Revenue From Contracts With Customers - Schedule of Disaggregation of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2025	Jun. 30, 2024	Jun. 30, 2025	Jun. 30, 2024
Disaggregation of Revenue [Line Items]
Total Revenue from Contracts with Customers	$ 1,102,361	$ 490,720	$ 2,119,767	$ 1,037,409
Total Coal Revenue
Disaggregation of Revenue [Line Items]
Total Revenue from Contracts with Customers	1,093,366	482,255	2,102,621	1,014,080
Power Generation
Disaggregation of Revenue [Line Items]
Total Revenue from Contracts with Customers	475,612	224,611	910,340	463,171
Industrial
Disaggregation of Revenue [Line Items]
Total Revenue from Contracts with Customers	273,545	180,921	475,610	386,949
Metallurgical
Disaggregation of Revenue [Line Items]
Total Revenue from Contracts with Customers	344,209	76,723	716,671	163,960
Third-Party Terminal Revenue
Disaggregation of Revenue [Line Items]
Total Revenue from Contracts with Customers	4,540	4,727	9,496	15,199
Other Revenue
Disaggregation of Revenue [Line Items]
Total Revenue from Contracts with Customers	4,455	3,738	7,650	8,130
Domestic | Total Coal Revenue
Disaggregation of Revenue [Line Items]
Total Revenue from Contracts with Customers	499,359	204,167	890,171	385,563
Domestic | Power Generation
Disaggregation of Revenue [Line Items]
Total Revenue from Contracts with Customers	414,634	186,657	756,443	351,390
Domestic | Industrial
Disaggregation of Revenue [Line Items]
Total Revenue from Contracts with Customers	40,671	7,745	66,170	11,151
Domestic | Metallurgical
Disaggregation of Revenue [Line Items]
Total Revenue from Contracts with Customers	44,054	9,765	67,558	23,022
Export | Total Coal Revenue
Disaggregation of Revenue [Line Items]
Total Revenue from Contracts with Customers	594,007	278,088	1,212,450	628,517
Export | Power Generation
Disaggregation of Revenue [Line Items]
Total Revenue from Contracts with Customers	60,978	37,954	153,897	111,781
Export | Industrial
Disaggregation of Revenue [Line Items]
Total Revenue from Contracts with Customers	232,874	173,176	409,440	375,798
Export | Metallurgical
Disaggregation of Revenue [Line Items]
Total Revenue from Contracts with Customers	$ 300,155	$ 66,958	$ 649,113	$ 140,938