Note 7 - Income Taxes - Deferred Tax Liabilities and Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Hedge contracts	$ 0	$ 0
Other	0	2,855
Total deferred tax liabilities	0	2,855
US full cost pool	17,533	24,464
Depletion	452	470
U.S. net operating loss carryforward	50,103	96,120
Alternative minimum tax credit	0	0
Unrealized losses	956	100
Interest disallowed	4,367	5,781
Other	239	0
Total deferred tax assets	73,650	126,935
Valuation allowance for deferred tax assets	(73,650)	(124,080)
Net deferred tax assets	0	2,855
Net deferred tax	$ 0	$ 0