Note 12 - Federal and State Income Taxes - Significant Components of Deferred Tax Liabilities and Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Deferred tax liabilities:
Property and equipment	$ 84,081	$ 100,736
Unrealized gains on securities	2,580	2,580
Prepaid expenses and other	2,783	2,599
Total deferred tax liabilities	89,444	105,915
Deferred tax assets:
Current expected credit losses	1,165	896
Tax credit carryforwards	0	988
Compensated absences	185	189
Self-insurance allowances	1,207	674
Marketable equity securities	0	2,129
Net operating loss carryover	0	32,031
Other	172	125
Total deferred tax assets	2,729	37,032
Net deferred tax liability	$ 86,715	$ 68,883