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LOANS AND ALLOWANCE FOR CREDIT LOSSES - Loan Risk by Category (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022	Dec. 31, 2022
Current period gross write-offs
Total	$ 7,937	$ 6,047
Term Loans Amortized Cost Basis by Origination Year
Total loans	8,681,967		$ 8,335,309
Construction and commercial multifamily | Construction
Current period gross write-offs
Write-offs, originated in current year	0
Write-offs, originated in prior year	0
Write-offs, originated two years before current year	0
Write-offs, originated three years before current year	0
Write-offs, originated four years before current year	0
Write-offs, originated five years before current year	0
Write-offs, Revolving Loans Amortized Cost Basis	0
Write-offs, Revolving Loans Converted to Term	0
Total	0	0
Term Loans Amortized Cost Basis by Origination Year
Loans originated in current fiscal year	14,566		153,393
Loans originated in fiscal year before current fiscal year	177,174		133,708
Loans originated two years before current fiscal year	152,773		25,634
Loans originated three years before current fiscal year	26,327		3,432
Loans originated four years before current fiscal year	2,967		1,361
Loans originated more than five years before current fiscal year	146		1,924
Revolving Loans Amortized Cost Basis	0		0
Revolving Loans Converted to Term	0		0
Total loans	373,953		319,452
Construction and commercial multifamily | Commercial multifamily
Current period gross write-offs
Write-offs, originated in current year	0
Write-offs, originated in prior year	0
Write-offs, originated two years before current year	0
Write-offs, originated three years before current year	0
Write-offs, originated four years before current year	0
Write-offs, originated five years before current year	0
Write-offs, Revolving Loans Amortized Cost Basis	0
Write-offs, Revolving Loans Converted to Term	0
Total	0	0
Term Loans Amortized Cost Basis by Origination Year
Loans originated in current fiscal year	3,938		205,124
Loans originated in fiscal year before current fiscal year	204,570		61,032
Loans originated two years before current fiscal year	57,851		30,211
Loans originated three years before current fiscal year	30,036		100,696
Loans originated four years before current fiscal year	99,583		73,187
Loans originated more than five years before current fiscal year	221,105		149,633
Revolving Loans Amortized Cost Basis	990		205
Revolving Loans Converted to Term	0		0
Total loans	618,073		620,088
Commercial real estate | Commercial real estate owner occupied
Current period gross write-offs
Write-offs, originated in current year	0
Write-offs, originated in prior year	0
Write-offs, originated two years before current year	0
Write-offs, originated three years before current year	0
Write-offs, originated four years before current year	0
Write-offs, originated five years before current year	70
Write-offs, Revolving Loans Amortized Cost Basis	0
Write-offs, Revolving Loans Converted to Term	0
Total	70	130
Term Loans Amortized Cost Basis by Origination Year
Loans originated in current fiscal year	25,216		132,099
Loans originated in fiscal year before current fiscal year	129,567		127,392
Loans originated two years before current fiscal year	127,872		59,253
Loans originated three years before current fiscal year	58,387		82,858
Loans originated four years before current fiscal year	106,619		76,378
Loans originated more than five years before current fiscal year	245,227		159,045
Revolving Loans Amortized Cost Basis	3,002		3,464
Revolving Loans Converted to Term	0		0
Total loans	695,890		640,489
Commercial real estate | Commercial real estate non-owner occupied
Current period gross write-offs
Write-offs, originated in current year	0
Write-offs, originated in prior year	0
Write-offs, originated two years before current year	0
Write-offs, originated three years before current year	0
Write-offs, originated four years before current year	0
Write-offs, originated five years before current year	0
Write-offs, Revolving Loans Amortized Cost Basis	0
Write-offs, Revolving Loans Converted to Term	0
Total	0	4,884
Term Loans Amortized Cost Basis by Origination Year
Loans originated in current fiscal year	114,007		621,685
Loans originated in fiscal year before current fiscal year	630,920		410,359
Loans originated two years before current fiscal year	410,481		182,693
Loans originated three years before current fiscal year	180,408		347,406
Loans originated four years before current fiscal year	303,759		348,734
Loans originated more than five years before current fiscal year	875,118		567,514
Revolving Loans Amortized Cost Basis	17,253		17,846
Revolving Loans Converted to Term	0		0
