Note 11 - Stockholders' Equity - Accumulated Other Comprehensive Income (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Balance	$ 2,418,144	$ 2,294,283	$ 2,121,866
Total other comprehensive (loss)/income, net of tax	(8,375)	3,008	20,308
Balance	2,446,251	2,418,144	2,294,283
AOCI, Accumulated Gain (Loss), Debt Securities, Available-for-sale, Parent [Member]
Balance	12,200	5,714
Net unrealized (losses)/gains arising during the period, pre-tax	(16,167)	10,903
Net unrealized (losses)/gains arising during the period, tax	(4,779)	3,223
Net unrealized (losses)/gains arising during the period, net of tax	(11,388)	7,680
Reclassification adjustment for net losses/(gains) included in net income, pre-tax	853	1,695
Reclassification adjustment for net losses/(gains) included in net income, tax	252	501
Reclassification adjustment for net losses/(gains) included in net income, net of tax	601	1,194
Total other comprehensive (loss)/income, pre-tax	(17,020)	9,208
Total other comprehensive (loss)/income, tax	(5,031)	2,722
Total other comprehensive (loss)/income, net of tax	(11,989)	6,486
Balance	211	12,200	5,714
Accumulated Gain (Loss), Net, Cash Flow Hedge, Parent [Member]
Balance	(6,890)	(3,412)
Net unrealized (losses)/gains arising during the period, pre-tax	5,131	(4,938)
Net unrealized (losses)/gains arising during the period, tax	1,517	(1,460)
Net unrealized (losses)/gains arising during the period, net of tax	3,614	(3,478)
Reclassification adjustment for net losses/(gains) included in net income, pre-tax	0	0
Reclassification adjustment for net losses/(gains) included in net income, tax	0	0
Reclassification adjustment for net losses/(gains) included in net income, net of tax	0	0
Total other comprehensive (loss)/income, pre-tax	5,131	(4,938)
Total other comprehensive (loss)/income, tax	1,517	(1,460)
Total other comprehensive (loss)/income, net of tax	3,614	(3,478)
Balance	(3,276)	(6,890)	(3,412)
AOCI Attributable to Parent [Member]
Balance	5,310	2,302	(18,006)
Net unrealized (losses)/gains arising during the period, pre-tax	(11,036)	5,965
Net unrealized (losses)/gains arising during the period, tax	(3,262)	1,763
Net unrealized (losses)/gains arising during the period, net of tax	(7,774)	4,202
Reclassification adjustment for net losses/(gains) included in net income, pre-tax	853	1,695
Reclassification adjustment for net losses/(gains) included in net income, tax	252	501
Reclassification adjustment for net losses/(gains) included in net income, net of tax	601	1,194
Total other comprehensive (loss)/income, pre-tax	(11,889)	4,270
Total other comprehensive (loss)/income, tax	(3,514)	1,262
Total other comprehensive (loss)/income, net of tax	(8,375)	3,008	20,308
Balance	$ (3,065)	$ 5,310	$ 2,302