Note 4 - Miscellaneous Other Income - Miscellaneous Other Income (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Contract Buyout	$ 0	$ 1,193	$ 40,969	$ 3,583
Sale of Certain Coal Lease Contracts	17,847	0	17,847	0
Royalty Income - Non-Operated Coal	2,241	4,976	9,638	16,863
Rental Income	255	625	1,077	1,923
Property Easements and Option Income	19	100	495	1,529
Interest Income	76	755	442	2,399
Purchased Coal Sales	0	3,136	0	9,052
Other	563	403	639	1,325
Miscellaneous Other Income	$ 21,001	$ 11,188	$ 71,107	$ 36,674