Total loans	2,531,946		2,496,237
Commercial and industrial
Current period gross write-offs
Write-offs, originated in current year	0
Write-offs, originated in prior year	0
Write-offs, originated two years before current year	191
Write-offs, originated three years before current year	669
Write-offs, originated four years before current year	580
Write-offs, originated five years before current year	4,593
Write-offs, Revolving Loans Amortized Cost Basis	0
Write-offs, Revolving Loans Converted to Term	0
Total	6,033	653
Term Loans Amortized Cost Basis by Origination Year
Loans originated in current fiscal year	56,951		282,985
Loans originated in fiscal year before current fiscal year	280,405		153,377
Loans originated two years before current fiscal year	149,560		61,810
Loans originated three years before current fiscal year	54,028		77,446
Loans originated four years before current fiscal year	70,690		96,706
Loans originated more than five years before current fiscal year	185,708		103,134
Revolving Loans Amortized Cost Basis	720,214		669,778
Revolving Loans Converted to Term	0		0
Total loans	1,517,556		1,445,236
Residential real estate | Residential real estate
Current period gross write-offs
Write-offs, originated in current year	0
Write-offs, originated in prior year	25
Write-offs, originated two years before current year	0
Write-offs, originated three years before current year	0
Write-offs, originated four years before current year	0
Write-offs, originated five years before current year	6
Write-offs, Revolving Loans Amortized Cost Basis	0
Write-offs, Revolving Loans Converted to Term	0
Total	31	164
Term Loans Amortized Cost Basis by Origination Year
Loans originated in current fiscal year	136,527		997,981
Loans originated in fiscal year before current fiscal year	1,008,913		280,956
Loans originated two years before current fiscal year	276,891		96,996
Loans originated three years before current fiscal year	94,922		71,973
Loans originated four years before current fiscal year	72,722		140,953
Loans originated more than five years before current fiscal year	873,845		723,423
Revolving Loans Amortized Cost Basis	161		165
Revolving Loans Converted to Term	0		0
Total loans	2,463,981		2,312,447
Consumer loans | Home equity
Current period gross write-offs
Write-offs, originated in current year	0
Write-offs, originated in prior year	0
Write-offs, originated two years before current year	0
Write-offs, originated three years before current year	0
Write-offs, originated four years before current year	0
Write-offs, originated five years before current year	0
Write-offs, Revolving Loans Amortized Cost Basis	10
Write-offs, Revolving Loans Converted to Term	0
Total	10	0
Term Loans Amortized Cost Basis by Origination Year
Loans originated in current fiscal year	0		0
Loans originated in fiscal year before current fiscal year	0		114
Loans originated two years before current fiscal year	111		454
Loans originated three years before current fiscal year	450		0
Loans originated four years before current fiscal year	0		0
Loans originated more than five years before current fiscal year	2,423		17
Revolving Loans Amortized Cost Basis	219,409		226,865
Revolving Loans Converted to Term	0		0
Total loans	222,393		227,450
Consumer loans | Home equity | Performing
Term Loans Amortized Cost Basis by Origination Year
Loans originated in current fiscal year	0		0
Loans originated in fiscal year before current fiscal year	0		114
Loans originated two years before current fiscal year	111		454
Loans originated three years before current fiscal year	450		0
Loans originated four years before current fiscal year	0		0
Loans originated more than five years before current fiscal year	2,423		17
Revolving Loans Amortized Cost Basis	217,685		224,746
Revolving Loans Converted to Term	0		0
Total loans	220,669		225,331
Consumer loans | Home equity | Nonperforming
Term Loans Amortized Cost Basis by Origination Year
Loans originated in current fiscal year	0		0
Loans originated in fiscal year before current fiscal year	0		0
Loans originated two years before current fiscal year	0		0
Loans originated three years before current fiscal year	0		0
Loans originated four years before current fiscal year	0		0
Loans originated more than five years before current fiscal year	0		0
Revolving Loans Amortized Cost Basis	1,724		2,119
Revolving Loans Converted to Term	0		0
Total loans	1,724		2,119
Consumer loans | Consumer other
Current period gross write-offs
Write-offs, originated in current year	0
Write-offs, originated in prior year	1,510
Write-offs, originated two years before current year	181
Write-offs, originated three years before current year	7
