Note 5 - Loans - Loan Held for Investment by Loan Portfolio Segments, Internal Risk Ratings and Vintage Year (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Loans originated in current year	$ 3,724,618	$ 3,943,040
Loans originated year prior	3,581,730	3,489,846
Loans originated three years prior	3,052,314	1,905,136
Loans originated four years prior	1,588,314	1,908,992
Loans originated five years prior	1,686,965	1,530,238
Total, Loans Amortized Cost Basis by Origination Year Prior	3,571,544	3,138,606
Total, Revolving Loans	2,306,710	2,303,152
Total, Revolving Converted to Term Loans	25,225	28,373
Total loans	19,537,420	18,247,383
Loans originated in current year, write offs	0	212
Loans originated year prior, write offs	992	587
Loans originated three years prior, write offs	1,520	120
Loans originated four years prior, write offs	384	71
Loans originated five years prior, write offs	4,641	3,938
Total, Loans Amortized Cost Basis by Origination Year Prior, Write Offs	14,429	360
Total, Revolving Loans Write Offs	1,520	202
Total, Revolving Converted to Term Loans, Write Offs	0	0
YTD gross write-offs	23,486	5,490
Total loans	19,537,420	18,247,383
Commercial Portfolio Segment [Member]
Loans originated in current year	387,945	489,985
Loans originated year prior	329,467	464,093
Loans originated three years prior	345,104	183,386
Loans originated four years prior	122,567	125,786
Loans originated five years prior	76,044	113,155
Total, Loans Amortized Cost Basis by Origination Year Prior	141,937	117,988
Total, Revolving Loans	1,890,712	1,816,937
Total, Revolving Converted to Term Loans	8,424	6,693
Total loans	3,302,200	3,318,023
Loans originated in current year, write offs	0	96
Loans originated year prior, write offs	977	587
Loans originated three years prior, write offs	1,312	120
Loans originated four years prior, write offs	384	71
Loans originated five years prior, write offs	3,672	1,786
Total, Loans Amortized Cost Basis by Origination Year Prior, Write Offs	6,044	360
Total, Revolving Loans Write Offs	1,520	202
Total, Revolving Converted to Term Loans, Write Offs	0	0
YTD gross write-offs	13,909	3,222
Total loans	3,302,200	3,318,023
Commercial Portfolio Segment [Member] | Pass [Member]
Loans originated in current year	381,705	488,748
Loans originated year prior	323,939	446,647
Loans originated three years prior	326,650	180,226
Loans originated four years prior	96,725	119,355
Loans originated five years prior	75,281	107,896
Total, Loans Amortized Cost Basis by Origination Year Prior	136,162	106,649
Total, Revolving Loans	1,775,162	1,753,509
Total, Revolving Converted to Term Loans	8,308	6,560
Total loans	3,123,932	3,209,590
Total loans	3,123,932	3,209,590
Commercial Portfolio Segment [Member] | Special Mention [Member]
Loans originated in current year	4,488	1,212
Loans originated year prior	4,875	4,696
Loans originated three years prior	8,559	2,818
Loans originated four years prior	23,380	68
Loans originated five years prior	0	308
Total, Loans Amortized Cost Basis by Origination Year Prior	0	4,354
Total, Revolving Loans	75,419	41,110
Total, Revolving Converted to Term Loans	0	0
Total loans	116,721	54,566
Total loans	116,721	54,566
Commercial Portfolio Segment [Member] | Substandard [Member]
Loans originated in current year	1,752	25
Loans originated year prior	653	12,750
Loans originated three years prior	9,895	342
Loans originated four years prior	2,462	4,859
Loans originated five years prior	763	2,766
Total, Loans Amortized Cost Basis by Origination Year Prior	5,775	6,985
Total, Revolving Loans	40,131	22,084
Total, Revolving Converted to Term Loans	116	133
Total loans	61,547	49,944
Total loans	61,547	49,944
Commercial Portfolio Segment [Member] | Doubtful [Member]
