Other Accrued Liabilities (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Other Liabilities Disclosure [Abstract]
Subsidence Liability	$ 104,265	$ 96,623
Accrued Compensation and Benefits	72,754	67,893
Accrued Income Taxes	17,229	1,513
Accrued Other Taxes	7,865	10,551
Accrued Interest	3,212	7,942
Other	19,115	9,880
Current Portion of Long-Term Liabilities:
Asset Retirement Obligations	32,974	29,644
Postretirement Benefits Other than Pensions	21,697	22,436
Pneumoconiosis Benefits	12,571	12,723
Workers' Compensation	9,615	10,451
Total Other Accrued Liabilities	$ 301,297	$ 269,656