Note 9 - Loans - Loan Held for Investment by Loan Portfolio Segments, Internal Risk Ratings and Vintage Year (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022	Dec. 31, 2022
Loans originated in current year	$ 2,801,037		$ 2,801,037		$ 3,943,040
Loans originated year prior	3,697,058		3,697,058		3,489,846
Loans originated three years prior	3,189,006		3,189,006		1,905,136
Loans originated four years prior	1,662,819		1,662,819		1,908,992
Loans originated five years prior	1,742,356		1,742,356		1,530,238
Total, Loans Amortized Cost Basis by Origination Year Prior	3,817,666		3,817,666		3,138,606
Total, Revolving Loans	2,079,465		2,079,465		2,303,152
Total, Revolving Converted to Term Loans	24,894		24,894		28,373
Total loans	19,014,301		19,014,301		18,247,383
Loans originated in current year, write offs			0		211
Loans originated year prior, write offs			291		587
Loans originated three years prior, write offs			967		120
Loans originated four years prior, write offs			245		71
Loans originated five years prior, write offs			4,641		3,877
Total, Loans Amortized Cost Basis by Origination Year Prior, Write Offs			10,208		360
Total, Revolving Loans Write Offs			1,521		264
Total, Revolving Converted to Term Loans, Write Offs			0		0
YTD gross write-offs	7,483	$ 2,228	17,873	$ 2,500	5,490
Total loans	19,014,301		19,014,301		18,247,383
Commercial Portfolio Segment [Member]
Loans originated in current year	263,680		263,680		489,985
Loans originated year prior	390,597		390,597		464,093
Loans originated three years prior	377,397		377,397		183,386
Loans originated four years prior	142,939		142,939		125,786
Loans originated five years prior	92,562		92,562		113,155
Total, Loans Amortized Cost Basis by Origination Year Prior	162,292		162,292		117,988
Total, Revolving Loans	1,651,639		1,651,639		1,816,937
Total, Revolving Converted to Term Loans	7,397		7,397		6,693
Total loans	3,088,503		3,088,503		3,318,023
Loans originated in current year, write offs			0		96
Loans originated year prior, write offs			276		587
Loans originated three years prior, write offs			760		120
Loans originated four years prior, write offs			245		71
Loans originated five years prior, write offs			3,672		1,786
Total, Loans Amortized Cost Basis by Origination Year Prior, Write Offs			6,043		360
Total, Revolving Loans Write Offs			1,521		202
Total, Revolving Converted to Term Loans, Write Offs			0		0
YTD gross write-offs	6,254	2,091	12,517	2,362	3,222
Total loans	3,088,503		3,088,503		3,318,023
Commercial Portfolio Segment [Member] | Pass [Member]
Loans originated in current year	259,326		259,326		488,748
Loans originated year prior	387,990		387,990		446,647
Loans originated three years prior	357,365		357,365		180,226
Loans originated four years prior	113,463		113,463		119,355
Loans originated five years prior	90,879		90,879		107,896
Total, Loans Amortized Cost Basis by Origination Year Prior	155,766		155,766		106,649
Total, Revolving Loans	1,568,766		1,568,766		1,753,509
Total, Revolving Converted to Term Loans	7,175		7,175		6,560
Total loans	2,940,730		2,940,730		3,209,590
Total loans	2,940,730		2,940,730		3,209,590
Commercial Portfolio Segment [Member] | Special Mention [Member]
Loans originated in current year	4,188		4,188		1,212
Loans originated year prior	2,083		2,083		4,696
Loans originated three years prior	8,582		8,582		2,818
Loans originated four years prior	29,311		29,311		68
Loans originated five years prior	915		915		308
Total, Loans Amortized Cost Basis by Origination Year Prior	773		773		4,354
Total, Revolving Loans	53,164		53,164		41,110
Total, Revolving Converted to Term Loans	0		0		0
Total loans	99,016		99,016		54,566
Total loans	99,016		99,016		54,566
Commercial Portfolio Segment [Member] | Substandard [Member]
Loans originated in current year	166		166		25
Loans originated year prior	524		524		12,750
Loans originated three years prior	11,450		11,450		342
Loans originated four years prior	165		165		4,859
