Note 6 - Fair Value Measurements and Fair Value of Financial Instruments - Carrying Value and Fair Value of Financial Instruments (Details) - USD ($) $ in Thousands	Jun. 30, 2024	Dec. 31, 2023
Securities available-for-sale	$ 620,579	$ 617,162
Reported Value Measurement [Member]
Cash and due from banks	293,513	242,714
Securities available-for-sale	620,579	617,162
Restricted investments in bank stocks	43,403	51,457
Equity securities	19,743	18,564
Net loans	8,075,826	8,263,171
Derivatives - interest rate contracts	48,734	43,805
Accrued interest receivable	48,262	49,108
Noninterest-bearing deposits	1,268,882	1,259,364
Interest-bearing deposits	6,307,132	6,276,838
Borrowings	756,144	933,579
Subordinated debentures	79,692	79,439
Accrued interest payable	10,309	10,152
Estimate of Fair Value Measurement [Member]
Cash and due from banks	293,513	242,714
Securities available-for-sale	620,579	617,162
Equity securities	19,743	18,564
Net loans	7,832,816	8,001,504
Derivatives - interest rate contracts	48,734	43,805
Accrued interest receivable	48,262	49,108
Noninterest-bearing deposits	1,268,882	1,259,364
Interest-bearing deposits	6,287,889	6,256,444
Borrowings	753,394	932,081
Subordinated debentures	79,680	77,952
Accrued interest payable	10,309	10,152
Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 1 [Member]
Cash and due from banks	293,513	242,714
Securities available-for-sale	146	165
Equity securities	9,693	9,867
Net loans	0	0
Derivatives - interest rate contracts	0	0
Accrued interest receivable	0	0
Noninterest-bearing deposits	1,268,882	1,259,364
Interest-bearing deposits	3,713,967	3,745,467
Borrowings	0
Subordinated debentures	0	0
Accrued interest payable	0	0
Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 2 [Member]
Cash and due from banks	0	0
Securities available-for-sale	613,682	609,875
Equity securities	10,050	8,697
Net loans	0	0
Derivatives - interest rate contracts	48,734	43,805
Accrued interest receivable	5,891	5,387
Noninterest-bearing deposits	0	0
Interest-bearing deposits	2,573,922	2,510,977
Borrowings	753,394	932,081
Subordinated debentures	79,680	77,952
Accrued interest payable	10,309	10,152
Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 3 [Member]
Cash and due from banks	0	0
Securities available-for-sale	6,751	7,122
Equity securities	0	0
Net loans	7,832,816	8,001,504
Derivatives - interest rate contracts	0	0
Accrued interest receivable	42,371	43,721
Noninterest-bearing deposits	0	0
Interest-bearing deposits	0	0
Borrowings	0	0
Subordinated debentures	0	0
Accrued interest payable	$ 0	$ 0