Arch Resources (ARCH) 10-Q 26 Oct 23 2023 Q3 Quarterly report Financial data

Cover Page

Cover Page - shares	9 Months Ended
	Sep. 30, 2023	Oct. 23, 2023
Cover page.
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Sep. 30, 2023
Document Transition Report	false
Entity File Number	1-13105
Entity Registrant Name	Arch Resources, Inc.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	43-0921172
Entity Address, Address Line One	One CityPlace Drive
Entity Address, Address Line Two	Suite 300
Entity Address, City or Town	St. Louis
Entity Address, State or Province	MO
Entity Address, Postal Zip Code	63141
City Area Code	314
Local Phone Number	994-2700
Title of 12(b) Security	Common stock, $.01 par value
Trading Symbol	ARCH
Security Exchange Name	NYSE
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business Company	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding (in shares)		18,369,460
Amendment Flag	false
Entity Central Index Key	0001037676
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2023
Document Fiscal Period Focus	Q3

Condensed Consolidated Income S

Condensed Consolidated Income Statements - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Condensed Consolidated Income Statements
Revenues	$ 744,601	$ 863,835	$ 2,371,826	$ 2,865,129
Costs, expenses and other operating
Cost of sales (exclusive of items shown separately below)	596,889	610,027	1,774,753	1,758,012
Depreciation, depletion and amortization	36,717	33,958	108,273	98,948
Accretion on asset retirement obligations	5,292	4,430	15,877	13,290
Change in fair value of coal derivatives, net	(46)	(12,252)	1,361	5,144
Selling, general and administrative expenses	24,279	26,107	73,092	79,271
Other operating (income) expense, net	(2,812)	16,997	(11,398)	18,796
Costs, expenses and other operating	660,319	679,267	1,961,958	1,973,461
Income from operations	84,282	184,568	409,868	891,668
Interest income (expense), net
Interest expense	(3,120)	(4,060)	(10,783)	(16,245)
Interest and investment income	4,803	2,224	12,340	2,776
Interest income (expense), net	1,683	(1,836)	1,557	(13,469)
Income before nonoperating expenses	85,965	182,732	411,425	878,199
Nonoperating expense
Non-service related pension and postretirement benefit credits (costs)	4,507	(857)	5,692	(2,189)
Net loss resulting from early retirement of debt		(394)	(1,126)	(14,143)
Nonoperating expenses	4,507	(1,251)	4,566	(16,332)
Income before income taxes	90,472	181,481	415,991	861,867
Provision for income taxes	16,781	474	66,839	1,424
Net income	$ 73,691	$ 181,007	$ 349,152	$ 860,443
Net income per common share
Basic earnings per share (in dollars per share)	$ 4.05	$ 9.84	$ 19.20	$ 50.97
Diluted earnings per share (in dollars per share)	$ 3.91	$ 8.68	$ 18.12	$ 41
Weighted average shares outstanding
Basic weighted average shares outstanding (in shares)	18,187	18,396	18,189	16,881
Diluted weighted average shares outstanding (in shares)	18,840	20,908	19,270	21,210
Dividends declared per common share (in dollars per share)	$ 3.97	$ 6	$ 9.53	$ 14.36

Condensed Consolidated Statemen

Condensed Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Condensed Consolidated Statements of Comprehensive Income
Net Income (Loss)	$ 73,691	$ 181,007	$ 349,152	$ 860,443
Derivative instruments
Comprehensive income before tax				1,763
Other comprehensive income, derivative instruments, net of tax				1,763
Pension, postretirement and other post-employment benefits
Comprehensive loss before tax	(9,770)	(1,473)	(15,560)	(10,896)
Provision for income taxes	2,147		3,419
Other comprehensive loss, pension, postretirement and other post-employment benefits, net of tax	(7,623)	(1,473)	(12,141)	(10,896)
Available-for-sale securities
Comprehensive income (loss) before tax	54	(4)	15	178
Provision for income taxes	(12)		(4)
Other comprehensive (loss) income, available-for-sale securities, net of tax	42	(4)	11	178
Total other comprehensive loss	(7,581)	(1,477)	(12,130)	(8,955)
Total comprehensive income	$ 66,110	$ 179,530	$ 337,022	$ 851,488

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Current assets
Cash and cash equivalents	$ 183,097	$ 236,059
Short-term investments	30,447	36,993
Restricted cash	1,100	1,100
Trade accounts receivable (net of $0 allowance at September 30, 2023 and December 31, 2022)	289,994	236,999
Other receivables	16,439	18,301
Inventories	233,213	223,015
Other current assets	51,854	71,384
Total current assets	806,144	823,851
Property, plant and equipment, net	1,200,109	1,187,028
Other assets
Deferred income taxes	146,324	209,470
Equity investments	21,273	17,267
Fund for asset retirement obligations	140,413	135,993
Other noncurrent assets	51,595	59,499
Total other assets	359,605	422,229
Total assets	2,365,858	2,433,108
Current Liabilities
Accounts payable	198,374	211,848
Accrued expenses and other current liabilities	135,163	157,043
Current maturities of debt	21,926	57,988
Total current liabilities	355,463	426,879
Long-term debt	107,515	116,288
Asset retirement obligations	234,386	235,736
Accrued pension benefits	1,057	1,101
Accrued postretirement benefits other than pension	50,360	49,674
Accrued workers' compensation	144,714	155,756
Other noncurrent liabilities	76,213	82,094
Total liabilities	969,708	1,067,528
Stockholders' equity
Common stock, $0.01 par value, authorized 300,000 shares, issued 30,501 and 28,761 shares at September 30, 2023 and December 31, 2022, respectively	305	288
Paid-in capital	716,956	724,660
Retained earnings	1,737,468	1,565,374
Treasury stock, 12,168 and 11,207 shares at September 30, 2023 and December 31, 2022, respectively, at cost	(1,107,878)	(986,171)
Accumulated other comprehensive income	49,299	61,429
Total stockholders' equity	1,396,150	1,365,580
Total liabilities and stockholders' equity	$ 2,365,858	$ 2,433,108

Condensed Consolidated Balanc_2

Condensed Consolidated Balance Sheets (Parenthetical) - USD ($) shares in Thousands, $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Condensed Consolidated Balance Sheets
Trade accounts receivable, allowance	$ 0	$ 0
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized (in shares)	300,000	300,000
Common stock, shares issued (in shares)	30,501	28,761
Treasury stock, shares (in shares)	12,168	11,207

Condensed Consolidated Statem_2

Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022
Operating activities
Net income	$ 349,152	$ 860,443
Adjustments to reconcile to cash from operating activities:
Depreciation, depletion and amortization	108,273	98,948
Accretion on asset retirement obligations	15,877	13,290
Deferred income taxes	66,561
Employee stock-based compensation expense	19,699	20,837
Amortization relating to financing activities	1,317	1,958
Gain on disposals and divestitures, net	(714)	(1,012)
Reclamation work completed	(17,642)	(11,229)
Contribution to fund for asset retirement obligations	(4,421)	(110,000)
Changes in:
Receivables	(49,950)	108,635
Inventories	(10,199)	(58,438)
Accounts payable, accrued expenses and other current liabilities	(31,241)	58,791
Income taxes, net	(999)	826
Coal derivative assets and liabilities, including margin account	1,361	5,144
Other	6,744	27,038
Cash provided by operating activities	453,818	1,015,231
Investing activities
Capital expenditures	(121,030)	(94,517)
Minimum royalty payments	(1,113)	(1,069)
Proceeds from disposals and divestitures	1,363	1,963
Purchases of short-term investments	(23,386)	(10,675)
Proceeds from sales of short-term investments	30,417	14,450
Investments in and advances to affiliates, net	(12,210)	(6,692)
Cash used in investing activities	(125,959)	(96,540)
Financing activities
Payments on term loan due 2024	(2,250)	(273,038)
Payments on convertible debt	(58,430)	(149,273)
Net payments on other debt	(30,568)	(23,942)
Debt financing costs		(690)
Purchases of treasury stock	(122,502)	(56,498)
Dividends paid	(183,790)	(264,638)
Payments for taxes related to net share settlement of equity awards	(27,230)	(4,908)
Proceeds from warrants exercised	43,949	19,422
Cash used in financing activities	(380,821)	(753,565)
(Decrease) increase in cash and cash equivalents, including restricted cash	(52,962)	165,126
Cash and cash equivalents, including restricted cash, beginning of period	237,159	326,295
Cash and cash equivalents, including restricted cash, end of period	184,197	491,421
Cash and cash equivalents, including restricted cash, end of period
Cash and cash equivalents	183,097	490,321
Restricted Cash	1,100	1,100
Cash and cash equivalents, including restricted cash	$ 184,197	$ 491,421

Condensed Consolidated Statem_3

Condensed Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Common Stock	Paid-in Capital	Retained Earnings	Treasury Stock at Cost	Accumulated Other Comprehensive Income	Total
Beginning Balance at Dec. 31, 2021	$ 255	$ 784,356	$ 712,478	$ (827,381)	$ 14,158	$ 683,866
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cumulative effect of accounting change on convertible debt		(39,239)	6,718			(32,521)
Dividends on common shares			(4,271)			(4,271)
Employee stock-based compensation		8,203				8,203
Issuance of shares of common stock under long-term incentive plan	1					1
Common stock withheld related to net share settlement of equity awards		(4,827)				(4,827)
Issuance of shares of common stock for warrants exercised		506				506
Total comprehensive income (loss)			271,872		1,423	273,295
Ending Balance at Mar. 31, 2022	256	748,999	986,797	(827,381)	15,581	924,252
Beginning Balance at Dec. 31, 2021	255	784,356	712,478	(827,381)	14,158	683,866
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Total comprehensive income (loss)						851,488
Ending Balance at Sep. 30, 2022	286	766,427	1,299,024	(884,879)	5,203	1,186,061
Beginning Balance at Mar. 31, 2022	256	748,999	986,797	(827,381)	15,581	924,252
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Dividends on common shares			(150,716)			(150,716)
Dividend Equivalents earned on RSU grants			(8,665)			(8,665)
Employee stock-based compensation		6,349				6,349
Issuance of shares of common stock for convertible debt exchanged	26	(29)				(3)
Common stock withheld related to net share settlement of equity awards		(81)				(81)
Issuance of shares of common stock for warrants exercised	4	18,906				18,910
Total comprehensive income (loss)			407,563		(8,901)	398,662
Ending Balance at Jun. 30, 2022	286	774,144	1,234,979	(827,381)	6,680	1,188,708
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Dividends on common shares			(110,071)			(110,071)
Dividend Equivalents earned on RSU grants		464	(6,891)			(6,427)
Purchase of common stock under share repurchase program				(57,498)		(57,498)
Employee stock-based compensation		6,285				6,285
Cash paid for convertible debt repurchased		(14,466)				(14,466)
Total comprehensive income (loss)			181,007		(1,477)	179,530
Ending Balance at Sep. 30, 2022	286	766,427	1,299,024	(884,879)	5,203	1,186,061
Beginning Balance at Dec. 31, 2022	288	724,660	1,565,374	(986,171)	61,429	1,365,580
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Dividends on common shares			(55,140)			(55,140)
Dividend Equivalents earned on RSU grants		120	(2,354)			(2,234)
Purchase of common stock under share repurchase program		(13)		(18,994)		(19,007)
Employee stock-based compensation		6,767				6,767
Cash paid for convertible debt repurchased		(44,486)				(44,486)
Issuance of shares of common stock under long-term incentive plan	3					3
Common stock withheld related to net share settlement of equity awards		(27,055)				(27,055)
Issuance of shares of common stock for warrants exercised	10	43,719				43,729
Total comprehensive income (loss)			198,108		(2,271)	195,837
Ending Balance at Mar. 31, 2023	301	703,712	1,705,988	(1,005,165)	59,158	1,463,994
Beginning Balance at Dec. 31, 2022	288	724,660	1,565,374	(986,171)	61,429	1,365,580
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Total comprehensive income (loss)						337,022
Ending Balance at Sep. 30, 2023	305	716,956	1,737,468	(1,107,878)	49,299	1,396,150
Beginning Balance at Mar. 31, 2023	301	703,712	1,705,988	(1,005,165)	59,158	1,463,994
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Dividends on common shares			(45,011)			(45,011)
Dividend Equivalents earned on RSU grants		98	(669)			(571)
Purchase of common stock under share repurchase program				(74,231)		(74,231)
Employee stock-based compensation		6,439				6,439
Common stock withheld related to net share settlement of equity awards		(162)				(162)
Issuance of shares of common stock for warrants exercised		31				31
Total comprehensive income (loss)			77,353		(2,278)	75,075
Ending Balance at Jun. 30, 2023	301	710,118	1,737,661	(1,079,396)	56,880	1,425,564
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Dividends on common shares			(71,573)			(71,573)
Dividend Equivalents earned on RSU grants		159	(2,311)			(2,152)
Purchase of common stock under share repurchase program				(28,482)		(28,482)
Employee stock-based compensation		6,493				6,493
Common stock withheld related to net share settlement of equity awards		(13)				(13)
Issuance of shares of common stock for warrants exercised	4	199				203
Total comprehensive income (loss)			73,691		(7,581)	66,110
Ending Balance at Sep. 30, 2023	$ 305	$ 716,956	$ 1,737,468	$ (1,107,878)	$ 49,299	$ 1,396,150

Condensed Consolidated Statem_4

Condensed Consolidated Statements of Stockholders' Equity (Parenthetical) - shares	3 Months Ended
	Sep. 30, 2023	Jun. 30, 2023	Mar. 31, 2023	Sep. 30, 2022	Jun. 30, 2022	Mar. 31, 2022
Condensed Consolidated Statements of Stockholders' Equity
Purchase of shares of common stock under share repurchase program	215,551	623,304	131,156	428,864
Issuance of shares of common stock under long-term incentive plan (in shares)			275,053			71,338
Issuance of shares of common stock for convertible debt exchanged (in shares)					2,630,272
Issuance of shares of common stock for warrants exercised (in shares)	386,782	29,487	1,037,679	273	445,497	13,239

Basis of Presentation

Basis of Presentation	9 Months Ended
	Sep. 30, 2023
Basis of Presentation
Basis of Presentation	1. The accompanying unaudited condensed consolidated financial statements include the accounts of Arch Resources, Inc. (“Arch Resources”) and its subsidiaries and controlled entities (“Arch” or the “Company”). Unless the context indicates otherwise, the terms “Arch” and the “Company” are used interchangeably in this Quarterly Report on Form 10-Q. The Company’s primary business is the production of metallurgical and thermal coal from underground and surface mines located throughout the United States, for sale to steel producers, utility companies, and industrial accounts both in the United States and around the world. The Company currently operates mining complexes in West Virginia, Wyoming and Colorado. All subsidiaries are wholly owned. Intercompany transactions and accounts have been eliminated in consolidation. The accompanying unaudited condensed consolidated financial statements have been prepared in accordance with accounting principles generally accepted in the United States for interim financial reporting and U.S. Securities and Exchange Commission regulations. In the opinion of management, all adjustments, consisting of normal, recurring accruals considered necessary for a fair presentation, have been included. Results of operations for the three and nine months ended September 30, 2023 are not necessarily indicative of results to be expected for the year ending December 31, 2023. These financial statements should be read in conjunction with the audited financial statements and related notes as of and for the year ended December 31, 2022 included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2022 filed with the U.S. Securities and Exchange Commission.