Loans originated five years prior	768		768		2,766
Total, Loans Amortized Cost Basis by Origination Year Prior	5,753		5,753		6,985
Total, Revolving Loans	29,709		29,709		22,084
Total, Revolving Converted to Term Loans	222		222		133
Total loans	48,757		48,757		49,944
Total loans	48,757		48,757		49,944
Commercial Portfolio Segment [Member] | Doubtful [Member]
Loans originated in current year					0
Loans originated year prior					0
Loans originated three years prior					0
Loans originated four years prior					1,504
Loans originated five years prior					2,185
Total, Loans Amortized Cost Basis by Origination Year Prior					0
Total, Revolving Loans					234
Total, Revolving Converted to Term Loans					0
Total loans					3,923
Total loans					3,923
Real Estate Construction Portfolio Segment [Member]
Loans originated in current year	23,786		23,786		99,798
Loans originated year prior	118,205		118,205		264,557
Loans originated three years prior	226,250		226,250		122,761
Loans originated four years prior	44,627		44,627		33,858
Loans originated five years prior	24,269		24,269		35,321
Total, Loans Amortized Cost Basis by Origination Year Prior	35,385		35,385		0
Total, Revolving Loans	0		0		0
Total, Revolving Converted to Term Loans	0		0		0
Total loans	472,522		472,522		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			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)	0	(0)	0
Total loans	472,522		472,522		556,295
Real Estate Construction Portfolio Segment [Member] | Pass [Member]
Loans originated in current year	22,304		22,304		99,798
Loans originated year prior	118,205		118,205		264,197
Loans originated three years prior	218,002		218,002		113,312
Loans originated four years prior	44,627		44,627		20,479
Loans originated five years prior	16,533		16,533		3,067
Total, Loans Amortized Cost Basis by Origination Year Prior	3,132		3,132		0
Total, Revolving Loans	0		0		0
Total, Revolving Converted to Term Loans	0		0		0
Total loans	422,803		422,803		500,853
Total loans	422,803		422,803		500,853
Real Estate Construction Portfolio Segment [Member] | Special Mention [Member]
Loans originated in current year	1,482		1,482		0
Loans originated year prior	0		0		360
Loans originated three years prior	8,248		8,248		9,449
Loans originated four years prior	0		0		11,643
Loans originated five years prior	0		0		22,945
Total, Loans Amortized Cost Basis by Origination Year Prior	22,998		22,998		0
Total, Revolving Loans	0		0		0
Total, Revolving Converted to Term Loans	0		0		0
Total loans	32,728		32,728		44,397
Total loans	32,728		32,728		44,397
Real Estate Construction Portfolio Segment [Member] | Substandard [Member]
Loans originated in current year	0		0		0
Loans originated year prior	0		0		0
Loans originated three years prior	0		0		0
Loans originated four years prior	0		0		1,736
Loans originated five years prior	7,736		7,736		9,309
Total, Loans Amortized Cost Basis by Origination Year Prior	9,255		9,255		0
Total, Revolving Loans	0		0		0
Total, Revolving Converted to Term Loans	0		0		0
Total loans	16,991		16,991		11,045
Total loans	16,991		16,991		11,045
Commercial Real Estate Portfolio Segment [Member]
Loans originated in current year	1,661,430		1,661,430		2,122,120
Loans originated year prior	2,036,965		2,036,965		1,793,483
Loans originated three years prior	1,664,536		1,664,536		1,015,938
Loans originated four years prior	932,785		932,785		1,146,596
Loans originated five years prior	1,065,872		1,065,872		961,646
Total, Loans Amortized Cost Basis by Origination Year Prior	1,952,259		1,952,259		1,566,608
Total, Revolving Loans	190,572		190,572		182,347
Total, Revolving Converted to Term Loans	0		0		0
Total loans	9,504,419		9,504,419		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			207		0
Loans originated four years prior, write offs			0		0
Loans originated five years prior, write offs			969		2,091
Total, Loans Amortized Cost Basis by Origination Year Prior, Write Offs			4,165		0
