Note 9 - Loans - Loan Held for Investment by Loan Portfolio Segments, Internal Risk Ratings and Vintage Year (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022	Dec. 31, 2022
Loans originated in current year	$ 1,940,174		$ 1,940,174		$ 3,943,040
Loans originated year prior	3,770,143		3,770,143		3,489,846
Loans originated three years prior	3,288,929		3,288,929		1,905,136
Loans originated four years prior	1,773,983		1,773,983		1,908,992
Loans originated five years prior	1,800,491		1,800,491		1,530,238
Total, Loans Amortized Cost Basis by Origination Year Prior	4,059,406		4,059,406		3,138,606
Total, Revolving Loans	2,285,847		2,285,847		2,303,152
Total, Revolving Converted to Term Loans	24,324		24,324		28,373
Total loans	18,943,297		18,943,297		18,247,383
Loans originated in current year, write offs			0		211
Loans originated year prior, write offs			259		587
Loans originated three years prior, write offs			967		120
Loans originated four years prior, write offs			194		71
Loans originated five years prior, write offs			3,255		3,877
Total, Loans Amortized Cost Basis by Origination Year Prior, Write Offs			5,704		360
Total, Revolving Loans Write Offs			11		264
Total, Revolving Converted to Term Loans, Write Offs			0		0
YTD gross write-offs	2,483	$ 51	10,390	$ 272	5,490
Total loans	18,943,297		18,943,297		18,247,383
Commercial Portfolio Segment [Member]
Loans originated in current year	190,202		190,202		489,985
Loans originated year prior	419,053		419,053		464,093
Loans originated three years prior	409,107		409,107		183,386
Loans originated four years prior	158,704		158,704		125,786
Loans originated five years prior	98,343		98,343		113,155
Total, Loans Amortized Cost Basis by Origination Year Prior	186,459		186,459		117,988
Total, Revolving Loans	1,848,477		1,848,477		1,816,937
Total, Revolving Converted to Term Loans	5,372		5,372		6,693
Total loans	3,315,717		3,315,717		3,318,023
Loans originated in current year, write offs			0		96
Loans originated year prior, write offs			252		587
Loans originated three years prior, write offs			760		120
Loans originated four years prior, write offs			194		71
Loans originated five years prior, write offs			3,255		1,786
Total, Loans Amortized Cost Basis by Origination Year Prior, Write Offs			1,791		360
Total, Revolving Loans Write Offs			11		202
Total, Revolving Converted to Term Loans, Write Offs			0		0
YTD gross write-offs	2,352	50	6,263	271	3,222
Total loans	3,315,717		3,315,717		3,318,023
Commercial Portfolio Segment [Member] | Pass [Member]
Loans originated in current year	188,200		188,200		488,748
Loans originated year prior	415,771		415,771		446,647
Loans originated three years prior	393,243		393,243		180,226
Loans originated four years prior	156,101		156,101		119,355
Loans originated five years prior	97,152		97,152		107,896
Total, Loans Amortized Cost Basis by Origination Year Prior	177,860		177,860		106,649
Total, Revolving Loans	1,764,173		1,764,173		1,753,509
Total, Revolving Converted to Term Loans	5,053		5,053		6,560
Total loans	3,197,553		3,197,553		3,209,590
Total loans	3,197,553		3,197,553		3,209,590
Commercial Portfolio Segment [Member] | Special Mention [Member]
Loans originated in current year	1,826		1,826		1,212
Loans originated year prior	2,917		2,917		4,696
Loans originated three years prior	3,829		3,829		2,818
Loans originated four years prior	2,536		2,536		68
Loans originated five years prior	0		0		308
Total, Loans Amortized Cost Basis by Origination Year Prior	2,782		2,782		4,354
Total, Revolving Loans	60,040		60,040		41,110
Total, Revolving Converted to Term Loans	0		0		0
Total loans	73,930		73,930		54,566
Total loans	73,930		73,930		54,566
Commercial Portfolio Segment [Member] | Substandard [Member]
Loans originated in current year	176		176		25
Loans originated year prior	365		365		12,750
Loans originated three years prior	12,035		12,035		342
Loans originated four years prior	67		67		4,859
Loans originated five years prior	1,191		1,191		2,766
Total, Loans Amortized Cost Basis by Origination Year Prior	5,817		5,817		6,985
Total, Revolving Loans	24,264		24,264		22,084
Total, Revolving Converted to Term Loans	319		319		133
Total loans	44,234		44,234		49,944
Total loans	44,234		44,234		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	18,471		18,471		99,798
