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, 2023	Dec. 31, 2022
Securities available-for-sale	$ 629,001	$ 634,884
Reported Value Measurement [Member]
Cash and due from banks	562,416	268,315
Securities available-for-sale	629,001	634,884
Restricted investments in bank stocks	46,379	46,604
Equity securities	18,025	15,811
Net loans	8,045,117	8,009,176
Derivatives - interest rate contracts	47,620	56,797
Accrued interest receivable	46,301	46,062
Noninterest-bearing deposits	1,345,265	1,501,614
Interest-bearing deposits	6,407,911	5,855,008
Borrowings	852,611	857,622
Subordinated debentures	79,060	153,255
Accrued interest payable	8,639	6,925
Estimate of Fair Value Measurement [Member]
Cash and due from banks	562,416	268,315
Securities available-for-sale	629,001	634,884
Equity securities	18,025	15,811
Net loans		7,723,378
Derivatives - interest rate contracts	47,620	56,797
Accrued interest receivable	46,301	46,062
Noninterest-bearing deposits	1,345,265	1,501,614
Interest-bearing deposits	6,378,261	5,811,291
Borrowings	850,698	854,698
Subordinated debentures	78,040	153,581
Accrued interest payable	8,639	6,925
Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 1 [Member]
Cash and due from banks	562,416	268,315
Securities available-for-sale	132	242
Equity securities	9,892	9,733
Net loans	0	0
Derivatives - interest rate contracts	0	0
Accrued interest receivable	0	0
Noninterest-bearing deposits	1,345,265	1,501,614
Interest-bearing deposits	3,701,249	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	621,381	627,293
Equity securities	8,133	6,078
Net loans	0	0
Derivatives - interest rate contracts	47,620	56,797
Accrued interest receivable	4,829	4,685
Noninterest-bearing deposits	0	0
Interest-bearing deposits	2,677,012	2,350,473
Borrowings	850,698	854,698
Subordinated debentures	78,040	153,581
Accrued interest payable	8,639	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	7,488	7,349
Equity securities	0	0
Net loans		7,723,378
Derivatives - interest rate contracts	0	0
Accrued interest receivable	41,472	41,377
Noninterest-bearing deposits	0	0
Interest-bearing deposits	0	0
Borrowings	0	0
Subordinated debentures	0	0
Accrued interest payable	$ 0	$ 0