Total, Revolving Loans Write Offs			0		0
Total, Revolving Converted to Term Loans, Write Offs			0		0
YTD gross write-offs	1,221	(0)	5,341	(0)	2,091
Total loans	9,504,419		9,504,419		8,788,738
Commercial Real Estate Portfolio Segment [Member] | Pass [Member]
Loans originated in current year	1,626,562		1,626,562		2,087,650
Loans originated year prior	2,005,931		2,005,931		1,728,607
Loans originated three years prior	1,617,398		1,617,398		975,953
Loans originated four years prior	923,929		923,929		1,094,505
Loans originated five years prior	1,032,298		1,032,298		908,748
Total, Loans Amortized Cost Basis by Origination Year Prior	1,855,014		1,855,014		1,420,982
Total, Revolving Loans	186,502		186,502		178,116
Total, Revolving Converted to Term Loans	0		0		0
Total loans	9,247,634		9,247,634		8,394,561
Total loans	9,247,634		9,247,634		8,394,561
Commercial Real Estate Portfolio Segment [Member] | Special Mention [Member]
Loans originated in current year	34,868		34,868		22,150
Loans originated year prior	19,097		19,097		57,015
Loans originated three years prior	34,891		34,891		25,593
Loans originated four years prior	3,330		3,330		32,119
Loans originated five years prior	16,198		16,198		17,999
Total, Loans Amortized Cost Basis by Origination Year Prior	34,985		34,985		63,782
Total, Revolving Loans	1,399		1,399		1,600
Total, Revolving Converted to Term Loans	0		0		0
Total loans	144,768		144,768		220,258
Total loans	144,768		144,768		220,258
Commercial Real Estate Portfolio Segment [Member] | Substandard [Member]
Loans originated in current year	0		0		12,320
Loans originated year prior	11,937		11,937		7,861
Loans originated three years prior	12,247		12,247		14,392
Loans originated four years prior	5,526		5,526		19,972
Loans originated five years prior	17,376		17,376		34,899
Total, Loans Amortized Cost Basis by Origination Year Prior	62,260		62,260		81,844
Total, Revolving Loans	2,671		2,671		2,631
Total, Revolving Converted to Term Loans	0		0		0
Total loans	112,017		112,017		173,919
Total loans	112,017		112,017		173,919
Residential Portfolio Segment [Member]
Loans originated in current year	847,550		847,550		1,228,597
Loans originated year prior	1,148,442		1,148,442		965,561
Loans originated three years prior	920,818		920,818		583,051
Loans originated four years prior	542,468		542,468		602,752
Loans originated five years prior	559,653		559,653		420,116
Total, Loans Amortized Cost Basis by Origination Year Prior	1,667,730		1,667,730		1,454,010
Total, Revolving Loans	0		0		0
Total, Revolving Converted to Term Loans	0		0		0
Total loans	5,686,661		5,686,661		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	5,686,661		5,686,661		5,254,087
Residential Portfolio Segment [Member] | Pass [Member]
Loans originated in current year	847,550		847,550		1,228,391
Loans originated year prior	1,147,491		1,147,491		964,799
Loans originated three years prior	920,385		920,385		580,990
Loans originated four years prior	538,989		538,989		600,786
Loans originated five years prior	557,098		557,098		417,565
Total, Loans Amortized Cost Basis by Origination Year Prior	1,652,948		1,652,948		1,444,320
Total, Revolving Loans	0		0		0
Total, Revolving Converted to Term Loans	0		0		0
Total loans	5,664,461		5,664,461		5,236,851
Total loans	5,664,461		5,664,461		5,236,851
Residential Portfolio Segment [Member] | Special Mention [Member]
Loans originated in current year	0		0		0
Loans originated year prior	0		0		0
Loans originated three years prior	0		0		33
Loans originated four years prior	33		33		0
Loans originated five years prior	0		0		752
Total, Loans Amortized Cost Basis by Origination Year Prior	1,632		1,632		905
Total, Revolving Loans	0		0		0
Total, Revolving Converted to Term Loans	0		0		0
Total loans	1,665		1,665		1,690
Total loans	1,665		1,665		1,690
Residential Portfolio Segment [Member] | Substandard [Member]
Loans originated in current year	0		0		206
Loans originated year prior	951		951		762
Loans originated three years prior	433		433		2,028
