Note 19 - Stockholders' Equity - Accumulated Other Comprehensive Income (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Beginning balance, loss, net of tax	$ 2,342,448	$ 2,199,297	$ 2,294,283	$ 2,121,866
Total other comprehensive (loss)/income, net of tax	(1,964)	525	4,087	17,173
Ending balance, loss, net of tax	2,374,723	2,245,894	2,374,723	2,245,894
AOCI, Accumulated Gain (Loss), Debt Securities, Available-for-sale, Parent [Member]
Beginning balance, loss, net of tax	16,278	2,209	5,714	(17,765)
Net unrealized (losses)/gains arising during the period, pre-tax	(3,543)	1,750	12,607	30,119
Net unrealized (losses)/gains arising during the period, tax	(1,047)	517	3,727	8,903
Net unrealized (losses)/gains arising during the period, net of tax	(2,496)	1,233	8,880	21,216
Reclassification adjustment for net losses/(gains) included in net income, pre-tax	0	(121)	1,153	(108)
Reclassification adjustment for net losses/(gains) included in net income, tax	0	(36)	341	(32)
Reclassification adjustment for net losses/(gains) included in net income, net of tax	0	(85)	812	(76)
Total other comprehensive (loss)/income, pre-tax	(3,543)	1,871	11,454	30,227
Total other comprehensive (loss)/income, tax	(1,047)	553	3,386	8,935
Total other comprehensive (loss)/income, net of tax	(2,496)	1,318	8,068	21,292
Ending balance, loss, net of tax	13,782	3,527	13,782	3,527
Accumulated Gain (Loss), Net, Cash Flow Hedge, Parent [Member]
Beginning balance, loss, net of tax	(7,925)	(3,567)	(3,412)	(241)
Net unrealized (losses)/gains arising during the period, pre-tax	755	(1,126)	(5,652)	(5,848)
Net unrealized (losses)/gains arising during the period, tax	223	(333)	(1,671)	(1,729)
Net unrealized (losses)/gains arising during the period, net of tax	532	(793)	(3,981)	(4,119)
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	755	(1,126)	(5,652)	(5,848)
Total other comprehensive (loss)/income, tax	223	(333)	(1,671)	(1,729)
Total other comprehensive (loss)/income, net of tax	532	(793)	(3,981)	(4,119)
Ending balance, loss, net of tax	(7,393)	(4,360)	(7,393)	(4,360)
AOCI Attributable to Parent [Member]
Beginning balance, loss, net of tax	8,353	(1,358)	2,302	(18,006)
Net unrealized (losses)/gains arising during the period, pre-tax	(2,788)	624	6,955	24,271
Net unrealized (losses)/gains arising during the period, tax	(824)	184	2,056	7,174
Net unrealized (losses)/gains arising during the period, net of tax	(1,964)	440	4,899	17,097
Reclassification adjustment for net losses/(gains) included in net income, pre-tax	0	(121)	1,153	(108)
Reclassification adjustment for net losses/(gains) included in net income, tax	0	(36)	341	(32)
Reclassification adjustment for net losses/(gains) included in net income, net of tax	0	(85)	812	(76)
Total other comprehensive (loss)/income, pre-tax	(2,788)	745	5,802	24,379
Total other comprehensive (loss)/income, tax	(824)	220	1,715	7,206
Total other comprehensive (loss)/income, net of tax	(1,964)	525	4,087	17,173
Ending balance, loss, net of tax	$ 6,389	$ (833)	$ 6,389	$ (833)