ​ 16,532 ​ ​ 24,451 ​ ​ (14,024) ​ 1,404,718 ​ Segment Adjusted EBITDA (3) ​ 514,118 ​ ​ 330,723 ​ ​ 121,508 ​ ​ 41,163 ​ ​ 4,661 ​ 1,012,173 ​ Total assets ​ 966,102 ​ ​ 488,427 ​ ​ 781,184 ​ ​ 315,592 ​ ​ 237,121 ​ 2,788,426 ​ Capital expenditures (4) ​ 257,885 ​ ​ 116,217 ​ ​ — ​ ​ 400 ​ ​ 4,836 ​ 379,338 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, 2022 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Revenues - Outside (1) ​ $ 1,296,305 ​ $ 928,087 ​ $ 154,897 ​ $ 56 ​ $ 40,622 ​ $ 2,419,967 ​ Revenues - Intercompany ​ ​ — ​ ​ — ​ ​ — ​ ​ 60,624 ​ ​ (60,624) ​ ​ — ​ Total revenues (1) ​ ​ 1,296,305 ​ ​ 928,087 ​ ​ 154,897 ​ ​ 60,680 ​ ​ (20,002) ​ ​ 2,419,967 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Segment Adjusted EBITDA Expense (2) ​ 806,080 ​ ​ 464,029 ​ ​ 15,395 ​ ​ 21,871 ​ ​ (23,497) ​ 1,283,878 ​ Segment Adjusted EBITDA (3) ​ 420,684 ​ ​ 426,402 ​ ​ 143,179 ​ ​ 38,809 ​ ​ 3,495 ​ 1,032,569 ​ Total assets ​ 779,018 ​ ​ 431,913 ​ ​ 778,465 ​ ​ 321,587 ​ ​ 417,038 ​ 2,728,021 ​ Capital expenditures (4) ​ 158,624 ​ ​ 76,603 ​ ​ — ​ ​ 38,276 ​ ​ 12,891 ​ 286,394 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, 2021 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Revenues - Outside (1) ​ $ 919,597 ​ $ 545,539 ​ $ 86,439 ​ $ 69 ​ $ 27,586 ​ $ 1,579,230 ​ Revenues - Intercompany ​ ​ — ​ ​ — ​ ​ — ​ ​ 51,402 ​ ​ (51,402) ​ ​ — ​ Total revenues (1) ​ ​ 919,597 ​ ​ 545,539 ​ ​ 86,439 ​ ​ 51,471 ​ ​ (23,816) ​ ​ 1,579,230 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Segment Adjusted EBITDA Expense (2) ​ 613,303 ​ 344,332 ​ 11,051 ​ 18,269 ​ ​ (33,198) ​ 953,757 ​ Segment Adjusted EBITDA (3) ​ 265,292 ​ 172,601 ​ 76,920 ​ 33,202 ​ ​ 9,383 ​ 557,398 ​ Total assets ​ 676,091 ​ 420,144 ​ 698,702 ​ 285,943 ​ ​ 146,601 ​ 2,227,481 ​ Capital expenditures (4) ​ 60,166 ​ 47,577 ​ — ​ 45 ​ ​ 15,196 ​ 122,984 ​ (1) Revenues included in the Other, Corporate and Elimination column are attributable to intercompany eliminations, which are primarily intercompany coal royalties eliminations, outside revenues at the Matrix Group and other outside miscellaneous sales and revenue activities. ​ (2) Segment Adjusted EBITDA Expense includes operating expenses, coal purchases and other income. Transportation expenses are excluded as transportation revenues are recognized in an amount equal to transportation expenses when title passes to the customer. ​ The following is a reconciliation of Operating expenses (excluding depreciation, depletion and amortization) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, ​ 2023 2022 2021 ​ ​ (in thousands) ​ Operating expenses (excluding depreciation, depletion and amortization) ​ $ 1,368,787 ​ $ 1,288,082 ​ $ 944,419 ​ Outside coal purchases ​ 36,149 ​ 151 ​ 6,372 ​ Other expense (income) ​ (218) ​ (4,355) ​ 2,966 ​ Segment Adjusted EBITDA Expense ​ $ 1,404,718 ​ $ 1,283,878 ​ $ 953,757 ​ ​ (3) Segment Adjusted EBITDA is defined as net income attributable to ARLP before net interest expense, income taxes, depreciation, depletion and amortization and general and administrative expense. Management therefore is able to focus solely on the evaluation of segment operating profitability as it relates to our revenues and operating expenses, which are primarily controlled by our segments. Net income , the most comparable GAAP financial measure, is reconciled to consolidated Segment Adjusted EBITDA: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, ​ 2023 2022 2021 ​ ​ (in thousands) ​ Net income ​ $ 636,170 ​ $ 588,158 ​ $ 183,369 ​ Noncontrolling interest ​ ​ (6,052) ​ ​ (1,958) ​ ​ (598) ​ Net income attributable to ARLP ​ $ 630,118 ​ $ 586,200 ​ $ 182,771 ​ General and administrative ​ 79,096 ​ 80,425 ​ 70,275 ​ Depreciation, depletion and amortization ​ 267,982 ​ 276,670 ​ 264,794 ​ Interest expense, net ​ 26,697 ​ 35,296 ​ 39,141 ​ Income tax expense ​ 8,280 ​ 53,978 ​ 417 ​ Consolidated Segment Adjusted EBITDA ​ $ 1,012,173 ​ $ 1,032,569 $ 557,398 ​ ​ (4) Capital expenditures shown exclude $110.9 million, $92.6 million and $31.0 million paid for oil & gas acquisitions in 2023, 2022 and 2021, respectively. See Note 3 – Acquisitions for more information.
Reconciliation of consolidated Segment Adjusted EBITDA Expense to operating expenses (excluding depreciation, depletion and amortization)	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, ​ 2023 2022 2021 ​ ​ (in thousands) ​ Operating expenses (excluding depreciation, depletion and amortization) ​ $ 1,368,787 ​ $ 1,288,082 ​ $ 944,419 ​ Outside coal purchases ​ 36,149 ​ 151 ​ 6,372 ​ Other expense (income) ​ (218) ​ (4,355) ​ 2,966 ​ Segment Adjusted EBITDA Expense ​ $ 1,404,718 ​ $ 1,283,878 ​ $ 953,757 ​
Reconciliation of consolidated Segment Adjusted EBITDA to net income	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, ​ 2023 2022 2021 ​ ​ (in thousands) ​ Net income ​ $ 636,170 ​ $ 588,158 ​ $ 183,369 ​ Noncontrolling interest ​ ​ (6,052) ​ ​ (1,958) ​ ​ (598) ​ Net income attributable to ARLP ​ $ 630,118 ​ $ 586,200 ​ $ 182,771 ​ General and administrative ​ 79,096 ​ 80,425 ​ 70,275 ​ Depreciation, depletion and amortization ​ 267,982 ​ 276,670 ​ 264,794 ​ Interest expense, net ​ 26,697 ​ 35,296 ​ 39,141 ​ Income tax expense ​ 8,280 ​ 53,978 ​ 417 ​ Consolidated Segment Adjusted EBITDA ​ $ 1,012,173 ​ $ 1,032,569 $ 557,398 ​

ORGANIZATION AND PRESENTATION (

ORGANIZATION AND PRESENTATION (Details) $ in Thousands								12 Months Ended
	Dec. 07, 2023 USD ($) a	Sep. 08, 2023 USD ($)	Feb. 22, 2023 USD ($) a	Oct. 26, 2022 USD ($) a	Sep. 09, 2022 USD ($) a	Apr. 05, 2022 USD ($)	Oct. 13, 2021 USD ($) a	Dec. 31, 2023 USD ($) a	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)	Aug. 22, 2023 USD ($)	Jun. 02, 2022 USD ($)
Ownership interests
Royalty acres, net | a								67,700
Oil & gas royalty acquisition								$ 24,225		$ 30,960
Payments for acquisitions of businesses								14,459	$ 92,618
JC Resources acquisition								(72,250)
Revenues								2,566,701	2,419,967	1,579,230
Income from operations								672,397	667,443	223,763
Contributions to equity method investments								(2,518)	(24,087)
Payment to acquire investment								49,560	42,000
Equity investment without readily determinable fair value								92,541	42,000
Infinitum
Ownership interests
Payment to acquire investment		$ 24,600							42,000
Ascend
Ownership interests
Equity investment without readily determinable fair value											$ 25,000
Francis Renewable Energy
Ownership interests
Contributions to equity method investments						$ (20,000)			(20,000)
NGP ET IV
Ownership interests
Contributions to equity method investments								(2,518)	(4,087)
Funding commitment												$ 25,000
Belvedere
Ownership interests
Royalty acres, net | a					394
Payments for acquisitions of businesses					$ 11,400
Jase
Ownership interests
Royalty acres, net | a				3,928
Payments for acquisitions of businesses				$ 81,200
Skyland
Ownership interests
Royalty acres, net | a	2,372
Payments for acquisitions of businesses	$ 14,500
Boulders
Ownership interests
Royalty acres, net | a							1,480
Oil & gas royalty acquisition							$ 31,000
JC Resources
Ownership interests
Royalty acres, net | a			2,682
JC Resources acquisition			$ 72,300
Revenues								$ 10,600	13,500	9,300
Income from operations									$ 9,000	$ 4,600

SUMMARY OF SIGNIFICANT ACCOUN_4

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Cash Management (Details) $ in Millions	Dec. 31, 2023 USD ($)
Cash Management
Book overdrafts	$ 6.7

SUMMARY OF SIGNIFICANT ACCOUN_5

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Advance Royalties (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Advance Royalties
Advance royalties, affiliates	$ 64,599	$ 60,608
Advance royalties, third-parties	14,306	14,661
Total advance royalties, net	$ 78,905	$ 75,269

