Note 19 - Stockholders' Equity - Accumulated Other Comprehensive Income (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Beginning balance, loss, net of tax	$ 2,313,037	$ 2,163,329	$ 2,294,283	$ 2,121,866
Total other comprehensive (loss)/income, net of tax	(1,524)	9,073	6,051	16,648
Ending balance, loss, net of tax	2,342,448	2,199,297	2,342,448	2,199,297
AOCI, Accumulated Gain (Loss), Debt Securities, Available-for-sale, Parent [Member]
Beginning balance, loss, net of tax	17,567	(8,966)	5,714	(17,765)
Net unrealized (losses)/gains arising during the period, pre-tax	(683)	15,865	16,150	28,356
Net unrealized (losses)/gains arising during the period, tax	(202)	4,690	4,774	8,382
Net unrealized (losses)/gains arising during the period, net of tax	(481)	11,175	11,376	19,974
Reclassification adjustment for net losses/(gains) included in net income, pre-tax	1,147	0	1,153	0
Reclassification adjustment for net losses/(gains) included in net income, tax	339	0	341	0
Reclassification adjustment for net losses/(gains) included in net income, net of tax	808	0	812	0
Total other comprehensive (loss)/income, pre-tax	(1,830)	15,865	14,997	28,356
Total other comprehensive (loss)/income, tax	(541)	4,690	4,433	8,382
Total other comprehensive (loss)/income, net of tax	(1,289)	11,175	10,564	19,974
Ending balance, loss, net of tax	16,278	2,209	16,278	2,209
Accumulated Gain (Loss), Net, Cash Flow Hedge, Parent [Member]
Beginning balance, loss, net of tax	(7,690)	(1,465)	(3,412)	(241)
Net unrealized (losses)/gains arising during the period, pre-tax	(334)	(2,984)	(6,407)	(4,722)
Net unrealized (losses)/gains arising during the period, tax	(99)	(882)	(1,894)	(1,396)
Net unrealized (losses)/gains arising during the period, net of tax	(235)	(2,102)	(4,513)	(3,326)
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	(334)	(2,984)	(6,407)	(4,722)
Total other comprehensive (loss)/income, tax	(99)	(882)	(1,894)	(1,396)
Total other comprehensive (loss)/income, net of tax	(235)	(2,102)	(4,513)	(3,326)
Ending balance, loss, net of tax	(7,925)	(3,567)	(7,925)	(3,567)
AOCI Attributable to Parent [Member]
Beginning balance, loss, net of tax	9,877	(10,431)	2,302	(18,006)
Net unrealized (losses)/gains arising during the period, pre-tax	(1,017)	12,881	9,743	23,634
Net unrealized (losses)/gains arising during the period, tax	(301)	3,808	2,880	6,986
Net unrealized (losses)/gains arising during the period, net of tax	(716)	9,073	6,863	16,648
Reclassification adjustment for net losses/(gains) included in net income, pre-tax	1,147	0	1,153	0
Reclassification adjustment for net losses/(gains) included in net income, tax	339	0	341	0
Reclassification adjustment for net losses/(gains) included in net income, net of tax	808	0	812	0
Total other comprehensive (loss)/income, pre-tax	(2,164)	12,881	8,590	23,634
Total other comprehensive (loss)/income, tax	(640)	3,808	2,539	6,986
Total other comprehensive (loss)/income, net of tax	(1,524)	9,073	6,051	16,648
Ending balance, loss, net of tax	$ 8,353	$ (1,358)	$ 8,353	$ (1,358)