Note 5 - Loans and the Allowance for Credit Losses - Loans by Origination and Risk Designation (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Originated Current Fiscal Year	$ 326,424	$ 1,940,802
Originated One Year Prior	1,882,973	1,948,742
Originated Two Years Prior	1,894,432	462,092
Originated Three Years Prior	426,257	417,698
Originated Four Years Prior	394,216	479,498
Originated Five or More Years Prior	1,555,800	1,289,624
Revolving Loans	1,708,108	1,570,705
Gross loans	8,188,210	8,109,161
Pass [Member]
Originated Current Fiscal Year	326,120	1,930,147
Originated One Year Prior	1,881,320	1,946,667
Originated Two Years Prior	1,891,721	462,077
Originated Three Years Prior	425,815	408,820
Originated Four Years Prior	389,473	449,120
Originated Five or More Years Prior	1,482,236	1,194,037
Revolving Loans	1,673,845	1,535,858
Gross loans	8,070,530	7,926,726
Special Mention [Member]
Originated Current Fiscal Year	0	3,040
Originated One Year Prior	337	0
Originated Two Years Prior	86	0
Originated Three Years Prior	0	583
Originated Four Years Prior	567	26
Originated Five or More Years Prior	30,521	46,325
Revolving Loans	6,819	12,131
Gross loans	38,330	62,105
Substandard [Member]
Originated Current Fiscal Year	304	7,615
Originated One Year Prior	1,316	2,075
Originated Two Years Prior	2,625	15
Originated Three Years Prior	442	8,295
Originated Four Years Prior	4,176	30,352
Originated Five or More Years Prior	43,043	49,262
Revolving Loans	27,444	22,716
Gross loans	79,350	120,330
Doubtful [Member]
Originated Current Fiscal Year	0	0
Originated One Year Prior	0	0
Originated Two Years Prior	0	0
Originated Three Years Prior	0	0
Originated Four Years Prior	0	0
Originated Five or More Years Prior	0	0
Revolving Loans	0	0
Gross loans	0	0
Commercial Portfolio Segment [Member]
Originated Current Fiscal Year	146,545	309,251
Originated One Year Prior	261,256	305,867
Originated Two Years Prior	271,829	47,967
Originated Three Years Prior	41,463	30,529
Originated Four Years Prior	15,867	64,190
Originated Five or More Years Prior	142,596	158,886
Revolving Loans	596,015	556,044
Gross loans	1,475,571	1,472,734
Commercial Portfolio Segment [Member] | Pass [Member]
Originated Current Fiscal Year	146,241	301,636
Originated One Year Prior	259,603	305,721
Originated Two Years Prior	271,580	47,952
Originated Three Years Prior	41,459	28,177
Originated Four Years Prior	13,749	52,950
Originated Five or More Years Prior	119,592	127,739
Revolving Loans	590,667	550,483
Gross loans	1,442,891	1,414,658
Commercial Portfolio Segment [Member] | Special Mention [Member]
Originated Current Fiscal Year	0	0
Originated One Year Prior	337	0
Originated Two Years Prior	86	0
Originated Three Years Prior	0	583
Originated Four Years Prior	567	26
Originated Five or More Years Prior	3,445	8,551
Revolving Loans	3,989	3,292
Gross loans	8,424	12,452
Commercial Portfolio Segment [Member] | Substandard [Member]
Originated Current Fiscal Year	304	7,615
Originated One Year Prior	1,316	146
Originated Two Years Prior	163	15
Originated Three Years Prior	4	1,769
Originated Four Years Prior	1,551	11,214
Originated Five or More Years Prior	19,559	22,596
Revolving Loans	1,359	2,269
Gross loans	24,256	45,624
Commercial Portfolio Segment [Member] | Doubtful [Member]
Originated Current Fiscal Year	0	0
Originated One Year Prior	0	0
Originated Two Years Prior	0	0
Originated Three Years Prior	0	0