Accounting Policies

Accounting Policies	9 Months Ended
	Sep. 30, 2023
Accounting Policies
Accounting Policies	2. Recently Adopted Accounting Guidance There is no recently issued accounting guidance effective that is expected to have a material impact on the Company’s financial position, results of operations, or liquidity. ​ Recent Accounting Guidance Issued Not Yet Effective There are no new pronouncements issued but not yet effective that are expected to have a material impact on the Company’s financial position, results of operations, or liquidity. ​

Accumulated Other Comprehensive

Accumulated Other Comprehensive Income (Loss)	9 Months Ended
	Sep. 30, 2023
Accumulated Other Comprehensive Income (Loss).
Accumulated Other Comprehensive Income (Loss)	3. The following items are included in accumulated other comprehensive income (loss) (“AOCI”), net of tax: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Pension, ​ ​ ​ ​ ​ ​ ​ ​ ​ Postretirement ​ ​ ​ ​ Accumulated ​ ​ ​ ​ ​ and Other Post- ​ ​ ​ ​ Other ​ ​ Derivative ​ Employment ​ Available-for- ​ Comprehensive ​ ​ Instruments ​ Benefits ​ Sale Securities ​ Income (loss) ​ (In thousands) Balances at December 31, 2022 ​ $ — ​ $ 61,485 ​ $ (56) $ 61,429 Unrealized (losses) ​ — ​ — ​ (46) (46) Amounts reclassified from accumulated other comprehensive income (loss) ​ — ​ (15,560) ​ 61 (15,499) Tax effect ​ ​ — ​ ​ 3,419 ​ ​ (4) ​ ​ 3,415 Balances at September 30, 2023 ​ $ — ​ $ 49,344 ​ $ (45) $ 49,299 ​ The following amounts were reclassified out of AOCI: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended September 30, ​ Nine Months Ended September 30, Line Item in the Condensed Consolidated Details About AOCI Components 2023 2022 2023 2022 Income Statements ​ ​ (In thousands) ​ ​ Interest rate hedges ​ — ​ — ​ — ​ (112) ​ Interest expense Interest rate hedges (ineffective portion) ​ ​ — ​ ​ — ​ ​ — ​ ​ (1,428) Net loss resulting from early retirement of debt ​ ​ — ​ — ​ — ​ — Provision for income taxes ​ ​ $ — ​ $ — ​ $ — ​ $ (1,540) Net of tax ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Pension, postretirement and other post-employment benefits ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Amortization of actuarial gains, net 1 ​ $ 2,792 ​ $ 571 ​ $ 8,509 ​ $ 1,544 Non-service related pension and postretirement benefit credits (costs) Amortization of prior service credits ​ ​ 25 ​ ​ 38 ​ ​ 98 ​ ​ 111 ​ Non-service related pension and postretirement benefit credits Pension settlement ​ ​ 6,953 ​ 201 ​ ​ 6,953 ​ 615 Non-service related pension and postretirement benefit credits (costs) ​ ​ ​ 9,770 ​ ​ 810 ​ ​ 15,560 ​ ​ 2,270 Total before tax ​ ​ (2,147) ​ — ​ (3,419) ​ — Provision for income taxes ​ ​ $ 7,623 ​ $ 810 ​ $ 12,141 ​ $ 2,270 Net of tax ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Available-for-sale securities 2 ​ $ (40) ​ $ — ​ $ (61) ​ $ (182) Interest and investment income ​ ​ 12 ​ — ​ 4 ​ — Provision for income taxes ​ ​ $ (28) ​ $ — ​ $ (57) ​ $ (182) Net of tax 1 2

Inventories

Inventories	9 Months Ended
	Sep. 30, 2023
Inventories
Inventories	4. Inventories consist of the following: ​ ​ ​ ​ ​ ​ ​ ​ ​ September 30, December 31, ​ 2023 2022 ​ ​ (In thousands) Coal ​ $ 80,074 ​ $ 96,954 Repair parts and supplies ​ 153,139 ​ 126,061 ​ ​ $ 233,213 ​ $ 223,015 ​ The repair parts and supplies are stated net of an allowance for slow-moving and obsolete inventories of $2.8 million at September 30, 2023 and $2.4 million at December 31, 2022.

Investments in Available-for-Sa

Investments in Available-for-Sale Securities	9 Months Ended
	Sep. 30, 2023
Investments in Available-for-Sale Securities
Investments in Available-for-Sale Securities	5. The Company has invested in marketable debt securities, primarily highly liquid U.S. Treasury securities and investment grade corporate bonds. These investments are held in the custody of a major financial institution. These securities are classified as available-for-sale securities and, accordingly, the unrealized gains and losses are recorded through other comprehensive income. The Company’s investments in available-for-sale marketable securities are as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ September 30, 2023 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Gross ​ ​ Allowance ​ ​ ​ ​ ​ ​ ​ ​ Unrealized ​ ​ for - Credit ​ Fair ​ Cost Basis Gains Losses ​ ​ Losses Value ​ ​ (In thousands) Available-for-sale: ​ ​ ​ ​ ​ ​ ​ U.S. government and agency securities ​ $ 26,506 ​ $ 1 ​ $ (38) ​ $ — ​ $ 26,469 Corporate notes and bonds ​ 3,987 ​ 4 ​ (13) ​ — ​ 3,978 Total Investments ​ $ 30,493 ​ $ 5 ​ $ (51) ​ $ — ​ $ 30,447 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, 2022 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Gross ​ ​ Allowance ​ ​ ​ ​ ​ ​ ​ ​ Unrealized ​ ​ for - Credit ​ Fair ​ Cost Basis Gains ​ Losses ​ ​ Losses Value ​ (In thousands) Available-for-sale: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ U.S. government and agency securities ​ $ 28,325 ​ $ 1 ​ $ (25) ​ $ — ​ $ 28,301 Corporate notes and bonds ​ 8,689 ​ 20 ​ (17) ​ — ​ 8,692 Total Investments ​ $ 37,014 ​ $ 21 ​ $ (42) ​ $ — ​ $ 36,993 ​ The aggregate fair value of investments with unrealized losses that had been owned for less than a year was $7.4 million and $22.6 million at September 30, 2023 and December 31, 2022, respectively. The aggregate fair value of investments with unrealized losses that were owned for over a year was million at both September 30, 2023 and December 31, 2022. The unrealized losses in the Company’s portfolio at September 30, 2023 are the result of normal market fluctuations. The Company does not intend to sell these investments before recovery of their amortized cost base. The debt securities outstanding at September 30, 2023 have maturity dates ranging from the fourth quarter of 2023 through the third quarter of 2024. The Company classifies its investments as current based on the nature of the investments and their availability to provide cash for use in current operations, if needed.

Derivatives

Derivatives	9 Months Ended
	Sep. 30, 2023
Derivatives
Derivatives	6. Diesel fuel price risk management The Company is exposed to price risk with respect to diesel fuel purchased for use in its operations. The Company anticipates purchasing approximately 30 to 35 million gallons of diesel fuel for use in its operations during 2023. To protect the Company’s cash flows from increases in the price of diesel fuel for its operations, the Company has purchased heating oil call options. At September 30, 2023, the Company had protected the price of expected diesel fuel purchases for the remainder of 2023 with approximately per gallon. These positions are not designated as hedges for accounting purposes, and therefore, changes in the fair value are recorded immediately to earnings. Coal price risk management positions The Company may sell or purchase forward contracts, swaps and options in the over-the-counter coal market or on an exchange in order to manage its exposure to coal prices. The Company has exposure to the risk of fluctuating coal prices related to forecasted, index-priced sales or purchases of coal or to the risk of changes in the fair value of a fixed price physical sales contract. Certain derivative contracts may be designated as hedges of these risks. At September 30, 2023, the Company held derivatives for risk management purposes that are expected to settle in the following years. ​ ​ ​ ​ ​ ​ ​ ​ (Tons in thousands) 2023 2024 Total Coal sales — — — Coal purchases — 7 7 ​ ​ Tabular derivatives disclosures The Company has master netting agreements with all of its counterparties which allow for the settlement of contracts in an asset position with contracts in a liability position in the event of default or termination. Such netting arrangements reduce the Company’s credit exposure related to these counterparties. For classification purposes, the Company records the net fair value of all the positions with a given counterparty as a net asset or liability in the Condensed Consolidated Balance Sheets. The amounts shown in the table below represent the fair value position of individual contracts, and not the net position presented in the accompanying Condensed Consolidated Balance Sheets. The fair value and location of derivatives reflected in the accompanying Condensed Consolidated Balance Sheets are as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ September 30, 2023 ​ ​ ​ December 31, 2022 ​ ​ Fair Value of Derivatives Asset ​ Liability ​ ​ ​ ​ Asset ​ Liability ​ ​ (In thousands) ​ Derivative ​ Derivative ​ ​ ​ ​ Derivative ​ Derivative ​ ​ ​ Derivatives Not Designated as Hedging Instruments ​ ​ ​ ​ ​ ​ Heating oil -- diesel purchases ​ 1,235 ​ — ​ ​ 1,300 ​ — ​ Coal -- risk management ​ 46 ​ — ​ ​ 1,407 ​ — ​ Total ​ $ 1,281 ​ $ — ​ ​ $ 2,707 ​ $ — ​ Total derivatives ​ $ 1,281 ​ $ — ​ ​ $ 2,707 ​ $ — ​ Effect of counterparty netting ​ — ​ — ​ ​ — ​ — ​ Net derivatives as classified in the balance sheets ​ $ 1,281 ​ $ — ​ $ 1,281 ​ $ 2,707 ​ $ — ​ $ 2,707 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Fair Value of Derivatives September 30, December 31, (In thousands) ​ ​ ​ 2023 ​ 2022 Net derivatives as reflected on the balance sheets (in thousands) ​ ​ Heating Oil and coal Other current assets ​ $ 1,281 ​ $ 2,707 Coal Accrued expenses and other current liabilities ​ — ​ — ​ ​ ​ ​ $ 1,281 ​ $ 2,707 ​ The Company had a current asset representing cash collateral posted to a margin account for derivative positions primarily related to coal derivatives of $0.6 million and $0.0 million at September 30, 2023 and December 31, 2022, respectively. These amounts are not included with the derivatives presented in the table above and are included in “other current assets” in the accompanying Condensed Consolidated Balance Sheets. The effects of derivatives on measures of financial performance are as follows: Derivatives Not Designated as Hedging Instruments (in thousands) Three and Nine Months Ended September 30, ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Gain (Loss) Recognized ​ Three Months Ended September 30, Nine Months Ended September 30, ​ ​ ​ 2023 ​ ​ 2022 ​ ​ 2023 ​ ​ 2022 Coal risk management — unrealized (1) $ 46 ​ $ 12,252 ​ $ (1,361) ​ $ (5,144) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Coal risk management — realized (2) $ — ​ $ (14,700) ​ $ 6,254 ​ $ (41,159) Heating oil — diesel purchases (2) $ 1,341 ​ $ (4,146) ​ $ (1,037) ​ $ 9,386 ​ Location in Condensed Consolidated Income Statements: (1) — Change in fair value of coal derivatives, net (2) — Other operating expense (income), net ​ At September 30, 2023 and December 31, 2022, the Company did not have any derivative contracts designated as hedging instruments.

Accrued Expenses and Other Curr

Accrued Expenses and Other Current Liabilities	9 Months Ended
	Sep. 30, 2023
Accrued Expenses and Other Current Liabilities.
Accrued Expenses and Other Current Liabilities	7. Accrued expenses and other current liabilities consist of the following: ​ ​ ​ ​ ​ ​ ​ ​ ​ September 30, December 31, ​ ​ 2023 ​ 2022 ​ ​ (In thousands) Payroll and employee benefits ​ $ 39,838 ​ $ 61,836 Taxes other than income taxes ​ 50,683 ​ 53,105 Interest ​ 1,260 ​ 2,511 Workers’ compensation ​ 19,256 ​ 17,584 Asset retirement obligations ​ 8,217 ​ 8,632 Other ​ 15,909 ​ 13,375 ​ ​ $ 135,163 ​ $ 157,043 ​ ​

