Note 13 - Fair Value Measurements and Fair Value of Financial Instruments - Fair Value Hierarchy of Financial Instruments (Details) - USD ($) $ in Thousands		Sep. 30, 2023	Dec. 31, 2022
Warrants		$ 83,434	$ 90,451
Estimate of Fair Value Measurement [Member]
Cash and due from banks		145,580	195,440
Short-term investments		1,017,354	966,962
Loans, net	[1]	18,838,004	17,944,588
Investment in Federal Home Loan Bank stock		17,250	17,250
Deposits		19,746,224	18,572,387
Advances from Federal Home Loan Bank		14,186	482,737
Other borrowings		18,282	18,385
Long-term debt		68,536	68,231
Estimate of Fair Value Measurement [Member] | Warrants [Member]
Warrants		42	50
Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 1 [Member]
Cash and due from banks		145,580	195,440
Short-term investments		1,017,354	966,962
Loans, net	[1]	0	0
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
Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 2 [Member]
Cash and due from banks		0	0
Short-term investments		0	0
Loans, net	[1]	0	0
Investment in Federal Home Loan Bank stock		17,250	17,250
Deposits		0	0
Advances from Federal Home Loan Bank		14,186	482,737
Other borrowings		0	0
Long-term debt		68,536	68,231
Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 2 [Member] | Warrants [Member]
Warrants			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
Loans, net	[1]	18,838,004	17,944,588
Investment in Federal Home Loan Bank stock		0	0
Deposits		19,746,224	18,572,387
Advances from Federal Home Loan Bank		0	0
Other borrowings		18,282	18,385
Long-term debt		$ 0	0
Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 3 [Member] | Warrants [Member]
Warrants			$ 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.