Note 13 - Fair Value Measurements and Fair Value of Financial Instruments - Fair Value of Financial Instruments (Details) - USD ($) $ in Thousands		Sep. 30, 2023	Dec. 31, 2022
Securities available-for-sale		$ 1,508,798	$ 1,473,348
Equity securities		31,456	22,158
Warrants		83,434	90,451
Foreign exchange contracts with gain		220,784	72,996
Foreign exchange contracts with gain, fair value		858	448
Interest rate swaps		1,502,403	817,615
Interest rate swaps, fair value		83,434	44,443
Foreign exchange contracts with loss		64,971	170,213
Foreign exchange contracts with loss, fair value		939	942
Interest rate swaps		642,054	595,426
Interest rate swaps, fair value		56,058	51,864
Commitments to extend credit		3,989,855	3,630,304
Commitments to extend credit, fair value		(15,038)	(14,797)
Standby letters of credit		329,789	315,821
Standby letters of credit, fair value		(2,308)	(2,738)
Other letters of credit		10,214	29,416
Other letters of credit, fair value		(10)	(33)
Reported Value Measurement [Member]
Cash and due from banks		145,580	195,440
Short-term investments		1,017,354	966,962
Securities available-for-sale		1,508,798	1,473,348
Loans, net		18,859,682	18,100,898
Equity securities		31,456	22,158
Investment in Federal Home Loan Bank stock		17,250	17,250
Deposits		19,635,588	18,505,279
Advances from Federal Home Loan Bank		15,000	485,000
Other borrowings		22,374	22,600
Long-term debt		119,136	119,136
Reported Value Measurement [Member] | Warrants [Member]
Warrants		42	50
Estimate of Fair Value Measurement [Member]
Cash and due from banks		145,580	195,440
Short-term investments		1,017,354	966,962
Securities available-for-sale		1,508,798	1,473,348
Loans, net	[1]	18,838,004	17,944,588
Equity securities		31,456	22,158
Investment in Federal Home Loan Bank stock		17,250	17,250
Deposits		19,746,224	18,572,387
Advances from Federal Home Loan Bank		14,186	482,737
Other borrowings		18,282	18,385
Long-term debt		68,536	68,231
Estimate of Fair Value Measurement [Member] | Warrants [Member]
Warrants		$ 42	$ 50

[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.