Note 13 - Fair Value Measurements and Fair Value of Financial Instruments - Fair Value of Financial Instruments (Details) - USD ($) $ in Thousands		Jun. 30, 2022	Mar. 31, 2022	Dec. 31, 2021
Securities available-for-sale		$ 1,234,571		$ 1,127,309
Equity securities		26,785		22,319
Warrants		58,335		10,090
Foreign exchange contracts with gain		134,895		181,997
Foreign exchange contracts with gain, fair value		344		1,113
Interest rate swaps		1,454,544		904,635
Interest rate swaps, fair value		58,335		10,090
Option contracts		202		676
Option contracts, fair value		2		3
Foreign exchange contracts with loss		105,824		51,782
Foreign exchange contracts with loss, fair value		914		327
Interest rate swaps		727,649		872,400
Interest rate swaps, fair value		33,706		12,642
Commitments to extend credit			$ 3,395,976	3,297,362
Commitments to extend credit, fair value			(13,504)	(12,594)
Standby letters of credit			303,882	266,490
Standby letters of credit, fair value			(2,664)	(2,640)
Other letters of credit			28,789	16,652
Other letters of credit, fair value			$ (21)	(13)
Reported Value Measurement [Member]
Cash and due from banks		141,734		134,141
Short-term investments		1,012,228		2,315,563
Securities available-for-sale		1,234,571		1,127,309
Loans, net		17,633,576		16,202,001
Equity securities		26,785		22,319
Investment in Federal Home Loan Bank stock		17,250		17,250
Deposits		18,287,327		18,058,842
Advances from Federal Home Loan Bank		95,000		20,000
Other borrowings		22,319		23,145
Long-term debt		119,136		119,136
Reported Value Measurement [Member] | Warrants [Member]
Warrants		30		23
Estimate of Fair Value Measurement [Member]
Cash and due from banks		141,734		134,141
Short-term investments		1,012,228		2,315,563
Securities available-for-sale		1,234,571		1,127,309
Loans, net	[1]	17,440,309		16,499,869
Equity securities		26,785		22,319
Investment in Federal Home Loan Bank stock		17,250		17,250
Deposits		18,266,740		18,051,720
Advances from Federal Home Loan Bank		94,969		21,279
Other borrowings		15,667		18,945
Long-term debt		55,126		62,274
Estimate of Fair Value Measurement [Member] | Warrants [Member]
Warrants		$ 30		$ 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.