SUMMARY OF SIGNIFICANT ACCOUN_6

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Leases (Details)	12 Months Ended
	Dec. 31, 2023
Lease renewal term	10 years
Lease termination option term	1 year
Minimum
Lease term	1 year
Maximum
Lease term	19 years

SUMMARY OF SIGNIFICANT ACCOUN_7

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Additional Information (Details)	12 Months Ended
	Dec. 31, 2023
Minimum
Revenue Recognition
Coal shipments, payment period	14 days
Maximum
Revenue Recognition
Coal shipments, payment period	28 days
Defined benefit pension plan
Employee Benefit Plans
Threshold for amortization of unrecognized actuarial gains and losses (as a percent)	10%

ACQUISITIONS - Asset acquisitio

ACQUISITIONS - Asset acquisition (Details) $ in Thousands			12 Months Ended
	Feb. 22, 2023 USD ($) a	Oct. 13, 2021 USD ($) a	Dec. 31, 2023 USD ($) a	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)	Feb. 19, 2024 USD ($)	Jan. 27, 2023 USD ($)
Asset acquisition
Oil & gas royalty acquisition			$ 24,225		$ 30,960
JC Resources acquisition			$ 64,999
Royalty acres, net | a			67,700
Revenues			$ 2,566,701	$ 2,419,967	1,579,230
Boulders
Asset acquisition
Oil & gas royalty acquisition		$ 31,000
Royalty acres, net | a		1,480
Mineral interests in proved properties		$ 12,542
Mineral interests in unproved properties		18,418
Total mineral interest		$ 30,960
Acquisition Agreement
Asset acquisition
Funding commitment						$ 25,000	$ 35,000
Mineral interests in proved properties			6,500
Mineral interests in unproved properties			6,700
Miscellaneous Acquisitions
Asset acquisition
Mineral interests in proved properties			6,800	1,300
Mineral interests in unproved properties			4,300	400
JC Resources
Asset acquisition
JC Resources acquisition	$ 65,000
Royalty acres, net | a	2,682
Mineral interests in proved properties	$ 25,400
Mineral interests in unproved properties	$ 37,800
Revenues			$ 10,600	$ 13,500	$ 9,300

ACQUISITIONS - Business Combina

ACQUISITIONS - Business Combination (Details) $ in Thousands				12 Months Ended
	Dec. 07, 2023 USD ($) a	Oct. 26, 2022 USD ($) a	Sep. 09, 2022 USD ($) a	Dec. 31, 2023 USD ($) a	Dec. 31, 2022 USD ($)
Acquisition
Royalty acres, net | a				67,700
Payments for acquisitions of businesses				$ 14,459	$ 92,618
Belvedere
Acquisition
Royalty acres, net | a			394
Payments for acquisitions of businesses			$ 11,400
Assets acquired and liabilities assumed
Mineral interests in proved properties			7,724
Mineral interests in unproved properties			3,667
Net assets acquired			$ 11,391
Jase
Acquisition
Royalty acres, net | a		3,928
Payments for acquisitions of businesses		$ 81,200
Assets acquired and liabilities assumed
Mineral interests in proved properties		35,918
Mineral interests in unproved properties		43,740
Receivables		1,569
Net assets acquired		$ 81,227
Skyland
Acquisition
Royalty acres, net | a	2,372
Payments for acquisitions of businesses	$ 14,500
Assets acquired and liabilities assumed
Mineral interests in proved properties	8,694
Mineral interests in unproved properties	5,765
Net assets acquired	$ 14,459

ACQUISITIONS - Pro Forma (Detai

ACQUISITIONS - Pro Forma (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Belvedere
Acquisitions, additional information
Revenue of acquired business		$ 722
Net income of acquired business		488
Pro forma condensed consolidated income statement
Total revenues, Pro forma		2,420,824	$ 1,580,373
Net income, Pro forma		588,916	184,361
Jase
Acquisitions, additional information
Revenue of acquired business		1,689
Net income of acquired business		854
Pro forma condensed consolidated income statement
Total revenues, Pro forma		2,430,734	1,588,914
Net income, Pro forma		596,759	$ 190,765
Skyland
Pro forma condensed consolidated income statement
Total revenues, Pro forma	$ 2,568,516	2,423,313
Net income, Pro forma	$ 637,757	$ 591,140

INVENTORIES (Details)

INVENTORIES (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
INVENTORIES
Coal	$ 56,549	$ 23,553
Supplies (net of reserve for obsolescence of $8,167 and $6,601, respectively)	71,007	53,773
Total inventories, net	127,556	77,326
Reserve for obsolescence	8,167	6,601
Reduce inventory carrying value to market	$ 33,296	$ 364	$ 70

PROPERTY, PLANT AND EQUIPMENT_2

PROPERTY, PLANT AND EQUIPMENT (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
PROPERTY, PLANT AND EQUIPMENT
Property, plant and equipment, at cost	$ 4,172,544	$ 3,931,422
Less accumulated depreciation, depletion and amortization	(2,149,881)	(2,050,754)
Total property, plant and equipment, net	2,022,663	1,880,668
Depreciation	$ 276,400	273,800	$ 260,300
Minimum
PROPERTY, PLANT AND EQUIPMENT
Estimated useful life	1 year
Maximum
PROPERTY, PLANT AND EQUIPMENT
Estimated useful life	20 years
Mining Equipment
PROPERTY, PLANT AND EQUIPMENT
Property, plant and equipment, at cost	$ 1,989,541	1,927,603
Land And Mineral Rights
PROPERTY, PLANT AND EQUIPMENT
Property, plant and equipment, at cost	504,736	499,950
Coal reserves not subject to depletion	13,400	29,900
Oil and gas mineral interests
PROPERTY, PLANT AND EQUIPMENT
Property, plant and equipment, at cost	853,350	814,667
Unproved properties	411,600	422,700
Buildings, Office Equipment And Improvements
PROPERTY, PLANT AND EQUIPMENT
Property, plant and equipment, at cost	310,876	300,436
Construction and mine development in progress
PROPERTY, PLANT AND EQUIPMENT
Property, plant and equipment, at cost	184,895	99,042
Mine development costs
PROPERTY, PLANT AND EQUIPMENT
Property, plant and equipment, at cost	329,146	289,724
Mine development costs	$ 44,400	$ 11,300

LONG-TERM DEBT - Components (De

LONG-TERM DEBT - Components (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Principal
Aggregate maturities of long-term debt	$ 347,584	$ 427,009
Less current maturities	(20,789)	(24,970)
Total long-term debt	326,795	402,039
Unamortized Discount and Debt Issuance Costs
Unamortized debt issuance costs including current and non-current	(10,425)	(4,836)
Less current maturities	451
Total unamortized debt issuance costs	(9,974)	(4,836)
Revolving credit facility
Unamortized Discount and Debt Issuance Costs
Unamortized debt issuance costs including current and non-current	(8,118)	(2,702)
Term loan
Principal
Aggregate maturities of long-term debt	60,938
Unamortized Discount and Debt Issuance Costs
Unamortized debt issuance costs including current and non-current	(1,416)
Senior notes
Principal
Aggregate maturities of long-term debt	284,607	400,000
Unamortized Discount and Debt Issuance Costs
Unamortized debt issuance costs including current and non-current	(891)	(2,134)
November 2019 equipment financing
Principal
Aggregate maturities of long-term debt		21,072
June 2020 equipment financing
Principal
Aggregate maturities of long-term debt	$ 2,039	$ 5,937

LONG-TERM DEBT - Credit Facilit

LONG-TERM DEBT - Credit Facility (Details) - USD ($) $ in Thousands		12 Months Ended
	Jan. 13, 2023	Dec. 31, 2023	Dec. 31, 2021	Mar. 09, 2020
Long-Term Debt
Debt issuance costs incurred		$ 12,376	$ 113
Credit Agreement
Long-Term Debt
Maximum borrowing capacity	$ 425,000
Minimum liquidity to extend maturity	$ 200,000
Periodic payments (as a percent)	6.25%
Debt issuance costs incurred		$ 12,400
Interest coverage ratio	3
Actual cash flow to interest expense ratio for trailing twelve months		63.86
ARLP debt arrangements requirements, period over which the ratios are required to be maintained		12 months
Credit Agreement | Overnight Bank Funding Rate
Long-Term Debt
Basis spread for variable interest rate (as a percent)	0.50%
Credit Agreement | Daily Simple Secured Overnight Financing Rate
Long-Term Debt
Basis spread for variable interest rate (as a percent)	1%
Credit Agreement | Alliance Coal
Long-Term Debt
ARLP debt arrangements requirements, debt to cash flow ratio	1.5
Actual debt to cash flow ratio for trailing twelve months		0.08
Credit Agreement | Alliance Coal and Intermediate Partnership
Long-Term Debt
ARLP debt arrangements requirements, debt to cash flow ratio	2.5
Actual debt to cash flow ratio for trailing twelve months		0.46
Letters of credit subfacility
Long-Term Debt
Maximum borrowing capacity	$ 425,000
Swingline subfacility
Long-Term Debt
Maximum borrowing capacity	15,000
Term loan
Long-Term Debt
Maximum borrowing term loan	$ 75,000
Term loan | Three-month term rate
Long-Term Debt
Effective interest rate (as a percent)		8.50%
Revolving credit facility
Long-Term Debt
Maximum borrowing capacity				$ 459,500
Letters of credit outstanding		$ 41,000
Debt available for borrowing		$ 384,000
Annual commitment fee percentage, undrawn portion		0.50%
Restricted net assets of subsidiaries		$ 797,200
Other
Long-Term Debt
Maximum borrowing capacity		5,000
Letters of credit outstanding		$ 5,000

