Note 18 - Stockholders' Equity - Accumulated Other Comprehensive Income (Details) - USD ($) $ in Thousands	3 Months Ended			6 Months Ended
	Jun. 30, 2021		Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Beginning balance, loss, net of tax	$ 2,460,948	[1]	$ 2,313,037	$ 2,418,144	$ 2,294,283
Total other comprehensive (loss)/income, net of tax	686		(1,524)	(2,938)	6,051
Ending balance, loss, net of tax	2,452,357		2,342,448	2,452,357	2,342,448
AOCI, Accumulated Gain (Loss), Debt Securities, Available-for-sale, Parent [Member]
Beginning balance, loss, net of tax	7,313		17,567	12,200	5,714
Net unrealized (losses)/gains arising during the period, pre-tax	352		(683)	(5,733)	16,150
Net unrealized (losses)/gains arising during the period, tax	104		(202)	(1,695)	4,774
Net unrealized (losses)/gains arising during the period, net of tax	247		(481)	(4,039)	11,376
Reclassification adjustment for net losses/(gains) included in net income, pre-tax	0		1,147	853	1,153
Reclassification adjustment for net losses/(gains) included in net income, tax	0		339	252	341
Reclassification adjustment for net losses/(gains) included in net income, net of tax	0		808	601	812
Total other comprehensive (loss)/income, pre-tax	352		(1,830)	(6,586)	14,997
Total other comprehensive (loss)/income, tax	104		(541)	(1,947)	4,433
Total other comprehensive (loss)/income, net of tax	247		(1,289)	(4,640)	10,564
Ending balance, loss, net of tax	7,560		16,278	7,560	16,278
Accumulated Gain (Loss), Net, Cash Flow Hedge, Parent [Member]
Beginning balance, loss, net of tax	(5,627)		(7,690)	(6,890)	(3,412)
Net unrealized (losses)/gains arising during the period, pre-tax	623		(334)	2,416	(6,407)
Net unrealized (losses)/gains arising during the period, tax	184		(99)	714	(1,894)
Net unrealized (losses)/gains arising during the period, net of tax	439		(235)	1,702	(4,513)
Reclassification adjustment for net losses/(gains) included in net income, pre-tax	0		0	0	0
Reclassification adjustment for net losses/(gains) included in net income, tax	0		0	0	0
Reclassification adjustment for net losses/(gains) included in net income, net of tax	0		0	0	0
Total other comprehensive (loss)/income, pre-tax	623		(334)	2,416	(6,407)
Total other comprehensive (loss)/income, tax	184		(99)	714	(1,894)
Total other comprehensive (loss)/income, net of tax	439		(235)	1,702	(4,513)
Ending balance, loss, net of tax	(5,188)		(7,925)	(5,188)	(7,925)
AOCI Attributable to Parent [Member]
Beginning balance, loss, net of tax	1,686	[1]	9,877	5,310	2,302
Net unrealized (losses)/gains arising during the period, pre-tax	975		(1,017)	(3,317)	9,743
Net unrealized (losses)/gains arising during the period, tax	288		(301)	(981)	2,880
Net unrealized (losses)/gains arising during the period, net of tax	686		(716)	(2,337)	6,863
Reclassification adjustment for net losses/(gains) included in net income, pre-tax	0		1,147	853	1,153
Reclassification adjustment for net losses/(gains) included in net income, tax	0		339	252	341
Reclassification adjustment for net losses/(gains) included in net income, net of tax	0		808	601	812
Total other comprehensive (loss)/income, pre-tax	975		(2,164)	(4,170)	8,590
Total other comprehensive (loss)/income, tax	288		(640)	(1,233)	2,539
Total other comprehensive (loss)/income, net of tax	686		(1,524)	(2,938)	6,051
Ending balance, loss, net of tax	$ 2,372		$ 8,353	$ 2,372	$ 8,353

[1] Balance sheet amounts previously reported for the impact of the initial adoption of CECL on January 1, 2021 have been corrected. The correction had an after-tax decrease to the cumulative effect of the change in accounting principle related to ASC326 of $2.3 million.