Note 13 - Fair Value Measurements and Fair Value of Financial Instruments - Fair Value Hierarchy of Financial Instruments (Details) - USD ($) $ in Thousands		Jun. 30, 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
Fair Value, Inputs, Level 1 [Member]
Securities available-for-sale		118,998	0
Equity securities		26,785	22,319
Fair Value, Inputs, Level 2 [Member]
Securities available-for-sale		1,115,573	1,127,309
Equity securities		0	0
Fair Value, Inputs, Level 3 [Member]
Securities available-for-sale		0	0
Equity securities		0	0
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
Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 1 [Member]
Cash and due from banks		141,734	134,141
Short-term investments		1,012,228	2,315,563
Securities available-for-sale		118,998	0
Loans, net	[1]	0	0
Equity securities		26,785	22,319
Investment in Federal Home Loan Bank stock		0	0
Deposits		0	0
Advances from Federal Home Loan Bank		0	0
Other borrowings		0	0
Long-term debt		0	0
Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 1 [Member] | Warrants [Member]
Warrants		0	0
Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 2 [Member]
Cash and due from banks		0	0
Short-term investments		0	0
Securities available-for-sale		1,115,573	1,127,309
Loans, net	[1]	0	0
Equity securities		0	0
Investment in Federal Home Loan Bank stock		17,250	17,250
Deposits		0	0
Advances from Federal Home Loan Bank		94,969	21,279
Other borrowings		0	0
Long-term debt		55,126	62,274
Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 2 [Member] | Warrants [Member]
Warrants		0	0
Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 3 [Member]
Cash and due from banks		0	0
Short-term investments		0	0
Securities available-for-sale		0	0
Loans, net	[1]	17,440,309	16,499,869
Equity securities		0	0
Investment in Federal Home Loan Bank stock		0	0
Deposits		18,266,740	18,051,720
Advances from Federal Home Loan Bank		0	0
Other borrowings		15,667	18,945
Long-term debt		0	0
Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 3 [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.