Note 13 - Income Taxes - Components of Deferred Income Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Deferred tax assets:
Loss carryforwards U.S. - Federal/States	$ 15,975	$ 22,873
Asset retirement obligations	5,175	3,972
Accrued expenses	744	856
Equity-based compensation	2,331	2,200
Total deferred tax assets	24,225	29,901
Deferred tax liabilities:
Depreciation & amortization	(30,631)	(31,663)
Net deferred tax liabilities, net of valuation allowance	$ (6,406)	$ (1,762)