Debt and Financing Arrangements

Debt and Financing Arrangements	9 Months Ended
	Sep. 30, 2023
Debt and Financing Arrangements
Debt and Financing Arrangements	8. ​ ​ ​ ​ ​ ​ ​ ​ ​ September 30, December 31, ​ ​ 2023 ​ 2022 ​ (In thousands) Term loan due 2024 ($4.3 million face value) ​ $ 4,252 ​ $ 6,502 Tax Exempt Bonds ($98.1 million face value) ​ ​ 98,075 ​ ​ 98,075 Convertible Debt ​ ​ — ​ ​ 13,156 Other ​ 28,904 ​ 59,472 Debt issuance costs ​ (1,790) ​ (2,929) ​ ​ ​ 129,441 ​ ​ 174,276 Less: current maturities of debt ​ 21,926 ​ 57,988 Long-term debt ​ $ 107,515 ​ $ 116,288 ​ Term Loan Facility In 2017, the Company entered into a senior secured term loan credit agreement in an aggregate principal amount of $300 million (the “Term Loan Debt Facility”) with Credit Suisse AG, Cayman Islands Branch, as administrative agent and collateral agent, and the other financial institutions from time to time party thereto. The Term Loan Debt Facility was issued at 99.50% of the face amount and will mature on March 7, 2024. The term loan provided under the Term Loan Debt Facility (the “Term Loan”) is subject to quarterly principal amortization payments in an amount equal to $750,000 . The interest rate on the Term Loan Debt Facility is, at the option of Arch Resources, either (i) LIBOR plus an applicable margin of The Term Loan Debt Facility is guaranteed by all existing and future wholly owned domestic subsidiaries of the Company (collectively, the “Subsidiary Guarantors” and, together with Arch Resources, the “Loan Parties”), subject to customary exceptions, and is secured by first priority security interests on substantially all assets of the Loan Parties, including 100% of the voting equity interests of directly owned domestic subsidiaries and 65% of the voting equity interests of directly owned foreign subsidiaries, subject to customary exceptions. During the year ended December 31, 2022, the Company repaid $273.8 million of the Term Loan. The remaining balance of $4.3 million, as of September 30, 2023, remains outstanding as certain terms and conditions governing the Term Loan are incorporated into the Company’s outstanding indebtedness. Accounts Receivable Securitization Facility On August 3, 2022, the Company amended and extended its existing trade accounts receivable securitization facility provided to Arch Receivable Company, LLC, a special-purpose entity that is a wholly owned subsidiary of Arch Resources (“Arch Receivable”) (the “Securitization Facility”), which supports the issuance of letters of credit and requests for cash advances. The amendment to the Securitization Facility increased the size of the facility from $110 million to $150 million of borrowing capacity and extended the maturity date to August 1, 2025. Under the Securitization Facility, Arch Receivable, Arch Resources and certain of Arch Resources’ subsidiaries party to the Securitization Facility have granted to the administrator of the Securitization Facility a first priority security interest in eligible trade accounts receivable generated by such parties from the sale of coal and all proceeds thereof. As of September 30, 2023, letters of credit totaling Inventory-Based Revolving Credit Facility On August 3, 2022, Arch Resources amended the senior secured inventory-based revolving credit facility in an aggregate principal amount of $50 million (the “Inventory Facility”). Availability under the Inventory Facility is subject to a borrowing base consisting of (i) 85% of the net orderly liquidation value of eligible coal inventory, plus (ii) the lesser of (x) 85% of the net orderly liquidation value of eligible parts and supplies inventory and (y) 35% of the amount determined pursuant to clause (i), plus (iii) 100% of Arch Resources’ Eligible Cash (defined in the Inventory Facility), subject to reduction for reserves imposed by Regions. The amendment of the Inventory Facility extended the maturity of the facility to August 3, 2025; maintained the minimum liquidity requirement of $100 million and included provisions that reduce the advance rates for coal inventory and parts and supplies, depending on liquidity, as defined in the agreement. The Inventory Facility contains certain customary affirmative and negative covenants; events of default, subject to customary thresholds and exceptions; and representations, including certain cash management and reporting requirements that are customary for asset-based credit facilities. The Inventory Facility also includes a requirement to maintain liquidity equal to or exceeding $100 million at all times. As of September 30, 2023, letters of credit totaling $26.2 million were outstanding under the facility with $23.8 million available for borrowings. Equipment Financing On March 4, 2020, the Company entered into an equipment financing arrangement accounted for as debt. The Company received million in exchange for conveying an interest in certain equipment in operation at its Leer mine and entered into a master lease arrangement for that equipment. The financing arrangement contains customary terms and events of default and provides for maturing on March 4, 2024. Upon maturity, all interests in the subject equipment will revert back to the Company. On July 29, 2021, the Company entered into an additional equipment financing arrangement accounted for as debt. The Company received maturing on February 1, 2025. Upon maturity, the Company will have the option to purchase the equipment. Tax Exempt Bonds On July 2, 2020, the West Virginia Economic Development Authority (the “Issuer”) issued $53.1 million aggregate principal amount of Solid Waste Disposal Facility Revenue Bonds (Arch Resources Project), Series 2020 (the “Tax Exempt Bonds”) pursuant to an Indenture of Trust dated as of June 1, 2020 (the “Indenture of Trust”) between the Issuer and Citibank, N.A., as trustee (the “Trustee”). On March 4, 2021, the Issuer issued an additional million of Series 2021 Tax Exempt Bonds. The proceeds of the Tax Exempt Bonds were loaned to the Company pursuant to a Loan Agreement dated as of June 1, as supplemented by a First Amendment to Loan Agreement dated as of March 1, 2021 (collectively, the “Loan Agreement”), each between the Issuer and the Company. The Tax Exempt Bonds are payable solely from payments to be made by the Company under the Loan Agreement as evidenced by a Note from the Company to the Trustee. The proceeds of the Tax Exempt Bonds have been used to finance certain costs of the acquisition, construction, reconstruction, and equipping of solid waste disposal facilities at the Company’s Leer South development, and for capitalized interest and certain costs related to issuance of the Tax Exempt Bonds. The Tax Exempt Bonds bear interest payable each January 1 and July 1, commencing January 1, 2021 for the Series 2020 and July 1, 2021 for the Series 2021, and have a final maturity of July 1, 2045; however, the Tax Exempt Bonds are subject to mandatory tender on July 1, 2025 at a purchase price equal to 100% of the principal amount of the Tax Exempt Bonds, plus accrued interest to July 1, 2025. The Series 2020 and Series 2021 Tax Exempt Bonds bear interest of Convertible Debt On November 3, 2020, the Company issued $155.3 million in aggregate principal amount of 5.25% convertible senior notes due 2025 (“Convertible Notes ” or “Convertible Debt”). The net proceeds from the issuance of the Convertible Notes, after deducting offering related costs of $5.1 million and cost of a “Capped Call Transaction” as defined below of $17.5 million, were approximately $132.7 million. ​ During the first half of 2023, the Company repurchased the remaining Convertible Notes with a principal amount of $13.2 million for aggregate consideration consisting of $58.4 million in cash. In connection with the repurchase for the nine months ended September 30, 2023, the Company recognized a loss of $1.1 million. This amount is included as “Net loss resulting from early retirement of debt” in the accompanying Condensed Consolidated Income Statements. ​ Capped Call Transactions ​ In connection with the offering of the Convertible Notes, the Company entered into privately negotiated convertible note hedge transactions (collectively, the “Capped Call Transactions”). The Capped Call Transactions cover, subject to customary anti-dilution adjustments, the number of shares of the Company’s common stock that initially underlie the Convertible Notes. ​ The Capped Call Transactions are expected generally to reduce the potential dilution and/or offset any cash payments the Company is required to make in excess of the principal amount due upon conversion of the Convertible Notes in the event that the market price of the Company’s common stock is greater than the strike price of the Capped Call Transactions, which was initially $37.325 per share and the initial cap price was $52.255 per share. The initial call and cap prices are subject to adjustments under the terms of the underlying capped call agreements, including for various transactions such as the payment of dividends. The initial number of shares underlying the Capped Call Transactions is ​ As of September 30, 2023, the Capped Call Transactions remain outstanding and have an intrinsic value of $62.1 million. ​ The Capped Call Transactions are separate transactions, in each case entered into between the Company and the respective Option Counterparty, and are not part of the terms of the Convertible Notes. As the Capped Call Transactions meet certain accounting criteria, they were classified as equity and are not accounted for as derivatives.

Income Taxes

Income Taxes	9 Months Ended
	Sep. 30, 2023
Income Taxes
Taxes	9. The Company's effective tax rate for the three and nine months ended September 30, 2023 is based on its estimated full year effective tax rate, adjusted for the discrete items. The effective tax rate for the three and nine months ended September 30, 2023 was 18.6% and 16.1%, respectively. The effective tax rate for the three and nine months ended September 30, 2023 differ from the U.S. federal statutory rate of 21%, primarily due to the income tax benefit for excess percentage depletion. The effective tax rate for the nine months ended September 30, 2023 also includes the impact of discrete tax benefits related to equity compensation. ​ For the three and nine months ended September 30, 2022, the Company's effective tax rate was 0.1% and 0.2%, respectively. The effective tax rate for the three and nine months ended September 30, 2022 was impacted by the valuation allowance the Company maintained against its deferred tax assets until the fourth quarter of 2022.

Fair Value Measurements

Fair Value Measurements	9 Months Ended
	Sep. 30, 2023
Fair Value Measurements
Fair Value Measurements	10. The hierarchy of fair value measurements assigns a level to fair value measurements based on the inputs used in the respective valuation techniques. The levels of the hierarchy, as defined below, give the highest priority to unadjusted quoted prices in active markets for identical assets or liabilities and the lowest priority to unobservable inputs. ● Level 1 is defined as observable inputs such as quoted prices in active markets for identical assets. Level 1 assets include U.S. Treasury securities, and coal swaps and futures that are submitted for clearing on the New York Mercantile Exchange. ● Level 2 is defined as observable inputs other than Level 1 prices. These include quoted prices for similar assets or liabilities in an active market, quoted prices for identical assets and liabilities in markets that are not active, or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the assets or liabilities. The Company’s Level 2 assets and liabilities include U.S. government agency securities, coal commodity contracts, and interest rate swaps with fair values derived from quoted prices in over-the-counter markets or from prices received from direct broker quotes. ● Level 3 is defined as unobservable inputs in which little or no market data exists, therefore requiring an entity to develop its own assumptions. These include the Company’s commodity option contracts (heating oil) valued using modeling techniques, such as Black-Scholes, that require the use of inputs, particularly volatility, that are rarely observable. The table below sets forth, by level, the Company’s financial assets and liabilities that are recorded at fair value in the accompanying Condensed Consolidated Balance Sheet: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ September 30, 2023 ​ Total Level 1 Level 2 Level 3 ​ ​ (In thousands) Assets: ​ ​ ​ ​ Investments in marketable securities ​ $ 30,447 ​ $ 26,469 ​ $ 3,978 ​ $ — Derivatives ​ 1,281 ​ — ​ 46 ​ 1,235 Fund for asset retirement obligations ​ ​ 140,413 ​ ​ 140,413 ​ ​ — ​ ​ — Total assets ​ $ 172,141 ​ $ 166,882 ​ $ 4,024 ​ $ 1,235 Liabilities: ​ ​ ​ ​ ​ ​ ​ ​ Derivatives ​ $ — ​ $ — ​ $ — ​ $ — ​ The Company’s contracts with its counterparties allow for the settlement of contracts in an asset position with contracts in a liability position in the event of default or termination. For classification purposes, the Company records the net fair value of all the positions with these counterparties as a net asset or liability. Each level in the table above displays the underlying contracts according to their classification in the accompanying Condensed Consolidated Balance Sheet, based on this counterparty netting. The Company has contributed $140.4 million to a fund that will serve to defease the long-term asset retirement obligation for its thermal asset base; this amount is recorded as “Fund for asset retirement obligations” on the Condensed Consolidated Balance Sheets. The funds are invested in highly rated securities, such as U.S. Treasuries, which fall within Level 1 of the fair value hierarchy. The funds will only be utilized for final mine closure reclamation activities. ​ The following table summarizes the change in fair values of financial instruments categorized as Level 3. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended September 30, 2023 ​ Nine Months Ended September 30, 2023 ​ (In thousands) ​ ​ ​ ​ ​ ​ ​ Balance, beginning of period ​ $ 230 ​ $ 1,300 ​ Realized and unrealized gains (losses) recognized in earnings, net ​ 1,341 ​ (1,037) ​ Purchases ​ — ​ 1,800 ​ Settlements ​ (336) ​ (828) ​ Ending balance ​ $ 1,235 ​ $ 1,235 ​ ​ Fair Value of Long-Term Debt At September 30, 2023 and December 31, 2022, the fair value of the Company’s debt, including amounts classified as current, was $131.2 million and $223.0 million, respectively. Fair values are based upon observed prices in an active market, when available, or from valuation models using market information, which fall into Level 2 in the fair value hierarchy.

Earnings per Common Share

Earnings per Common Share	9 Months Ended
	Sep. 30, 2023
Earnings per Common Share
Earnings per Common Share	11. The Company computes basic net income per share using the weighted average number of common shares outstanding during the period. Diluted net income per share is computed using the weighted average number of common shares and the effect of potentially dilutive securities outstanding during the period. Potentially dilutive securities may consist of warrants, restricted stock units, and convertible debt. The dilutive effect of outstanding warrants and restricted stock units is reflected in diluted earnings per share by application of the treasury stock method whereas the Convertible Debt uses the if converted method. The following table provides the basic and diluted earnings per share by reconciling the numerators and denominators of the computations: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended September 30, ​ Nine Months Ended September 30, ​ ​ 2023 ​ 2022 2023 2022 (In Thousands) ​ ​ ​ Net income attributable to common shares $ 73,691 $ 181,007 $ 349,152 $ 860,443 Adjustment of interest expense attributable to Convertible Notes ​ ​ — ​ ​ 346 ​ ​ 108 ​ ​ 4,345 Adjustment for inducement payments ​ ​ — ​ ​ 217 ​ ​ — ​ ​ 4,914 Diluted net income attributable to common stockholders ​ ​ 73,691 ​ ​ 181,570 ​ ​ 349,260 ​ ​ 869,702 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Basic weighted average shares outstanding ​ ​ 18,187 ​ ​ 18,396 ​ ​ 18,189 ​ ​ 16,881 Effect of dilutive securities ​ ​ 653 ​ ​ 1,698 ​ ​ 969 ​ ​ 1,716 Convertible Notes (a) ​ ​ — ​ ​ 814 ​ ​ 112 ​ ​ 2,613 Diluted weighted average shares outstanding ​ 18,840 ​ 20,908 ​ 19,270 ​ 21,210 (a) Diluted weighted average common shares outstanding includes the dilutive effect had the Company's Convertible Notes been converted at the beginning of the year ended December 31, 2023. If converted by the holder, the Company may settle in cash, shares of the Company's common stock or a combination thereof, at the Company's election. The Capped Call Transaction is anti-dilutive and is excluded from the calculation of diluted earnings per share. ​

Workers Compensation Expense

Workers Compensation Expense	9 Months Ended
	Sep. 30, 2023
Workers Compensation Expense
Workers' Compensation Expense	12. The Company is liable under the Federal Mine Safety and Health Act of 1969, as subsequently amended, to provide for pneumoconiosis (occupational disease) benefits to eligible employees, former employees and dependents. The Company currently provides for federal claims principally through a self-insurance program. The Company is also liable under various state workers’ compensation statutes for occupational disease benefits. The occupational disease benefit obligation represents the present value of the actuarially computed present and future liabilities for such benefits over the employees’ applicable years of service. In October 2019, the Company filed an application with the Office of Workers’ Compensation Programs (“OWCP”) within the Department of Labor for reauthorization to self-insure federal black lung benefits. In February 2020, the Company received a reply from the OWCP confirming its status to remain self-insured contingent upon posting additional collateral of of receipt of the letter. The Company is currently appealing the ruling from the OWCP and has received an extension to self-insure during the appeal process. On January 18, 2023, the OWCP proposed revisions to regulations under the Black Lung Benefits Act governing authorization of self-insurers. The revisions seek to codify the practice of basing a self-insured operator’s security requirement on an actuarial assessment of its total present and future black lung liability. A material change to the regulations is the requirement that all self-insured operators must post security equal to The proposed regulations were posted to the Federal Register on January 19, 2023 with written comments to be accepted within 60 days of this date. A subsequent extended comment period expired on April 19, 2023; however, the final regulations have not yet been published. ​ If the above regulation is codified into law, the Company will be required to post additional collateral to maintain its self-insured status. The Company is evaluating alternatives to self-insurance, including the purchase of commercial insurance to cover these claims. Additionally, the Company is assessing additional sources of liquidity, and other items to satisfy the proposed regulations. ​ In addition, the Company is liable for workers’ compensation benefits for traumatic injuries which are calculated using actuarially-based loss rates, loss development factors and discounted based on a risk free rate. Traumatic workers’ compensation claims are insured with varying retentions/deductibles, or through state-sponsored workers’ compensation programs. Workers’ compensation expense consists of the following components: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended September 30, ​ Nine Months Ended September 30, ​ 2023 2022 2023 2022 ​ ​ (In thousands) ​ ​ ​ ​ ​ ​ Self-insured occupational disease benefits: ​ ​ ​ ​ Service cost ​ $ 993 ​ $ 1,498 ​ $ 2,980 ​ $ 4,493 Interest cost (1) ​ 1,511 ​ 1,153 ​ 4,531 ​ 3,458 Net amortization (1) ​ (241) ​ 157 ​ (723) ​ 471 Total occupational disease ​ $ 2,263 ​ $ 2,808 ​ $ 6,788 ​ $ 8,422 Traumatic injury claims and assessments ​ (6,834) ​ 2,218 ​ (2,403) ​ 6,424 Total workers’ compensation (credit) expense ​ $ (4,571) ​ $ 5,026 ​ $ 4,385 ​ $ 14,846 (1) In accordance with the adoption of ASU 2017-07, “Compensation-Retirement Benefits (Topic 715): Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost,” these costs are recorded within Nonoperating expenses in the Condensed Consolidated Income Statements on the line item “Non-service related pension and postretirement benefit (credits) costs.”

