Note 12 - Related Party Transactions (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020
Royalties paid				$ 3,300
On-Going Administrative Services
Royalties paid	$ 40	$ 79
Related party fees		16		$ 31
Ramaco Coal, LLC
Royalties paid	1,300	$ 1,000	$ 3,900
Ramaco Coal, LLC | Accounts Payable and Accrued Liabilities | Mineral Lease and Surface Rights Agreements
Due to Related Parties, Total	$ 600		$ 600		$ 400