Originated Four Years Prior	0	0
Originated Five or More Years Prior	0	0
Revolving Loans	0	0
Gross loans	0	0
Commercial Real Estate Portfolio Segment [Member]
Originated Current Fiscal Year	170,541	1,574,791
Originated One Year Prior	1,572,880	1,609,952
Originated Two Years Prior	1,583,111	382,987
Originated Three Years Prior	356,251	365,104
Originated Four Years Prior	358,290	395,024
Originated Five or More Years Prior	1,317,063	1,049,043
Revolving Loans	479,403	418,327
Gross loans	5,837,539	5,795,228
Commercial Real Estate Portfolio Segment [Member] | Pass [Member]
Originated Current Fiscal Year	170,541	1,571,751
Originated One Year Prior	1,572,880	1,608,023
Originated Two Years Prior	1,581,212	382,987
Originated Three Years Prior	356,251	358,578
Originated Four Years Prior	355,665	375,886
Originated Five or More Years Prior	1,269,678	987,982
Revolving Loans	462,573	401,365
Gross loans	5,768,800	5,686,572
Commercial Real Estate Portfolio Segment [Member] | Special Mention [Member]
Originated Current Fiscal Year	0	3,040
Originated One Year Prior	0	0
Originated Two Years Prior	0	0
Originated Three Years Prior	0	0
Originated Four Years Prior	0	0
Originated Five or More Years Prior	26,421	37,774
Revolving Loans	0	8,839
Gross loans	26,421	49,653
Commercial Real Estate Portfolio Segment [Member] | Substandard [Member]
Originated Current Fiscal Year	0	0
Originated One Year Prior	0	1,929
Originated Two Years Prior	1,899	0
Originated Three Years Prior	0	6,526
Originated Four Years Prior	2,625	19,138
Originated Five or More Years Prior	20,964	23,287
Revolving Loans	16,830	8,123
Gross loans	42,318	59,003
Commercial Real Estate Portfolio Segment [Member] | Doubtful [Member]
Originated Current Fiscal Year	0	0
Originated One Year Prior	0	0
Originated Two Years Prior	0	0
Originated Three Years Prior	0	0
Originated Four Years Prior	0	0
Originated Five or More Years Prior	0	0
Revolving Loans	0	0
Gross loans	0	0
Commercial Construction Portfolio Segment [Member]
Originated Current Fiscal Year	582	8,615
Originated One Year Prior	5,693	7,605
Originated Two Years Prior	15,682	6,720
Originated Three Years Prior	6,236	508
Originated Four Years Prior	0	0
Originated Five or More Years Prior	0	0
Revolving Loans	594,555	550,691
Gross loans	622,748	574,139
Commercial Construction Portfolio Segment [Member] | Pass [Member]
Originated Current Fiscal Year	582	8,615
Originated One Year Prior	5,693	7,605
Originated Two Years Prior	15,682	6,720
Originated Three Years Prior	6,236	508
Originated Four Years Prior	0	0
Originated Five or More Years Prior	0	0
Revolving Loans	585,855	542,460
Gross loans	614,048	565,908
Commercial Construction Portfolio Segment [Member] | Special Mention [Member]
Originated Current Fiscal Year	0	0
Originated One Year Prior	0	0
Originated Two Years Prior	0	0
Originated Three Years Prior	0	0
Originated Four Years Prior	0	0
Originated Five or More Years Prior	0	0
Revolving Loans	0	0
Gross loans	0	0
Commercial Construction Portfolio Segment [Member] | Substandard [Member]
Originated Current Fiscal Year	0	0
Originated One Year Prior	0	0
Originated Two Years Prior	0	0
Originated Three Years Prior	0	0
Originated Four Years Prior	0	0
Originated Five or More Years Prior	0	0
Revolving Loans	8,700	8,231
Gross loans	8,700	8,231
Commercial Construction Portfolio Segment [Member] | Doubtful [Member]