Employee Benefit Plans

Employee Benefit Plans	9 Months Ended
	Sep. 30, 2023
Employee Benefit Plans
Employee Benefit Plans	13. Employee Benefit Plans The following table details the components of pension benefit credit: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended September 30, ​ Nine Months Ended September 30, ​ 2023 2022 2023 2022 ​ ​ (In thousands) Interest cost (1) ​ $ 1,023 ​ $ 1,486 ​ $ 4,090 ​ $ 3,673 Expected return on plan assets (1) ​ (1,012) ​ ​ (1,557) ​ ​ (4,048) ​ ​ (4,422) Pension settlement (1) ​ ​ (3,986) ​ (201) ​ (3,986) ​ (615) Amortization of prior service credits (1) ​ (25) ​ (38) ​ (98) ​ (111) Amortization of other actuarial (gains) (1) ​ (129) ​ (101) ​ (519) ​ (134) Net benefit credit ​ $ (4,129) ​ $ (411) ​ $ (4,561) ​ $ (1,609) ​ The following table details the components of other postretirement benefit credit: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended September 30, ​ Nine Months Ended September 30, ​ 2023 2022 2023 2022 ​ ​ (In thousands) Service cost ​ $ 58 ​ $ 71 ​ $ 173 ​ $ 212 Interest cost (1) ​ 674 ​ 501 ​ 2,021 ​ 1,504 Amortization of other actuarial gains (1) ​ (2,422) ​ (627) ​ (7,267) ​ (1,881) Net benefit credit ​ $ (1,690) ​ $ (55) ​ $ (5,073) ​ $ (165) (1) In accordance with the adoption of ASU 2017-07, “Compensation-Retirement Benefits (Topic 715): Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost,” these costs are recorded within Nonoperating expenses in the Condensed Consolidated Income Statements on the line item “Non-service related pension and postretirement benefit credits (costs).” ​ In February 2022, the Board of Directors approved the termination of the Company’s Cash Balance Pension Plan. The Company has executed plan amendments regarding the termination and filed an Application for Determination for Terminating Pension Plan with the Internal Revenue Service (“IRS”), which was approved by the IRS during the first quarter of 2023. The Company also prepared and filed appropriate notices and documents related to the Pension Plan's termination and wind-down with the Pension Benefit Guaranty Corporation (“PBGC”). To complete the termination of the plan, the Company made a $3.2 million cash contribution into the plan in order to complete lump sum payments and to purchase annuity contracts for plan participants. A gain of $4.0 million was recognized on the plan termination, which is reflected in the Condensed Consolidated Incomes Statements line item “Non-service related pension and postretirement benefits credits (costs)”. The Company no longer administers or pays the retirement benefits of the Company’s Cash Balance Pension Plan going forward.

Commitments and Contingencies

Commitments and Contingencies	9 Months Ended
	Sep. 30, 2023
Commitments and Contingencies
Commitments and Contingencies	14. Commitments and Contingencies The Company accrues for costs related to contingencies when a loss is probable and the amount is reasonably determinable. Disclosure of contingencies is included in the financial statements when it is at least reasonably possible that a material loss or an additional material loss in excess of amounts already accrued may be incurred. The Company is a party to numerous claims and lawsuits with respect to various matters. The ultimate resolution of any such legal matter could result in outcomes that may be materially different from amounts the Company has accrued for such matters. The Company believes it has recorded adequate reserves for these matters. In the normal course of business, the Company is a party to certain financial instruments with off-balance sheet risk, such as bank letters of credit, performance or surety bonds, and other guarantees and indemnities related to the obligations of affiliated entities which are not reflected in the Company’s Condensed Consolidated Balance Sheets. However, the underlying liabilities that they secure, such as asset retirement obligations, workers’ compensation liabilities, and other obligations, are reflected in the Company’s Condensed Consolidated Balance Sheets. As of September 30, 2023, the Company had outstanding surety bonds with a face amount of $553.0 million to secure various obligations and commitments and $76.8 million of letters of credit under its Securitization and Inventory Facilities used to collateralize certain obligations. The Company posted million in cash collateral related to various obligations; this amount is recorded within “Other noncurrent assets” on the Condensed Consolidated Balance Sheets. As of September 30, 2023, the Company’s reclamation-related obligations of $242.6 million were supported by surety bonds of $456.1 million. The Company has posted million in cash collateral related to reclamation surety bonds. Additionally, in the third quarter of 2023, the Company contributed an additional million as of September 30, 2023. This amount is recorded as “Fund for asset retirement obligations” on the Condensed Consolidated Balance Sheets.

Segment Information

Segment Information	9 Months Ended
	Sep. 30, 2023
Segment Information
Segment Information	15. The Company’s reportable business segments are based on two distinct lines of business, metallurgical and thermal, and may include a number of mine complexes. The Company manages its coal sales by market and coal quality, not by individual mining complex. Geology, coal transportation routes to customers, and regulatory environments also have a significant impact on the Company’s marketing and operations management. Mining operations are evaluated based on Adjusted EBITDA, per-ton cash operating costs (defined as including all mining costs except depreciation, depletion, amortization, accretion on asset retirement obligations, and pass-through transportation expenses, divided by segment tons sold), and on other non-financial measures, such as safety and environmental performance. Adjusted EBITDA is not a measure of financial performance in accordance with generally accepted accounting principles, and items excluded from Adjusted EBITDA are significant in understanding and assessing the Company’s financial condition. Therefore, Adjusted EBITDA should not be considered in isolation, nor as an alternative to net income, income from operations, cash flows from operations or as a measure of our profitability, liquidity or performance under generally accepted accounting principles. The Company uses Adjusted EBITDA to measure the operating performance of its segments and allocate resources to the segments. Furthermore, analogous measures are used by industry analysts and investors to evaluate the Company’s operating performance. Investors should be aware that the Company’s presentation of Adjusted EBITDA may not be comparable to similarly titled measures used by other companies. The Company reports its results of operations primarily through the following reportable segments: Metallurgical (MET) segment, containing the Company’s metallurgical operations in West Virginia, and the Thermal segment containing the Company’s thermal operations in Wyoming and Colorado. Reporting segment results for the three and nine months ended September 30, 2023 and 2022 are presented below. The Corporate, Other, and Eliminations grouping includes these charges: idle operations; change in fair value of coal derivatives, net; corporate overhead; land management activities; other support functions; and the elimination of intercompany transactions. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Corporate, ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Other and ​ ​ ​ (In thousands) ​ MET ​ Thermal ​ Eliminations ​ Consolidated Three Months Ended September 30, 2023 ​ ​ ​ ​ Revenues ​ $ 432,835 ​ $ 311,766 ​ $ — $ 744,601 Adjusted EBITDA ​ 128,322 ​ 23,373 ​ (25,404) 126,291 Depreciation, depletion and amortization ​ 29,494 ​ 7,001 ​ 222 36,717 Accretion on asset retirement obligation ​ 651 ​ 4,314 ​ 327 5,292 Total assets ​ 1,046,404 ​ 415,373 ​ 904,081 2,365,858 Capital expenditures ​ 33,806 ​ 10,369 ​ 249 44,424 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended September 30, 2022 ​ ​ ​ ​ ​ ​ ​ Revenues ​ $ 444,306 ​ $ 419,529 ​ $ — ​ $ 863,835 Adjusted EBITDA ​ 155,185 ​ 96,812 ​ (29,041) ​ 222,956 Depreciation, depletion and amortization ​ 28,354 ​ 5,388 ​ 216 ​ 33,958 Accretion on asset retirement obligation ​ 553 ​ 3,444 ​ 433 ​ 4,430 Total assets ​ 1,020,849 ​ 325,580 ​ 973,433 ​ 2,319,862 Capital expenditures ​ 36,389 ​ 4,604 ​ 367 ​ 41,360 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Nine Months Ended September 30, 2023 ​ ​ ​ ​ ​ ​ ​ ​ Revenues ​ $ 1,420,758 ​ $ 951,068 ​ $ — $ 2,371,826 Adjusted EBITDA ​ 524,218 ​ 98,807 ​ (89,007) 534,018 Depreciation, depletion and amortization ​ 85,575 ​ 22,057 ​ 641 108,273 Accretion on asset retirement obligation ​ 1,880 ​ 12,941 ​ 1,056 15,877 Total assets ​ 1,046,404 ​ 415,373 ​ 904,081 2,365,858 Capital expenditures ​ 94,205 ​ 25,904 ​ 921 121,030 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Nine Months Ended September 30, 2022 ​ ​ ​ ​ ​ ​ ​ Revenues ​ $ 1,640,970 ​ $ 1,224,159 ​ $ — ​ $ 2,865,129 Adjusted EBITDA ​ 810,615 ​ 290,648 ​ (97,357) ​ 1,003,906 Depreciation, depletion and amortization ​ 82,738 ​ 15,554 ​ 656 ​ 98,948 Accretion on asset retirement obligation ​ 1,660 ​ 10,331 ​ 1,299 ​ 13,290 Total assets ​ 1,020,849 ​ 325,580 ​ 973,433 ​ 2,319,862 Capital expenditures ​ 79,896 ​ 13,200 ​ 1,421 ​ 94,517 ​ A reconciliation of net income to Adjusted EBITDA and segment Adjusted EBITDA from coal operations follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended September 30, ​ Nine Months Ended September 30, (In thousands) 2023 2022 2023 2022 Net income ​ $ 73,691 ​ $ 181,007 ​ $ 349,152 ​ $ 860,443 Provision for income taxes ​ ​ 16,781 ​ ​ 474 ​ ​ 66,839 ​ ​ 1,424 Interest (income) expense, net ​ (1,683) ​ 1,836 ​ (1,557) ​ 13,469 Depreciation, depletion and amortization ​ 36,717 ​ 33,958 ​ 108,273 ​ 98,948 Accretion on asset retirement obligations ​ 5,292 ​ 4,430 ​ 15,877 ​ 13,290 Non-service related pension and postretirement benefit (credits) costs ​ ​ (4,507) ​ ​ 857 ​ ​ (5,692) ​ ​ 2,189 Net loss resulting from early retirement of debt ​ — ​ 394 ​ 1,126 ​ 14,143 Adjusted EBITDA ​ $ 126,291 ​ $ 222,956 ​ $ 534,018 ​ $ 1,003,906 EBITDA from idled or otherwise disposed operations ​ ​ 30 ​ ​ 3,624 ​ ​ 8,726 ​ ​ 9,972 Selling, general and administrative expenses ​ ​ 24,279 ​ ​ 26,107 ​ ​ 73,092 ​ ​ 79,271 Other ​ ​ 1,095 ​ ​ (690) ​ ​ 7,189 ​ ​ 8,114 Segment Adjusted EBITDA from coal operations ​ $ 151,695 ​ $ 251,997 ​ $ 623,025 ​ $ 1,101,263 ​

Revenue Recognition

Revenue Recognition	9 Months Ended
	Sep. 30, 2023
Revenue Recognition
Revenue Recognition	16. ASC 606-10-50-5 requires that entities disclose disaggregated revenue information in categories (such as type of goods or services, geography, market, type of contract, etc.) that depict how the nature, amount, timing, and uncertainty of revenue and cash flow are affected by economic factors. ASC 606-10-55-89 explains that the extent to which an entity’s revenue is disaggregated depends on the facts and circumstances that pertain to the entity’s contracts with customers and that some entities may need to use more than one type of category to meet the objective for disaggregating revenue. In general, the Company’s business segmentation is aligned according to the nature and economic characteristics of its coal and customer relationships and provides meaningful disaggregation of each segment’s results. The Company has further disaggregated revenue between North America and Seaborne revenues which depicts the pricing and contract differences between the two. North America revenue is characterized by contracts with a term of one year or longer and typically the pricing is fixed; whereas Seaborne revenue generally is derived by spot or short term contracts with an index-based pricing mechanism. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Corporate, ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Other and ​ ​ ​ ​ ​ MET ​ Thermal ​ Eliminations ​ Consolidated ​ (in thousands) Three Months Ended September 30, 2023 ​ ​ ​ ​ North America revenues ​ $ 108,895 ​ $ 251,759 ​ $ — ​ $ 360,654 Seaborne revenues ​ 323,940 ​ 60,007 ​ — ​ 383,947 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total revenues ​ $ 432,835 ​ $ 311,766 ​ $ — ​ $ 744,601 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended September 30, 2022 ​ ​ ​ ​ ​ ​ ​ ​ North America revenues ​ $ 70,491 ​ $ 307,060 ​ $ — ​ $ 377,551 Seaborne revenues ​ 373,815 ​ 112,469 ​ — ​ 486,284 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total revenues ​ $ 444,306 ​ $ 419,529 ​ $ — ​ $ 863,835 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Nine Months Ended September 30, 2023 ​ ​ ​ ​ ​ ​ ​ ​ North America revenues ​ $ 274,017 ​ $ 786,111 ​ $ — ​ $ 1,060,128 Seaborne revenues ​ 1,146,741 ​ 164,957 ​ — ​ 1,311,698 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total revenues ​ $ 1,420,758 ​ $ 951,068 ​ $ — ​ $ 2,371,826 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Nine Months Ended September 30, 2022 ​ ​ ​ ​ ​ ​ ​ ​ North America revenues ​ $ 125,906 ​ $ 905,829 ​ $ — ​ $ 1,031,735 Seaborne revenues ​ 1,515,064 ​ 318,330 ​ — ​ 1,833,394 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total revenues ​ $ 1,640,970 ​ $ 1,224,159 ​ $ — ​ $ 2,865,129 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ As of September 30, 2023, the Company has outstanding performance obligations for the remainder of 2023 of 18.5 million tons of fixed price contracts and 2.2 million tons of variable price contracts. Additionally, the Company has outstanding performance obligations beyond 2023 of approximately 95.2 million tons of fixed price contracts and 3.7 million tons of variable price contracts.

