Note 13 - Fair Value Measurements and Fair Value of Financial Instruments - Fair Value of Financial Instruments (Details) - USD ($) $ in Thousands		Sep. 30, 2022	Dec. 31, 2021
Securities available-for-sale		$ 1,414,411	$ 1,127,309
Equity securities		23,123	22,319
Warrants		98,498	10,090
Foreign exchange contracts with gain		162,518	181,997
Foreign exchange contracts with gain, fair value		752	1,113
Interest rate swaps		1,464,567	904,635
Interest rate swaps, fair value		98,498	10,090
Option contracts		0	676
Option contracts, fair value		0	3
Foreign exchange contracts with loss		45,990	51,782
Foreign exchange contracts with loss, fair value		2,054	327
Interest rate swaps		691,872	872,400
Interest rate swaps, fair value		54,443	12,642
Commitments to extend credit		3,537,547	3,297,362
Commitments to extend credit, fair value		(14,650)	(12,594)
Standby letters of credit		290,618	266,490
Standby letters of credit, fair value		(2,048)	(2,640)
Other letters of credit		13,070	16,652
Other letters of credit, fair value		(12)	(13)
Reported Value Measurement [Member]
Cash and due from banks		200,051	134,141
Short-term investments		1,063,294	2,315,563
Securities available-for-sale		1,414,411	1,127,309
Loans, net		17,951,050	16,202,001
Equity securities		23,123	22,319
Investment in Federal Home Loan Bank stock		17,250	17,250
Deposits		18,575,751	18,058,842
Advances from Federal Home Loan Bank		360,000	20,000
Other borrowings		22,651	23,145
Long-term debt		119,136	119,136
Reported Value Measurement [Member] | Warrants [Member]
Warrants		46	23
Estimate of Fair Value Measurement [Member]
Cash and due from banks		200,051	134,141
Short-term investments		1,063,294	2,315,563
Securities available-for-sale		1,414,411	1,127,309
Loans, net	[1]	17,676,365	16,499,869
Equity securities		23,123	22,319
Investment in Federal Home Loan Bank stock		17,250	17,250
Deposits		18,573,442	18,051,720
Advances from Federal Home Loan Bank		359,416	21,279
Other borrowings		18,357	18,945
Long-term debt		56,317	62,274
Estimate of Fair Value Measurement [Member] | Warrants [Member]
Warrants		$ 46	$ 23

[1] In accordance with the prospective adoption of ASU 2016-01, the fair value of loans as of December 31, 2019 & 2018 was measured using an exit price notion.