Note 4 - Other Long-term Assets (Tables)

6 Months Ended

Jun. 30, 2022

Notes Tables

Schedule of Other Assets, Noncurrent [Table Text Block]

	June 30,		December 31,
	2022		2021
Advanced coal royalties	$	6,464	$	6,678
Other		1,670		1,694
Total other assets	$	8,134	$	8,372