Coal Workers' Pneumoconiosis and Workers' Compensation - Schedule of Expected Benefit Payments (Details) $ in Thousands	Dec. 31, 2025 USD ($)
Defined Benefit Plan Disclosure [Line Items]
2026	$ 13,460
2027	15,222
2028	16,397
2029	17,182
2030	17,835
Years 2031-2035	98,643
CWP Benefits
Defined Benefit Plan Disclosure [Line Items]
2026	24,539
2027	23,669
2028	22,956
2029	22,207
2030	21,682
Years 2031-2035	108,676
Actuarial Benefits
Defined Benefit Plan Disclosure [Line Items]
2026	11,845
2027	13,566
2028	14,700
2029	15,442
2030	16,052
Years 2031-2035	89,036
Other Benefits
Defined Benefit Plan Disclosure [Line Items]
2026	1,615
2027	1,656
2028	1,697
2029	1,740
2030	1,783
Years 2031-2035	$ 9,607