Leases

Leases	9 Months Ended
	Sep. 30, 2023
Leases
Leases	17. The Company has operating and financing leases for mining equipment, office equipment, office space and transloading terminals with remaining lease terms ranging from less than one year to approximately four years. Some of these leases include both lease and non-lease components which are accounted for as a single lease component as the Company has elected the practical expedient to combine these components for all leases. As most of the leases do not provide an implicit rate, the Company calculated the “right-of-use” (“ROU”) assets and lease liabilities using its secured incremental borrowing rate at the lease commencement date. As of September 30, 2023 and December 31, 2022, the Company had the following ROU assets and lease liabilities within its Condensed Consolidated Balance Sheets: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ September 30, December 31, ​ ​ ​ ​ 2023 ​ 2022 Assets Balance Sheet Classification ​ ​ Operating lease right-of-use assets Other noncurrent assets ​ $ 10,134 ​ $ 12,106 Financing lease right-of-use assets Other noncurrent assets ​ ​ 1,945 ​ ​ 2,918 Total Lease Assets ​ ​ ​ $ 12,079 ​ $ 15,024 ​ ​ ​ ​ ​ ​ ​ ​ ​ Liabilities ​ Balance Sheet Classification ​ ​ ​ ​ ​ ​ Financing lease liabilities - current ​ Accrued expenses and other current liabilities ​ $ 1,025 ​ $ 977 Operating lease liabilities - current ​ Accrued expenses and other current liabilities ​ ​ 2,719 ​ ​ 2,722 Financing lease liabilities - long-term ​ Other noncurrent liabilities ​ ​ 2,346 ​ ​ 3,121 Operating lease liabilities - long-term ​ Other noncurrent liabilities ​ ​ 7,929 ​ ​ 9,993 ​ ​ ​ ​ $ 14,019 ​ $ 16,813 ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted average remaining lease term in years ​ ​ ​ ​ ​ ​ ​ ​ Operating leases ​ ​ ​ ​ 3.53 ​ ​ 4.14 Finance leases ​ ​ ​ ​ 1.50 ​ ​ 2.25 ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted average discount rate ​ ​ ​ ​ ​ ​ ​ ​ Operating leases ​ ​ ​ ​ 5.5% ​ ​ 5.5% Finance leases ​ ​ ​ ​ 6.4% ​ ​ 6.4% ​ Information related to leases was as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended September 30, ​ ​ Nine Months Ended September 30, ​ ​ ​ 2023 ​ 2022 ​ ​ 2023 ​ 2022 ​ ​ (In thousands) ​ (In thousands) Operating lease information: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Operating lease cost ​ ​ $ 801 ​ ​ $ 831 ​ ​ $ 2,462 ​ ​ $ 2,492 Operating cash flows from operating leases ​ ​ 851 ​ ​ ​ 876 ​ ​ 2,555 ​ ​ ​ 2,562 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Financing lease information: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Financing lease cost ​ ​ $ 393 ​ ​ $ 393 ​ ​ $ 1,179 ​ ​ $ 1,179 Operating cash flows from financing leases ​ ​ 303 ​ ​ ​ 303 ​ ​ 908 ​ ​ ​ 908 ​ ​ ​ Future minimum lease payments under non-cancellable leases as of September 30, 2023 were as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ Operating ​ ​ Finance Year ​ Leases ​ ​ Leases ​ (In thousands) 2023 ​ $ 801 ​ ​ $ 303 2024 ​ 3,200 ​ ​ 1,210 2025 ​ 3,185 ​ ​ 2,111 2026 ​ 3,080 ​ ​ — 2027 ​ 1,533 ​ ​ — Thereafter ​ — ​ ​ — Total minimum lease payments ​ $ 11,799 ​ ​ $ 3,624 Less imputed interest ​ (1,151) ​ ​ (253) ​ ​ ​ ​ ​ ​ ​ ​ Total lease liabilities ​ $ 10,648 ​ ​ $ 3,371 ​

Subsequent Event

Subsequent Event	9 Months Ended
	Sep. 30, 2023
Subsequent Event.
Subsequent Event	​ 18. Subsequent Event ​ On October 26, 2023, the Company announced the board approval of a quarterly dividend of $1.13 per share for stockholders of record on November 30, 2023, with a payment date of December 15, 2023. The dividend consists of a fixed component of ​ ​

Accounting Policies (Policies)

Accounting Policies (Policies)	9 Months Ended
	Sep. 30, 2023
Accounting Policies
Basis of Presentation	The accompanying unaudited condensed consolidated financial statements have been prepared in accordance with accounting principles generally accepted in the United States for interim financial reporting and U.S. Securities and Exchange Commission regulations. In the opinion of management, all adjustments, consisting of normal, recurring accruals considered necessary for a fair presentation, have been included. Results of operations for the three and nine months ended September 30, 2023 are not necessarily indicative of results to be expected for the year ending December 31, 2023. These financial statements should be read in conjunction with the audited financial statements and related notes as of and for the year ended December 31, 2022 included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2022 filed with the U.S. Securities and Exchange Commission.
Recently Adopted Accounting Guidance	Recently Adopted Accounting Guidance There is no recently issued accounting guidance effective that is expected to have a material impact on the Company’s financial position, results of operations, or liquidity. ​ Recent Accounting Guidance Issued Not Yet Effective There are no new pronouncements issued but not yet effective that are expected to have a material impact on the Company’s financial position, results of operations, or liquidity.

Accumulated Other Comprehensi_2

Accumulated Other Comprehensive Income (Loss) (Tables)	9 Months Ended
	Sep. 30, 2023
Accumulated Other Comprehensive Income (Loss).
Schedule of Accumulated Other Comprehensive Income (Loss)	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Pension, ​ ​ ​ ​ ​ ​ ​ ​ ​ Postretirement ​ ​ ​ ​ Accumulated ​ ​ ​ ​ ​ and Other Post- ​ ​ ​ ​ Other ​ ​ Derivative ​ Employment ​ Available-for- ​ Comprehensive ​ ​ Instruments ​ Benefits ​ Sale Securities ​ Income (loss) ​ (In thousands) Balances at December 31, 2022 ​ $ — ​ $ 61,485 ​ $ (56) $ 61,429 Unrealized (losses) ​ — ​ — ​ (46) (46) Amounts reclassified from accumulated other comprehensive income (loss) ​ — ​ (15,560) ​ 61 (15,499) Tax effect ​ ​ — ​ ​ 3,419 ​ ​ (4) ​ ​ 3,415 Balances at September 30, 2023 ​ $ — ​ $ 49,344 ​ $ (45) $ 49,299
Schedule of Comprehensive Income Reclassifications	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended September 30, ​ Nine Months Ended September 30, Line Item in the Condensed Consolidated Details About AOCI Components 2023 2022 2023 2022 Income Statements ​ ​ (In thousands) ​ ​ Interest rate hedges ​ — ​ — ​ — ​ (112) ​ Interest expense Interest rate hedges (ineffective portion) ​ ​ — ​ ​ — ​ ​ — ​ ​ (1,428) Net loss resulting from early retirement of debt ​ ​ — ​ — ​ — ​ — Provision for income taxes ​ ​ $ — ​ $ — ​ $ — ​ $ (1,540) Net of tax ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Pension, postretirement and other post-employment benefits ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Amortization of actuarial gains, net 1 ​ $ 2,792 ​ $ 571 ​ $ 8,509 ​ $ 1,544 Non-service related pension and postretirement benefit credits (costs) Amortization of prior service credits ​ ​ 25 ​ ​ 38 ​ ​ 98 ​ ​ 111 ​ Non-service related pension and postretirement benefit credits Pension settlement ​ ​ 6,953 ​ 201 ​ ​ 6,953 ​ 615 Non-service related pension and postretirement benefit credits (costs) ​ ​ ​ 9,770 ​ ​ 810 ​ ​ 15,560 ​ ​ 2,270 Total before tax ​ ​ (2,147) ​ — ​ (3,419) ​ — Provision for income taxes ​ ​ $ 7,623 ​ $ 810 ​ $ 12,141 ​ $ 2,270 Net of tax ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Available-for-sale securities 2 ​ $ (40) ​ $ — ​ $ (61) ​ $ (182) Interest and investment income ​ ​ 12 ​ — ​ 4 ​ — Provision for income taxes ​ ​ $ (28) ​ $ — ​ $ (57) ​ $ (182) Net of tax 1 2

Inventories (Tables)

Inventories (Tables)	9 Months Ended
	Sep. 30, 2023
Inventories
Inventories	​ ​ ​ ​ ​ ​ ​ ​ ​ September 30, December 31, ​ 2023 2022 ​ ​ (In thousands) Coal ​ $ 80,074 ​ $ 96,954 Repair parts and supplies ​ 153,139 ​ 126,061 ​ ​ $ 233,213 ​ $ 223,015

Investments in Available-for-_2

Investments in Available-for-Sale Securities (Tables)	9 Months Ended
	Sep. 30, 2023
Investments in Available-for-Sale Securities
Available-for-sale Securities	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ September 30, 2023 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Gross ​ ​ Allowance ​ ​ ​ ​ ​ ​ ​ ​ Unrealized ​ ​ for - Credit ​ Fair ​ Cost Basis Gains Losses ​ ​ Losses Value ​ ​ (In thousands) Available-for-sale: ​ ​ ​ ​ ​ ​ ​ U.S. government and agency securities ​ $ 26,506 ​ $ 1 ​ $ (38) ​ $ — ​ $ 26,469 Corporate notes and bonds ​ 3,987 ​ 4 ​ (13) ​ — ​ 3,978 Total Investments ​ $ 30,493 ​ $ 5 ​ $ (51) ​ $ — ​ $ 30,447 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, 2022 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Gross ​ ​ Allowance ​ ​ ​ ​ ​ ​ ​ ​ Unrealized ​ ​ for - Credit ​ Fair ​ Cost Basis Gains ​ Losses ​ ​ Losses Value ​ (In thousands) Available-for-sale: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ U.S. government and agency securities ​ $ 28,325 ​ $ 1 ​ $ (25) ​ $ — ​ $ 28,301 Corporate notes and bonds ​ 8,689 ​ 20 ​ (17) ​ — ​ 8,692 Total Investments ​ $ 37,014 ​ $ 21 ​ $ (42) ​ $ — ​ $ 36,993

Derivatives (Tables)

Derivatives (Tables)	9 Months Ended
	Sep. 30, 2023
Derivatives
Schedule of Price Risk Derivatives	​ ​ ​ ​ ​ ​ ​ ​ (Tons in thousands) 2023 2024 Total Coal sales — — — Coal purchases — 7 7
Disclosure of Fair Value of Derivatives	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ September 30, 2023 ​ ​ ​ December 31, 2022 ​ ​ Fair Value of Derivatives Asset ​ Liability ​ ​ ​ ​ Asset ​ Liability ​ ​ (In thousands) ​ Derivative ​ Derivative ​ ​ ​ ​ Derivative ​ Derivative ​ ​ ​ Derivatives Not Designated as Hedging Instruments ​ ​ ​ ​ ​ ​ Heating oil -- diesel purchases ​ 1,235 ​ — ​ ​ 1,300 ​ — ​ Coal -- risk management ​ 46 ​ — ​ ​ 1,407 ​ — ​ Total ​ $ 1,281 ​ $ — ​ ​ $ 2,707 ​ $ — ​ Total derivatives ​ $ 1,281 ​ $ — ​ ​ $ 2,707 ​ $ — ​ Effect of counterparty netting ​ — ​ — ​ ​ — ​ — ​ Net derivatives as classified in the balance sheets ​ $ 1,281 ​ $ — ​ $ 1,281 ​ $ 2,707 ​ $ — ​ $ 2,707 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Fair Value of Derivatives September 30, December 31, (In thousands) ​ ​ ​ 2023 ​ 2022 Net derivatives as reflected on the balance sheets (in thousands) ​ ​ Heating Oil and coal Other current assets ​ $ 1,281 ​ $ 2,707 Coal Accrued expenses and other current liabilities ​ — ​ — ​ ​ ​ ​ $ 1,281 ​ $ 2,707
Effects of Derivatives on Measures of Financial Performance	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Gain (Loss) Recognized ​ Three Months Ended September 30, Nine Months Ended September 30, ​ ​ ​ 2023 ​ ​ 2022 ​ ​ 2023 ​ ​ 2022 Coal risk management — unrealized (1) $ 46 ​ $ 12,252 ​ $ (1,361) ​ $ (5,144) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Coal risk management — realized (2) $ — ​ $ (14,700) ​ $ 6,254 ​ $ (41,159) Heating oil — diesel purchases (2) $ 1,341 ​ $ (4,146) ​ $ (1,037) ​ $ 9,386 Location in Condensed Consolidated Income Statements: (1) — Change in fair value of coal derivatives, net (2) — Other operating expense (income), net ​

Accrued Expenses and Other Cu_2

Accrued Expenses and Other Current Liabilities (Tables)	9 Months Ended
	Sep. 30, 2023
Accrued Expenses and Other Current Liabilities.
Schedule of Accrued Expenses and Other Current Liabilities	​ ​ ​ ​ ​ ​ ​ ​ ​ September 30, December 31, ​ ​ 2023 ​ 2022 ​ ​ (In thousands) Payroll and employee benefits ​ $ 39,838 ​ $ 61,836 Taxes other than income taxes ​ 50,683 ​ 53,105 Interest ​ 1,260 ​ 2,511 Workers’ compensation ​ 19,256 ​ 17,584 Asset retirement obligations ​ 8,217 ​ 8,632 Other ​ 15,909 ​ 13,375 ​ ​ $ 135,163 ​ $ 157,043

Debt and Financing Arrangemen_2

Debt and Financing Arrangements (Tables)	9 Months Ended
	Sep. 30, 2023
Debt and Financing Arrangements
Schedule of Long-term debt	​ ​ ​ ​ ​ ​ ​ ​ ​ September 30, December 31, ​ ​ 2023 ​ 2022 ​ (In thousands) Term loan due 2024 ($4.3 million face value) ​ $ 4,252 ​ $ 6,502 Tax Exempt Bonds ($98.1 million face value) ​ ​ 98,075 ​ ​ 98,075 Convertible Debt ​ ​ — ​ ​ 13,156 Other ​ 28,904 ​ 59,472 Debt issuance costs ​ (1,790) ​ (2,929) ​ ​ ​ 129,441 ​ ​ 174,276 Less: current maturities of debt ​ 21,926 ​ 57,988 Long-term debt ​ $ 107,515 ​ $ 116,288

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	9 Months Ended
	Sep. 30, 2023
Fair Value Measurements
Summary of Financial Assets and Liabilities Accounted for at Fair Value	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ September 30, 2023 ​ Total Level 1 Level 2 Level 3 ​ ​ (In thousands) Assets: ​ ​ ​ ​ Investments in marketable securities ​ $ 30,447 ​ $ 26,469 ​ $ 3,978 ​ $ — Derivatives ​ 1,281 ​ — ​ 46 ​ 1,235 Fund for asset retirement obligations ​ ​ 140,413 ​ ​ 140,413 ​ ​ — ​ ​ — Total assets ​ $ 172,141 ​ $ 166,882 ​ $ 4,024 ​ $ 1,235 Liabilities: ​ ​ ​ ​ ​ ​ ​ ​ Derivatives ​ $ — ​ $ — ​ $ — ​ $ —
Summary of Change in the Fair Values of Financial Instruments Categorized as Level 3	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended September 30, 2023 ​ Nine Months Ended September 30, 2023 ​ (In thousands) ​ ​ ​ ​ ​ ​ ​ Balance, beginning of period ​ $ 230 ​ $ 1,300 ​ Realized and unrealized gains (losses) recognized in earnings, net ​ 1,341 ​ (1,037) ​ Purchases ​ — ​ 1,800 ​ Settlements ​ (336) ​ (828) ​ Ending balance ​ $ 1,235 ​ $ 1,235 ​

Earnings per Common Share (Tabl

Earnings per Common Share (Tables)	9 Months Ended
	Sep. 30, 2023
Earnings per Common Share
Schedule of Weighted Average Number of Shares	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended September 30, ​ Nine Months Ended September 30, ​ ​ 2023 ​ 2022 2023 2022 (In Thousands) ​ ​ ​ Net income attributable to common shares $ 73,691 $ 181,007 $ 349,152 $ 860,443 Adjustment of interest expense attributable to Convertible Notes ​ ​ — ​ ​ 346 ​ ​ 108 ​ ​ 4,345 Adjustment for inducement payments ​ ​ — ​ ​ 217 ​ ​ — ​ ​ 4,914 Diluted net income attributable to common stockholders ​ ​ 73,691 ​ ​ 181,570 ​ ​ 349,260 ​ ​ 869,702 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Basic weighted average shares outstanding ​ ​ 18,187 ​ ​ 18,396 ​ ​ 18,189 ​ ​ 16,881 Effect of dilutive securities ​ ​ 653 ​ ​ 1,698 ​ ​ 969 ​ ​ 1,716 Convertible Notes (a) ​ ​ — ​ ​ 814 ​ ​ 112 ​ ​ 2,613 Diluted weighted average shares outstanding ​ 18,840 ​ 20,908 ​ 19,270 ​ 21,210 (a) Diluted weighted average common shares outstanding includes the dilutive effect had the Company's Convertible Notes been converted at the beginning of the year ended December 31, 2023. If converted by the holder, the Company may settle in cash, shares of the Company's common stock or a combination thereof, at the Company's election. The Capped Call Transaction is anti-dilutive and is excluded from the calculation of diluted earnings per share.

