Note 4 - Other Long-term Assets (Tables)

12 Months Ended

Dec. 31, 2021

Notes Tables

Schedule of Other Assets, Noncurrent [Table Text Block]

	December 31,
	2021		2020
Advanced coal royalties	$	6,678	$	6,449
Other		1,694		1,809
Total other assets	$	8,372	$	8,258