Note 10 - Income Taxes - Income Tax Reconciliation (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Tax provision at Federal statutory rate, amount	$ 80,187	$ 53,333	$ 73,368
Tax provision at Federal statutory rate, percent	21.00%	21.00%	21.00%
State income taxes, net of Federal income tax benefit, amount	$ 37,602	$ 23,602	$ 33,276
State income taxes, net of Federal income tax benefit, percent	9.80%	9.30%	9.50%
Excess deduction for stock option and RSUs, amount	$ (20)	$ 264	$ (398)
Excess deduction for stock option and RSUs, percent	(0.00%)	0.10%	(0.10%)
Low income housing and other tax credits, amount	$ (32,795)	$ (52,979)	$ (37,519)
Low income housing and other tax credits, percent	(8.60%)	(20.80%)	(10.70%)
Other, net, amount	$ (1,435)	$ 885	$ 1,507
Other, net, percent	(0.40%)	0.30%	0.40%
Total income tax expense, amount	$ 83,539	$ 25,105	$ 70,234
Total income tax expense, percent	21.90%	9.90%	20.10%