Note 6 - Fair Value Measurements and Fair Value of Financial Instruments - Carrying Value and Fair Value of Financial Instruments (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Securities available-for-sale	$ 619,397	$ 617,162
Reported Value Measurement [Member]
Cash and due from banks	277,583	242,714
Securities available-for-sale	619,397	617,162
Restricted investments in bank stocks	48,931	51,457
Equity securities	19,457	18,564
Net loans	8,215,088	8,263,171
Derivatives - interest rate contracts	50,508	43,805
Accrued interest receivable	49,731	49,108
Noninterest-bearing deposits	1,290,523	1,259,364
Interest-bearing deposits	6,298,131	6,276,838
Borrowings	877,568	933,579
Subordinated debentures	79,566	79,439
Accrued interest payable	12,304	10,152
Estimate of Fair Value Measurement [Member]
Cash and due from banks	277,583	242,714
Securities available-for-sale	619,397	617,162
Equity securities	19,457	18,564
Net loans	7,946,659	8,001,504
Derivatives - interest rate contracts	50,508	43,805
Accrued interest receivable	49,731	49,108
Noninterest-bearing deposits	1,290,523	1,259,364
Interest-bearing deposits	6,276,751	6,256,444
Borrowings	874,778	932,081
Subordinated debentures	79,748	77,952
Accrued interest payable	12,304	10,152
Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 1 [Member]
Cash and due from banks	277,583	242,714
Securities available-for-sale	127	165
Equity securities	9,743	9,867
Net loans	0	0
Derivatives - interest rate contracts	0	0
Accrued interest receivable	0	0
Noninterest-bearing deposits	1,290,523	1,259,364
Interest-bearing deposits	3,674,740	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	612,380	609,875
Equity securities	9,714	8,697
Net loans	0	0
Derivatives - interest rate contracts	50,508	43,805
Accrued interest receivable	5,847	5,387
Noninterest-bearing deposits	0	0
Interest-bearing deposits	2,602,011	2,510,977
Borrowings	874,778	932,081
Subordinated debentures	79,748	77,952
Accrued interest payable	12,304	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	6,890	7,122
Equity securities	0	0
Net loans	7,946,659	8,001,504
Derivatives - interest rate contracts	0	0
Accrued interest receivable	43,884	43,721
Noninterest-bearing deposits	0	0
Interest-bearing deposits	0	0
Borrowings	0	0
Subordinated debentures	0	0
Accrued interest payable	$ 0	$ 0