Originated Current Fiscal Year	0	0
Originated One Year Prior	0	0
Originated Two Years Prior	0	0
Originated Three Years Prior	0	0
Originated Four Years Prior	0	0
Originated Five or More Years Prior	0	0
Revolving Loans	0	0
Gross loans	0	0
Residential Portfolio Segment [Member]
Originated Current Fiscal Year	8,009	45,926
Originated One Year Prior	43,048	25,318
Originated Two Years Prior	23,810	24,409
Originated Three Years Prior	22,301	21,557
Originated Four Years Prior	20,059	20,284
Originated Five or More Years Prior	96,141	81,693
Revolving Loans	38,048	45,561
Gross loans	251,416	264,748
Residential Portfolio Segment [Member] | Pass [Member]
Originated Current Fiscal Year	8,009	45,926
Originated One Year Prior	43,048	25,318
Originated Two Years Prior	23,247	24,409
Originated Three Years Prior	21,863	21,557
Originated Four Years Prior	20,059	20,284
Originated Five or More Years Prior	92,966	78,314
Revolving Loans	34,663	41,468
Gross loans	243,855	257,276
Residential Portfolio Segment [Member] | Special Mention [Member]
Originated Current Fiscal Year	0	0
Originated One Year Prior	0	0
Originated Two Years Prior	0	0
Originated Three Years Prior	0	0
Originated Four Years Prior	0	0
Originated Five or More Years Prior	655	0
Revolving Loans	2,830	0
Gross loans	3,485	0
Residential Portfolio Segment [Member] | Substandard [Member]
Originated Current Fiscal Year	0	0
Originated One Year Prior	0	0
Originated Two Years Prior	563	0
Originated Three Years Prior	438	0
Originated Four Years Prior	0	0
Originated Five or More Years Prior	2,520	3,379
Revolving Loans	555	4,093
Gross loans	4,076	7,472
Residential Portfolio Segment [Member] | Doubtful [Member]
Originated Current Fiscal Year	0	0
Originated One Year Prior	0	0
Originated Two Years Prior	0	0
Originated Three Years Prior	0	0
Originated Four Years Prior	0	0
Originated Five or More Years Prior	0	0
Revolving Loans	0	0
Gross loans	0	0
Consumer Portfolio Segment [Member]
Originated Current Fiscal Year	747	2,219
Originated One Year Prior	96	0
Originated Two Years Prior	0	9
Originated Three Years Prior	6	0
Originated Four Years Prior	0	0
Originated Five or More Years Prior	0	2
Revolving Loans	87	82
Gross loans	936	2,312
Consumer Portfolio Segment [Member] | Pass [Member]
Originated Current Fiscal Year	747	2,219
Originated One Year Prior	96	0
Originated Two Years Prior	0	9
Originated Three Years Prior	6	0
Originated Four Years Prior	0	0
Originated Five or More Years Prior	0	2
Revolving Loans	87	82
Gross loans	936	2,312
Consumer Portfolio Segment [Member] | Special Mention [Member]
Originated Current Fiscal Year	0	0
Originated One Year Prior	0	0
Originated Two Years Prior	0	0
Originated Three Years Prior	0	0
Originated Four Years Prior	0	0
Originated Five or More Years Prior	0	0
Revolving Loans	0	0
Gross loans	0	0
Consumer Portfolio Segment [Member] | Substandard [Member]
Originated Current Fiscal Year	0	0
Originated One Year Prior	0	0
Originated Two Years Prior	0	0
Originated Three Years Prior	0	0
Originated Four Years Prior	0	0
Originated Five or More Years Prior	0	0
Revolving Loans	0	0
Gross loans	0	0
Consumer Portfolio Segment [Member] | Doubtful [Member]
Originated Current Fiscal Year	0	0
Originated One Year Prior	0	0
Originated Two Years Prior	0	0
Originated Three Years Prior	0	0
Originated Four Years Prior	0	0
Originated Five or More Years Prior	0	0
Revolving Loans	0	0
Gross loans	$ 0	$ 0