Note 5 - Income Taxes - Components of Provision for Income Taxes (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Current:
Federal	$ 21,312	$ (1,210)	$ 7,575
State	3,498	1,782	3,076
Total current	24,810	572	10,651
Deferred:
Federal	(1,557)	15,572	5,815
State	633	473	(464)
Total deferred	(924)	16,045	5,351
Total expense (benefit)	$ 23,886	$ 16,617	$ 16,002