Note 5 - Components of Coal Workers' Pneumoconiosis (CWP) and Workers' Compensation Net Periodic Benefit Costs - Schedule of Components of Net Periodic Benefit Costs (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Coal Workers Pneumoconiosis [Member]
Service Cost	$ 726	$ 1,115
Interest Cost	1,265	1,178
Amortization of Actuarial Loss	1,060	2,091
State Administrative Fees and Insurance Bond Premiums	0	0
Net Periodic Benefit (Credit) Cost	3,051	4,384
Workers Compensation [Member]
Service Cost	1,230	1,059
Interest Cost	342	282
Amortization of Actuarial Loss	(105)	(45)
State Administrative Fees and Insurance Bond Premiums	437	468
Net Periodic Benefit (Credit) Cost	$ 1,904	$ 1,764