Loans originated year prior	100,659		100,659		264,557
Loans originated three years prior	239,665		239,665		122,761
Loans originated four years prior	93,512		93,512		33,858
Loans originated five years prior	31,839		31,839		35,321
Total, Loans Amortized Cost Basis by Origination Year Prior	35,325		35,325		0
Total, Revolving Loans	0		0		0
Total, Revolving Converted to Term Loans	0		0		0
Total loans	519,471		519,471		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	519,471		519,471		556,295
Real Estate Construction Portfolio Segment [Member] | Pass [Member]
Loans originated in current year	17,334		17,334		99,798
Loans originated year prior	100,659		100,659		264,197
Loans originated three years prior	239,665		239,665		113,312
Loans originated four years prior	93,512		93,512		20,479
Loans originated five years prior	10,464		10,464		3,067
Total, Loans Amortized Cost Basis by Origination Year Prior	3,072		3,072		0
Total, Revolving Loans	0		0		0
Total, Revolving Converted to Term Loans	0		0		0
Total loans	464,706		464,706		500,853
Total loans	464,706		464,706		500,853
Real Estate Construction Portfolio Segment [Member] | Special Mention [Member]
Loans originated in current year	1,137		1,137		0
Loans originated year prior	0		0		360
Loans originated three years prior	0		0		9,449
Loans originated four years prior	0		0		11,643
Loans originated five years prior	19,639		19,639		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	43,774		43,774		44,397
Total loans	43,774		43,774		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	1,736		1,736		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	10,991		10,991		11,045
Total loans	10,991		10,991		11,045
Commercial Real Estate Portfolio Segment [Member]
Loans originated in current year	1,167,344		1,167,344		2,122,120
Loans originated year prior	2,079,926		2,079,926		1,793,483
Loans originated three years prior	1,700,596		1,700,596		1,015,938
Loans originated four years prior	963,763		963,763		1,146,596
Loans originated five years prior	1,097,289		1,097,289		961,646
Total, Loans Amortized Cost Basis by Origination Year Prior	2,094,226		2,094,226		1,566,608
Total, Revolving Loans	183,317		183,317		182,347
Total, Revolving Converted to Term Loans	0		0		0
Total loans	9,286,461		9,286,461		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			0		2,091
Total, Loans Amortized Cost Basis by Origination Year Prior, Write Offs			3,913		0
Total, Revolving Loans Write Offs			0		0
Total, Revolving Converted to Term Loans, Write Offs			0		0
YTD gross write-offs	130	(0)	4,120	(0)	2,091
Total loans	9,286,461		9,286,461		8,788,738
Commercial Real Estate Portfolio Segment [Member] | Pass [Member]
Loans originated in current year	1,146,281		1,146,281		2,087,650
Loans originated year prior	2,065,253		2,065,253		1,728,607
Loans originated three years prior	1,672,273		1,672,273		975,953
Loans originated four years prior	936,526		936,526		1,094,505
Loans originated five years prior	1,052,485		1,052,485		908,748
Total, Loans Amortized Cost Basis by Origination Year Prior	1,975,795		1,975,795		1,420,982
Total, Revolving Loans	179,848		179,848		178,116
Total, Revolving Converted to Term Loans	0		0		0
Total loans	9,028,461		9,028,461		8,394,561
Total loans	9,028,461		9,028,461		8,394,561
Commercial Real Estate Portfolio Segment [Member] | Special Mention [Member]
Loans originated in current year	21,063		21,063		22,150
Loans originated year prior	1,685		1,685		57,015
Loans originated three years prior	16,038		16,038		25,593
Loans originated four years prior	25,501		25,501		32,119
Loans originated five years prior	24,674		24,674		17,999
Total, Loans Amortized Cost Basis by Origination Year Prior	50,593		50,593		63,782
Total, Revolving Loans	800		800		1,600
Total, Revolving Converted to Term Loans	0		0		0
Total loans	140,354		140,354		220,258
Total loans	140,354		140,354		220,258
Commercial Real Estate Portfolio Segment [Member] | Substandard [Member]
Loans originated in current year	0		0		12,320
Loans originated year prior	12,988		12,988		7,861
Loans originated three years prior	12,285		12,285		14,392
Loans originated four years prior	1,736		1,736		19,972
Loans originated five years prior	20,130		20,130		34,899
Total, Loans Amortized Cost Basis by Origination Year Prior	67,838		67,838		81,844
