Note 2 - Revenue from Contracts with Customers:- Disaggregation of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Total Revenue from Contracts with Customers	$ 536,154	$ 330,760
Domestic Coal Revenue [Member]
Total Revenue from Contracts with Customers	225,444	159,216
Export Coal Revenue [Member]
Total Revenue from Contracts with Customers	250,924	126,319
Coal [Member]
Total Revenue from Contracts with Customers	476,368	285,535
Terminal Revenue [Member]
Total Revenue from Contracts with Customers	21,397	18,212
Freight Revenue [Member]
Total Revenue from Contracts with Customers	38,389	27,013
Power Generated, Coal [Member] | Domestic Coal Revenue [Member]
Total Revenue from Contracts with Customers	223,500	155,310
Power Generated, Coal [Member] | Export Coal Revenue [Member]
Total Revenue from Contracts with Customers	120,441	33,131
Power Generated, Coal [Member] | Coal [Member]
Total Revenue from Contracts with Customers	343,941	188,441
Industrial, Coal [Member] | Domestic Coal Revenue [Member]
Total Revenue from Contracts with Customers	1,944	2,836
Industrial, Coal [Member] | Export Coal Revenue [Member]
Total Revenue from Contracts with Customers	97,549	80,574
Industrial, Coal [Member] | Coal [Member]
Total Revenue from Contracts with Customers	99,493	83,410
Metallurgical, Coal [Member] | Domestic Coal Revenue [Member]
Total Revenue from Contracts with Customers	0	1,070
Metallurgical, Coal [Member] | Export Coal Revenue [Member]
Total Revenue from Contracts with Customers	32,934	12,614
Metallurgical, Coal [Member] | Coal [Member]
Total Revenue from Contracts with Customers	$ 32,934	$ 13,684