Workers Compensation Expense (T

Workers Compensation Expense (Tables)	9 Months Ended
	Sep. 30, 2023
Workers Compensation Expense
Workers' compensation expense	Workers’ compensation expense consists of the following components: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended September 30, ​ Nine Months Ended September 30, ​ 2023 2022 2023 2022 ​ ​ (In thousands) ​ ​ ​ ​ ​ ​ Self-insured occupational disease benefits: ​ ​ ​ ​ Service cost ​ $ 993 ​ $ 1,498 ​ $ 2,980 ​ $ 4,493 Interest cost (1) ​ 1,511 ​ 1,153 ​ 4,531 ​ 3,458 Net amortization (1) ​ (241) ​ 157 ​ (723) ​ 471 Total occupational disease ​ $ 2,263 ​ $ 2,808 ​ $ 6,788 ​ $ 8,422 Traumatic injury claims and assessments ​ (6,834) ​ 2,218 ​ (2,403) ​ 6,424 Total workers’ compensation (credit) expense ​ $ (4,571) ​ $ 5,026 ​ $ 4,385 ​ $ 14,846 (1) In accordance with the adoption of ASU 2017-07, “Compensation-Retirement Benefits (Topic 715): Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost,” these costs are recorded within Nonoperating expenses in the Condensed Consolidated Income Statements on the line item “Non-service related pension and postretirement benefit (credits) costs.”

Employee Benefit Plans (Tables)

Employee Benefit Plans (Tables)	9 Months Ended
	Sep. 30, 2023
Employee Benefit Plans
Schedule of Pension Benefit Costs (Credits)	The following table details the components of pension benefit credit: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended September 30, ​ Nine Months Ended September 30, ​ 2023 2022 2023 2022 ​ ​ (In thousands) Interest cost (1) ​ $ 1,023 ​ $ 1,486 ​ $ 4,090 ​ $ 3,673 Expected return on plan assets (1) ​ (1,012) ​ ​ (1,557) ​ ​ (4,048) ​ ​ (4,422) Pension settlement (1) ​ ​ (3,986) ​ (201) ​ (3,986) ​ (615) Amortization of prior service credits (1) ​ (25) ​ (38) ​ (98) ​ (111) Amortization of other actuarial (gains) (1) ​ (129) ​ (101) ​ (519) ​ (134) Net benefit credit ​ $ (4,129) ​ $ (411) ​ $ (4,561) ​ $ (1,609) ​ The following table details the components of other postretirement benefit credit: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended September 30, ​ Nine Months Ended September 30, ​ 2023 2022 2023 2022 ​ ​ (In thousands) Service cost ​ $ 58 ​ $ 71 ​ $ 173 ​ $ 212 Interest cost (1) ​ 674 ​ 501 ​ 2,021 ​ 1,504 Amortization of other actuarial gains (1) ​ (2,422) ​ (627) ​ (7,267) ​ (1,881) Net benefit credit ​ $ (1,690) ​ $ (55) ​ $ (5,073) ​ $ (165) (1) In accordance with the adoption of ASU 2017-07, “Compensation-Retirement Benefits (Topic 715): Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost,” these costs are recorded within Nonoperating expenses in the Condensed Consolidated Income Statements on the line item “Non-service related pension and postretirement benefit credits (costs).” ​

Segment Information (Tables)

Segment Information (Tables)	9 Months Ended
	Sep. 30, 2023
Segment Information
Schedule of Operating Segment Results	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Corporate, ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Other and ​ ​ ​ (In thousands) ​ MET ​ Thermal ​ Eliminations ​ Consolidated Three Months Ended September 30, 2023 ​ ​ ​ ​ Revenues ​ $ 432,835 ​ $ 311,766 ​ $ — $ 744,601 Adjusted EBITDA ​ 128,322 ​ 23,373 ​ (25,404) 126,291 Depreciation, depletion and amortization ​ 29,494 ​ 7,001 ​ 222 36,717 Accretion on asset retirement obligation ​ 651 ​ 4,314 ​ 327 5,292 Total assets ​ 1,046,404 ​ 415,373 ​ 904,081 2,365,858 Capital expenditures ​ 33,806 ​ 10,369 ​ 249 44,424 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended September 30, 2022 ​ ​ ​ ​ ​ ​ ​ Revenues ​ $ 444,306 ​ $ 419,529 ​ $ — ​ $ 863,835 Adjusted EBITDA ​ 155,185 ​ 96,812 ​ (29,041) ​ 222,956 Depreciation, depletion and amortization ​ 28,354 ​ 5,388 ​ 216 ​ 33,958 Accretion on asset retirement obligation ​ 553 ​ 3,444 ​ 433 ​ 4,430 Total assets ​ 1,020,849 ​ 325,580 ​ 973,433 ​ 2,319,862 Capital expenditures ​ 36,389 ​ 4,604 ​ 367 ​ 41,360 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Nine Months Ended September 30, 2023 ​ ​ ​ ​ ​ ​ ​ ​ Revenues ​ $ 1,420,758 ​ $ 951,068 ​ $ — $ 2,371,826 Adjusted EBITDA ​ 524,218 ​ 98,807 ​ (89,007) 534,018 Depreciation, depletion and amortization ​ 85,575 ​ 22,057 ​ 641 108,273 Accretion on asset retirement obligation ​ 1,880 ​ 12,941 ​ 1,056 15,877 Total assets ​ 1,046,404 ​ 415,373 ​ 904,081 2,365,858 Capital expenditures ​ 94,205 ​ 25,904 ​ 921 121,030 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Nine Months Ended September 30, 2022 ​ ​ ​ ​ ​ ​ ​ Revenues ​ $ 1,640,970 ​ $ 1,224,159 ​ $ — ​ $ 2,865,129 Adjusted EBITDA ​ 810,615 ​ 290,648 ​ (97,357) ​ 1,003,906 Depreciation, depletion and amortization ​ 82,738 ​ 15,554 ​ 656 ​ 98,948 Accretion on asset retirement obligation ​ 1,660 ​ 10,331 ​ 1,299 ​ 13,290 Total assets ​ 1,020,849 ​ 325,580 ​ 973,433 ​ 2,319,862 Capital expenditures ​ 79,896 ​ 13,200 ​ 1,421 ​ 94,517
Schedule of Reconciliation of Net Income to Adjusted EBITDA	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended September 30, ​ Nine Months Ended September 30, (In thousands) 2023 2022 2023 2022 Net income ​ $ 73,691 ​ $ 181,007 ​ $ 349,152 ​ $ 860,443 Provision for income taxes ​ ​ 16,781 ​ ​ 474 ​ ​ 66,839 ​ ​ 1,424 Interest (income) expense, net ​ (1,683) ​ 1,836 ​ (1,557) ​ 13,469 Depreciation, depletion and amortization ​ 36,717 ​ 33,958 ​ 108,273 ​ 98,948 Accretion on asset retirement obligations ​ 5,292 ​ 4,430 ​ 15,877 ​ 13,290 Non-service related pension and postretirement benefit (credits) costs ​ ​ (4,507) ​ ​ 857 ​ ​ (5,692) ​ ​ 2,189 Net loss resulting from early retirement of debt ​ — ​ 394 ​ 1,126 ​ 14,143 Adjusted EBITDA ​ $ 126,291 ​ $ 222,956 ​ $ 534,018 ​ $ 1,003,906 EBITDA from idled or otherwise disposed operations ​ ​ 30 ​ ​ 3,624 ​ ​ 8,726 ​ ​ 9,972 Selling, general and administrative expenses ​ ​ 24,279 ​ ​ 26,107 ​ ​ 73,092 ​ ​ 79,271 Other ​ ​ 1,095 ​ ​ (690) ​ ​ 7,189 ​ ​ 8,114 Segment Adjusted EBITDA from coal operations ​ $ 151,695 ​ $ 251,997 ​ $ 623,025 ​ $ 1,101,263 ​

Revenue Recognition (Tables)

Revenue Recognition (Tables)	9 Months Ended
	Sep. 30, 2023
Revenue Recognition
Schedule of effects of revenue recognition	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Corporate, ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Other and ​ ​ ​ ​ ​ MET ​ Thermal ​ Eliminations ​ Consolidated ​ (in thousands) Three Months Ended September 30, 2023 ​ ​ ​ ​ North America revenues ​ $ 108,895 ​ $ 251,759 ​ $ — ​ $ 360,654 Seaborne revenues ​ 323,940 ​ 60,007 ​ — ​ 383,947 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total revenues ​ $ 432,835 ​ $ 311,766 ​ $ — ​ $ 744,601 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended September 30, 2022 ​ ​ ​ ​ ​ ​ ​ ​ North America revenues ​ $ 70,491 ​ $ 307,060 ​ $ — ​ $ 377,551 Seaborne revenues ​ 373,815 ​ 112,469 ​ — ​ 486,284 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total revenues ​ $ 444,306 ​ $ 419,529 ​ $ — ​ $ 863,835 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Nine Months Ended September 30, 2023 ​ ​ ​ ​ ​ ​ ​ ​ North America revenues ​ $ 274,017 ​ $ 786,111 ​ $ — ​ $ 1,060,128 Seaborne revenues ​ 1,146,741 ​ 164,957 ​ — ​ 1,311,698 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total revenues ​ $ 1,420,758 ​ $ 951,068 ​ $ — ​ $ 2,371,826 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Nine Months Ended September 30, 2022 ​ ​ ​ ​ ​ ​ ​ ​ North America revenues ​ $ 125,906 ​ $ 905,829 ​ $ — ​ $ 1,031,735 Seaborne revenues ​ 1,515,064 ​ 318,330 ​ — ​ 1,833,394 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total revenues ​ $ 1,640,970 ​ $ 1,224,159 ​ $ — ​ $ 2,865,129 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​

Leases (Tables)

Leases (Tables)	9 Months Ended
	Sep. 30, 2023
Leases
Schedule of right-of-use assets and lease liabilities	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ September 30, December 31, ​ ​ ​ ​ 2023 ​ 2022 Assets Balance Sheet Classification ​ ​ Operating lease right-of-use assets Other noncurrent assets ​ $ 10,134 ​ $ 12,106 Financing lease right-of-use assets Other noncurrent assets ​ ​ 1,945 ​ ​ 2,918 Total Lease Assets ​ ​ ​ $ 12,079 ​ $ 15,024 ​ ​ ​ ​ ​ ​ ​ ​ ​ Liabilities ​ Balance Sheet Classification ​ ​ ​ ​ ​ ​ Financing lease liabilities - current ​ Accrued expenses and other current liabilities ​ $ 1,025 ​ $ 977 Operating lease liabilities - current ​ Accrued expenses and other current liabilities ​ ​ 2,719 ​ ​ 2,722 Financing lease liabilities - long-term ​ Other noncurrent liabilities ​ ​ 2,346 ​ ​ 3,121 Operating lease liabilities - long-term ​ Other noncurrent liabilities ​ ​ 7,929 ​ ​ 9,993 ​ ​ ​ ​ $ 14,019 ​ $ 16,813 ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted average remaining lease term in years ​ ​ ​ ​ ​ ​ ​ ​ Operating leases ​ ​ ​ ​ 3.53 ​ ​ 4.14 Finance leases ​ ​ ​ ​ 1.50 ​ ​ 2.25 ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted average discount rate ​ ​ ​ ​ ​ ​ ​ ​ Operating leases ​ ​ ​ ​ 5.5% ​ ​ 5.5% Finance leases ​ ​ ​ ​ 6.4% ​ ​ 6.4%
Schedule of Information Related to Leases	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended September 30, ​ ​ Nine Months Ended September 30, ​ ​ ​ 2023 ​ 2022 ​ ​ 2023 ​ 2022 ​ ​ (In thousands) ​ (In thousands) Operating lease information: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Operating lease cost ​ ​ $ 801 ​ ​ $ 831 ​ ​ $ 2,462 ​ ​ $ 2,492 Operating cash flows from operating leases ​ ​ 851 ​ ​ ​ 876 ​ ​ 2,555 ​ ​ ​ 2,562 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Financing lease information: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Financing lease cost ​ ​ $ 393 ​ ​ $ 393 ​ ​ $ 1,179 ​ ​ $ 1,179 Operating cash flows from financing leases ​ ​ 303 ​ ​ ​ 303 ​ ​ 908 ​ ​ ​ 908
Schedule of Future Minimum Lease Payments	Future minimum lease payments under non-cancellable leases as of September 30, 2023 were as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ Operating ​ ​ Finance Year ​ Leases ​ ​ Leases ​ (In thousands) 2023 ​ $ 801 ​ ​ $ 303 2024 ​ 3,200 ​ ​ 1,210 2025 ​ 3,185 ​ ​ 2,111 2026 ​ 3,080 ​ ​ — 2027 ​ 1,533 ​ ​ — Thereafter ​ — ​ ​ — Total minimum lease payments ​ $ 11,799 ​ ​ $ 3,624 Less imputed interest ​ (1,151) ​ ​ (253) ​ ​ ​ ​ ​ ​ ​ ​ Total lease liabilities ​ $ 10,648 ​ ​ $ 3,371 ​

Accumulated Other Comprehensi_3

Accumulated Other Comprehensive Income (Loss) - Schedule of accumulated other comprehensive income (loss) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Accumulated Other Comprehensive Income (Loss)
Beginning Balance	$ 1,425,564	$ 1,188,708	$ 1,365,580	$ 683,866
Tax effect	16,781	474	66,839	1,424
Ending Balance	1,396,150	1,186,061	1,396,150	1,186,061
Accumulated Other Comprehensive Income (loss)
Accumulated Other Comprehensive Income (Loss)
Beginning Balance	56,880	6,680	61,429	14,158
Unrealized (losses)			(46)
Amounts reclassified from accumulated other comprehensive income (loss)			(15,499)
Tax effect			3,415
Ending Balance	49,299	$ 5,203	49,299	$ 5,203
Pension, Postretirement and Other Post-Employment Benefits
Accumulated Other Comprehensive Income (Loss)
Beginning Balance			61,485
Amounts reclassified from accumulated other comprehensive income (loss)			(15,560)
Tax effect			3,419
Ending Balance	49,344		49,344
Available-for-Sale Securities
Accumulated Other Comprehensive Income (Loss)
Beginning Balance			(56)
Unrealized (losses)			(46)
Amounts reclassified from accumulated other comprehensive income (loss)			61
Tax effect			(4)
Ending Balance	$ (45)		$ (45)

Accumulated Other Comprehensi_4

Accumulated Other Comprehensive Income (Loss) - Schedule of reclassifications (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Accumulated Other Comprehensive Income (Loss)
Interest expense	$ (3,120)	$ (4,060)	$ (10,783)	$ (16,245)
Net loss resulting from early retirement of debt		394	1,126	14,143
Interest and investment income	4,803	2,224	12,340	2,776
Total before tax	90,472	181,481	415,991	861,867
Provision for income taxes	16,781	474	66,839	1,424
Net Income (Loss)	73,691	181,007	349,152	860,443
Pension, postretirement and other post-employment benefits
Accumulated Other Comprehensive Income (Loss)
Provision for income taxes			3,419
Available-for-sale securities
Accumulated Other Comprehensive Income (Loss)
Provision for income taxes			(4)
Reclassification out of Accumulated Other Comprehensive Income | Derivative instruments
Accumulated Other Comprehensive Income (Loss)
Interest expense				(112)
Net loss resulting from early retirement of debt				(1,428)
Provision for income taxes	0	0	0	0
Net Income (Loss)				(1,540)
Reclassification out of Accumulated Other Comprehensive Income | Pension, postretirement and other post-employment benefits
Accumulated Other Comprehensive Income (Loss)
Amortization of actuarial gains (losses), net	2,792	571	8,509	1,544
Amortization of prior service credits	25	38	98	111
Pension settlement	6,953	201	6,953	615
Total before tax	9,770	810	15,560	2,270
Provision for income taxes	2,147	0	3,419	0
Net Income (Loss)	7,623	810	12,141	2,270
Reclassification out of Accumulated Other Comprehensive Income | Available-for-sale securities
Accumulated Other Comprehensive Income (Loss)
Interest and investment income	(40)		(61)	(182)
Provision for income taxes	(12)	$ 0	(4)	0
Net Income (Loss)	$ (28)		$ (57)	$ (182)