Loans originated four years prior	3,446		3,446		1,966
Loans originated five years prior	2,555		2,555		1,799
Total, Loans Amortized Cost Basis by Origination Year Prior	13,150		13,150		8,785
Total, Revolving Loans	0		0		0
Total, Revolving Converted to Term Loans	0		0		0
Total loans	20,535		20,535		15,546
Total loans	20,535		20,535		15,546
Equity Lines Portfolio Segment [Member]
Loans originated in current year	0		0		748
Loans originated year prior	108		108		0
Loans originated three years prior	0		0		0
Loans originated four years prior	0		0		0
Loans originated five years prior	0		0		0
Total, Loans Amortized Cost Basis by Origination Year Prior	0		0		0
Total, Revolving Loans	237,254		237,254		303,868
Total, Revolving Converted to Term Loans	17,497		17,497		21,680
Total loans	254,859		254,859		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	254,859		254,859		326,296
Equity Lines Portfolio Segment [Member] | Pass [Member]
Loans originated in current year	0		0		731
Loans originated year prior	108		108		0
Loans originated three years prior	0		0		0
Loans originated four years prior	0		0		0
Loans originated five years prior	0		0		0
Total, Loans Amortized Cost Basis by Origination Year Prior	0		0		0
Total, Revolving Loans	233,892		233,892		302,825
Total, Revolving Converted to Term Loans	17,322		17,322		21,460
Total loans	251,322		251,322		325,016
Total loans	251,322		251,322		325,016
Equity Lines Portfolio Segment [Member] | Special Mention [Member]
Loans originated in current year	0		0		5
Loans originated year prior	0		0		0
Loans originated three years prior	0		0		0
Loans originated four years prior	0		0		0
Loans originated five years prior	0		0		0
Total, Loans Amortized Cost Basis by Origination Year Prior	0		0		0
Total, Revolving Loans	0		0		0
Total, Revolving Converted to Term Loans	0		0		0
Total loans	0		0		5
Total loans	0		0		5
Equity Lines Portfolio Segment [Member] | Substandard [Member]
Loans originated in current year	0		0		12
Loans originated year prior	0		0		0
Loans originated three years prior	0		0		0
Loans originated four years prior	0		0		0
Loans originated five years prior	0		0		0
Total, Loans Amortized Cost Basis by Origination Year Prior	0		0		0
Total, Revolving Loans	3,362		3,362		1,043
Total, Revolving Converted to Term Loans	175		175		220
Total loans	3,537		3,537		1,275
Total loans	3,537		3,537		1,275
Installment and Other Loans [Member ]
Loans originated in current year	4,591		4,591		1,792
Loans originated year prior	2,741		2,741		2,152
Loans originated three years prior	5		5		0
Loans originated four years prior	0		0		0
Loans originated five years prior	0		0		0
Total, Loans Amortized Cost Basis by Origination Year Prior	0		0		0
Total, Revolving Loans	0		0		0
Total, Revolving Converted to Term Loans	0		0		0
Total loans	7,337		7,337		3,944
Loans originated in current year, write offs			0		115
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		62
Total, Revolving Converted to Term Loans, Write Offs			0		0
YTD gross write-offs	8	$ 79	15	$ 80	177
Total loans	7,337		7,337		3,944
Installment and Other Loans [Member ] | Pass [Member]
Loans originated in current year	4,591		4,591		1,792
Loans originated year prior	2,735		2,735		2,152
Loans originated three years prior	5		5		0
Loans originated four years prior	0		0		0
Loans originated five years prior	0		0		0
Total, Loans Amortized Cost Basis by Origination Year Prior	0		0		0
Total, Revolving Loans	0		0		0
Total, Revolving Converted to Term Loans	0		0		0
Total loans	7,331		7,331		3,944
Total loans	7,331		7,331		$ 3,944
Installment and Other Loans [Member ] | Special Mention [Member]
Loans originated in current year	0		0
Loans originated year prior	6		6
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	6		6
Total loans	6		6
Installment and Other Loans [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		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	0		0
Total loans	$ 0		$ 0