Note 4 - Loans and the Allowance for Credit Losses - Impairment Evaluation on Loans and Allowance for Credit Losses (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Individually analyzed	$ 941	$ 8,479
Collectively evaluated	80,616	77,955
Total	81,974	90,513	$ 78,773	$ 79,226
Financing Receivable, Individually Evaluated for Impairment	69,963	91,976
Collectively evaluated	8,281,394	8,006,720
Total	8,351,841	8,109,161
Financial Asset Acquired with Credit Deterioration [Member]
Individually analyzed	417	4,079
Financing Receivable, Individually Evaluated for Impairment	484	10,465
Commercial Portfolio Segment [Member]
Individually analyzed	0	7,426
Collectively evaluated	20,215	19,319
Total	20,632	28,903	25,969	28,443
Financing Receivable, Individually Evaluated for Impairment	15,336	30,994
Collectively evaluated	1,562,910	1,436,866
Total	1,578,730	1,472,734
Commercial Portfolio Segment [Member] | Financial Asset Acquired with Credit Deterioration [Member]
Individually analyzed	417	2,158
Financing Receivable, Individually Evaluated for Impairment	484	4,874
Commercial Real Estate Portfolio Segment [Member]
Individually analyzed	941	1,003
Collectively evaluated	51,337	50,818
Total	52,278	53,742	45,589	39,330
Financing Receivable, Individually Evaluated for Impairment	39,986	46,886
Collectively evaluated	5,855,559	5,742,751
Total	5,895,545	5,795,228
Commercial Real Estate Portfolio Segment [Member] | Financial Asset Acquired with Credit Deterioration [Member]
Individually analyzed	0	1,921
Financing Receivable, Individually Evaluated for Impairment	0	5,591
Commercial Construction Portfolio Segment [Member]
Individually analyzed	0	0
Collectively evaluated	4,739	3,718
Total	4,739	3,718	3,580	8,194
Financing Receivable, Individually Evaluated for Impairment	8,700	8,232
Collectively evaluated	611,796	565,907
Total	620,496	574,139
Commercial Construction Portfolio Segment [Member] | Financial Asset Acquired with Credit Deterioration [Member]
Individually analyzed	0	0
Financing Receivable, Individually Evaluated for Impairment	0	0
Residential Portfolio Segment [Member]
Individually analyzed	0	50
Collectively evaluated	4,320	4,093
Total	4,320	4,143	3,628	2,687
Financing Receivable, Individually Evaluated for Impairment	5,941	5,864
Collectively evaluated	250,100	258,884
Total	256,041	264,748
Residential Portfolio Segment [Member] | Financial Asset Acquired with Credit Deterioration [Member]
Individually analyzed	0	0
Financing Receivable, Individually Evaluated for Impairment	0	0
Consumer Portfolio Segment [Member]
Individually analyzed	0	0
Collectively evaluated	5	7
Total	5	7	$ 7	$ 4
Financing Receivable, Individually Evaluated for Impairment	0	0
Collectively evaluated	1,029	2,312
Total	1,029	2,312
Consumer Portfolio Segment [Member] | Financial Asset Acquired with Credit Deterioration [Member]
Individually analyzed	0	0
Financing Receivable, Individually Evaluated for Impairment	$ 0	$ 0