ACCRUED WORKERS' COMPENSATION AND PNEUMOCONIOSIS BENEFITS - AOCL (Details) - Pneumoconiosis benefits - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Other changes in plan assets and benefit obligations recognized in accumulated other comprehensive loss:
Net actuarial gain (loss)	$ 13,990	$ (25,615)	$ 9,840
Reversal of amortization item: Net actuarial loss (gain)	3,356	1,382	1,038
Total recognized in accumulated other comprehensive Income	$ 17,346	$ (24,233)	$ 10,878
Estimated present value of future obligations and other information
Pneumoconiosis discount rate	5.51%	4.81%	5.00%
Amount recognized in accumulated other comprehensive income consists of:
Net actuarial loss	$ 32,399	$ 49,745	$ 25,510

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Amount, before tax, of accumulated other comprehensive income (loss) for gain (loss) of defined benefit plan, that has not been recognized in net periodic benefit (cost) credit.

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