LONG-TERM DEBT - 2025 Senior No

LONG-TERM DEBT - 2025 Senior Notes (Details) - USD ($) $ in Thousands		12 Months Ended
	Apr. 24, 2017	Dec. 31, 2023
Issuance of Senior Notes
Senior debt repaid		$ 129,455
Senior notes due 2025
Issuance of Senior Notes
Principal amount	$ 400,000
Term	8 years
Interest rate (as a percent)	7.50%
Senior debt repaid		$ 115,400

LONG-TERM DEBT - Securitization

LONG-TERM DEBT - Securitization Facility (Details) - Securitization facility - USD ($) $ in Millions	Jan. 31, 2024	Dec. 31, 2023
Long-Term Debt
Maximum borrowing capacity	$ 90	$ 60
Letters of credit outstanding		11.7
Debt available for borrowing		48.3
Facility outstanding amount		$ 0

LONG-TERM DEBT - Equipment fina

LONG-TERM DEBT - Equipment financing and other (Details) - USD ($) $ in Millions	Jun. 05, 2020	Nov. 06, 2019
November 2019 Equipment Financing
Long-Term Debt
Principal amount		$ 53.1
Effective interest rate (as a percent)		4.75%
June 2020 equipment financing
Long-Term Debt
Principal amount	$ 14.7
Term	48 months
Effective interest rate (as a percent)	6.10%

LONG-TERM DEBT - Maturities (De

LONG-TERM DEBT - Maturities (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Aggregate maturities of long-term debt
2024	$ 20,789
2025	303,357
2026	18,750
2027	4,688
Aggregate maturities of long-term debt	$ 347,584	$ 427,009

INCOME TAXES - Components (Deta

INCOME TAXES - Components (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Current:
Federal	$ 15,917	$ 17,572	$ (1)
State	1,336	1,605	70
Total current income tax expense	17,253	19,177	69
Deferred:
Federal	(7,235)	33,038	356
State	(1,738)	1,763	(8)
Total deferred income tax expense	(8,973)	34,801	348
Income tax expense	$ 8,280	$ 53,978	$ 417

INCOME TAXES - Tax election (De

INCOME TAXES - Tax election (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Taxes
Deferred tax liability	$ 26,154	$ 35,126
Earnings per limited partner unit - basic (in dollars per unit)	$ 4.81	$ 4.39	$ 1.36
Earnings per limited partner unit - diluted (in dollars per unit)	$ 4.81	$ 4.39	$ 1.36
AllDale I and II
Taxes
Acquisition gain				$ 177,000
Change in tax accounting
Taxes
Deferred tax liability		$ 37,300
Earnings per limited partner unit - basic (in dollars per unit)		$ 0.29
Earnings per limited partner unit - diluted (in dollars per unit)		$ 0.29

INCOME TAXES - Reconciliation (

INCOME TAXES - Reconciliation (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
INCOME TAXES
Income taxes at statutory rate	$ 135,335	$ 134,849	$ 38,595
Less: Income taxes at statutory rate on Partnership income not subject to income taxes	(119,556)	(113,925)	(37,546)
Increase/(decrease) resulting from:
State taxes, net of federal income tax	864	1,492	275
Change in valuation allowance of deferred tax assets		(317)	(834)
Deferred taxes related to tax election		37,253
Tax effect of noncontrolling interest income not subject to income taxes	(1,361)	(5,399)
Return to accrual adjustments	(7,008)	69	(1)
Other	6	(44)	(72)
Income tax expense	$ 8,280	$ 53,978	$ 417

INCOME TAXES - Deferred tax (De

INCOME TAXES - Deferred tax (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Deferred tax liabilities:
Property, plant and equipment	$ (36,453)	$ (38,349)
Deferred tax liabilities	(36,453)	(38,349)
Deferred tax assets:
Federal loss carryovers and credits	4,508	2,139
State loss carryovers and credits	2,126	951
Capitalized research and development	2,567
Other	1,098	133
Total deferred tax assets	10,299	3,223
Overall net deferred tax liabilities	$ (26,154)	$ (35,126)

LEASES - Lease expense (Details

LEASES - Lease expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
LEASES
Amortization of right-of-use assets	$ 96	$ 597	$ 597
Interest on lease liabilities	27	73	147
Operating lease cost	3,572	2,884	2,404
Short-term lease cost			200
Variable lease cost	1,680	1,665	1,306
Total lease cost	5,375	5,219	4,654
Rental expense	$ 5,700	$ 5,100	$ 3,300

LEASES - Cash flow (Details)

LEASES - Cash flow (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
LEASES
Operating cash flows for operating leases	$ 3,720	$ 2,880	$ 2,367
Operating cash flows for finance leases	27	73	147
Financing cash flows for finance leases	363	840	766
Operating leases, Right-of-use assets obtained in exchange for lease obligations	$ 2,596	$ 1,315	$ 189

LEASES - Balance Sheet (Details

LEASES - Balance Sheet (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Lease balance sheet information
Property and equipment finance lease assets, gross	$ 1,085	$ 5,485
Accumulated depreciation	(507)	(5,061)
Property and equipment finance lease assets, net	$ 578	$ 424
Finance Lease, Right-of-Use Asset, Statement of Financial Position [Extensible Enumeration]	Property, Plant, and Equipment and Finance Lease Right-of-Use Asset, after Accumulated Depreciation and Amortization	Property, Plant, and Equipment and Finance Lease Right-of-Use Asset, after Accumulated Depreciation and Amortization

LEASES - Weighted Average (Deta

LEASES - Weighted Average (Details)	Dec. 31, 2023	Dec. 31, 2022
LEASES
Weighted average remaining lease term of operating leases	11 years 8 months 12 days	13 years 4 months 24 days
Weighted average remaining lease term of finance leases	4 years	5 years
Weighted average discount rate of operating leases (as a percent)	6%	6%
Weighted average discount rate of finance leases (as a percent)	4.80%	4.80%

LEASES - Maturities (Details)

LEASES - Maturities (Details) $ in Thousands	Dec. 31, 2023 USD ($)
Operating leases
2024	$ 3,437
2025	2,403
2026	1,923
2027	1,930
2028	1,646
Thereafter	12,122
Total lease payments	23,461
Less imputed interest	(6,869)
Total	$ 16,592
Operating Lease, Liability, Statement of Financial Position [Extensible Enumeration]	Operating Lease, Liability, Noncurrent, Other Liabilities, Current
Finance leases
2024	$ 140
2025	140
2026	140
2027	140
Total lease payments	560
Less imputed interest	(55)
Total	$ 505
Finance Lease, Liability, Statement of Financial Position [Extensible Enumeration]	Other Liabilities, Current, Other Liabilities, Noncurrent

FAIR VALUE MEASUREMENTS (Detail

FAIR VALUE MEASUREMENTS (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Estimated fair value | Significant Observable Inputs (Level 2)
FAIR VALUE MEASUREMENTS
Long-term debt	$ 347,116	$ 424,420

PARTNERS' CAPITAL - Distributio

PARTNERS' CAPITAL - Distributions (Details) - USD ($) $ / shares in Units, $ in Thousands

3 Months Ended

12 Months Ended

Jan. 26, 2024

Dec. 31, 2023

Sep. 30, 2023

Jun. 30, 2023

Mar. 31, 2023

Dec. 31, 2022

Sep. 30, 2022

Jun. 30, 2022

Mar. 31, 2022

Dec. 31, 2021

Sep. 30, 2021

Jun. 30, 2021

Dec. 31, 2023

Dec. 31, 2022

Dec. 31, 2021

PARTNERS' CAPITAL

Period following quarter end for distribution of available cash

45 days

Quarterly distribution paid (in dollars per unit)

$ 0.700

$ 0.700

$ 0.700

$ 0.700

$ 0.500

$ 0.400

$ 0.350

$ 0.250

$ 0.200

$ 0.100

$ 0.100

Total Cash Distribution

$ 364,579

$ 196,347

$ 52,158

Distribution declared (in dollars per unit)

$ 0.70

Quarterly distribution declared

$ 89,000

PARTNERS' CAPITAL - Narrative (

PARTNERS' CAPITAL - Narrative (Details) - Limited Partners' Capital - USD ($) $ / shares in Units, $ in Millions	1 Months Ended	12 Months Ended
	Jan. 31, 2023	Dec. 31, 2023	Dec. 31, 2022
Partners' capital
Increase in authorization amount	$ 93.5
Remaining authorized amount		$ 80.6	$ 6.5
Repurchase and retire authorization	$ 100
Treasury units retired		$ 19.4
Number of units retired		929,842
Repurchase price (in dollars per unit)		$ 20.90
Aggregate
Partners' capital
Treasury units retired		$ 112.9
Number of units retired		6,390,446
Repurchase price (in dollars per unit)		$ 17.67

VARIABLE INTEREST ENTITIES - Al

VARIABLE INTEREST ENTITIES - AllDale (Detail)	12 Months Ended
	Dec. 31, 2023
AllDale I & II | Cavalier Minerals
Equity Investments
Ownership percentage by limited partners	72%
Cavalier Minerals
Equity Investments
Ownership interest in VIE (as a percent)	96%
Cavalier Minerals | Bluegrass Minerals
Equity Investments
Distributions to be received (as a percent)	25%
Noncontrolling ownership interest (as a percent)	4%
All Dale Minerals III
Equity Investments
Distribution after hurdles (as a percent)	25%
Specified internal rate of return (as a percent)	0.10%
Percentage of available cash distributed	125%
Variable Interest Entity, Primary Beneficiary | AllDale I and II | AllDale I & II
Equity Investments
Ownership percentage by limited partners	97%
Variable Interest Entity, Primary Beneficiary | AllDale I and II | General Partners' Capital
Equity Investments
Distributions to be received (as a percent)	20%
Variable Interest Entity, Primary Beneficiary | AllDale I and II | Limited Partners' Capital
Equity Investments
Distributions to be received (as a percent)	80%
Variable Interest Entity, Not Primary Beneficiary | All Dale Minerals III | All Dale Minerals III
Equity Investments
Ownership percentage by limited partners	13.90%

