CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income (loss)	$ 579,148	$ 178,755	$ (129,051)
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Depreciation, depletion and amortization	273,759	261,377	313,387
Non-cash compensation expense	11,029	5,709	3,345
Equity investment income	(5,634)	(2,130)	(907)
Distributions from equity method investments	5,634	2,130	907
Net gain on sale of property, plant and equipment	(3,665)	(6,592)	(5,850)
Asset impairment			24,977
Goodwill impairment	0	0	132,026
Change in deferred income tax	34,775	349	112
Other	5,677	3,970	13,909
Changes in operating assets and liabilities:
Trade receivables	(107,510)	(24,952)	56,172
Other receivables	(7,921)	3,109	(3,225)
Inventories, net	(20,138)	(4,673)	30,522
Prepaid expenses and other assets	(9,179)	211	(2,514)
Advance royalties	(6,787)	(7,523)	(7,690)
Accounts payable	14,580	19,481	(24,282)
Accrued taxes other than income taxes	5,180	(7,267)	9,286
Accrued payroll and related benefits	2,818	8,281	(8,051)
Pneumoconiosis benefits	3,849	6,832	2,340
Workers' compensation	(3,996)	(1,292)	1,355
Other	20,193	(10,573)	(6,123)
Total net adjustments	212,664	246,447	529,696
Net cash provided by operating activities	791,812	425,202	400,645
Property, plant and equipment:
Capital expenditures	(286,394)	(122,984)	(121,101)
Change in accounts payable and accrued liabilities	35,956	2,594	(8,773)
Proceeds from sale of property, plant and equipment	7,468	7,719	3,762
Contributions to equity method investments	24,087
Purchase of equity securities	(42,000)
Payments for acquisitions of businesses	(92,618)
Oil & gas reserve acquisition		(30,960)
Other	(1,663)	943	988
Net cash used in investing activities	(403,338)	(142,688)	(125,124)
CASH FLOWS FROM FINANCING ACTIVITIES:
Borrowings under securitization facility	27,500	35,000	46,100
Payments under securitization facility	(27,500)	(90,900)	(64,000)
Proceeds from equipment financings			14,705
Payments on equipment financings	(16,071)	(17,299)	(14,805)
Borrowings under revolving credit facilities		15,000	70,000
Payments under revolving credit facilities		(102,500)	(237,500)
Borrowings from line of credit		5,340
Payment on line of credit		(5,340)
Payments on finance lease obligations	(840)	(766)	(8,368)
Cash settlement of grants under deferred compensation plan			(2,490)
Distributions paid to Partners	(196,347)	(52,158)	(51,753)
Other	(1,596)	(2,062)	(8,318)
Net cash used in financing activities	(214,854)	(215,685)	(256,429)
NET CHANGE IN CASH AND CASH EQUIVALENTS	173,620	66,829	19,092
CASH AND CASH EQUIVALENTS AT BEGINNING OF PERIOD	122,403	55,574	36,482
CASH AND CASH EQUIVALENTS AT END OF PERIOD	$ 296,023	$ 122,403	$ 55,574