Loans originated in current year	0	0
Loans originated year prior	0	0
Loans originated three years prior	0	0
Loans originated four years prior	0	1,504
Loans originated five years prior	0	2,185
Total, Loans Amortized Cost Basis by Origination Year Prior	0	0
Total, Revolving Loans	0	234
Total, Revolving Converted to Term Loans	0	0
Total loans	0	3,923
Total loans	0	3,923
Real Estate Construction Portfolio Segment [Member]
Loans originated in current year	31,461	99,798
Loans originated year prior	131,984	264,557
Loans originated three years prior	165,684	122,761
Loans originated four years prior	44,850	33,858
Loans originated five years prior	21,034	35,321
Total, Loans Amortized Cost Basis by Origination Year Prior	26,129	0
Total, Revolving Loans	0	0
Total, Revolving Converted to Term Loans	0	0
Total loans	421,142	556,295
Loans originated in current year, write offs	0	0
Loans originated year prior, write offs	0	0
Loans originated three years prior, write offs	0	0
Loans originated four years prior, write offs	0	0
Loans originated five years prior, write offs	0	0
Total, Loans Amortized Cost Basis by Origination Year Prior, Write Offs	4,221	0
Total, Revolving Loans Write Offs	0	0
Total, Revolving Converted to Term Loans, Write Offs	0	0
YTD gross write-offs	4,221	0
Total loans	421,142	556,295
Real Estate Construction Portfolio Segment [Member] | Pass [Member]
Loans originated in current year	29,550	99,798
Loans originated year prior	131,984	264,197
Loans originated three years prior	153,977	113,312
Loans originated four years prior	19,461	20,479
Loans originated five years prior	13,298	3,067
Total, Loans Amortized Cost Basis by Origination Year Prior	3,131	0
Total, Revolving Loans	0	0
Total, Revolving Converted to Term Loans	0	0
Total loans	351,401	500,853
Total loans	351,401	500,853
Real Estate Construction Portfolio Segment [Member] | Special Mention [Member]
Loans originated in current year	1,911	0
Loans originated year prior	0	360
Loans originated three years prior	11,707	9,449
Loans originated four years prior	25,389	11,643
Loans originated five years prior	0	22,945
Total, Loans Amortized Cost Basis by Origination Year Prior	22,998	0
Total, Revolving Loans	0	0
Total, Revolving Converted to Term Loans	0	0
Total loans	62,005	44,397
Total loans	62,005	44,397
Real Estate Construction Portfolio Segment [Member] | Substandard [Member]
Loans originated in current year	0	0
Loans originated year prior	0	0
Loans originated three years prior	0	0
Loans originated four years prior	0	1,736
Loans originated five years prior	7,736	9,309
Total, Loans Amortized Cost Basis by Origination Year Prior	0	0
Total, Revolving Loans	0	0
Total, Revolving Converted to Term Loans	0	0
Total loans	7,736	11,045
Total loans	7,736	11,045
Commercial Real Estate Portfolio Segment [Member]
Loans originated in current year	2,159,093	2,122,120
Loans originated year prior	1,990,019	1,793,483
Loans originated three years prior	1,635,585	1,015,938
Loans originated four years prior	893,972	1,146,596
Loans originated five years prior	1,047,548	961,646
Total, Loans Amortized Cost Basis by Origination Year Prior	1,809,430	1,566,608
Total, Revolving Loans	185,985	182,347
Total, Revolving Converted to Term Loans	0	0
Total loans	9,721,632	8,788,738
Loans originated in current year, write offs	0	0
Loans originated year prior, write offs	0	0
Loans originated three years prior, write offs	208	0
Loans originated four years prior, write offs	0	0
Loans originated five years prior, write offs	969	2,152
Total, Loans Amortized Cost Basis by Origination Year Prior, Write Offs	4,164	0
Total, Revolving Loans Write Offs	0	0
Total, Revolving Converted to Term Loans, Write Offs	0	0
YTD gross write-offs	5,341	2,152
Total loans	9,721,632	8,788,738