VARIABLE INTEREST ENTITIES - Ba

VARIABLE INTEREST ENTITIES - Bal Sheet (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Balance Sheet Related Disclosures
Cash and cash equivalents	$ 59,813	$ 296,023
Trade receivables	282,622	241,412
Total property, plant and equipment, net	2,022,663	1,880,668
Accounts payable	(108,269)	(95,122)
Due to affiliates	(28,498)	(53,790)
Accrued taxes other than income taxes	(21,007)	(22,967)
AllDale I and II
Balance Sheet Related Disclosures
Cash and cash equivalents	4,690	4,698
Trade receivables	16,058	13,933
Total property, plant and equipment, net	389,767	406,135
Accounts payable	$ (175)	(257)
Due to affiliates		$ (24)
Other Liability, Current, Related Party, Type [Extensible Enumeration]	us-gaap:RelatedPartyMember	us-gaap:RelatedPartyMember
Accrued taxes other than income taxes	$ (958)	$ (206)

VARIABLE INTEREST ENTITIES - In

VARIABLE INTEREST ENTITIES - Investments (Detail) - USD ($) $ in Thousands			12 Months Ended
	Jun. 02, 2022	Apr. 05, 2022	Dec. 31, 2023	Dec. 31, 2022
Equity Investments
Contributions to equity method investments			$ 2,518	$ 24,087
Francis Renewable Energy
Equity Investments
Contributions to equity method investments		$ 20,000		20,000
Francis Renewable Energy | Francis Renewable Energy
Equity Investments
Ownership percentage by limited partners			17%
NGP ET IV
Equity Investments
Contributions to equity method investments			$ 2,518	$ 4,087
Funding commitment	$ 25,000
Contributions to investee to date			$ 6,600
NGP ET IV | NGP ET IV
Equity Investments
Ownership percentage by limited partners	3.60%

EQUITY INVESTMENTS - Equity met

EQUITY INVESTMENTS - Equity method (Details) - USD ($) $ in Thousands		12 Months Ended
	Apr. 05, 2022	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Equity Investments
Beginning balance		$ 49,371
Contributions		2,518	$ 24,087
Equity method investment income (loss)		(1,468)	5,634	$ 2,130
Other income (expense)		218	4,355	(2,966)
Ending balance		46,503	49,371
All Dale Minerals III
Equity Investments
Beginning balance		25,284	26,325	27,268
Equity method investment income (loss)		2,567	5,634	2,130
Distributions received		(3,918)	(6,675)	(3,073)
Ending balance		23,933	25,284	$ 26,325
Francis Renewable Energy
Equity Investments
Beginning balance		20,000
Contributions	$ 20,000		20,000
Equity method investment income (loss)		(3,513)
Ending balance		16,487	20,000
NGP ET IV
Equity Investments
Beginning balance		4,087
Contributions		2,518	4,087
Equity method investment income (loss)		(522)
Ending balance		$ 6,083	$ 4,087

EQUITY INVESTMENTS - Non-equity

EQUITY INVESTMENTS - Non-equity method (Details) - USD ($) $ in Thousands		12 Months Ended
	Sep. 08, 2023	Dec. 31, 2023	Dec. 31, 2022	Aug. 22, 2023
Equity securities without readily determinable fair value
Equity securities		$ 92,541	$ 42,000
Contributions		49,560	42,000
Ending balance		$ 92,541	42,000
Infinitum Electric
Equity securities without readily determinable fair value
Contributions	$ 24,600		$ 42,000
Ascend
Equity securities without readily determinable fair value
Equity securities				$ 25,000

REVENUE FROM CONTRACTS WITH C_3

REVENUE FROM CONTRACTS WITH CUSTOMERS - Disaggregation (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Disaggregation of revenues
Revenues	$ 2,566,701	$ 2,419,967	$ 1,579,230
Coal sales
Disaggregation of revenues
Revenues	2,210,210	2,102,229	1,386,923
Oil & gas royalties
Disaggregation of revenues
Revenues	137,751	151,060	84,183
Transportation
Disaggregation of revenues
Revenues	142,290	113,860	69,607
Other revenues
Disaggregation of revenues
Revenues	76,450	52,818	38,517
Coal Royalties
Disaggregation of revenues
Revenues	65,614	60,680	51,471
Operating segments
Disaggregation of revenues
Revenues	2,566,701
Operating segments | Illinois Basin Coal
Disaggregation of revenues
Revenues	1,481,556	1,296,305	919,597
Operating segments | Illinois Basin Coal | Coal sales
Disaggregation of revenues
Revenues	1,364,901	1,219,943	873,930
Operating segments | Illinois Basin Coal | Transportation
Disaggregation of revenues
Revenues	106,150	69,540	41,001
Operating segments | Illinois Basin Coal | Other revenues
Disaggregation of revenues
Revenues	10,505	6,822	4,666
Operating segments | Appalachia Coal
Disaggregation of revenues
Revenues	883,334	928,087	545,539
Operating segments | Appalachia Coal | Coal sales
Disaggregation of revenues
Revenues	845,309	882,286	512,993
Operating segments | Appalachia Coal | Transportation
Disaggregation of revenues
Revenues	36,140	44,320	28,606
Operating segments | Appalachia Coal | Other revenues
Disaggregation of revenues
Revenues	1,885	1,481	3,940
Operating segments | Oil & Gas Royalties
Disaggregation of revenues
Revenues	141,525	154,897	86,439
Operating segments | Oil & Gas Royalties | Oil & gas royalties
Disaggregation of revenues
Revenues	137,751	151,060	84,183
Operating segments | Oil & Gas Royalties | Other revenues
Disaggregation of revenues
Revenues	3,774	3,837	2,256
Operating segments | Coal Royalties
Disaggregation of revenues
Revenues	42	56	69
Operating segments | Coal Royalties | Coal royalties
Disaggregation of revenues
Revenues	65,572	60,624	51,402
Operating segments | Coal Royalties | Other revenues
Disaggregation of revenues
Revenues	42	56	69
Other, Corporate and Elimination
Disaggregation of revenues
Revenues	(5,328)	(20,002)	(23,816)
Other, Corporate and Elimination | Coal royalties
Disaggregation of revenues
Revenues	(65,572)	(60,624)	(51,402)
Other, Corporate and Elimination | Other revenues
Disaggregation of revenues
Revenues	60,244	40,622	27,586
Elimination
Disaggregation of revenues
Revenues	(65,572)	(60,624)	(51,402)
Elimination | Coal Royalties
Disaggregation of revenues
Revenues	$ 65,572	$ 60,624	$ 51,402

REVENUE FROM CONTRACTS WITH C_4

REVENUE FROM CONTRACTS WITH CUSTOMERS - Supply contracts (Details) $ in Thousands	Dec. 31, 2023 USD ($)
Performance obligations unsatisfied or partially unsatisfied
Total	$ 3,358,711
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2024-01-01
Performance obligations unsatisfied or partially unsatisfied
Total	$ 2,045,335
Expected timing of satisfaction period	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2025-01-01
Performance obligations unsatisfied or partially unsatisfied
Total	$ 819,811
Expected timing of satisfaction period	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2026-01-01
Performance obligations unsatisfied or partially unsatisfied
Total	$ 255,065
Expected timing of satisfaction period	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2027-01-01
Performance obligations unsatisfied or partially unsatisfied
Total	$ 238,500
Expected timing of satisfaction period	1 year
Illinois Basin Coal
Performance obligations unsatisfied or partially unsatisfied
Total	$ 2,277,503
Illinois Basin Coal | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2024-01-01
Performance obligations unsatisfied or partially unsatisfied
Total	$ 1,291,152
Expected timing of satisfaction period	1 year
Illinois Basin Coal | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2025-01-01
Performance obligations unsatisfied or partially unsatisfied
Total	$ 494,386
Expected timing of satisfaction period	1 year
Illinois Basin Coal | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2026-01-01
Performance obligations unsatisfied or partially unsatisfied
Total	$ 253,465
Expected timing of satisfaction period	1 year
Illinois Basin Coal | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2027-01-01
Performance obligations unsatisfied or partially unsatisfied
Total	$ 238,500
Expected timing of satisfaction period	1 year
Appalachia Coal
Performance obligations unsatisfied or partially unsatisfied
Total	$ 1,081,208
Appalachia Coal | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2024-01-01
Performance obligations unsatisfied or partially unsatisfied
Total	$ 754,183
Expected timing of satisfaction period	1 year
Appalachia Coal | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2025-01-01
Performance obligations unsatisfied or partially unsatisfied
Total	$ 325,425
Expected timing of satisfaction period	1 year
Appalachia Coal | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2026-01-01
Performance obligations unsatisfied or partially unsatisfied
Total	$ 1,600
Expected timing of satisfaction period	1 year
Appalachia Coal | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2027-01-01
Performance obligations unsatisfied or partially unsatisfied
Expected timing of satisfaction period	1 year

