Note 13 - Fair Value Measurements and Fair Value of Financial Instruments - Fair Value of Financial Instruments (Details) - USD ($) $ in Thousands		Mar. 31, 2023	Dec. 31, 2022
Securities available-for-sale		$ 1,541,250	$ 1,473,348
Equity securities		27,011	22,158
Warrants		71,840	90,451
Foreign exchange contracts with gain		234,733	72,996
Foreign exchange contracts with gain, fair value		975	448
Interest rate swaps		933,688	817,615
Interest rate swaps, fair value		49,620	44,443
Foreign exchange contracts with loss		42,753	170,213
Foreign exchange contracts with loss, fair value		429	942
Interest rate swaps		592,514	595,426
Interest rate swaps, fair value		42,027	51,864
Commitments to extend credit		3,806,329	3,630,304
Commitments to extend credit, fair value		(13,896)	(14,797)
Standby letters of credit		332,575	315,821
Standby letters of credit, fair value		(2,825)	(2,738)
Other letters of credit		9,073	29,416
Other letters of credit, fair value		(8)	(33)
Reported Value Measurement [Member]
Cash and due from banks		252,048	195,440
Short-term investments		881,282	966,962
Securities available-for-sale		1,541,250	1,473,348
Loans, net		18,166,583	18,100,898
Equity securities		27,011	22,158
Investment in Federal Home Loan Bank stock		17,250	17,250
Deposits		18,648,872	18,505,279
Advances from Federal Home Loan Bank		360,000	485,000
Other borrowings		22,481	22,600
Long-term debt		119,136	119,136
Reported Value Measurement [Member] | Warrants [Member]
Warrants		0	50
Estimate of Fair Value Measurement [Member]
Cash and due from banks		252,048	195,440
Short-term investments		881,282	966,962
Securities available-for-sale		1,541,250	1,473,348
Loans, net	[1]	18,195,465	17,944,588
Equity securities		27,011	22,158
Investment in Federal Home Loan Bank stock		17,250	17,250
Deposits		18,798,687	18,572,387
Advances from Federal Home Loan Bank		358,334	482,737
Other borrowings		18,461	18,385
Long-term debt		61,939	68,231
Estimate of Fair Value Measurement [Member] | Warrants [Member]
Warrants		$ 0	$ 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.