Note 15 - Fair Value Measurements and Fair Value of Financial Instruments - Fair Value of Financial Instruments (Details) - USD ($) $ in Thousands		Dec. 31, 2021	Dec. 31, 2020
Securities available-for-sale		$ 1,127,309	$ 1,036,550
Equity securities		22,319	23,744
Warrants		10,090	3,409
Foreign exchange contracts with gain		181,997	151,244
Foreign exchange contracts with gain, fair value		1,113	4,658
Interest rate swaps		904,635	96,889
Interest rate swaps, fair value		10,090	3,409
Option contracts		676	0
Option contracts		2,911	0
Foreign exchange contracts with loss		51,782	132,813
Foreign exchange contracts with loss, fair value		327	2,200
Interest rate swaps		872,400	679,648
Interest rate swaps, fair value		12,642	10,286
Commitments to extend credit		3,297,362	2,977,528
Commitments to extend credit, fair value		(12,594)	(8,432)
Standby letters of credit		266,490	234,200
Standby letters of credit, fair value		(2,640)	(1,630)
Other letters of credit		16,652	16,821
Other letters of credit, fair value		(13)	(16)
Bill of lading guarantees		0	238
Bill of lading guarantees, fair value		0	0
Reported Value Measurement [Member]
Cash and due from banks		134,141	138,616
Short-term investments		2,315,563	1,282,462
Securities available-for-sale		1,127,309	1,036,550
Loans, net		16,202,001	15,475,364
Equity securities		22,319	23,744
Investment in Federal Home Loan Bank stock		17,250	17,250
Deposits		18,058,842	16,109,401
Advances from Federal Home Loan Bank		20,000	150,000
Other borrowings		23,145	23,714
Long-term debt		119,136	119,136
Reported Value Measurement [Member] | Warrants [Member]
Warrants		23	21
Estimate of Fair Value Measurement [Member]
Cash and due from banks		134,141	138,616
Short-term investments		2,315,563	1,282,462
Securities available-for-sale		1,127,309	1,036,550
Loans, net	[1]	16,499,869	16,103,471
Equity securities		22,319	23,744
Investment in Federal Home Loan Bank stock		17,250	17,250
Deposits		18,051,720	16,125,808
Advances from Federal Home Loan Bank		21,279	155,133
Other borrowings		18,945	19,632
Long-term debt		62,274	65,487
Estimate of Fair Value Measurement [Member] | Warrants [Member]
Warrants		$ 23	$ 21

[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.