Note 18 - Stockholders' Equity - Accumulated Other Comprehensive Income (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Beginning balance, loss, net of tax	$ 2,418,144	$ 2,294,283
Total other comprehensive (loss)/income, net of tax	(3,624)	7,575
Ending balance, loss, net of tax	2,463,289	2,313,037
AOCI, Accumulated Gain (Loss), Debt Securities, Available-for-sale, Parent [Member]
Beginning balance, loss, net of tax	12,200	5,714
Net unrealized (losses)/gains arising during the period, pre-tax	(6,085)	16,833
Net unrealized (losses)/gains arising during the period, tax	(1,799)	4,976
Net unrealized (losses)/gains arising during the period, net of tax	(4,286)	11,857
Reclassification adjustment for net losses/(gains) included in net income, pre-tax	853	6
Reclassification adjustment for net losses/(gains) included in net income, tax	252	2
Reclassification adjustment for net losses/(gains) included in net income, net of tax	601	4
Total other comprehensive (loss)/income, pre-tax	(6,938)	16,827
Total other comprehensive (loss)/income, tax	(2,051)	4,974
Total other comprehensive (loss)/income, net of tax	(4,887)	11,853
Ending balance, loss, net of tax	7,313	17,567
Accumulated Gain (Loss), Net, Cash Flow Hedge, Parent [Member]
Beginning balance, loss, net of tax	(6,890)	(3,412)
Net unrealized (losses)/gains arising during the period, pre-tax	1,793	(6,073)
Net unrealized (losses)/gains arising during the period, tax	530	(1,795)
Net unrealized (losses)/gains arising during the period, net of tax	1,263	(4,278)
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	1,793	(6,073)
Total other comprehensive (loss)/income, tax	530	(1,795)
Total other comprehensive (loss)/income, net of tax	1,263	(4,278)
Ending balance, loss, net of tax	(5,627)	(7,690)
AOCI Attributable to Parent [Member]
Beginning balance, loss, net of tax	5,310	2,302
Net unrealized (losses)/gains arising during the period, pre-tax	(4,292)	10,760
Net unrealized (losses)/gains arising during the period, tax	(1,269)	3,181
Net unrealized (losses)/gains arising during the period, net of tax	(3,023)	7,579
Reclassification adjustment for net losses/(gains) included in net income, pre-tax	853	6
Reclassification adjustment for net losses/(gains) included in net income, tax	252	2
Reclassification adjustment for net losses/(gains) included in net income, net of tax	601	4
Total other comprehensive (loss)/income, pre-tax	(5,145)	10,754
Total other comprehensive (loss)/income, tax	(1,521)	3,179
Total other comprehensive (loss)/income, net of tax	(3,624)	7,575
Ending balance, loss, net of tax	$ 1,686	$ 9,877