Segment Information - Schedule of operating segment results (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2024 USD ($) item	Mar. 31, 2023 USD ($)
Segment Reporting Information [Line Items]
Number of distinct lines of business | item	2
Revenues	$ 680,190	$ 869,931
Adjusted EBITDA	102,863	277,341
Depreciation, depletion and amortization	38,820	35,479
Accretion on asset retirement obligation	5,869	5,292
Capital expenditures	45,446	30,541
Operating Segments | MET
Segment Reporting Information [Line Items]
Revenues	417,065	536,172
Adjusted EBITDA	129,536	263,057
Depreciation, depletion and amortization	31,390	27,853
Accretion on asset retirement obligation	647	615
Capital expenditures	37,033	24,761
Operating Segments | Thermal
Segment Reporting Information [Line Items]
Revenues	263,125	333,759
Adjusted EBITDA	930	46,255
Depreciation, depletion and amortization	7,168	7,408
Accretion on asset retirement obligation	4,810	4,314
Capital expenditures	7,544	5,493
Corporate, Other and Eliminations
Segment Reporting Information [Line Items]
Revenues	0	0
Adjusted EBITDA	(27,603)	(31,971)
Depreciation, depletion and amortization	262	218
Accretion on asset retirement obligation	412	363
Capital expenditures	$ 869	$ 287