Note 1 - Summary of Significant Accounting Policies (Tables)

12 Months Ended

Dec. 31, 2021

Notes Tables

Schedule of Asset Retirement Obligations [Table Text Block]

	Year Ended December 31,
	2021			2020
Balance, beginning of year	$	16,277		$	15,764
Accretion		1,504			1,381
Change in estimate		(3,510	)		—
Payments		(146	)		(868	)
Balance, end of year		14,125			16,277
Less current portion		(100	)		(100	)
Long-term balance, end of year	$	14,025		$	16,177