Note 12 - Fair Value Measurements and Fair Value of Financial Instruments - Assets and Liabilities Measured at Fair Value on a Recurring Basis (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023	Mar. 31, 2023
Securities available-for-sale	$ 1,653,167	$ 1,604,570
Equity securities	31,380	40,406	$ 40,400
Derivative asset	55,138	54,268
Assets, fair value disclosure	1,740,019	1,699,623
Derivative liability	42,014	45,762
Liabilities, fair value disclosure	42,200	45,937
Interest Rate Swap [Member]
Derivative asset	55,138	54,268
Derivative liability	42,014	45,762
Foreign Exchange Contract [Member]
Derivative asset	334	379
Derivative liability	186	175
Mutual Funds [Member]
Equity securities	5,526	5,585
Preferred Stock of Government Sponsored Entities [Member]
Equity securities	2,384	1,821
Other Equity Securities [Member]
Equity securities	23,470	33,000
Fair Value, Inputs, Level 1 [Member]
Securities available-for-sale	541,798	495,300
Equity securities	31,380	40,406
Assets, fair value disclosure	573,178	535,706
Liabilities, fair value disclosure	0	0
Fair Value, Inputs, Level 1 [Member] | Interest Rate Swap [Member]
Derivative asset	0	0
Derivative liability	0	0
Fair Value, Inputs, Level 1 [Member] | Foreign Exchange Contract [Member]
Derivative asset	0	0
Derivative liability	0	0
Fair Value, Inputs, Level 1 [Member] | Mutual Funds [Member]
Equity securities	5,526	5,585
Fair Value, Inputs, Level 1 [Member] | Preferred Stock of Government Sponsored Entities [Member]
Equity securities	2,384	1,821
Fair Value, Inputs, Level 1 [Member] | Other Equity Securities [Member]
Equity securities	23,470	33,000
Fair Value, Inputs, Level 2 [Member]
Securities available-for-sale	1,111,369	1,109,270
Equity securities	0	0
Assets, fair value disclosure	1,166,841	1,163,917
Liabilities, fair value disclosure	42,200	45,937
Fair Value, Inputs, Level 2 [Member] | Interest Rate Swap [Member]
Derivative asset	55,138	54,268
Derivative liability	42,014	45,762
Fair Value, Inputs, Level 2 [Member] | Foreign Exchange Contract [Member]
Derivative asset	334	379
Derivative liability	186	175
Fair Value, Inputs, Level 2 [Member] | Mutual Funds [Member]
Equity securities	0	0
Fair Value, Inputs, Level 2 [Member] | Preferred Stock of Government Sponsored Entities [Member]
Equity securities	0	0
Fair Value, Inputs, Level 2 [Member] | Other Equity Securities [Member]
Equity securities	0	0
Fair Value, Inputs, Level 3 [Member]
Securities available-for-sale	0	0
Equity securities	0	0
Assets, fair value disclosure	0	0
Liabilities, fair value disclosure	0	0
Fair Value, Inputs, Level 3 [Member] | Interest Rate Swap [Member]
Derivative asset	0	0
Derivative liability	0	0
Fair Value, Inputs, Level 3 [Member] | Foreign Exchange Contract [Member]
Derivative asset	0	0
Derivative liability	0	0
Fair Value, Inputs, Level 3 [Member] | Mutual Funds [Member]
Equity securities	0	0
Fair Value, Inputs, Level 3 [Member] | Preferred Stock of Government Sponsored Entities [Member]
Equity securities	0	0
Fair Value, Inputs, Level 3 [Member] | Other Equity Securities [Member]
Equity securities	0	0
US Treasury Securities [Member]
Securities available-for-sale	541,798	495,300
US Treasury Securities [Member] | Fair Value, Inputs, Level 1 [Member]
Securities available-for-sale	541,798	495,300
US Treasury Securities [Member] | Fair Value, Inputs, Level 2 [Member]
Securities available-for-sale	0	0
US Treasury Securities [Member] | Fair Value, Inputs, Level 3 [Member]
Securities available-for-sale	0	0
US Government Corporations and Agencies Securities [Member]
Securities available-for-sale	12,058	48,169
US Government Corporations and Agencies Securities [Member] | Fair Value, Inputs, Level 1 [Member]
Securities available-for-sale	0	0
US Government Corporations and Agencies Securities [Member] | Fair Value, Inputs, Level 2 [Member]
Securities available-for-sale	12,058	48,169
US Government Corporations and Agencies Securities [Member] | Fair Value, Inputs, Level 3 [Member]
Securities available-for-sale	0	0
US Government-sponsored Enterprises Debt Securities [Member]
Securities available-for-sale	59,745
US Government-sponsored Enterprises Debt Securities [Member] | Fair Value, Inputs, Level 1 [Member]
Securities available-for-sale	0
US Government-sponsored Enterprises Debt Securities [Member] | Fair Value, Inputs, Level 2 [Member]
Securities available-for-sale	59,745
US Government-sponsored Enterprises Debt Securities [Member] | Fair Value, Inputs, Level 3 [Member]
Securities available-for-sale	0
Commercial Mortgage-Backed Securities [Member]
Securities available-for-sale	754,162	786,723
Commercial Mortgage-Backed Securities [Member] | Fair Value, Inputs, Level 1 [Member]
Securities available-for-sale	0	0
Commercial Mortgage-Backed Securities [Member] | Fair Value, Inputs, Level 2 [Member]
Securities available-for-sale	754,162	786,723
Commercial Mortgage-Backed Securities [Member] | Fair Value, Inputs, Level 3 [Member]
Securities available-for-sale	0	0
Collateralized Mortgage Obligations [Member]
Securities available-for-sale	27,198	28,044
Collateralized Mortgage Obligations [Member] | Fair Value, Inputs, Level 1 [Member]
Securities available-for-sale	0	0
Collateralized Mortgage Obligations [Member] | Fair Value, Inputs, Level 2 [Member]
Securities available-for-sale	27,198	28,044
Collateralized Mortgage Obligations [Member] | Fair Value, Inputs, Level 3 [Member]
Securities available-for-sale	0	0
Corporate Debt Securities [Member]
Securities available-for-sale	258,206	246,334
Corporate Debt Securities [Member] | Fair Value, Inputs, Level 1 [Member]
Securities available-for-sale	0	0
Corporate Debt Securities [Member] | Fair Value, Inputs, Level 2 [Member]
Securities available-for-sale	258,206	246,334
Corporate Debt Securities [Member] | Fair Value, Inputs, Level 3 [Member]
Securities available-for-sale	$ 0	$ 0