Write-offs, originated four years before current year	21
Write-offs, originated five years before current year	74
Write-offs, Revolving Loans Amortized Cost Basis	0
Write-offs, Revolving Loans Converted to Term	0
Total	1,793	$ 216
Term Loans Amortized Cost Basis by Origination Year
Loans originated in current fiscal year	11,962		161,745
Loans originated in fiscal year before current fiscal year	148,710		28,416
Loans originated two years before current fiscal year	26,319		8,356
Loans originated three years before current fiscal year	7,695		12,950
Loans originated four years before current fiscal year	11,315		28,085
Loans originated more than five years before current fiscal year	42,596		25,249
Revolving Loans Amortized Cost Basis	9,578		9,109
Revolving Loans Converted to Term	0		0
Total loans	258,175		273,910
Consumer loans | Consumer other | Performing
Term Loans Amortized Cost Basis by Origination Year
Loans originated in current fiscal year	11,962		161,157
Loans originated in fiscal year before current fiscal year	148,658		28,279
Loans originated two years before current fiscal year	26,235		8,312
Loans originated three years before current fiscal year	7,661		12,670
Loans originated four years before current fiscal year	11,125		27,608
Loans originated more than five years before current fiscal year	41,923		24,682
Revolving Loans Amortized Cost Basis	9,556		9,070
Revolving Loans Converted to Term	0		0
Total loans	257,120		271,778
Consumer loans | Consumer other | Nonperforming
Term Loans Amortized Cost Basis by Origination Year
Loans originated in current fiscal year	0		588
Loans originated in fiscal year before current fiscal year	52		137
Loans originated two years before current fiscal year	84		44
Loans originated three years before current fiscal year	34		280
Loans originated four years before current fiscal year	190		477
Loans originated more than five years before current fiscal year	673		567
Revolving Loans Amortized Cost Basis	22		39
Revolving Loans Converted to Term	0		0
Total loans	1,055		2,132
Pass | Construction and commercial multifamily | Construction
Term Loans Amortized Cost Basis by Origination Year
Loans originated in current fiscal year	14,566		153,393
Loans originated in fiscal year before current fiscal year	177,174		133,708
Loans originated two years before current fiscal year	152,773		25,634
Loans originated three years before current fiscal year	26,327		3,432
Loans originated four years before current fiscal year	2,967		1,361
Loans originated more than five years before current fiscal year	145		1,924
Revolving Loans Amortized Cost Basis	0		0
Revolving Loans Converted to Term	0		0
Total loans	373,952		319,452
Pass | Construction and commercial multifamily | Commercial multifamily
Term Loans Amortized Cost Basis by Origination Year
Loans originated in current fiscal year	3,938		205,124
Loans originated in fiscal year before current fiscal year	204,570		61,032
Loans originated two years before current fiscal year	57,851		27,583
Loans originated three years before current fiscal year	27,427		100,696
Loans originated four years before current fiscal year	99,583		67,675
Loans originated more than five years before current fiscal year	215,608		149,633
Revolving Loans Amortized Cost Basis	990		205
Revolving Loans Converted to Term	0		0
Total loans	609,967		611,948
Pass | Commercial real estate | Commercial real estate owner occupied
Term Loans Amortized Cost Basis by Origination Year
Loans originated in current fiscal year	25,216		131,096
Loans originated in fiscal year before current fiscal year	124,314		127,270
Loans originated two years before current fiscal year	127,750		58,835
Loans originated three years before current fiscal year	57,507		82,576
Loans originated four years before current fiscal year	102,523		75,322
Loans originated more than five years before current fiscal year	238,771		154,056
Revolving Loans Amortized Cost Basis	3,002		3,464
Revolving Loans Converted to Term	0		0
Total loans	679,083		632,619
Pass | Commercial real estate | Commercial real estate non-owner occupied
Term Loans Amortized Cost Basis by Origination Year
Loans originated in current fiscal year	114,007		621,685
Loans originated in fiscal year before current fiscal year	630,920		410,359
Loans originated two years before current fiscal year	409,821		175,456
Loans originated three years before current fiscal year	173,271		333,783
Loans originated four years before current fiscal year	290,200		313,124
Loans originated more than five years before current fiscal year	818,573		530,322
Revolving Loans Amortized Cost Basis	17,253		17,846
Revolving Loans Converted to Term	0		0
Total loans	2,454,045		2,402,575
Pass | Commercial and industrial
