Other Accrued Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2024	Dec. 31, 2023
Other Liabilities Disclosure [Abstract]
Subsidence Liability	$ 88,259	$ 105,322
Accrued Compensation and Benefits	54,138	73,763
Other	38,289	38,533
Current Portion of Long-Term Liabilities:
Asset Retirement Obligations	35,554	28,571
Postretirement Benefits Other than Pensions	17,887	19,327
Pneumoconiosis Benefits	16,389	15,071
Workers' Compensation	11,056	10,019
Total Other Accrued Liabilities	$ 261,572	$ 290,606