Note 5 - Loans and the Allowance for Credit Losses - Impairment Evaluation on Loans and Allowance for Credit Losses (Details) - USD ($) $ in Thousands	Jun. 30, 2023	Dec. 31, 2022
Individually evaluated impairment	$ 9,493	$ 8,479
Collectively evaluated impairment	78,979	77,955
Total	89,205	90,513
Individually evaluated impairment	89,717	91,976
Collectively evaluated impairment	8,065,998	8,006,720
Total	8,156,217	8,109,161
Financial Asset Acquired with Credit Deterioration [Member]
Individually evaluated impairment	733	4,079
Individually evaluated impairment	502	10,465
Commercial Portfolio Segment [Member]
Individually evaluated impairment	8,482	7,426
Collectively evaluated impairment	20,111	19,319
Total	29,326	28,903
Individually evaluated impairment	27,207	30,994
Collectively evaluated impairment	1,445,086	1,436,866
Total	1,472,795	1,472,734
Commercial Portfolio Segment [Member] | Financial Asset Acquired with Credit Deterioration [Member]
Individually evaluated impairment	733	2,158
Individually evaluated impairment	502	4,874
Commercial Real Estate Portfolio Segment [Member]
Individually evaluated impairment	902	1,003
Collectively evaluated impairment	51,607	50,818
Total	52,509	53,742
Individually evaluated impairment	47,478	46,886
Collectively evaluated impairment	5,783,904	5,742,751
Total	5,831,382	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	3,546	3,718
Total	3,546	3,718
Individually evaluated impairment	8,650	8,232
Collectively evaluated impairment	587,569	565,907
Total	596,219	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	109	50
Collectively evaluated impairment	3,710	4,093
Total	3,819	4,143
Individually evaluated impairment	6,382	5,864
Collectively evaluated impairment	248,023	258,884
Total	254,405	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	5	7
Total	5	7
Individually evaluated impairment	0	0
Collectively evaluated impairment	1,416	2,312
Total	1,416	2,312
Consumer Portfolio Segment [Member] | Financial Asset Acquired with Credit Deterioration [Member]
Individually evaluated impairment	0	0
Individually evaluated impairment	$ 0	$ 0