Note 6 - Fair Value Measurements and Fair Value of Financial Instruments - Carrying Value and Fair Value of Financial Instruments (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Securities available-for-sale	$ 581,867	$ 634,884
Reported Value Measurement [Member]
Cash and due from banks	253,298	268,315
Securities available-for-sale	581,867	634,884
Restricted investments in bank stocks	49,387	46,604
Equity securities	17,677	15,811
Net loans	8,092,879	8,009,176
Derivatives - interest rate contracts	61,972	56,797
Accrued interest receivable	46,795	46,062
Noninterest-bearing deposits	1,224,125	1,501,614
Interest-bearing deposits	6,214,370	5,855,008
Borrowings	887,590	857,622
Subordinated debentures	79,313	153,255
Accrued interest payable	9,800	6,925
Estimate of Fair Value Measurement [Member]
Cash and due from banks	253,298	268,315
Securities available-for-sale	581,867	634,884
Equity securities	17,677	15,811
Net loans	7,725,439	7,723,378
Derivatives - interest rate contracts	61,972	56,797
Accrued interest receivable	46,795	46,062
Noninterest-bearing deposits	1,224,125	1,501,614
Interest-bearing deposits	6,181,082	5,811,291
Borrowings	884,745	854,698
Subordinated debentures	77,588	153,581
Accrued interest payable	9,800	6,925
Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 1 [Member]
Cash and due from banks	253,298	268,315
Securities available-for-sale	1,362	242
Equity securities	9,394	9,733
Net loans	0	0
Derivatives - interest rate contracts	0	0
Accrued interest receivable	0	0
Noninterest-bearing deposits	1,224,125	1,501,614
Interest-bearing deposits	3,692,159	3,460,818
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	573,488	627,293
Equity securities	8,283	6,078
Net loans	0	0
Derivatives - interest rate contracts	61,972	56,797
Accrued interest receivable	5,160	4,685
Noninterest-bearing deposits	0	0
Interest-bearing deposits	2,488,923	2,350,473
Borrowings	884,745	854,698
Subordinated debentures	77,588	153,581
Accrued interest payable	9,800	6,925
Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 3 [Member]
Cash and due from banks	0	0
Securities available-for-sale	7,017	7,349
Equity securities	0	0
Net loans	7,725,439	7,723,378
Derivatives - interest rate contracts	0	0
Accrued interest receivable	41,635	41,377
Noninterest-bearing deposits	0	0
Interest-bearing deposits	0	0
Borrowings	0	0
Subordinated debentures	0	0
Accrued interest payable	$ 0	$ 0