Note 5 - Loans and the Allowance for Credit Losses - Impairment Evaluation on Loans and Allowance for Credit Losses (Details) - USD ($) $ in Thousands	Mar. 31, 2023	Dec. 31, 2022
Individually evaluated impairment	$ 6,857	$ 8,479
Collectively evaluated impairment	79,412	77,955
Total	87,002	90,513
Individually evaluated impairment	88,214	91,976
Collectively evaluated impairment	8,050,678	8,006,720
Total	8,141,176	8,109,161
Financial Asset Acquired with Credit Deterioration [Member]
Individually evaluated impairment	733	4,079
Individually evaluated impairment	2,284	10,465
Commercial Portfolio Segment [Member]
Individually evaluated impairment	5,861	7,426
Collectively evaluated impairment	19,568	19,319
Total	26,162	28,903
Individually evaluated impairment	24,204	30,994
Collectively evaluated impairment	1,387,738	1,436,866
Total	1,414,226	1,472,734
Commercial Portfolio Segment [Member] | Financial Asset Acquired with Credit Deterioration [Member]
Individually evaluated impairment	733	2,158
Individually evaluated impairment	2,284	4,874
Commercial Real Estate Portfolio Segment [Member]
Individually evaluated impairment	924	1,003
Collectively evaluated impairment	52,076	50,818
Total	53,000	53,742
Individually evaluated impairment	49,529	46,886
Collectively evaluated impairment	5,786,351	5,742,751
Total	5,835,880	5,795,228
Commercial Real Estate Portfolio Segment [Member] | Financial Asset Acquired with Credit Deterioration [Member]
Individually evaluated impairment	0	1,921
Individually evaluated impairment	0	5,591
Commercial Construction Portfolio Segment [Member]
Individually evaluated impairment	0	0
Collectively evaluated impairment	3,966	3,718
Total	3,966	3,718
Individually evaluated impairment	8,366	8,232
Collectively evaluated impairment	622,103	565,907
Total	630,469	574,139
Commercial Construction Portfolio Segment [Member] | Financial Asset Acquired with Credit Deterioration [Member]
Individually evaluated impairment	0	0
Individually evaluated impairment	0	0
Residential Portfolio Segment [Member]
Individually evaluated impairment	72	50
Collectively evaluated impairment	3,796	4,093
Total	3,868	4,143
Individually evaluated impairment	6,115	5,864
Collectively evaluated impairment	253,051	258,884
Total	259,166	264,748
Residential Portfolio Segment [Member] | Financial Asset Acquired with Credit Deterioration [Member]
Individually evaluated impairment	0	0
Individually evaluated impairment	0	0
Consumer Portfolio Segment [Member]
Individually evaluated impairment	0	0
Collectively evaluated impairment	6	7
Total	6	7
Individually evaluated impairment	0	0
Collectively evaluated impairment	1,435	2,312
Total	1,435	2,312
Consumer Portfolio Segment [Member] | Financial Asset Acquired with Credit Deterioration [Member]
Individually evaluated impairment	0	0
Individually evaluated impairment	$ 0	$ 0