Note 5 - Loans and the Allowance for Credit Losses - Loans by Origination and Risk Designation (Details) - USD ($) $ in Thousands	Mar. 31, 2023	Dec. 31, 2022
Originated Current Fiscal Year	$ 151,634	$ 1,940,802
Originated One Year Prior	1,924,350	1,948,742
Originated Two Years Prior	1,903,438	462,092
Originated Three Years Prior	449,767	417,698
Originated Four Years Prior	411,629	479,498
Originated Five or More Years Prior	1,664,200	1,289,624
Revolving Loans	1,636,158	1,570,705
Gross loans	8,141,176	8,109,161
Pass [Member]
Originated Current Fiscal Year	151,634	1,930,147
Originated One Year Prior	1,923,548	1,946,667
Originated Two Years Prior	1,901,379	462,077
Originated Three Years Prior	449,755	408,820
Originated Four Years Prior	404,290	449,120
Originated Five or More Years Prior	1,567,296	1,194,037
Revolving Loans	1,601,535	1,535,858
Gross loans	7,999,437	7,926,726
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	583
Originated Four Years Prior	578	26
Originated Five or More Years Prior	46,137	46,325
Revolving Loans	6,719	12,131
Gross loans	53,434	62,105
Substandard [Member]
Originated Current Fiscal Year	0	7,615
Originated One Year Prior	802	2,075
Originated Two Years Prior	2,059	15
Originated Three Years Prior	12	8,295
Originated Four Years Prior	6,761	30,352
Originated Five or More Years Prior	50,767	49,262
Revolving Loans	27,904	22,716
Gross loans	88,305	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	88,764	309,251
Originated One Year Prior	288,586	305,867
Originated Two Years Prior	275,291	47,967
Originated Three Years Prior	44,130	30,529
Originated Four Years Prior	20,794	64,190
Originated Five or More Years Prior	165,690	158,886
Revolving Loans	530,971	556,044
Gross loans	1,414,226	1,472,734
Commercial Portfolio Segment [Member] | Pass [Member]
Originated Current Fiscal Year	88,764	301,636
Originated One Year Prior	287,784	305,721
Originated Two Years Prior	275,151	47,952
Originated Three Years Prior	44,118	28,177
Originated Four Years Prior	18,468	52,950
Originated Five or More Years Prior	135,355	127,739
Revolving Loans	525,263	550,483
Gross loans	1,374,903	1,414,658
Commercial 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	583
Originated Four Years Prior	578	26
Originated Five or More Years Prior	8,468	8,551
Revolving Loans	3,312	3,292
Gross loans	12,358	12,452
Commercial Portfolio Segment [Member] | Substandard [Member]
Originated Current Fiscal Year	0	7,615
Originated One Year Prior	802	146
Originated Two Years Prior	140	15
Originated Three Years Prior	12	1,769
Originated Four Years Prior	1,748	11,214
Originated Five or More Years Prior	21,867	22,596
Revolving Loans	2,396	2,269
Gross loans	26,965	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	58,920	1,574,791
Originated One Year Prior	1,586,883	1,609,952
Originated Two Years Prior	1,595,666	382,987
Originated Three Years Prior	374,873	365,104
Originated Four Years Prior	369,441	395,024
Originated Five or More Years Prior	1,398,754	1,049,043
Revolving Loans	451,343	418,327
Gross loans	5,835,880	5,795,228
Commercial Real Estate Portfolio Segment [Member] | Pass [Member]
Originated Current Fiscal Year	58,920	1,571,751
Originated One Year Prior	1,586,883	1,608,023
Originated Two Years Prior	1,593,747	382,987
Originated Three Years Prior	374,873	358,578
Originated Four Years Prior	364,428	375,886
Originated Five or More Years Prior	1,335,482	987,982
Revolving Loans	434,426	401,365
Gross loans	5,748,759	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	37,007	37,774
Revolving Loans	0	8,839
Gross loans	37,007	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	1,919	0
Originated Three Years Prior	0	6,526
Originated Four Years Prior	5,013	19,138
Originated Five or More Years Prior	26,265	23,287
Revolving Loans	16,917	8,123
Gross loans	50,114	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	0	8,615
Originated One Year Prior	4,263	7,605
Originated Two Years Prior	7,340	6,720
Originated Three Years Prior	6,721	508
Originated Four Years Prior	0	0
Originated Five or More Years Prior	0	0
Revolving Loans	612,145	550,691
Gross loans	630,469	574,139
Commercial Construction Portfolio Segment [Member] | Pass [Member]
Originated Current Fiscal Year	0	8,615
Originated One Year Prior	4,263	7,605
Originated Two Years Prior	7,340	6,720
Originated Three Years Prior	6,721	508
Originated Four Years Prior	0	0
Originated Five or More Years Prior	0	0
Revolving Loans	603,779	542,460
Gross loans	622,103	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	8,366	8,231
Gross loans	8,366	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	2,768	45,926
Originated One Year Prior	44,461	25,318
Originated Two Years Prior	25,141	24,409
Originated Three Years Prior	24,036	21,557
Originated Four Years Prior	21,394	20,284
Originated Five or More Years Prior	99,755	81,693
Revolving Loans	41,611	45,561
Gross loans	259,166	264,748
Residential Portfolio Segment [Member] | Pass [Member]
Originated Current Fiscal Year	2,768	45,926
Originated One Year Prior	44,461	25,318
Originated Two Years Prior	25,141	24,409
Originated Three Years Prior	24,036	21,557
Originated Four Years Prior	21,394	20,284
Originated Five or More Years Prior	96,458	78,314
Revolving Loans	37,979	41,468
Gross loans	252,237	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	662	0
Revolving Loans	3,407	0
Gross loans	4,069	0
Residential 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	2,635	3,379
Revolving Loans	225	4,093
Gross loans	2,860	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	1,182	2,219
Originated One Year Prior	157	0
Originated Two Years Prior	0	9
Originated Three Years Prior	7	0
Originated Four Years Prior	0	0
Originated Five or More Years Prior	1	2
Revolving Loans	88	82
Gross loans	1,435	2,312
Consumer Portfolio Segment [Member] | Pass [Member]
Originated Current Fiscal Year	1,182	2,219
Originated One Year Prior	157	0
Originated Two Years Prior	0	9
Originated Three Years Prior	7	0
Originated Four Years Prior	0	0
Originated Five or More Years Prior	1	2
Revolving Loans	88	82
Gross loans	1,435	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