Inventories (Details)

Inventories (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Inventories
Coal	$ 80,074	$ 96,954
Repair parts and supplies	153,139	126,061
Inventories	233,213	223,015
Allowance for slow-moving and obsolete inventories	$ 2,800	$ 2,400

Investments in Available-for-_3

Investments in Available-for-Sale Securities - Schedule of investments (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Debt Securities, Available-for-sale [Line Items]
Available-for-sale, Cost Basis	$ 30,493	$ 37,014
Available-for-sale, Gross Unrealized Gains	5	21
Available-for-sale, Gross Unrealized Losses	(51)	(42)
Available-for-sale, Fair Value	30,447	36,993
U.S. government and agency securities
Debt Securities, Available-for-sale [Line Items]
Available-for-sale, Cost Basis	26,506	28,325
Available-for-sale, Gross Unrealized Gains	1	1
Available-for-sale, Gross Unrealized Losses	(38)	(25)
Available-for-sale, Fair Value	26,469	28,301
Corporate notes and bonds
Debt Securities, Available-for-sale [Line Items]
Available-for-sale, Cost Basis	3,987	8,689
Available-for-sale, Gross Unrealized Gains	4	20
Available-for-sale, Gross Unrealized Losses	(13)	(17)
Available-for-sale, Fair Value	$ 3,978	$ 8,692

Investments in Available-for-_4

Investments in Available-for-Sale securities (Details) - USD ($) $ in Millions	Sep. 30, 2023	Dec. 31, 2022
Investments in Available-for-Sale Securities
Unrealized losses owned for less than 12 months	$ 7.4	$ 22.6
Unrealized losses owed for over a year	$ 0	$ 0

Derivatives (Details)

Derivatives (Details) - Not Designated as Hedging Instrument gal in Millions	9 Months Ended
	Sep. 30, 2023 $ / Option gal
Call Option | Heating Oil
Derivative [Line Items]
Remainder of 2023 (in gallons)	6
2023 (in used per gallon) | $ / Option	3.06
Diesel Purchases | Minimum
Derivative [Line Items]
Diesel fuel purchased annually (in gallons)	30
Diesel Purchases | Maximum
Derivative [Line Items]
Diesel fuel purchased annually (in gallons)	35

Derivatives - Schedule of price

Derivatives - Schedule of price risk derivatives (Details) - Coal purchases T in Thousands	9 Months Ended
	Sep. 30, 2023 T
Derivative [Line Items]
Derivatives held (in tons)	7
2024
Derivative [Line Items]
Derivatives held (in tons)	7

Derivatives - Disclosure of fai

Derivatives - Disclosure of fair Value of derivatives (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Derivative [Line Items]
Derivative Assets	$ 1,281	$ 2,707
Derivative Liabilities		0
Effect of counterparty netting in derivative liabilities		0
Derivative Asset	$ 1,281	$ 2,707
Derivative Asset, Statement of Financial Position [Extensible Enumeration]	Other Assets, Current	Other Assets, Current
Derivative Liability		$ 0
Derivative Liability, Statement of Financial Position [Extensible Enumeration]	Accrued Liabilities, Current	Accrued Liabilities, Current
Net derivatives as classified in the balance sheets	$ 1,281	$ 2,707
Not Designated as Hedging Instrument
Derivative [Line Items]
Derivative Assets	1,281	2,707
Derivative Liabilities		0
Coal Contract | Not Designated as Hedging Instrument
Derivative [Line Items]
Derivative Assets	46	1,407
Derivative Liabilities		0
Heating oil - diesel purchases | Not Designated as Hedging Instrument
Derivative [Line Items]
Derivative Assets	$ 1,235	1,300
Derivative Liabilities		$ 0

Derivatives - Net derivatives a

Derivatives - Net derivatives as reflected on the balance sheets (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Derivatives, Fair Value [Line Items]
Net derivatives as classified in the balance sheet	$ 1,281	$ 2,707
Other current assets
Derivatives, Fair Value [Line Items]
Current asset representing cash collateral posted	600	0
Heating oil and coal | Other current assets
Derivatives, Fair Value [Line Items]
Net derivatives as classified in the balance sheet	$ 1,281	$ 2,707

Derivatives - Effects of deriva

Derivatives - Effects of derivatives on measures of financial performance (Details) - Not Designated as Hedging Instrument - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Coal Contract | Change in fair value of coal derivatives and coal trading activities, net
Derivative Instruments, Gain (Loss) [Line Items]
Unrealized Gain (Loss) on Derivatives	$ 46	$ 12,252	$ (1,361)	$ (5,144)
Coal Contract | Other operating (income) expense, net
Derivative Instruments, Gain (Loss) [Line Items]
Realized Gain (Loss) on Derivatives		(14,700)	6,254	(41,159)
Heating oil - diesel purchases | Other operating (income) expense, net
Derivative Instruments, Gain (Loss) [Line Items]
Heating oil realized and unrealized gains and losses	$ 1,341	$ (4,146)	$ (1,037)	$ 9,386

Accrued Expenses and Other Cu_3

Accrued Expenses and Other Current Liabilities (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Accrued Expenses and Other Current Liabilities.
Payroll and employee benefits	$ 39,838	$ 61,836
Taxes other than income taxes	50,683	53,105
Interest	1,260	2,511
Workers' compensation	19,256	17,584
Asset retirement obligations	8,217	8,632
Other	15,909	13,375
Accrued expenses and other current liabilities	$ 135,163	$ 157,043

Debt and Financing Arrangemen_3

Debt and Financing Arrangements - Long term debt (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Debt Instrument [Line Items]
Debt issuance costs	$ (1,790)	$ (2,929)
Total	129,441	174,276
Less: current maturities of debt	21,926	57,988
Long-term debt	107,515	116,288
Term loan due 2024
Debt Instrument [Line Items]
Long-term debt	4,252	6,502
Debt instrument, face amount	4,300
Tax Exempt Bonds
Debt Instrument [Line Items]
Long-term debt	98,075	98,075
Debt instrument, face amount	98,100
Convertible Debt.
Debt Instrument [Line Items]
Long-term debt		13,156
Other Debt
Debt Instrument [Line Items]
Long-term debt	$ 28,904	$ 59,472

Debt and Financing Arrangemen_4

Debt and Financing Arrangements (Details) $ / shares in Units, shares in Millions

9 Months Ended

12 Months Ended

Aug. 03, 2022 USD ($)

Jul. 29, 2021 USD ($) installment

Nov. 03, 2020 USD ($) $ / shares shares

Oct. 29, 2020 $ / shares

Jul. 02, 2020 USD ($)

Mar. 04, 2020 USD ($) installment

Sep. 30, 2023 USD ($)

Sep. 30, 2022 USD ($)

Dec. 31, 2022 USD ($)

Dec. 31, 2017 USD ($)

Aug. 02, 2022 USD ($)

Mar. 04, 2021 USD ($)

Debt Instrument [Line Items]

Restricted cash

$ 1,100,000

$ 1,100,000

$ 1,100,000

Debt financing costs

$ 690,000

Outstanding debt

129,441,000

174,276,000

Derivative Assets

1,281,000

2,707,000

New Term Loan Debt Facility | Senior Notes

Debt Instrument [Line Items]

Term loan, face value

$ 300,000,000

Percentage of face amount

99.50

Quarterly principal amortization payments

$ 750,000

Term loan repaid

$ 273,800,000

Amount of voting equity interests of domestic subsidiaries guaranteed (percent)

100

Amount of voting equity interests of foreign owned subsidiaries guaranteed (percent)

65

Outstanding debt

4,300,000

New Term Loan Debt Facility | Line of Credit | London Interbank Market Rate [Member]

Debt Instrument [Line Items]

Applicable margin on interest rate

2.75%

New Term Loan Debt Facility | Line of Credit | London Interbank Market Rate [Member] | Minimum

Debt Instrument [Line Items]

Applicable margin on interest rate

1%

New Term Loan Debt Facility | Line of Credit | Base Rate

Debt Instrument [Line Items]

Applicable margin on interest rate

1.75%

Accounts Receivable Securitization Facility | Line of Credit | Secured Debt

Debt Instrument [Line Items]

Current borrowing capacity

99,400,000

Letters of credit outstanding

50,600,000

Accounts Receivable Securitization Facility | Regions Bank | Line of Credit | Secured Debt

Debt Instrument [Line Items]

Current borrowing capacity

$ 150,000,000

$ 110,000,000

Inventory-Based Revolving Credit Facility

Debt Instrument [Line Items]

Covenant amount

23,800,000

Inventory-Based Revolving Credit Facility | Regions Bank | Line of Credit | Secured Debt

Debt Instrument [Line Items]

Term loan, face value

$ 50,000,000

Letters of credit outstanding

26,200,000

Borrowing base percentage, coal inventory

85

Borrowing base percentage, parts and supplies inventory

85

Borrowing base, percentage of clause

35

Percent of eligible cash

100%

Covenant amount

$ 100,000,000

Equipment financing arrangement | Secured Debt

Debt Instrument [Line Items]

Term loan, face value

$ 23,500,000

$ 53,600,000

Number of monthly payments | installment

42

48

Interest rate

7.35%

6.34%

Tax Exempt Bonds

Debt Instrument [Line Items]

Term loan, face value

98,100,000

Series 2020 Tax Exempt Bonds

Debt Instrument [Line Items]

Term loan, face value

$ 53,100,000

Interest rate

5%

Mandatory tender percentage

100%

Series 2021 Tax Exempt Bonds

Debt Instrument [Line Items]

Term loan, face value

$ 45,000,000

Interest rate

4.125%

Convertible Notes

Debt Instrument [Line Items]

Term loan, face value

$ 155,300,000

Interest rate

5.25%

Net proceeds of convertible debt

$ 132,700,000

Principal amount of convertible notes

13,200,000

Cash on convertible notes

58,400,000

Deferred Offering Costs

$ 5,100,000

Loss on debt conversion

1,100,000

Capped Call Transactions

Debt Instrument [Line Items]

Initial strike price (in dollars per share) | $ / shares

$ 37.325

Number of underlying shares | shares

4.2

Cap price | $ / shares

$ 52.255

Capped call, transaction cost

$ 17,500,000

Debt instrument capped call transaction intrinsic value

$ 62,100,000

Income Taxes (Details)

Income Taxes (Details)	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Income Taxes
Effective income tax rate (as a percent)	18.60%	0.10%	16.10%	0.20%
U.S. federal statutory rate (as percent)			21%

Fair Value Measurements - Finan

Fair Value Measurements - Financial assets and liabilities (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Assets:
Investments in marketable securities	$ 30,447	$ 36,993
Derivatives	1,281
Fund for asset retirement obligations	140,413
Total assets	172,141
Level 1
Assets:
Investments in marketable securities	26,469
Derivatives	0
Fund for asset retirement obligations	140,413
Total assets	166,882
Liabilities:
Derivatives	0
Level 2
Assets:
Investments in marketable securities	3,978
Derivatives	46
Total assets	4,024
Level 3
Assets:
Investments in marketable securities	0
Derivatives	1,235
Fund for asset retirement obligations	0
Total assets	1,235
Liabilities:
Derivatives	$ 0

Fair Value Measurements - Chang

Fair Value Measurements - Change in fair Values of financial instruments categorized as level 3 (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended	12 Months Ended
	Sep. 30, 2023	Sep. 30, 2023	Dec. 31, 2022
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, beginning of period	$ 230	$ 1,300
Realized and unrealized (losses) recognized in earnings, net	(1,341)	$ 1,037
Fair Value, Asset, Recurring Basis, Unobservable Input Reconciliation, Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]		Other Operating Income (Expense), Net	Other Operating Income (Expense), Net
Purchases		$ 1,800
Settlements	(336)	(828)
Ending balance	$ 1,235	$ 1,235	$ 1,300

Fair Value Measurements (Detail

Fair Value Measurements (Details) - USD ($) $ in Millions	Sep. 30, 2023	Dec. 31, 2022
Fair Value Measurements
Fair value of debt, including amounts classified as current	$ 131.2	$ 223

Earnings per Common Share (Deta

Earnings per Common Share (Details) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Earnings per Common Share
Net income attributable to common shares	$ 73,691	$ 181,007	$ 349,152	$ 860,443
Adjustment of interest expense attributable to Convertible Notes		346	108	4,345
Adjustment for inducement payments		217		4,914
Diluted net income attributable to common shareholders	$ 73,691	$ 181,570	$ 349,260	$ 869,702
Weighted average shares outstanding:
Basic weighted average shares outstanding (in shares)	18,187	18,396	18,189	16,881
Effect of dilutive securities (in shares)	653	1,698	969	1,716
Convertible Notes (in shares)		814	112	2,613
Diluted weighted average shares outstanding (in shares)	18,840	20,908	19,270	21,210

Workers Compensation Expense (D

Workers Compensation Expense (Details) - USD ($) $ in Millions		1 Months Ended
	Jan. 18, 2023	Feb. 29, 2020
Workers Compensation Expense
Self-insured operators must post security percent	120%
Additional collateral amount		$ 71.1
Number of days required to submit additional collateral to retain self-insurance status		30 days

Workers Compensation Expense -

Workers Compensation Expense - Worker's compensation expense (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Total workers' compensation expense
Accrued Workers' Compensation [Line Items]
Total workers' compensation expense	$ (4,571)	$ 5,026	$ 4,385	$ 14,846
Occupational disease
Accrued Workers' Compensation [Line Items]
Service cost	993	1,498	2,980	4,493
Interest cost	1,511	1,153	4,531	3,458
Net amortization	241	(157)	723	(471)
Net benefit credit	2,263	2,808	6,788	8,422
Traumatic injury claims and assessments
Accrued Workers' Compensation [Line Items]
Traumatic injury claims and assessments	$ (6,834)	$ 2,218	$ (2,403)	$ 6,424

