Segment Information (Schedule Of Operating Segment Results) (Details) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2022 USD ($)	Jun. 30, 2021 USD ($)	Jun. 30, 2022 USD ($) item	Jun. 30, 2021 USD ($)	Dec. 31, 2021 USD ($)
Segment Reporting Information [Line Items]
Number of distinct lines of business | item			2
Revenues	$ 1,133,358	$ 450,389	$ 2,001,294	$ 807,932
Adjusted EBITDA	459,967	66,526	780,950	97,423
Depreciation, depletion and amortization	32,780	27,884	64,990	53,681
Accretion on asset retirement obligation	4,430	5,437	8,860	10,874
Total assets	2,313,647	1,794,946	2,313,647	1,794,946	$ 2,117,160
Capital expenditures	30,869	71,199	53,157	147,957
Operating Segments | MET
Segment Reporting Information [Line Items]
Revenues	724,492	219,448	1,196,664	398,231
Adjusted EBITDA	396,426	61,246	655,429	102,843
Depreciation, depletion and amortization	27,432	22,654	54,384	43,536
Accretion on asset retirement obligation	553	507	1,106	1,016
Total assets	1,019,408	941,843	1,019,408	941,843
Capital expenditures	25,927	66,823	43,508	142,843
Operating Segments | Thermal
Segment Reporting Information [Line Items]
Revenues	408,866	230,759	804,630	408,297
Adjusted EBITDA	93,336	41,772	193,836	54,853
Depreciation, depletion and amortization	5,134	4,993	10,166	9,682
Accretion on asset retirement obligation	3,444	4,419	6,888	8,837
Total assets	287,039	191,164	287,039	191,164
Capital expenditures	4,594	575	8,596	864
Corporate, Other and Eliminations
Segment Reporting Information [Line Items]
Revenues	0	182	0	1,404
Adjusted EBITDA	(29,795)	(36,492)	(68,315)	(60,273)
Depreciation, depletion and amortization	214	237	440	463
Accretion on asset retirement obligation	433	511	866	1,021
Total assets	1,007,200	661,939	1,007,200	661,939
Capital expenditures	$ 348	$ 3,801	$ 1,053	$ 4,250