Note 19 - Stockholders' Equity - Accumulated Other Comprehensive Income (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Beginning balance, loss, net of tax	$ 2,294,283	$ 2,121,866
Total other comprehensive (loss)/income, net of tax	7,575	7,575
Ending balance, loss, net of tax	2,313,037	2,163,329
AOCI, Accumulated Gain (Loss), Debt Securities, Available-for-sale, Parent [Member]
Beginning balance, loss, net of tax	5,714	(17,765)
Net unrealized (losses)/gains arising during the period, pre-tax	16,833	12,491
Net unrealized (losses)/gains arising during the period, tax	4,976	3,692
Net unrealized (losses)/gains arising during the period, net of tax	11,857	8,799
Reclassification adjustment for net losses/(gains) included in net income, pre-tax	6	0
Reclassification adjustment for net losses/(gains) included in net income, tax	2	0
Reclassification adjustment for net losses/(gains) included in net income, net of tax	4	0
Total other comprehensive (loss)/income, pre-tax	16,827	12,491
Total other comprehensive (loss)/income, tax	4,974	3,692
Total other comprehensive (loss)/income, net of tax	11,853	8,799
Ending balance, loss, net of tax	17,567	(8,966)
Accumulated Gain (Loss), Net, Cash Flow Hedge, Parent [Member]
Beginning balance, loss, net of tax	(3,412)	(241)
Net unrealized (losses)/gains arising during the period, pre-tax	(6,073)	(1,738)
Net unrealized (losses)/gains arising during the period, tax	(1,795)	(514)
Net unrealized (losses)/gains arising during the period, net of tax	(4,278)	(1,224)
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	(6,073)	(1,738)
Total other comprehensive (loss)/income, tax	(1,795)	(514)
Total other comprehensive (loss)/income, net of tax	(4,278)	(1,224)
Ending balance, loss, net of tax	(7,690)	(1,465)
AOCI Attributable to Parent [Member]
Beginning balance, loss, net of tax	2,302	(18,006)
Net unrealized (losses)/gains arising during the period, pre-tax	10,760	10,753
Net unrealized (losses)/gains arising during the period, tax	3,181	3,178
Net unrealized (losses)/gains arising during the period, net of tax	7,579	7,575
Reclassification adjustment for net losses/(gains) included in net income, pre-tax	6	0
Reclassification adjustment for net losses/(gains) included in net income, tax	2	0
Reclassification adjustment for net losses/(gains) included in net income, net of tax	4	0
Total other comprehensive (loss)/income, pre-tax	10,754	10,753
Total other comprehensive (loss)/income, tax	3,179	3,178
Total other comprehensive (loss)/income, net of tax	7,575	7,575
Ending balance, loss, net of tax	$ 9,877	$ (10,431)