EARNINGS PER LIMITED PARTNER _3

EARNINGS PER LIMITED PARTNER UNIT (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
EARNINGS PER LIMITED PARTNER UNIT
NET INCOME ATTRIBUTABLE TO ARLP	$ 630,118	$ 586,200	$ 182,771
General partner's interest in net income attributable to ARLP	(1,384)	(9,010)	(4,614)
Limited partners' interest in net income attributable to ARLP	628,734	577,190	178,157
Distributions to participating securities	(9,688)	(8,527)	(2,334)
Undistributed earnings attributable to participating securities	(7,203)	(10,576)	(2,403)
Net income (loss) attributable to ARLP available to limited partners	$ 611,843	$ 558,087	$ 173,420
Weighted-average limited partner units outstanding - basic (in units)	127,180,312	127,195,219	127,195,219
Weighted-average limited partner units outstanding - diluted (in units)	127,180,000	127,195,000	127,195,000
Earnings per limited partner unit - basic (in dollars per unit)	$ 4.81	$ 4.39	$ 1.36
Earnings per limited partner unit - diluted (in dollars per unit)	$ 4.81	$ 4.39	$ 1.36
Anti-dilutive under the treasury stock method (in units)	2,922,384	3,540,385	1,967,672

EMPLOYEE BENEFIT PLANS - Define

EMPLOYEE BENEFIT PLANS - Defined Contribution (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
PSSP
Defined Contribution Plans
Contribution expense	$ 21.8	$ 19.4	$ 17.7

EMPLOYEE BENEFIT PLANS - Obliga

EMPLOYEE BENEFIT PLANS - Obligations, Assets, Reported Amounts (Details) - Defined benefit pension plan - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Change in benefit obligations:
Benefit obligations at beginning of year	$ 104,682	$ 139,566
Interest cost	5,180	3,749	$ 3,438
Actuarial gain	2,446	(32,996)
Benefits paid	(6,438)	(5,637)
Benefit obligations at end of year	105,870	104,682	139,566
Change in plan assets:
Fair value of plan assets at beginning of year	92,129	113,976
Actual return on plan assets	11,561	(16,210)
Benefits paid	(6,438)	(5,637)
Fair value of plan assets at end of year	97,252	92,129	$ 113,976
Funded status at the end of year	(8,618)	(12,553)
Amounts recognized in balance sheet:
Non-current liability	(8,618)	(12,553)
Amount recognized in accumulated other comprehensive income consists of:
Prior service cost	(196)	(382)
Net actuarial loss	(11,584)	(15,160)
Amounts recognized in accumulated other comprehensive income	$ (11,780)	$ (15,542)
Weighted-average assumption to determine benefit obligations
Discount rate	4.90%	5.10%
Weighted-average assumptions used to determine net periodic benefit cost
Discount rate	5.10%	2.73%
Expected return on plan assets	7%	6%

EMPLOYEE BENEFIT PLANS - Assump

EMPLOYEE BENEFIT PLANS - Assumptions (Details) - Defined benefit pension plan	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Asset allocation assumptions
Asset allocation assumption	100%
Actual return on plan assets (as a percent)	12.50%	(14.60%)
Equity securities
Asset allocation assumptions
Asset allocation assumption	75%
Fixed income securities
Asset allocation assumptions
Asset allocation assumption	25%

EMPLOYEE BENEFIT PLANS - Period

EMPLOYEE BENEFIT PLANS - Periodic Benefit Cost (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Other changes in plan assets and benefit obligations recognized in accumulated other comprehensive loss:
Total recognized in accumulated other comprehensive loss	$ (20,471)	$ 23,175	$ 23,445
Defined benefit pension plan
Components of net periodic benefit cost:
Interest cost	$ 5,180	$ 3,749	$ 3,438
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Interest Cost, Statement of Income or Comprehensive Income [Extensible Enumeration]	Other Nonoperating Income (Expense)	Other Nonoperating Income (Expense)	Other Nonoperating Income (Expense)
Expected return on plan assets	$ (6,220)	$ (6,638)	$ (6,580)
Defined Benefit Plan, Net Periodic Benefit (Cost) Credit, Expected Return (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]	Other Nonoperating Income (Expense)	Other Nonoperating Income (Expense)	Other Nonoperating Income (Expense)
Amortization of prior service cost	$ 186	$ 186	$ 186
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Amortization of Prior Service Cost (Credit), Statement of Income or Comprehensive Income [Extensible Enumeration]	Other Nonoperating Income (Expense)	Other Nonoperating Income (Expense)	Other Nonoperating Income (Expense)
Amortization of net loss	$ 682	$ 1,963	$ 4,327
Defined Benefit Plan, Net Periodic Benefit (Cost) Credit, Amortization of Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]	Other Nonoperating Income (Expense)	Other Nonoperating Income (Expense)	Other Nonoperating Income (Expense)
Net periodic benefit cost	$ (172)	$ (740)	$ 1,371
Other changes in plan assets and benefit obligations recognized in accumulated other comprehensive loss:
Net actuarial gain	2,894	10,148	14,921
Reversal of amortization item: Prior service cost	186	186	186
Reversal of amortization item: Net actuarial loss	682	1,963	4,327
Total recognized in accumulated other comprehensive loss	3,762	12,297	19,434
Net periodic benefit cost (credit)	172	740	$ (1,371)
Total recognized in net periodic benefit cost and accumulated other comprehensive loss	$ 3,934	$ 13,037

EMPLOYEE BENEFIT PLANS - Estima

EMPLOYEE BENEFIT PLANS - Estimated Benefit Payments (Details) - Defined benefit pension plan $ in Thousands	Dec. 31, 2023 USD ($)
Estimated future benefit payments
2024	$ 6,331
2025	6,490
2026	6,688
2027	6,820
2028	6,899
2029-2033	35,204
Estimated future benefit payments	68,432
Expected contribution for pension plan in next year	$ 0

EMPLOYEE BENEFIT PLANS - Asset

EMPLOYEE BENEFIT PLANS - Asset Allocations (Details) - Defined benefit pension plan	Dec. 31, 2023
Equity securities | Minimum
Employee Benefit Plans
Target allocation	50%
Equity securities | Maximum
Employee Benefit Plans
Target allocation	85%
Fixed income securities | Minimum
Employee Benefit Plans
Target allocation	15%
Fixed income securities | Maximum
Employee Benefit Plans
Target allocation	50%

EMPLOYEE BENEFIT PLANS - Fair V

EMPLOYEE BENEFIT PLANS - Fair Value of Plan Assets (Details) - Defined benefit pension plan - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Employee Benefit Plans
Defined benefit plan, fair value of plan assets	$ 97,252	$ 92,129	$ 113,976
Fair Value, Inputs, Level 1, Level 2, and Level 3 [Member]
Employee Benefit Plans
Defined benefit plan, fair value of plan assets	75,912	5,422
Level 1
Employee Benefit Plans
Defined benefit plan, fair value of plan assets	75,883	5,422
Level 2
Employee Benefit Plans
Defined benefit plan, fair value of plan assets	29
Consumer discretionary | Fair Value, Inputs, Level 1, Level 2, and Level 3 [Member]
Employee Benefit Plans
Defined benefit plan, fair value of plan assets	2,605
Consumer discretionary | Level 1
Employee Benefit Plans
Defined benefit plan, fair value of plan assets	2,605
Consumer durables | Fair Value, Inputs, Level 1, Level 2, and Level 3 [Member]
Employee Benefit Plans
Defined benefit plan, fair value of plan assets	2,088
Consumer durables | Level 1
Employee Benefit Plans
Defined benefit plan, fair value of plan assets	2,088
Energy | Fair Value, Inputs, Level 1, Level 2, and Level 3 [Member]
Employee Benefit Plans
Defined benefit plan, fair value of plan assets	952
Energy | Level 1
Employee Benefit Plans
Defined benefit plan, fair value of plan assets	952
Financials | Fair Value, Inputs, Level 1, Level 2, and Level 3 [Member]
Employee Benefit Plans
Defined benefit plan, fair value of plan assets	4,852
Financials | Level 1
Employee Benefit Plans
Defined benefit plan, fair value of plan assets	4,852
Health Care | Fair Value, Inputs, Level 1, Level 2, and Level 3 [Member]
Employee Benefit Plans
Defined benefit plan, fair value of plan assets	4,296
Health Care | Level 1
Employee Benefit Plans
Defined benefit plan, fair value of plan assets	4,296
Industrials & materials | Fair Value, Inputs, Level 1, Level 2, and Level 3 [Member]
Employee Benefit Plans
Defined benefit plan, fair value of plan assets	4,507
Industrials & materials | Level 1
Employee Benefit Plans
Defined benefit plan, fair value of plan assets	4,507
Information technology & communication | Fair Value, Inputs, Level 1, Level 2, and Level 3 [Member]
Employee Benefit Plans
Defined benefit plan, fair value of plan assets	8,102
Information technology & communication | Level 1
Employee Benefit Plans
Defined benefit plan, fair value of plan assets	8,102
Preferred stocks non-convertible | Fair Value, Inputs, Level 1, Level 2, and Level 3 [Member]
Employee Benefit Plans
Defined benefit plan, fair value of plan assets	37
Preferred stocks non-convertible | Level 1
Employee Benefit Plans
Defined benefit plan, fair value of plan assets	37
Mid-cap stock funds | Fair Value, Inputs, Level 1, Level 2, and Level 3 [Member]
Employee Benefit Plans
Defined benefit plan, fair value of plan assets	11,847
Mid-cap stock funds | Level 1
Employee Benefit Plans
Defined benefit plan, fair value of plan assets	11,847
Small-cap stock funds | Fair Value, Inputs, Level 1, Level 2, and Level 3 [Member]
Employee Benefit Plans
Defined benefit plan, fair value of plan assets	4,007
Small-cap stock funds | Level 1
Employee Benefit Plans
Defined benefit plan, fair value of plan assets	4,007
International stock funds | Fair Value, Inputs, Level 1, Level 2, and Level 3 [Member]
Employee Benefit Plans
Defined benefit plan, fair value of plan assets	7,849
International stock funds | Level 1
Employee Benefit Plans
Defined benefit plan, fair value of plan assets	7,849
Large-cap blend - S&P 500 index | Fair Value, Inputs, Level 1, Level 2, and Level 3 [Member]
Employee Benefit Plans
Defined benefit plan, fair value of plan assets	18,044
Large-cap blend - S&P 500 index | Level 1
Employee Benefit Plans
Defined benefit plan, fair value of plan assets	18,044
International - Developed markets | Fair Value, Inputs, Level 1, Level 2, and Level 3 [Member]
Employee Benefit Plans
Defined benefit plan, fair value of plan assets	3,138
International - Developed markets | Level 1
Employee Benefit Plans
Defined benefit plan, fair value of plan assets	3,138
International - Emerging markets | Fair Value, Inputs, Level 1, Level 2, and Level 3 [Member]
Employee Benefit Plans
Defined benefit plan, fair value of plan assets	1,894
International - Emerging markets | Level 1
Employee Benefit Plans
Defined benefit plan, fair value of plan assets	1,894
Accrued income | Fair Value, Inputs, Level 1, Level 2, and Level 3 [Member]
Employee Benefit Plans
Defined benefit plan, fair value of plan assets	29
Accrued income | Level 2
Employee Benefit Plans
Defined benefit plan, fair value of plan assets	29
Cash And Cash Equivalents | Fair Value, Inputs, Level 1, Level 2, and Level 3 [Member]
Employee Benefit Plans
Defined benefit plan, fair value of plan assets	1,665	5,422
Cash And Cash Equivalents | Level 1
Employee Benefit Plans
Defined benefit plan, fair value of plan assets	1,665	5,422
Equities - United States | Net asset value per share
Employee Benefit Plans
Defined benefit plan, fair value of plan assets		36,259
Equities - United States futures | Net asset value per share
Employee Benefit Plans
Defined benefit plan, fair value of plan assets		(697)
Equities - International developed markets | Net asset value per share
Employee Benefit Plans
Defined benefit plan, fair value of plan assets		14,214
Equities - International developed markets futures | Net asset value per share
Employee Benefit Plans
Defined benefit plan, fair value of plan assets		(1,693)
Equities - International emerging markets | Net asset value per share
Employee Benefit Plans
Defined benefit plan, fair value of plan assets		782
Equities - International emerging markets futures | Net asset value per share
Employee Benefit Plans
Defined benefit plan, fair value of plan assets		3,289
Fixed income - Investment grade | Net asset value per share
Employee Benefit Plans
Defined benefit plan, fair value of plan assets	$ 21,340	13,856
Fixed income - High yield | Net asset value per share
Employee Benefit Plans
Defined benefit plan, fair value of plan assets		156
Fixed income - Futures | Net asset value per share
Employee Benefit Plans
Defined benefit plan, fair value of plan assets		8,590
Alternatives | Net asset value per share
Employee Benefit Plans
Defined benefit plan, fair value of plan assets		$ 11,951