Term Loans Amortized Cost Basis by Origination Year
Loans originated in current fiscal year	56,776		282,781
Loans originated in fiscal year before current fiscal year	279,856		147,070
Loans originated two years before current fiscal year	142,925		56,880
Loans originated three years before current fiscal year	49,172		67,975
Loans originated four years before current fiscal year	60,597		83,223
Loans originated more than five years before current fiscal year	169,281		99,367
Revolving Loans Amortized Cost Basis	699,241		648,956
Revolving Loans Converted to Term	0		0
Total loans	1,457,848		1,386,252
Pass | Residential real estate | Residential real estate
Term Loans Amortized Cost Basis by Origination Year
Loans originated in current fiscal year	136,527		997,981
Loans originated in fiscal year before current fiscal year	1,008,711		280,308
Loans originated two years before current fiscal year	276,189		96,548
Loans originated three years before current fiscal year	94,488		70,845
Loans originated four years before current fiscal year	71,237		138,894
Loans originated more than five years before current fiscal year	862,274		713,744
Revolving Loans Amortized Cost Basis	161		165
Revolving Loans Converted to Term	0		0
Total loans	2,449,587		2,298,485
Special Mention | Performing
Term Loans Amortized Cost Basis by Origination Year
Total loans	55,751		68,127
Special Mention | Construction and commercial multifamily | Construction
Term Loans Amortized Cost Basis by Origination Year
Loans originated in current fiscal year	0		0
Loans originated in fiscal year before current fiscal year	0		0
Loans originated two years before current fiscal year	0		0
Loans originated three years before current fiscal year	0		0
Loans originated four years before current fiscal year	0		0
Loans originated more than five years before current fiscal year	1		0
Revolving Loans Amortized Cost Basis	0		0
Revolving Loans Converted to Term	0		0
Total loans	1		0
Special Mention | Construction and commercial multifamily | Commercial multifamily
Term Loans Amortized Cost Basis by Origination Year
Loans originated in current fiscal year	0		0
Loans originated in fiscal year before current fiscal year	0		0
Loans originated two years before current fiscal year	0		2,628
Loans originated three years before current fiscal year	0		0
Loans originated four years before current fiscal year	0		0
Loans originated more than five years before current fiscal year	0		0
Revolving Loans Amortized Cost Basis	0		0
Revolving Loans Converted to Term	0		0
Total loans	0		2,628
Special Mention | Commercial real estate | Commercial real estate owner occupied
Term Loans Amortized Cost Basis by Origination Year
Loans originated in current fiscal year	0		0
Loans originated in fiscal year before current fiscal year	4,281		0
Loans originated two years before current fiscal year	0		387
Loans originated three years before current fiscal year	387		0
Loans originated four years before current fiscal year	3,855		0
Loans originated more than five years before current fiscal year	0		0
Revolving Loans Amortized Cost Basis	0		0
Revolving Loans Converted to Term	0		0
Total loans	8,523		387
Special Mention | Commercial real estate | Commercial real estate non-owner occupied
Term Loans Amortized Cost Basis by Origination Year
Loans originated in current fiscal year	0		0
Loans originated in fiscal year before current fiscal year	0		0
Loans originated two years before current fiscal year	0		0
Loans originated three years before current fiscal year	0		0
Loans originated four years before current fiscal year	7,669		20,000
Loans originated more than five years before current fiscal year	23,821		18,462
Revolving Loans Amortized Cost Basis	0		0
Revolving Loans Converted to Term	0		0
Total loans	31,490		38,462
Special Mention | Commercial and industrial
Term Loans Amortized Cost Basis by Origination Year
Loans originated in current fiscal year	175		0
Loans originated in fiscal year before current fiscal year	0		5,811
Loans originated two years before current fiscal year	1,210		1,290
Loans originated three years before current fiscal year	1,290		1,332
Loans originated four years before current fiscal year	2,597		11,502
Loans originated more than five years before current fiscal year	1,805		912
Revolving Loans Amortized Cost Basis	6,342		2,632
Revolving Loans Converted to Term	0		0
Total loans	13,419		23,479
Special Mention | Residential real estate | Residential real estate
Term Loans Amortized Cost Basis by Origination Year
Loans originated in current fiscal year	0		0
Loans originated in fiscal year before current fiscal year	43		364
Loans originated two years before current fiscal year	371		0