Employee Benefit Plans - Schedu

Employee Benefit Plans - Schedule of net benefit credit (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Defined Benefit Plan Disclosure [Line Items]
Final contribution to the plan			$ 3,200
Gain recognized upon plan termination			4,000
Defined benefit pension plan
Defined Benefit Plan Disclosure [Line Items]
Interest cost	$ 1,023	$ 1,486	4,090	$ 3,673
Expected return on plan assets	(1,012)	(1,557)	(4,048)	(4,422)
Pension settlement	$ (3,986)	$ (201)	$ (3,986)	$ (615)
Defined Benefit Plan, Net Periodic Benefit (Cost) Credit, Settlement Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]	Pension and Other Postretirement Benefits Cost (Reversal of Cost)	Pension and Other Postretirement Benefits Cost (Reversal of Cost)	Pension and Other Postretirement Benefits Cost (Reversal of Cost)	Pension and Other Postretirement Benefits Cost (Reversal of Cost)
Amortization of prior service credits	$ (25)	$ (38)	$ (98)	$ (111)
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Amortization of Prior Service Cost (Credit), Statement of Income or Comprehensive Income [Extensible Enumeration]	Pension and Other Postretirement Benefits Cost (Reversal of Cost)	Pension and Other Postretirement Benefits Cost (Reversal of Cost)	Pension and Other Postretirement Benefits Cost (Reversal of Cost)	Pension and Other Postretirement Benefits Cost (Reversal of Cost)
Amortization of other actuarial losses (gains)	$ (129)	$ (101)	$ (519)	$ (134)
Net benefit credit	(4,129)	(411)	(4,561)	(1,609)
Other postretirement benefits plan
Defined Benefit Plan Disclosure [Line Items]
Service cost	58	71	173	212
Interest cost	674	501	2,021	1,504
Amortization of other actuarial losses (gains)	$ (2,422)	$ (627)	$ (7,267)	$ (1,881)
Defined Benefit Plan, Net Periodic Benefit (Cost) Credit, Amortization of Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]	Pension and Other Postretirement Benefits Cost (Reversal of Cost)	Pension and Other Postretirement Benefits Cost (Reversal of Cost)	Pension and Other Postretirement Benefits Cost (Reversal of Cost)	Pension and Other Postretirement Benefits Cost (Reversal of Cost)
Net benefit credit	$ (1,690)	$ (55)	$ (5,073)	$ (165)

Commitments and Contingencies (

Commitments and Contingencies (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 30, 2023	Sep. 30, 2023	Sep. 30, 2022	Dec. 31, 2022
Loss Contingencies [Line Items]
Surety Bonds Outstanding	$ 553,000	$ 553,000
Cash collateral for surety bond	5,600	5,600
Contribution to fund asset retirement obligations		4,421	$ 110,000
Long-term asset retirement obligation	140,413	140,413		$ 135,993
Securitization and Inventory Facilities
Loss Contingencies [Line Items]
Letters of credit outstanding	76,800	76,800
Asset retirement obligations
Loss Contingencies [Line Items]
Surety Bonds Outstanding	456,100	456,100
Cash collateral for surety bond	600	600
Reclamation-related obligations	242,600	242,600
Contribution to fund asset retirement obligations	1,800
Long-term asset retirement obligation	$ 140,400	$ 140,400

Segment Information - Schedule

Segment Information - Schedule of operating segment results (Details) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023 USD ($)	Sep. 30, 2022 USD ($)	Sep. 30, 2023 USD ($) item	Sep. 30, 2022 USD ($)	Dec. 31, 2022 USD ($)
Segment Reporting Information [Line Items]
Number of distinct lines of business | item			2
Revenues	$ 744,601	$ 863,835	$ 2,371,826	$ 2,865,129
Adjusted EBITDA	126,291	222,956	534,018	1,003,906
Depreciation, depletion and amortization	36,717	33,958	108,273	98,948
Accretion on asset retirement obligation	5,292	4,430	15,877	13,290
Total assets	2,365,858	2,319,862	2,365,858	2,319,862	$ 2,433,108
Capital expenditures	44,424	41,360	121,030	94,517
Operating Segments | MET
Segment Reporting Information [Line Items]
Revenues	432,835	444,306	1,420,758	1,640,970
Adjusted EBITDA	128,322	155,185	524,218	810,615
Depreciation, depletion and amortization	29,494	28,354	85,575	82,738
Accretion on asset retirement obligation	651	553	1,880	1,660
Total assets	1,046,404	1,020,849	1,046,404	1,020,849
Capital expenditures	33,806	36,389	94,205	79,896
Operating Segments | Thermal
Segment Reporting Information [Line Items]
Revenues	311,766	419,529	951,068	1,224,159
Adjusted EBITDA	23,373	96,812	98,807	290,648
Depreciation, depletion and amortization	7,001	5,388	22,057	15,554
Accretion on asset retirement obligation	4,314	3,444	12,941	10,331
Total assets	415,373	325,580	415,373	325,580
Capital expenditures	10,369	4,604	25,904	13,200
Corporate, Other and Eliminations
Segment Reporting Information [Line Items]
Revenues	0	0	0	0
Adjusted EBITDA	(25,404)	(29,041)	(89,007)	(97,357)
Depreciation, depletion and amortization	222	216	641	656
Accretion on asset retirement obligation	327	433	1,056	1,299
Total assets	904,081	973,433	904,081	973,433
Capital expenditures	$ 249	$ 367	$ 921	$ 1,421

Segment Information - Reconcili

Segment Information - Reconciliation segment income to net income (loss) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Segment Information
Net Income (Loss)	$ 73,691	$ 181,007	$ 349,152	$ 860,443
Provision for income taxes	16,781	474	66,839	1,424
Interest expense, net	(1,683)	1,836	(1,557)	13,469
Depreciation, depletion and amortization	36,717	33,958	108,273	98,948
Accretion on asset retirement obligation	5,292	4,430	15,877	13,290
Non-service related pension and postretirement benefit (credits) costs	(4,507)	857	(5,692)	2,189
Net loss resulting from early retirement of debt		394	1,126	14,143
Adjusted EBITDA	126,291	222,956	534,018	1,003,906
EBITDA from idled or otherwise disposed operations	30	3,624	8,726	9,972
Selling, general and administrative expenses	24,279	26,107	73,092	79,271
Other	1,095	(690)	7,189	8,114
Segment Adjusted EBITDA from coal operations	$ 151,695	$ 251,997	$ 623,025	$ 1,101,263

Revenue Recognition - Schedule

Revenue Recognition - Schedule of revenues (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Disaggregation of Revenue [Line Items]
Revenues	$ 744,601	$ 863,835	$ 2,371,826	$ 2,865,129
North America revenues
Disaggregation of Revenue [Line Items]
Revenues	360,654	377,551	1,060,128	1,031,735
Seaborne revenues
Disaggregation of Revenue [Line Items]
Revenues	383,947	486,284	1,311,698	1,833,394
Operating Segments | MET
Disaggregation of Revenue [Line Items]
Revenues	432,835	444,306	1,420,758	1,640,970
Operating Segments | MET | North America revenues
Disaggregation of Revenue [Line Items]
Revenues	108,895	70,491	274,017	125,906
Operating Segments | MET | Seaborne revenues
Disaggregation of Revenue [Line Items]
Revenues	323,940	373,815	1,146,741	1,515,064
Operating Segments | Thermal
Disaggregation of Revenue [Line Items]
Revenues	311,766	419,529	951,068	1,224,159
Operating Segments | Thermal | North America revenues
Disaggregation of Revenue [Line Items]
Revenues	251,759	307,060	786,111	905,829
Operating Segments | Thermal | Seaborne revenues
Disaggregation of Revenue [Line Items]
Revenues	60,007	112,469	164,957	318,330
Corporate, Other and Eliminations
Disaggregation of Revenue [Line Items]
Revenues	0	0	0	0
Corporate, Other and Eliminations | North America revenues
Disaggregation of Revenue [Line Items]
Revenues	0	0	0	0
Corporate, Other and Eliminations | Seaborne revenues
Disaggregation of Revenue [Line Items]
Revenues	$ 0	$ 0	$ 0	$ 0

Revenue Recognition (Details)

Revenue Recognition (Details) T in Millions	Sep. 30, 2023 T
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2023-10-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation (in tons)	18.5
Remaining performance obligation, variable price contracts (in tons)	2.2
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2024-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligations, fixed price contracts (in tons)	95.2
Remaining performance obligation, variable price contracts (in tons)	3.7

Leases (Narrative) (Details)

Leases (Narrative) (Details)	Sep. 30, 2023
Minimum
Lessee, Lease, Description [Line Items]
Operating lease, remaining lease terms	1 year
Maximum
Lessee, Lease, Description [Line Items]
Operating lease, remaining lease terms	4 years

Leases - Lease assets and liabi

Leases - Lease assets and liabilities (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Assets
Operating lease right-of-use assets	$ 10,134	$ 12,106
Operating Lease, Right-of-Use Asset, Statement of Financial Position [Extensible List]	Other Assets, Noncurrent	Other Assets, Noncurrent
Financing lease right-of-use assets	$ 1,945	$ 2,918
Finance Lease, Right-of-Use Asset, Statement of Financial Position [Extensible List]	Other Assets, Noncurrent	Other Assets, Noncurrent
Total Lease Assets	$ 12,079	$ 15,024
Liabilities
Financing lease liabilities - current	$ 1,025	$ 977
Finance Lease, Liability, Current, Statement of Financial Position [Extensible List]	Accrued Liabilities, Current	Accrued Liabilities, Current
Operating lease liabilities - current	$ 2,719	$ 2,722
Operating Lease, Liability, Current, Statement of Financial Position [Extensible List]	Accrued Liabilities, Current	Accrued Liabilities, Current
Financing lease liabilities - long-term	$ 2,346	$ 3,121
Finance Lease, Liability, Noncurrent, Statement of Financial Position [Extensible List]	Other Liabilities, Noncurrent	Other Liabilities, Noncurrent
Operating lease liabilities - long-term	$ 7,929	$ 9,993
Operating Lease, Liability, Noncurrent, Statement of Financial Position [Extensible List]	Other Liabilities, Noncurrent	Other Liabilities, Noncurrent
Total Lease Liabilities	$ 14,019	$ 16,813

Leases - Weighted average lease

Leases - Weighted average lease term and discount rate (Details)	Sep. 30, 2023	Dec. 31, 2022
Leases
Weighted average remaining lease term in years	3 years 6 months 10 days	4 years 1 month 20 days
Weighted average remaining lease term in years	1 year 6 months	2 years 3 months
Weighted average discount rate	5.50%	5.50%
Weighted average discount rate	6.40%	6.40%

Leases - Other information rela

Leases - Other information related to leases (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Lease information:
Operating lease cost	$ 801	$ 831	$ 2,462	$ 2,492
Operating cash flows from operating leases	851	876	2,555	2,562
Financing lease cost	393	393	1,179	1,179
Operating cash flows from financing leases	$ 303	$ 303	$ 908	$ 908

Leases - Future minimum lease p

Leases - Future minimum lease payments (Details) $ in Thousands	Sep. 30, 2023 USD ($)
Operating Leases
2023	$ 801
2024	3,200
2025	3,185
2026	3,080
2027	1,533
Total minimum lease payments	11,799
Less imputed interest	(1,151)
Total operating lease liability	10,648
Finance Leases
2023	303
2024	1,210
2025	2,111
Total minimum lease payments	3,624
Less imputed interest	(253)
Total finance lease liability	$ 3,371

Subsequent Event (Details)

Subsequent Event (Details) - Subsequent Event	Oct. 26, 2023 $ / shares
Subsequent Event [Line Items]
Quarterly dividend	$ 1.13
Fixed dividend	0.25
Variable dividend	$ 0.88

Pay vs Performance Disclosure

Pay vs Performance Disclosure - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Pay vs Performance Disclosure
Net Income (Loss)	$ 73,691	$ 181,007	$ 349,152	$ 860,443

Insider Trading Arrangements

Insider Trading Arrangements	3 Months Ended
	Sep. 30, 2023 shares
Trading Arrangements, by Individual
Material Terms of Trading Arrangement	Item 5. During the three months ended September 30, 2023, the following officers of the Company adopted “Rule 10b5-1 trading arrangements” as defined in Item 408 of Regulation S-K, as described in the table below: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Type of ​ ​ ​ Expiration ​ ​ ​ ​ Total Shares Name and Title ​ Trading Agreement ​ Date Adopted ​ Date ​ Duration 1 ​ To be Sold 2 Paul T. Demzik , Senior Vice President and Chief Commercial Officer Rule 10b5-1 Trading Arrangement ​ ​ 9/11/2023 1/31/2025 ​ 509 days ​ ​ Up to 38,675 Matthew C. Giljum , Senior Vice President and Chief Financial Officer Rule 10b5-1 Trading Arrangement ​ ​ 9/7/2023 10/17/2024 ​ 407 days ​ ​ Up to 3,097 John W. Lorson , Vice President and Chief Accounting Officer Rule 10b5-1 Trading Arrangement ​ ​ 9/11/2023 1/31/2025 ​ 509 days ​ ​ Up to 1,355 Deck S. Slone , Senior Vice President, Strategy and Public Policy Rule 10b5-1 Trading Arrangement ​ ​ 9/7/2023 10/17/2024 ​ 407 days ​ Up to 6,024 John A. Ziegler , Senior Vice President and Chief Administrative Officer ​ Rule 10b5-1 Trading Arrangement ​ ​ 9/7/2023 ​ 2/28/2024 ​ 174 days ​ ​ Up to 4,041 ​ ​ 1. Each Rule 10b5-1 trading arrangement permits transactions through and including the earlier to occur of (a) the completion of all sales or (b) the expiration date listed in the table. ​ 2. Represents the maximum number of shares that could potentially be sold pursuant to the Rule 10b5-1 trading arrangement, including sales made in connection with the vesting of future equity awards. Accordingly, in calculating this amount, we have not considered any potential reductions in shares available to be sold due to tax withholdings at the time such equity awards vest, and, for performance-based awards, we have assumed such awards will vest at maximum value. ​ Other than as discussed above, during the three months ended September 30, 2023, no director or officer of the Company adopted or terminated a “Rule 10b5-1 trading arrangement” or “non-Rule 10b5-1 trading arrangement,” as each term is defined in Item 408 of Regulation S-K. ​ Upon the recommendation of the Personnel and Compensation Committee of our Board of Directors, on October 25, 2023, the Board of Directors approved an amendment and restatement of the October 25, 2021 letter agreement with John W. Eaves to extend Mr. Eaves service as our Executive Chair of the Board until the date of the Company’s next annual meeting or such earlier time as determined by the Company or Mr. Eaves. ​
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
Paul T Demzik
Trading Arrangements, by Individual
Name	Paul T. Demzik
Title	Senior Vice President and Chief Commercial Officer
Rule 10b5-1 Arrangement Adopted	true
Adoption Date	9/11/2023
Arrangement Duration	509 days
Aggregate Available	38,675
Expiration Date	1/31/2025
Matthew C Giljum
Trading Arrangements, by Individual
Name	Matthew C. Giljum
Title	Senior Vice President and Chief Financial Officer
Rule 10b5-1 Arrangement Adopted	true
Adoption Date	9/7/2023
Arrangement Duration	407 days
Aggregate Available	3,097
Expiration Date	10/17/2024
John W Lorson
Trading Arrangements, by Individual
Name	John W. Lorson
Title	Vice President and Chief Accounting Officer
Rule 10b5-1 Arrangement Adopted	true
Adoption Date	9/11/2023
Arrangement Duration	509 days
Aggregate Available	1,355
Expiration Date	1/31/2025
Deck S Slone
Trading Arrangements, by Individual
Name	Deck S. Slone
Title	Senior Vice President, Strategy and Public Policy
Rule 10b5-1 Arrangement Adopted	true
Adoption Date	9/7/2023
Arrangement Duration	407 days
Aggregate Available	6,024
Expiration Date	10/17/2024
John A Ziegler
Trading Arrangements, by Individual
Name	John A. Ziegler
Title	Senior Vice President and Chief Administrative Officer
Rule 10b5-1 Arrangement Adopted	true
Adoption Date	9/7/2023
Arrangement Duration	174 days
Aggregate Available	4,041
Expiration Date	2/28/2024