COMMON UNIT-BASED COMPENSATIO_3

COMMON UNIT-BASED COMPENSATION PLANS - LTIP Grants (Details) - ARLP LTIP - USD ($) $ / shares in Units, $ in Thousands		12 Months Ended
	Jan. 24, 2024	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Number of units
Balance at the beginning of the period (in units)		3,697,133	3,130,475	1,430,489
Granted (in units)	425,470	450,125	769,907	1,818,190
Vested (in units)		(1,291,330)
Forfeited (in units)		(145,584)	(203,249)	(118,204)
Balance at the end of the period (in units)		2,710,344	3,697,133	3,130,475
Weighted average grant date fair value per unit
Balance at the beginning of the period (in dollars per unit)		$ 7.40	$ 5.59	$ 5.02
Granted (in dollars per unit)		21.54	14.65	6.03
Vested (in dollars per unit)		5.02
Forfeited (in dollars per unit)		6.86	6.93	5.48
Balance at the end of the period (in dollars per unit)		$ 10.91	$ 7.40	$ 5.59
Intrinsic value (in dollars)
Intrinsic value of outstanding grants (in dollars)		$ 57,405	$ 75,126	$ 39,569	$ 6,409
Other information
Common units issued		860,060

COMMON UNIT-BASED COMPENSATIO_4

COMMON UNIT-BASED COMPENSATION PLANS - LTIP Other (Details) - ARLP LTIP - USD ($) $ in Millions		12 Months Ended
	Jan. 24, 2024	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Other information
Unit-based compensation expense		$ 10.4	$ 9.4	$ 5.4
Total unit-based obligation recorded		19.5	$ 16
Unrecognized compensation expense (in dollars)		$ 10
Weighted-average period for recognition of expense		1 year 4 months 24 days
Additional grants authorized (in units)	440,470

COMMON UNIT-BASED COMPENSATIO_5

COMMON UNIT-BASED COMPENSATION PLANS - SERP and Directors (Details) - SERP and Deferred Compensation Plans - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Number of units
Balance at the beginning of the period (in units)	742,540	668,698	760,630
Granted (in units)	118,737	73,842	46,638
Settled (in units)	(49,331)		(138,570)
Balance at the end of the period (in units)	811,946	742,540	668,698
Weighted average grant date fair value per unit
Balance at the beginning of the period (in dollars per unit)	$ 20.28	$ 20.37	$ 22.04
Granted (in dollars per unit)	20.46	19.44	9.45
Settled (in dollars per unit)	20.27		25.86
Balance at the end of the period (in dollars per unit)	$ 20.44	$ 20.28	$ 20.37
Intrinsic value (in dollars)
Intrinsic value of outstanding grants (in dollars)	$ 17,197	$ 15,088	$ 8,452	$ 3,408
Other information
Purchased for awards (in shares)	27,576		102,962
Unit-based compensation expense	$ 2,400	1,400	$ 400
Total unit-based obligation recorded	$ 16,600	$ 15,100

SUPPLEMENTAL CASH FLOW INFORM_3

SUPPLEMENTAL CASH FLOW INFORMATION (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Cash Paid For:
Interest	$ 37,126	$ 34,844	$ 36,402
Income taxes	13,615	23,794	11
Non-Cash Activity:
Accounts payable for purchase of property, plant and equipment	14,586	44,281	8,325
Right-of-use assets acquired by operating lease	2,596	$ 1,315	189
Market value of common units distributed under deferred compensation plans before tax withholding requirements	$ 28,906		$ 1,082

ASSET RETIREMENT OBLIGATIONS -

ASSET RETIREMENT OBLIGATIONS - Activity (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Asset retirement and mine closing liability
Balance at the beginning of the period	$ 149,813	$ 131,099
Accretion expense	4,433	3,731
Payments	(2,317)	(2,445)
Allocation of liability associated with mine development and change in assumptions	(1,486)	17,428
Balance at the end of the period	$ 150,443	$ 149,813

ASSET RETIREMENT OBLIGATIONS _2

ASSET RETIREMENT OBLIGATIONS - Estimated Payments (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Estimated payments of asset retirement obligations:
2024	$ 3,518
2025	5,557
2026	4,063
2027	7,038
2028	4,291
Thereafter	242,134
Aggregate undiscounted asset retirement obligations	266,601
Less: effect of discounting	(116,158)	$ (110,400)
Total asset retirement obligations	150,443	149,813	$ 131,099
Less: current portion	(3,518)
Asset retirement obligations	146,925	142,254
Surety bonds outstanding to performance of reclamation obligations	$ 173,500	$ 174,300

ACCRUED WORKERS' COMPENSATION_3

ACCRUED WORKERS' COMPENSATION AND PNEUMOCONIOSIS BENEFITS - Workers' Comp (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Reconciliation of changes in the workers' compensation liability
Beginning balance	$ 49,452	$ 53,448
Changes in accruals	12,155	7,384
Payments	(14,438)	(12,708)
Interest accretion	2,202	1,147
Valuation loss (gain)	(1,396)	181
Ending balance	$ 47,975	$ 49,452
Estimated present value of future obligations and other information
Workers' compensation discount rate	4.66%	4.87%
Letters of credit outstanding to secure workers compensation obligations	$ 99,400	$ 99,800
Other long-term assets
Estimated present value of future obligations and other information
Receivables for traumatic injury claims	$ 4,100	$ 4,100

ACCRUED WORKERS' COMPENSATION_4

ACCRUED WORKERS' COMPENSATION AND PNEUMOCONIOSIS BENEFITS - Obligations (Details) - Pneumoconiosis benefits - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Reconciliation of the changes in black lung benefit obligations
Benefit obligations at beginning of year	$ 104,287	$ 111,316
Service cost	2,698	3,798	$ 4,021
Interest cost	4,951	2,991	2,545
Actuarial loss (gain)	25,615	(9,840)
Benefits and expenses paid	(5,107)	(3,978)
Benefit obligations at end of year	$ 132,444	$ 104,287	$ 111,316

ACCRUED WORKERS' COMPENSATION_5

ACCRUED WORKERS' COMPENSATION AND PNEUMOCONIOSIS BENEFITS - AOCL (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Other changes in plan assets and benefit obligations recognized in accumulated other comprehensive loss:
Total recognized in accumulated other comprehensive loss	$ (20,471)	$ 23,175	$ 23,445
Pneumoconiosis benefits
Other changes in plan assets and benefit obligations recognized in accumulated other comprehensive loss:
Net actuarial gain (loss)	(25,615)	9,840	(161)
Reversal of amortization item: Net actuarial loss (gain)	1,382	1,038	4,172
Total recognized in accumulated other comprehensive loss	$ (24,233)	$ 10,878	$ 4,011
Estimated present value of future obligations and other information
Pneumoconiosis discount rate	4.81%	5%	2.73%
Amount recognized in accumulated other comprehensive income consists of:
Net actuarial loss	$ 49,745	$ 25,510	$ 36,388

