Note 24 - Related Party Transactions - Changes for Services (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Total Services from CONSOL Energy	$ 13,424	$ 11,528	$ 11,218
Operating and Other Costs [Member]
Total Services from CONSOL Energy	3,820	3,219	2,918
Selling, General and Administrative Expenses [Member]
Total Services from CONSOL Energy	$ 9,604	$ 8,309	$ 8,300