Total, Revolving Loans	2,669		2,669		2,631
Total, Revolving Converted to Term Loans	0		0		0
Total loans	117,646		117,646		173,919
Total loans	117,646		117,646		173,919
Residential Portfolio Segment [Member]
Loans originated in current year	563,858		563,858		1,228,597
Loans originated year prior	1,168,179		1,168,179		965,561
Loans originated three years prior	936,928		936,928		583,051
Loans originated four years prior	558,004		558,004		602,752
Loans originated five years prior	573,020		573,020		420,116
Total, Loans Amortized Cost Basis by Origination Year Prior	1,743,396		1,743,396		1,454,010
Total, Revolving Loans	0		0		0
Total, Revolving Converted to Term Loans	0		0		0
Total loans	5,543,385		5,543,385		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	5,543,385		5,543,385		5,254,087
Residential Portfolio Segment [Member] | Pass [Member]
Loans originated in current year	563,858		563,858		1,228,391
Loans originated year prior	1,167,709		1,167,709		964,799
Loans originated three years prior	936,487		936,487		580,990
Loans originated four years prior	554,275		554,275		600,786
Loans originated five years prior	570,881		570,881		417,565
Total, Loans Amortized Cost Basis by Origination Year Prior	1,729,482		1,729,482		1,444,320
Total, Revolving Loans	0		0		0
Total, Revolving Converted to Term Loans	0		0		0
Total loans	5,522,692		5,522,692		5,236,851
Total loans	5,522,692		5,522,692		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	1,639		1,639		905
Total, Revolving Loans	0		0		0
Total, Revolving Converted to Term Loans	0		0		0
Total loans	1,672		1,672		1,690
Total loans	1,672		1,672		1,690
Residential Portfolio Segment [Member] | Substandard [Member]
Loans originated in current year	0		0		206
Loans originated year prior	470		470		762
Loans originated three years prior	441		441		2,028
Loans originated four years prior	3,696		3,696		1,966
Loans originated five years prior	2,139		2,139		1,799
Total, Loans Amortized Cost Basis by Origination Year Prior	12,275		12,275		8,785
Total, Revolving Loans	0		0		0
Total, Revolving Converted to Term Loans	0		0		0
Total loans	19,021		19,021		15,546
Total loans	19,021		19,021		15,546
Equity Lines Portfolio Segment [Member]
Loans originated in current year	0		0		748
Loans originated year prior	115		115		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	254,053		254,053		303,868
Total, Revolving Converted to Term Loans	18,952		18,952		21,680
Total loans	273,120		273,120		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	273,120		273,120		326,296
Equity Lines Portfolio Segment [Member] | Pass [Member]
Loans originated in current year	0		0		731
Loans originated year prior	115		115		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	252,786		252,786		302,825
Total, Revolving Converted to Term Loans	18,765		18,765		21,460
Total loans	271,666		271,666		325,016
Total loans	271,666		271,666		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	1		1		0
Total, Revolving Converted to Term Loans	0		0		0
Total loans	1		1		5
Total loans	1		1		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	1,266		1,266		1,043
Total, Revolving Converted to Term Loans	187		187		220
Total loans	1,453		1,453		1,275
Total loans	1,453		1,453		1,275
Installment and Other Loans [Member ]
Loans originated in current year	299		299		1,792
Loans originated year prior	2,211		2,211		2,152
Loans originated three years prior	2,633		2,633		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	5,143		5,143		3,944
Loans originated in current year, write offs			0		115
Loans originated year prior, write offs			7		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	1	$ 1	7	$ 1	177
Total loans	5,143		5,143		3,944
Installment and Other Loans [Member ] | Pass [Member]
Loans originated in current year	299		299		1,792
Loans originated year prior	2,203		2,203		2,152
Loans originated three years prior	2,633		2,633		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	5,135		5,135		3,944
Total loans	5,135		5,135		$ 3,944
Installment and Other Loans [Member ] | Special Mention [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
Installment and Other Loans [Member ] | Substandard [Member]
Loans originated in current year	0		0
Loans originated year prior	8		8
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	8		8
Total loans	$ 8		$ 8