ACCRUED WORKERS' COMPENSATION_6

ACCRUED WORKERS' COMPENSATION AND PNEUMOCONIOSIS BENEFITS - Balance Sheet (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
ACCRUED WORKERS' COMPENSATION AND PNEUMOCONIOSIS BENEFITS
Workers' compensation claims	$ 47,975	$ 49,452	$ 53,448
Pneumoconiosis benefit claims	132,444	104,287
Total obligations	180,419	153,739
Less current portion	(15,913)	(14,099)
Non-current obligations	$ 164,506	$ 139,640

ACCRUED WORKERS' COMPENSATION_7

ACCRUED WORKERS' COMPENSATION AND PNEUMOCONIOSIS BENEFITS - Expense (Details) - Pneumoconiosis benefits - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Black lung benefits:
Service cost	$ 2,698	$ 3,798	$ 4,021
Interest cost	$ 4,951	$ 2,991	$ 2,545
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Interest Cost, Statement of Income or Comprehensive Income [Extensible Enumeration]	Other Nonoperating Income (Expense)	Other Nonoperating Income (Expense)	Other Nonoperating Income (Expense)
Net amortization	$ 1,382	$ 1,038	$ 4,172
Defined Benefit Plan, Net Periodic Benefit (Cost) Credit, Amortization of Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]	Other Nonoperating Income (Expense)	Other Nonoperating Income (Expense)	Other Nonoperating Income (Expense)
Total pneumoconiosis and workers' compensation expense	$ 9,031	$ 7,827	$ 10,738
Workers' compensation expense	15,152	11,675	8,339
Net periodic benefit cost	$ 24,183	$ 19,502	$ 19,077

RELATED-PARTY TRANSACTIONS - Li

RELATED-PARTY TRANSACTIONS - Line of Credit (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Nov. 04, 2021	Feb. 19, 2021
Related Party Transaction
Payments under line of credit	$ 5,340
Proceeds from line of credit	5,340
Line of credit
Related Party Transaction
Maximum borrowing capacity		$ 5,500	$ 5,000
Interest rate (as a percent)		3.50%
Payments under line of credit	5,300
Proceeds from line of credit	$ 5,300

RELATED-PARTY TRANSACTIONS - Af

RELATED-PARTY TRANSACTIONS - Affiliate Royalty Agreements (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Related Party Transaction
As of the beginning of period	$ 60,608
As of the end of period	64,599	$ 60,608
Coal lease
Related Party Transaction
As of the beginning of period	60,608	55,613	$ 48,389
Payments	11,249	11,250	13,817
Recoupment	(7,258)	(6,255)	(4,025)
Unrecoupable			(2,568)
As of the end of period	64,599	60,608	55,613
Tunnel Ridge
Related Party Transaction
As of the beginning of period	1,500	1,500	1,500
Payments	3,000	3,000	3,000
Recoupment	(3,000)	(3,000)	(3,000)
As of the end of period	1,500	1,500	1,500
WKY CoalPlay | December 2014 coal lease - Henderson and Union Counties, Kentucky
Related Party Transaction
As of the beginning of period	22,092	21,750	19,178
Payments	3,597	3,597	3,597
Recoupment	(4,258)	(3,255)	(1,025)
As of the end of period	21,431	22,092	21,750
WKY CoalPlay | December 2014 coal lease - Webster County, Kentucky
Related Party Transaction
Payments			2,568
Unrecoupable			(2,568)
WKY CoalPlay | December 2014 coal lease - Henderson County, Kentucky
Related Party Transaction
As of the beginning of period	20,172	17,650	15,129
Payments	2,521	2,522	2,521
As of the end of period	22,693	20,172	17,650
WKY CoalPlay | February 2015 coal lease - Henderson and Union Counties, Kentucky
Related Party Transaction
As of the beginning of period	16,844	14,713	12,582
Payments	2,131	2,131	2,131
As of the end of period	$ 18,975	$ 16,844	$ 14,713

RELATED-PARTY TRANSACTIONS - Cr

RELATED-PARTY TRANSACTIONS - Craft Foundations (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2018
Tunnel Ridge
Related Party Transaction
Related party purchase	$ 0.2
Tunnel Ridge
Related Party Transaction
Annual minimum coal royalties	3
Payments for earned royalties	$ 12.1	$ 12.3	$ 5.8
Tunnel Ridge | Joseph W Craft III Foundation | Tunnel Ridge
Related Party Transaction
Property ownership (as a percent)				50%
Tunnel Ridge | Kathleen S Craft Foundation | Tunnel Ridge
Related Party Transaction
Property ownership (as a percent)				50%

RELATED-PARTY TRANSACTIONS - WK

RELATED-PARTY TRANSACTIONS - WKY CoalPlay (Details) - USD ($) $ in Millions	1 Months Ended		12 Months Ended
	Feb. 28, 2015	Dec. 31, 2014	Dec. 31, 2023
WKY CoalPlay | February 2015 coal lease - Henderson and Union Counties, Kentucky
Related Party Transaction
Initial term of lease	20 years
Percentage of earned royalty on coal sale price	4%
Annual minimum coal royalties	$ 2.1
WKY CoalPlay | December 2014 coal lease - Henderson and Union Counties, Kentucky
Related Party Transaction
Initial term of lease		20 years
Percentage of earned royalty on coal sale price		4%
Annual minimum coal royalties		$ 3.6
WKY CoalPlay | December 2014 coal lease - Webster County, Kentucky
Related Party Transaction
Initial term of lease		7 years
Percentage of earned royalty on coal sale price		4%
Annual minimum coal royalties		$ 2.6
WKY CoalPlay | December 2014 coal lease - Henderson County, Kentucky
Related Party Transaction
Annual minimum coal royalties		$ 2.5
Cavalier Minerals
Related Party Transaction
Ownership interest in VIE (as a percent)			96%
Cavalier Minerals | Bluegrass Minerals
Related Party Transaction
Noncontrolling ownership interest (as a percent)			4%

COMMITMENTS AND CONTINGENCIES -

COMMITMENTS AND CONTINGENCIES - Purchase Commitments (Details) $ in Millions	Dec. 31, 2023 USD ($)
Commitments for external coal purchases
Contractual Commitments
Commitments to purchase coal	$ 22.3
Commitments related to planned capital projects
Contractual Commitments
Contractual amount	$ 201.9

COMMITMENTS AND CONTINGENCIES_2

COMMITMENTS AND CONTINGENCIES - Insurance (Details) - Property and casualty insurance $ in Millions	Oct. 01, 2023 USD ($)
Commitments And Contingencies
Aggregate maximum insurance limit	$ 100
Insurance deductible	$ 1.5
Waiting period one	75 days
Waiting period two	90 days
Overall aggregate deductible	$ 25
Participating interest retained (in percent)	7.25%

CONCENTRATION OF CREDIT RISK _3

CONCENTRATION OF CREDIT RISK AND MAJOR CUSTOMERS (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Major Customers
Revenues	$ 2,566,701	$ 2,419,967	$ 1,579,230
Trade receivables	$ 282,622	$ 241,412
Revenue | Geographic Concentration Risk | End users in Europe, Africa, Asia, North America and South America
Major Customers
Concentration of risk (as a percent)	15.70%	12.50%	12.50%
Revenue | Customer Concentration Risk | Customer A
Major Customers
Revenues	$ 332,500
Revenue | Customer Concentration Risk | Customer B
Major Customers
Revenues	253,573	$ 260,146
Revenue | Customer Concentration Risk | Customer C
Major Customers
Revenues		328,406	$ 239,482
Revenue | Customer Concentration Risk | Customer D
Major Customers
Revenues		228,480
Trade accounts receivable | Customer Concentration Risk | Major Customers
Major Customers
Trade receivables	$ 54,300	$ 63,600

SEGMENT INFORMATION - General (

SEGMENT INFORMATION - General (Details)	12 Months Ended
	Dec. 31, 2023 segment
Segment Information
Number of reportable segments	4
Number Of Coal Reportable Segments	2
Number Of Mining Complex	7
Coal Royalties
Segment Information
Coal sold by coal operations (in percent)	60%

SEGMENT INFORMATION - Segment R

SEGMENT INFORMATION - Segment Results (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Reportable segment results
Revenues	$ 2,566,701	$ 2,419,967	$ 1,579,230
Segment Adjusted EBITDA Expense	1,404,718	1,283,878	953,757
Segment Adjusted EBITDA	1,012,173	1,032,569	557,398
Total assets	2,788,426	2,728,021	2,227,481
Capital expenditures	379,338	286,394	122,984
Other revenues
Reportable segment results
Revenues	76,450	52,818	38,517
Coal Royalties
Reportable segment results
Revenues	65,614	60,680	51,471
Operating segments
Reportable segment results
Revenues	2,566,701
Operating segments | Illinois Basin Coal
Reportable segment results
Revenues	1,481,556	1,296,305	919,597
Segment Adjusted EBITDA Expense	861,288	806,080	613,303
Segment Adjusted EBITDA	514,118	420,684	265,292
Total assets	966,102	779,018	676,091
Capital expenditures	257,885	158,624	60,166
Operating segments | Illinois Basin Coal | Other revenues
Reportable segment results
Revenues	10,505	6,822	4,666
Operating segments | Appalachia Coal
Reportable segment results
Revenues	883,334	928,087	545,539
Segment Adjusted EBITDA Expense	516,471	464,029	344,332
Segment Adjusted EBITDA	330,723	426,402	172,601
Total assets	488,427	431,913	420,144
Capital expenditures	116,217	76,603	47,577
Operating segments | Appalachia Coal | Other revenues
Reportable segment results
Revenues	1,885	1,481	3,940
Operating segments | Oil & Gas Royalties
Reportable segment results
Revenues	141,525	154,897	86,439
Segment Adjusted EBITDA Expense	16,532	15,395	11,051
Segment Adjusted EBITDA	121,508	143,179	76,920
Total assets	781,184	778,465	698,702
Operating segments | Oil & Gas Royalties | Other revenues
Reportable segment results
Revenues	3,774	3,837	2,256
Operating segments | Coal Royalties
Reportable segment results
Revenues	42	56	69
Segment Adjusted EBITDA Expense	24,451	21,871	18,269
Segment Adjusted EBITDA	41,163	38,809	33,202
Total assets	315,592	321,587	285,943
Capital expenditures	400	38,276	45
Operating segments | Coal Royalties | Other revenues
Reportable segment results
Revenues	42	56	69
Other, Corporate and Elimination
Reportable segment results
Revenues	(5,328)	(20,002)	(23,816)
Segment Adjusted EBITDA Expense	(14,024)	(23,497)	(33,198)
Segment Adjusted EBITDA	4,661	3,495	9,383
Total assets	237,121	417,038	146,601
Capital expenditures	4,836	12,891	15,196
Other, Corporate and Elimination | Other revenues
Reportable segment results
Revenues	60,244	40,622	27,586
Elimination
Reportable segment results
Revenues	(65,572)	(60,624)	(51,402)
Elimination | Coal Royalties
Reportable segment results
Revenues	$ 65,572	$ 60,624	$ 51,402

