Note 4 - Other Long-term Assets (Tables)

3 Months Ended

Mar. 31, 2021

Notes Tables

Schedule of Other Assets, Noncurrent [Table Text Block]

	March 31,		December 31,
	2021		2020
Advanced coal royalties	$	6,481	$	6,449
Other		1,780		1,809
Total other assets	$	8,261	$	8,258