Commercial Real Estate Portfolio Segment [Member] | Pass [Member]
Loans originated in current year	2,121,489	2,087,650
Loans originated year prior	1,959,239	1,728,607
Loans originated three years prior	1,585,010	975,953
Loans originated four years prior	887,508	1,094,505
Loans originated five years prior	1,019,952	908,748
Total, Loans Amortized Cost Basis by Origination Year Prior	1,726,015	1,420,982
Total, Revolving Loans	184,601	178,116
Total, Revolving Converted to Term Loans	0	0
Total loans	9,483,814	8,394,561
Total loans	9,483,814	8,394,561
Commercial Real Estate Portfolio Segment [Member] | Special Mention [Member]
Loans originated in current year	37,604	22,150
Loans originated year prior	18,910	57,015
Loans originated three years prior	38,405	25,593
Loans originated four years prior	3,499	32,119
Loans originated five years prior	10,303	17,999
Total, Loans Amortized Cost Basis by Origination Year Prior	17,210	63,782
Total, Revolving Loans	1,384	1,600
Total, Revolving Converted to Term Loans	0	0
Total loans	127,315	220,258
Total loans	127,315	220,258
Commercial Real Estate Portfolio Segment [Member] | Substandard [Member]
Loans originated in current year	0	12,320
Loans originated year prior	11,870	7,861
Loans originated three years prior	12,170	14,392
Loans originated four years prior	2,965	19,972
Loans originated five years prior	17,293	34,899
Total, Loans Amortized Cost Basis by Origination Year Prior	66,205	81,844
Total, Revolving Loans	0	2,631
Total, Revolving Converted to Term Loans	0	0
Total loans	110,503	173,919
Total loans	110,503	173,919
Residential Portfolio Segment [Member]
Loans originated in current year	1,141,005	1,228,597
Loans originated year prior	1,129,178	965,561
Loans originated three years prior	905,938	583,051
Loans originated four years prior	526,925	602,752
Loans originated five years prior	542,339	420,116
Total, Loans Amortized Cost Basis by Origination Year Prior	1,594,048	1,454,010
Total, Revolving Loans	0	0
Total, Revolving Converted to Term Loans	0	0
Total loans	5,839,433	5,254,087
Loans originated in current year, write offs	0	0
Loans originated year prior, write offs	0	0
Loans originated three years prior, write offs	0	0
Loans originated four years prior, write offs	0	0
Loans originated five years prior, write offs	0	0
Total, Loans Amortized Cost Basis by Origination Year Prior, Write Offs	0	0
Total, Revolving Loans Write Offs	0	0
Total, Revolving Converted to Term Loans, Write Offs	0	0
YTD gross write-offs	0	0
Total loans	5,839,433	5,254,087
Residential Portfolio Segment [Member] | Pass [Member]
Loans originated in current year	1,140,998	1,228,391
Loans originated year prior	1,128,526	964,799
Loans originated three years prior	902,613	580,990
Loans originated four years prior	524,315	600,786
Loans originated five years prior	541,005	417,565
Total, Loans Amortized Cost Basis by Origination Year Prior	1,583,118	1,444,320
Total, Revolving Loans	0	0
Total, Revolving Converted to Term Loans	0	0
Total loans	5,820,575	5,236,851
Total loans	5,820,575	5,236,851
Residential Portfolio Segment [Member] | Special Mention [Member]
Loans originated in current year	0	0
Loans originated year prior	0	0
Loans originated three years prior	0	33
Loans originated four years prior	33	0
Loans originated five years prior	0	752
Total, Loans Amortized Cost Basis by Origination Year Prior	1,619	905
Total, Revolving Loans	0	0
Total, Revolving Converted to Term Loans	0	0
Total loans	1,652	1,690
Total loans	1,652	1,690
Residential Portfolio Segment [Member] | Substandard [Member]
Loans originated in current year	7	206
Loans originated year prior	652	762
Loans originated three years prior	3,325	2,028
Loans originated four years prior	2,577	1,966
