Note 13 - Fair Value Measurements and Fair Value of Financial Instruments - Fair Value of Financial Instruments (Details) - USD ($) $ in Thousands	Mar. 31, 2022		Dec. 31, 2021		Dec. 31, 2020
Securities available-for-sale	$ 1,219,541		$ 1,127,309
Equity securities	27,740		22,319
Warrants	38,377		10,090
Foreign exchange contracts with gain	208,263		181,997
Foreign exchange contracts with gain, fair value	1,376		1,113
Interest rate swaps	989,849		904,635
Interest rate swaps, fair value	38,377		10,090
Option contracts	0		676
Option contracts, fair value	0		2,911
Foreign exchange contracts with loss	27,587		51,782
Foreign exchange contracts with loss, fair value	142		327
Interest rate swaps	852,894		872,400
Interest rate swaps, fair value	22,983		12,642
Commitments to extend credit	3,261,172		3,297,362
Commitments to extend credit, fair value	(13,200)		(12,594)
Standby letters of credit	284,608		266,490
Standby letters of credit, fair value	(2,648)		(2,640)
Other letters of credit	21,981		16,652
Other letters of credit, fair value	(20)		(13)
Reported Value Measurement [Member]
Cash and due from banks	138,979		134,141
Short-term investments	1,119,105		2,315,563
Securities available-for-sale	1,219,541		1,127,309
Loans, net	17,398,357		16,202,001
Equity securities	27,740		22,319
Investment in Federal Home Loan Bank stock	17,250		17,250
Deposits	18,060,261		18,058,842
Advances from Federal Home Loan Bank	20,000		20,000
Other borrowings	23,108		23,145
Long-term debt	119,136		119,136
Reported Value Measurement [Member] | Warrants [Member]
Warrants	24		23
Estimate of Fair Value Measurement [Member]
Cash and due from banks	138,979		134,141		$ 134,141
Short-term investments	1,119,105				2,315,563
Securities available-for-sale	1,219,541		1,127,309		1,127,309
Loans, net	17,184,664	[1]	16,499,869	[1]	16,499,869
Equity securities	27,740		22,319		22,319
Investment in Federal Home Loan Bank stock	17,250		17,250		17,250
Deposits	18,039,184		18,051,720
Advances from Federal Home Loan Bank	20,444		21,279
Other borrowings	18,803		18,945
Long-term debt	55,126		62,274
Estimate of Fair Value Measurement [Member] | Warrants [Member]
Warrants	$ 24		$ 23		$ 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.