Other Accrued Liabilities (Details) - USD ($) $ in Thousands	Jun. 30, 2025	Dec. 31, 2024
Other Liabilities Disclosure [Abstract]
Subsidence Liability	$ 108,100	$ 88,259
Accrued Compensation and Benefits	59,143	54,138
Accrued Other Taxes	44,564	6,973
Other	67,797	31,928
Current Portion of Long-Term Liabilities:
Asset Retirement Obligations	41,496	35,554
Pneumoconiosis Benefits	25,532	16,389
Postretirement Benefits Other than Pensions	21,310	17,887
Workers' Compensation	17,679	11,056
Total Other Accrued Liabilities	$ 385,621	$ 262,184