Loans originated five years prior	1,334	1,799
Total, Loans Amortized Cost Basis by Origination Year Prior	9,311	8,785
Total, Revolving Loans	0	0
Total, Revolving Converted to Term Loans	0	0
Total loans	17,206	15,546
Total loans	17,206	15,546
Equity Lines Portfolio Segment [Member]
Loans originated in current year	0	748
Loans originated year prior	101	0
Loans originated three years prior	0	0
Loans originated four years prior	0	0
Loans originated five years prior	0	0
Total, Loans Amortized Cost Basis by Origination Year Prior	0	0
Total, Revolving Loans	230,013	303,868
Total, Revolving Converted to Term Loans	16,801	21,680
Total loans	246,915	326,296
Loans originated in current year, write offs	0	0
Loans originated year prior, write offs	0	0
Loans originated three years prior, write offs	0	0
Loans originated four years prior, write offs	0	0
Loans originated five years prior, write offs	0	0
Total, Loans Amortized Cost Basis by Origination Year Prior, Write Offs	0	0
Total, Revolving Loans Write Offs	0	0
Total, Revolving Converted to Term Loans, Write Offs	0	0
YTD gross write-offs	0	0
Total loans	246,915	326,296
Equity Lines Portfolio Segment [Member] | Pass [Member]
Loans originated in current year	0	731
Loans originated year prior	98	0
Loans originated three years prior	0	0
Loans originated four years prior	0	0
Loans originated five years prior	0	0
Total, Loans Amortized Cost Basis by Origination Year Prior	0	0
Total, Revolving Loans	227,502	302,825
Total, Revolving Converted to Term Loans	16,628	21,460
Total loans	244,228	325,016
Total loans	244,228	325,016
Equity Lines Portfolio Segment [Member] | Special Mention [Member]
Loans originated in current year	0	5
Loans originated year prior	3	0
Loans originated three years prior	0	0
Loans originated four years prior	0	0
Loans originated five years prior	0	0
Total, Loans Amortized Cost Basis by Origination Year Prior	0	0
Total, Revolving Loans	0	0
Total, Revolving Converted to Term Loans	0	0
Total loans	3	5
Total loans	3	5
Equity Lines Portfolio Segment [Member] | Substandard [Member]
Loans originated in current year	0	12
Loans originated year prior	0	0
Loans originated three years prior	0	0
Loans originated four years prior	0	0
Loans originated five years prior	0	0
Total, Loans Amortized Cost Basis by Origination Year Prior	0	0
Total, Revolving Loans	2,511	1,043
Total, Revolving Converted to Term Loans	173	220
Total loans	2,684	1,275
Total loans	2,684	1,275
Installment and Other Loans [Member ]
Loans originated in current year	5,114	1,792
Loans originated year prior	981	2,152
Loans originated three years prior	3	0
Loans originated four years prior	0	0
Loans originated five years prior	0	0
Total, Loans Amortized Cost Basis by Origination Year Prior	0	0
Total, Revolving Loans	0	0
Total, Revolving Converted to Term Loans	0	0
Total loans	6,098	3,944
Loans originated in current year, write offs	0	116
Loans originated year prior, write offs	15	0
Loans originated three years prior, write offs	0	0
Loans originated four years prior, write offs	0	0
Loans originated five years prior, write offs	0	0
Total, Loans Amortized Cost Basis by Origination Year Prior, Write Offs	0	0
Total, Revolving Loans Write Offs	0	0
Total, Revolving Converted to Term Loans, Write Offs	0	0
YTD gross write-offs	15	116
Total loans	6,098	3,944
Installment and Other Loans [Member ] | Pass [Member]
Loans originated in current year	5,114	1,792
Loans originated year prior	981	2,152
Loans originated three years prior	3	0
Loans originated four years prior	0	0
Loans originated five years prior	0	0
Total, Loans Amortized Cost Basis by Origination Year Prior	0	0
Total, Revolving Loans	0	0
Total, Revolving Converted to Term Loans	0	0
Total loans	6,098	3,944
Total loans	$ 6,098	$ 3,944