Coal Workers' Pneumoconiosis and Workers' Compensation - Schedule of Weighted Average Discount Rates (Details)	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
CWP Benefits
Defined Benefit Plan Disclosure [Line Items]
Benefit obligations	5.14%	5.40%	2.85%
Net periodic benefit costs	5.40%	2.85%	2.53%
Workers Compensation
Defined Benefit Plan Disclosure [Line Items]
Benefit obligations	5.12%	5.38%	2.74%
Net periodic benefit costs	5.38%	2.74%	2.35%