Note 5 - Income Taxes - Net Deferred Tax Liability (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Deferred tax assets:
Reserves and accrued liabilities	$ 13,126	$ 13,244
Other	1,212	1,597
Deferred Tax Assets, Gross	14,338	14,841
Deferred tax liabilities:
Depreciation	133,634	148,285
Prepaid expenses	3,166	3,597
Deferred Tax Liabilities, Gross	136,800	151,882
Net deferred tax liability	$ 122,462	$ 137,041