Loans originated three years before current fiscal year	0		861
Loans originated four years before current fiscal year	0		202
Loans originated more than five years before current fiscal year	694		707
Revolving Loans Amortized Cost Basis	0		0
Revolving Loans Converted to Term	0		0
Total loans	1,108		2,134
Substandard | Performing
Term Loans Amortized Cost Basis by Origination Year
Total loans	99,551		88,665
Substandard | Construction and commercial multifamily | Construction
Term Loans Amortized Cost Basis by Origination Year
Loans originated in current fiscal year	0		0
Loans originated in fiscal year before current fiscal year	0		0
Loans originated two years before current fiscal year	0		0
Loans originated three years before current fiscal year	0		0
Loans originated four years before current fiscal year	0		0
Loans originated more than five years before current fiscal year	0		0
Revolving Loans Amortized Cost Basis	0		0
Revolving Loans Converted to Term	0		0
Total loans	0		0
Substandard | Construction and commercial multifamily | Commercial multifamily
Term Loans Amortized Cost Basis by Origination Year
Loans originated in current fiscal year	0		0
Loans originated in fiscal year before current fiscal year	0		0
Loans originated two years before current fiscal year	0		0
Loans originated three years before current fiscal year	2,609		0
Loans originated four years before current fiscal year	0		5,512
Loans originated more than five years before current fiscal year	5,497		0
Revolving Loans Amortized Cost Basis	0		0
Revolving Loans Converted to Term	0		0
Total loans	8,106		5,512
Substandard | Commercial real estate | Commercial real estate owner occupied
Term Loans Amortized Cost Basis by Origination Year
Loans originated in current fiscal year	0		1,003
Loans originated in fiscal year before current fiscal year	972		122
Loans originated two years before current fiscal year	122		31
Loans originated three years before current fiscal year	493		282
Loans originated four years before current fiscal year	241		1,056
Loans originated more than five years before current fiscal year	6,456		4,989
Revolving Loans Amortized Cost Basis	0		0
Revolving Loans Converted to Term	0		0
Total loans	8,284		7,483
Substandard | Commercial real estate | Commercial real estate non-owner occupied
Term Loans Amortized Cost Basis by Origination Year
Loans originated in current fiscal year	0		0
Loans originated in fiscal year before current fiscal year	0		0
Loans originated two years before current fiscal year	660		7,237
Loans originated three years before current fiscal year	7,137		13,623
Loans originated four years before current fiscal year	5,890		15,610
Loans originated more than five years before current fiscal year	32,724		18,730
Revolving Loans Amortized Cost Basis	0		0
Revolving Loans Converted to Term	0		0
Total loans	46,411		55,200
Substandard | Commercial and industrial
Term Loans Amortized Cost Basis by Origination Year
Loans originated in current fiscal year	0		204
Loans originated in fiscal year before current fiscal year	549		496
Loans originated two years before current fiscal year	5,425		3,640
Loans originated three years before current fiscal year	3,566		8,139
Loans originated four years before current fiscal year	7,496		1,981
Loans originated more than five years before current fiscal year	14,571		2,799
Revolving Loans Amortized Cost Basis	10,332		10,581
Revolving Loans Converted to Term	0		0
Total loans	41,939		27,840
Substandard | Residential real estate | Residential real estate
Term Loans Amortized Cost Basis by Origination Year
Loans originated in current fiscal year	0		0
Loans originated in fiscal year before current fiscal year	159		284
Loans originated two years before current fiscal year	331		448
Loans originated three years before current fiscal year	434		267
Loans originated four years before current fiscal year	1,485		1,857
Loans originated more than five years before current fiscal year	10,877		8,972
Revolving Loans Amortized Cost Basis	0		0
Revolving Loans Converted to Term	0		0
Total loans	13,286		11,828
Doubtful | Commercial and industrial
Term Loans Amortized Cost Basis by Origination Year
Loans originated in current fiscal year	0		0
Loans originated in fiscal year before current fiscal year	0		0
Loans originated two years before current fiscal year	0		0
Loans originated three years before current fiscal year	0		0
Loans originated four years before current fiscal year	0		0
Loans originated more than five years before current fiscal year	51		56
Revolving Loans Amortized Cost Basis	4,299		7,609
Revolving Loans Converted to Term	0		0
Total loans	$ 4,350		$ 7,665

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