Note 5 - Income Taxes - Net Deferred Tax Liability (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Deferred tax assets:
Reserves and accrued liabilities	$ 13,244	$ 11,975
Other	1,597	1,597
Deferred Tax Assets, Gross, Total	14,841	13,572
Deferred tax liabilities:
Depreciation	148,285	135,306
Prepaid expenses	3,597	3,429
Deferred Tax Liabilities, Gross, Total	151,882	138,735
Net deferred tax liability	$ 137,041	$ 125,163