Note 8 - Asset Retirement Obligations (Tables)

12 Months Ended

Dec. 31, 2021

Notes Tables

Schedule of Change in Asset Retirement Obligation [Table Text Block]

	As of December 31,
	2021			2020
Balance at Beginning of Period	$	248,769		$	271,952
Accretion Expense		18,652			17,905
Payments		(18,144	)		(13,529	)
Revisions in Estimated Cash Flows		(10,334	)		(9,248	)
Other		(825	)		(18,311	)
Balance at End of Period	$	238,118		$	248,769