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, 2023	Mar. 31, 2023	Dec. 31, 2022
Securities available-for-sale	$ 612,819	$ 612,819	$ 634,884
Reported Value Measurement [Member]
Cash and due from banks	319,924		268,315
Securities available-for-sale	612,819		634,884
Restricted investments in bank stocks	46,688		46,604
Equity securities	17,950		15,811
Net loans	8,059,335		8,009,176
Derivatives - interest rate contracts	57,545		56,797
Accrued interest receivable	46,237		46,062
Noninterest-bearing deposits	1,356,293		1,501,614
Interest-bearing deposits	6,182,004		5,855,008
Borrowings	827,601		857,622
Subordinated debentures	79,187		153,255
Accrued interest payable	8,083		6,925
Estimate of Fair Value Measurement [Member]
Cash and due from banks	319,924		268,315
Securities available-for-sale	612,819		634,884
Equity securities	17,950		15,811
Net loans			7,723,378
Derivatives - interest rate contracts	57,545		56,797
Accrued interest receivable	46,236		46,062
Noninterest-bearing deposits	1,356,293		1,501,614
Interest-bearing deposits	6,146,249		5,811,291
Borrowings	825,002		854,698
Subordinated debentures	77,576		153,581
Accrued interest payable	8,083		6,925
Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 1 [Member]
Cash and due from banks	319,924		268,315
Securities available-for-sale	151		242
Equity securities	9,736		9,733
Net loans	0		0
Derivatives - interest rate contracts	0		0
Accrued interest receivable	0		0
Noninterest-bearing deposits	1,356,293		1,501,614
Interest-bearing deposits	3,560,856		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	605,431		627,293
Equity securities	8,214		6,078
Net loans	0		0
Derivatives - interest rate contracts	57,545		56,797
Accrued interest receivable	5,201		4,685
Noninterest-bearing deposits	0		0
Interest-bearing deposits	2,585,393		2,350,473
Borrowings	825,002		854,698
Subordinated debentures	77,576		153,581
Accrued interest payable	8,083		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	7,237		7,349
Equity securities	0		0
Net loans			7,723,378
Derivatives - interest rate contracts	0		0
Accrued interest receivable	41,035		41,377
Noninterest-bearing deposits	0		0
Interest-bearing deposits	0		0
Borrowings	0		0
Subordinated debentures	0		0
Accrued interest payable	$ 0		$ 0