Note 5 - Loans and the Allowance for Credit Losses - Impairment Evaluation on Loans and Allowance for Credit Losses (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Individually evaluated impairment	$ 8,346	$ 8,479
Collectively evaluated impairment	79,151	77,955
Total	88,230	90,513
Individually evaluated impairment	81,767	91,976
Collectively evaluated impairment	8,105,953	8,006,720
Total	8,188,210	8,109,161
Financial Asset Acquired with Credit Deterioration [Member]
Individually evaluated impairment	733	4,079
Individually evaluated impairment	490	10,465
Commercial Portfolio Segment [Member]
Individually evaluated impairment	7,685	7,426
Collectively evaluated impairment	19,433	19,319
Total	27,851	28,903
Individually evaluated impairment	24,676	30,994
Collectively evaluated impairment	1,450,405	1,436,866
Total	1,475,571	1,472,734
Commercial Portfolio Segment [Member] | Financial Asset Acquired with Credit Deterioration [Member]
Individually evaluated impairment	733	2,158
Individually evaluated impairment	490	4,874
Commercial Real Estate Portfolio Segment [Member]
Individually evaluated impairment	661	1,003
Collectively evaluated impairment	52,072	50,818
Total	52,733	53,742
Individually evaluated impairment	41,636	46,886
Collectively evaluated impairment	5,795,903	5,742,751
Total	5,837,539	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	3,909	3,718
Total	3,909	3,718
Individually evaluated impairment	8,700	8,232
Collectively evaluated impairment	614,048	565,907
Total	622,748	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	0	50
Collectively evaluated impairment	3,732	4,093
Total	3,732	4,143
Individually evaluated impairment	6,755	5,864
Collectively evaluated impairment	244,661	258,884
Total	251,416	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	936	2,312
Total	936	2,312
Consumer Portfolio Segment [Member] | Financial Asset Acquired with Credit Deterioration [Member]
Individually evaluated impairment	0	0
Individually evaluated impairment	$ 0	$ 0