Note 18 - Stockholders' Equity - Accumulated Other Comprehensive Income (Details) - USD ($) $ in Thousands	3 Months Ended			9 Months Ended
	Sep. 30, 2021		Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Beginning balance, loss, net of tax	$ 2,452,357	[1]	$ 2,342,448	$ 2,418,144	$ 2,294,283
Total other comprehensive (loss)/income, net of tax	(2,740)		(1,964)	(5,678)	4,087
Ending balance, loss, net of tax	2,463,291		2,374,723	2,463,291	2,374,723
AOCI, Accumulated Gain (Loss), Debt Securities, Available-for-sale, Parent [Member]
Beginning balance, loss, net of tax	7,560		16,278	12,200	5,714
Net unrealized (losses)/gains arising during the period, pre-tax	(4,588)		(3,543)	(10,322)	12,607
Net unrealized (losses)/gains arising during the period, tax	(1,356)		(1,047)	(3,051)	3,727
Net unrealized (losses)/gains arising during the period, net of tax	(3,232)		(2,496)	(7,271)	8,880
Reclassification adjustment for net losses/(gains) included in net income, pre-tax	0		0	853	1,153
Reclassification adjustment for net losses/(gains) included in net income, tax	0		0	252	341
Reclassification adjustment for net losses/(gains) included in net income, net of tax	0		0	601	812
Total other comprehensive (loss)/income, pre-tax	(4,588)		(3,543)	(11,175)	11,454
Total other comprehensive (loss)/income, tax	(1,356)		(1,047)	(3,303)	3,386
Total other comprehensive (loss)/income, net of tax	(3,232)		(2,496)	(7,872)	8,068
Ending balance, loss, net of tax	4,328		13,782	4,328	13,782
Accumulated Gain (Loss), Net, Cash Flow Hedge, Parent [Member]
Beginning balance, loss, net of tax	(5,188)		(7,925)	(6,890)	(3,412)
Net unrealized (losses)/gains arising during the period, pre-tax	698		755	3,115	(5,652)
Net unrealized (losses)/gains arising during the period, tax	206		223	921	(1,671)
Net unrealized (losses)/gains arising during the period, net of tax	492		532	2,194	(3,981)
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	698		755	3,115	(5,652)
Total other comprehensive (loss)/income, tax	206		223	921	(1,671)
Total other comprehensive (loss)/income, net of tax	492		532	2,194	(3,981)
Ending balance, loss, net of tax	(4,696)		(7,393)	(4,696)	(7,393)
AOCI Attributable to Parent [Member]
Beginning balance, loss, net of tax	2,372	[1]	8,353	5,310	2,302
Net unrealized (losses)/gains arising during the period, pre-tax	(3,890)		(2,788)	(7,207)	6,955
Net unrealized (losses)/gains arising during the period, tax	(1,150)		(824)	(2,130)	2,056
Net unrealized (losses)/gains arising during the period, net of tax	(2,740)		(1,964)	(5,077)	4,899
Reclassification adjustment for net losses/(gains) included in net income, pre-tax	0		0	853	1,153
Reclassification adjustment for net losses/(gains) included in net income, tax	0		0	252	341
Reclassification adjustment for net losses/(gains) included in net income, net of tax	0		0	601	812
Total other comprehensive (loss)/income, pre-tax	(3,890)		(2,788)	(8,060)	5,802
Total other comprehensive (loss)/income, tax	(1,150)		(824)	(2,382)	1,715
Total other comprehensive (loss)/income, net of tax	(2,740)		(1,964)	(5,678)	4,087
Ending balance, loss, net of tax	$ (368)		$ 6,389	$ (368)	$ 6,389

[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.