SEGMENT INFORMATION - EBITDA Expense Reconciliation (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Reconciliation of consolidated Segment Adjusted EBITDA Expense
Litigation expense accrual	$ (15,250)
Outside coal purchases	9,112
Other expense (income)	606	$ 573
Segment Adjusted EBITDA Expense	358,327	339,296
Product
Reconciliation of consolidated Segment Adjusted EBITDA Expense
Operating expenses (excluding depreciation, depletion and amortization)	$ 363,859	$ 338,723