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Revenue - Disaggregation of Revenue by Segment (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2026	Jun. 30, 2025	Jun. 30, 2026	Jun. 30, 2025
Disaggregation of Revenue [Line Items]
Revenues	$ 491,505	$ 548,675	$ 1,015,038	$ 1,078,342
Coal
Disaggregation of Revenue [Line Items]
Revenues	491,505	548,675	1,015,038	1,078,342
Coal | Export
Disaggregation of Revenue [Line Items]
Revenues	353,683	394,979	757,104	790,694
Coal | Domestic
Disaggregation of Revenue [Line Items]
Revenues	137,822	153,696	257,934	287,648
Coal, Met
Disaggregation of Revenue [Line Items]
Revenues	453,519	525,398	959,701	1,030,800
Coal, Met | Export
Disaggregation of Revenue [Line Items]
Revenues	325,304	378,021	717,715	754,761
Coal, Met | Domestic
Disaggregation of Revenue [Line Items]
Revenues	128,215	147,377	241,986	276,039
Coal, Thermal
Disaggregation of Revenue [Line Items]
Revenues	37,986	23,277	55,337	47,542
Coal, Thermal | Export
Disaggregation of Revenue [Line Items]
Revenues	28,379	16,958	39,389	35,933
Coal, Thermal | Domestic
Disaggregation of Revenue [Line Items]
Revenues	$ 9,607	$ 6,319	$ 15,948	$ 11,609

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