SEGMENT INFORMATION - EBITDA Ex

SEGMENT INFORMATION - EBITDA Expense Reconciliation (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Reconciliation of consolidated Segment Adjusted EBITDA Expense
Outside coal purchases	$ 36,149	$ 151	$ 6,372
Other expense (income)	(218)	(4,355)	2,966
Segment Adjusted EBITDA Expense	1,404,718	1,283,878	953,757
Product
Reconciliation of consolidated Segment Adjusted EBITDA Expense
Operating expenses (excluding depreciation, depletion and amortization)	$ 1,368,787	$ 1,288,082	$ 944,419

SEGMENT INFORMATION - EBITDA Re

SEGMENT INFORMATION - EBITDA Reconciliation (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Reconciliation of consolidated Segment Adjusted EBITDA to net income
Net income	$ 636,170	$ 588,158	$ 183,369
Noncontrolling interest	(6,052)	(1,958)	(598)
NET INCOME ATTRIBUTABLE TO ARLP	630,118	586,200	182,771
General and administrative	79,096	80,425	70,275
Depreciation, depletion and amortization	267,982	276,670	264,794
Interest expense, net	26,697	35,296	39,141
Income tax expense	8,280	53,978	417
Consolidated Segment Adjusted EBITDA	1,012,173	1,032,569	557,398
Oil and gas acquisitions total	$ 110,900	$ 92,600	$ 31,000

SCHEDULE I - CONDENSED FINANCIA

SCHEDULE I - CONDENSED FINANCIAL INFORMATION OF REGISTRANT - BALANCE SHEETS (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
CURRENT ASSETS:
Cash and cash equivalents	$ 59,813	$ 296,023
Total current assets	516,121	657,593
OTHER ASSETS:
Total other assets	249,642	189,760
TOTAL ASSETS	2,788,426	2,728,021	$ 2,227,481
CURRENT LIABILITIES:
Accrued taxes other than income taxes	21,007	22,967
Total current liabilities	227,467	255,571
Total liabilities	929,829	1,019,995
PARTNERS' CAPITAL:
Limited Partners - Common Unitholders 127,125,437 and 127,195,219 units outstanding, respectively	1,896,027	1,656,025
General Partner's interest		66,548
Total Partners' Capital	1,834,502	1,681,519
TOTAL LIABILITIES AND PARTNERS' CAPITAL	2,788,426	2,728,021
Parent company
CURRENT ASSETS:
Cash and cash equivalents	2,043	2,174
Total current assets	2,043	2,174
OTHER ASSETS:
Investments in consolidated subsidiaries	1,894,158	1,720,499
Total other assets	1,894,158	1,720,499
TOTAL ASSETS	1,896,201	1,722,673
CURRENT LIABILITIES:
Accrued taxes other than income taxes	174	100
Total current liabilities	174	100
Total liabilities	174	100
PARTNERS' CAPITAL:
Limited Partners - Common Unitholders 127,125,437 and 127,195,219 units outstanding, respectively	1,896,027	1,656,025
General Partner's interest		66,548
Total Partners' Capital	1,896,027	1,722,573
TOTAL LIABILITIES AND PARTNERS' CAPITAL	$ 1,896,201	$ 1,722,673

SCHEDULE I - CONDENSED FINANC_2

SCHEDULE I - CONDENSED FINANCIAL INFORMATION OF REGISTRANT - BALANCE SHEETS (Parenthetical) (Details) - shares	Dec. 31, 2023	Dec. 31, 2022
Condensed Financial Statements
Common units outstanding	127,125,437	127,195,219
Parent company
Condensed Financial Statements
Common units outstanding	127,125,437	127,195,219

SCHEDULE I - CONDENSED FINANC_3

SCHEDULE I - CONDENSED FINANCIAL INFORMATION OF REGISTRANT - OPERATIONS (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
EXPENSES:
General and administrative	$ 79,096	$ 80,425	$ 70,275
Total operating expenses	1,894,304	1,752,524	1,355,467
LOSS FROM OPERATIONS	672,397	667,443	223,763
Interest income	9,394	2,035	88
NET INCOME ATTRIBUTABLE TO ARLP	630,118	586,200	182,771
NET INCOME ATTRIBUTABLE TO ARLP
GENERAL PARTNER	1,384	9,010	4,614
LIMITED PARTNERS	$ 628,734	$ 577,190	$ 178,157
EARNINGS PER LIMITED PARTNER UNIT - BASIC (in dollars per unit)	$ 4.81	$ 4.39	$ 1.36
EARNINGS PER LIMITED PARTNER UNIT - DILUTED (in dollars per unit)	$ 4.81	$ 4.39	$ 1.36
WEIGHTED-AVERAGE NUMBER OF UNITS OUTSTANDING - BASIC (in units)	127,180,312	127,195,219	127,195,219
WEIGHTED-AVERAGE NUMBER OF UNITS OUTSTANDING - DILUTED (in units)	127,180,000	127,195,000	127,195,000
Parent company
EXPENSES:
General and administrative	$ 151
Total operating expenses	151
LOSS FROM OPERATIONS	(151)
Interest income	57
Equity in earnings of consolidated subsidiaries	630,212	$ 586,200	$ 182,771
NET INCOME ATTRIBUTABLE TO ARLP	630,118	586,200	182,771
NET INCOME ATTRIBUTABLE TO ARLP
GENERAL PARTNER	1,384	9,010	4,614
LIMITED PARTNERS	$ 628,734	$ 577,190	$ 178,157
EARNINGS PER LIMITED PARTNER UNIT - BASIC (in dollars per unit)	$ 4.81	$ 4.39	$ 1.36
EARNINGS PER LIMITED PARTNER UNIT - DILUTED (in dollars per unit)	$ 4.81	$ 4.39	$ 1.36
WEIGHTED-AVERAGE NUMBER OF UNITS OUTSTANDING - BASIC (in units)	127,180,312	127,195,219	127,195,219
WEIGHTED-AVERAGE NUMBER OF UNITS OUTSTANDING - DILUTED (in units)	127,180,312	127,195,219	127,195,219

SCHEDULE I - CONDENSED FINANC_4

SCHEDULE I - CONDENSED FINANCIAL INFORMATION OF REGISTRANT - CASH FLOWS (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
CASH FLOWS FROM OPERATING ACTIVITIES:
CASH FLOWS FROM OPERATING ACTIVITIES	$ 830,642	$ 802,349	$ 432,173
CASH FLOWS FROM FINANCING ACTIVITIES:
Distributions paid to Partners	(364,579)	(196,347)	(52,158)
Net cash used in financing activities	(507,119)	(225,391)	(222,656)
NET CHANGE IN CASH AND CASH EQUIVALENTS	(236,210)	173,620	66,829
CASH AND CASH EQUIVALENTS AT BEGINNING OF PERIOD	296,023	122,403	55,574
CASH AND CASH EQUIVALENTS AT END OF PERIOD	59,813	296,023	122,403
Parent company
CASH FLOWS FROM OPERATING ACTIVITIES:
CASH FLOWS FROM OPERATING ACTIVITIES	364,448	196,348	52,157
CASH FLOWS FROM FINANCING ACTIVITIES:
Distributions paid to Partners	(364,579)	(196,347)	(52,158)
Net cash used in financing activities	(364,579)	(196,347)	(52,158)
NET CHANGE IN CASH AND CASH EQUIVALENTS	(131)	1	(1)
CASH AND CASH EQUIVALENTS AT BEGINNING OF PERIOD	2,174	2,173	2,174
CASH AND CASH EQUIVALENTS AT END OF PERIOD	$ 2,043	$ 2,174	$ 2,173

SCHEDULE I - CONDENSED FINANC_5

SCHEDULE I - CONDENSED FINANCIAL INFORMATION OF REGISTRANT - Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Condensed Financial Statements
Maximum undiscounted future payment obligation	$ 75.1
Parent company
Condensed Financial Statements
Cash contribution by affiliated entity	$ 364.6	$ 196.3	$ 52.2

Pay vs Performance Disclosure

Pay vs Performance Disclosure - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Pay vs Performance Disclosure
Net Income (Loss)	$ 630,118	$ 586,200	$ 182,771

Insider Trading Arrangements

Insider Trading Arrangements	3 Months Ended
	Dec. 31, 2023
Trading Arrangements, by Individual
Rule 10b5-1 Arrangement Adopted	false
Non-Rule 10b5-1 Arrangement Adopted	false
Rule 10b5-1 Arrangement Terminated	false
Non-Rule 10b5-1 Arrangement Terminated	false