ALLOWANCE FOR CREDIT LOSSES AND CREDIT QUALITY INFORMATION - Credit Quality Indicators (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022	Dec. 31, 2022
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans	$ 12,336,834	$ 11,480,118	$ 12,336,834	$ 11,480,118	$ 11,909,436
Total charge offs	15,874	3,967	29,540	8,818
Commercial | Commercial and industrial
Financing Receivable, Credit Quality Indicator [Line Items]
Year one, originated, current fiscal year	559,784		559,784		1,184,837
Year two, originated, fiscal year before current fiscal year	1,016,621		1,016,621		545,612
Year three, originated, two years before current fiscal year	383,943		383,943		401,753
Year four, originated, three years before current fiscal year	321,610		321,610		258,295
Year five, originated, four years before current fiscal year	180,544		180,544		191,193
Prior	479,142		479,142		284,366
Revolving loans amortized cost basis	8,277		8,277		8,099
Revolving loans converted to term	263,865		263,865		260,171
Total Loans	3,213,786	3,107,740	3,213,786	3,107,740	3,134,326
Year one, current fiscal year charge offs			82
Year two, current fiscal year charge offs			3,485
Year three, current fiscal year charge offs			5,595
Year four, current fiscal year charge offs			1,184
Year five, current fiscal year charge offs			3,171
Prior year charge offs			6,304
Revolving loans amortized cost basis charge offs			0
Revolving loans converted to term gross charge offs			0
Total charge offs	10,359	2,549	19,821	6,188
Commercial | Commercial and industrial | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Year one, originated, current fiscal year	497,648		497,648		1,123,803
Year two, originated, fiscal year before current fiscal year	971,490		971,490		501,761
Year three, originated, two years before current fiscal year	368,237		368,237		387,225
Year four, originated, three years before current fiscal year	310,758		310,758		211,310
Year five, originated, four years before current fiscal year	143,004		143,004		153,713
Prior	458,737		458,737		276,588
Revolving loans amortized cost basis	8,277		8,277		8,099
Revolving loans converted to term	246,341		246,341		250,486
Total Loans	3,004,492		3,004,492		2,912,985
Commercial | Commercial and industrial | Special mention
Financing Receivable, Credit Quality Indicator [Line Items]
Year one, originated, current fiscal year	7,658		7,658		28,672
Year two, originated, fiscal year before current fiscal year	27,040		27,040		27,689
Year three, originated, two years before current fiscal year	3,594		3,594		7,585
Year four, originated, three years before current fiscal year	768		768		9,451
Year five, originated, four years before current fiscal year	601		601		347
Prior	522		522		1,010
Revolving loans amortized cost basis	0		0		0
Revolving loans converted to term	2,455		2,455		2,596
Total Loans	42,638		42,638		77,350
Commercial | Commercial and industrial | Substandard or Lower
Financing Receivable, Credit Quality Indicator [Line Items]
Year one, originated, current fiscal year	54,478		54,478		32,362
Year two, originated, fiscal year before current fiscal year	18,091		18,091		16,162
Year three, originated, two years before current fiscal year	12,112		12,112		6,943
Year four, originated, three years before current fiscal year	10,084		10,084		37,534
Year five, originated, four years before current fiscal year	36,939		36,939		37,133
Prior	19,883		19,883		6,768
Revolving loans amortized cost basis	0		0		0
Revolving loans converted to term	15,069		15,069		7,089
Total Loans	166,656		166,656		143,991
Commercial | Owner-occupied commercial
Financing Receivable, Credit Quality Indicator [Line Items]
Year one, originated, current fiscal year	176,474		176,474		301,255
Year two, originated, fiscal year before current fiscal year	298,685		298,685		326,888
Year three, originated, two years before current fiscal year	304,053		304,053		281,461
Year four, originated, three years before current fiscal year	231,199		231,199		231,118
Year five, originated, four years before current fiscal year	215,196		215,196		118,254
Prior	460,314		460,314		400,897
Revolving loans amortized cost basis	0		0		0
Revolving loans converted to term	197,134		197,134		149,709
Total Loans	1,883,055	1,823,229	1,883,055	1,823,229	1,809,582
Year one, current fiscal year charge offs			0
Year two, current fiscal year charge offs			0
Year three, current fiscal year charge offs			0
Year four, current fiscal year charge offs			0
Year five, current fiscal year charge offs			184
Prior year charge offs			0
Revolving loans amortized cost basis charge offs			0
Revolving loans converted to term gross charge offs			0
Total charge offs	184	0	184	179
Commercial | Owner-occupied commercial | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Year one, originated, current fiscal year	164,939		164,939		280,898
Year two, originated, fiscal year before current fiscal year	279,655		279,655		325,388
Year three, originated, two years before current fiscal year	294,797		294,797		258,177
Year four, originated, three years before current fiscal year	216,730		216,730		226,717
Year five, originated, four years before current fiscal year	203,500		203,500		106,390
Prior	411,651		411,651		363,420
Revolving loans amortized cost basis	0		0		0
Revolving loans converted to term	177,666		177,666		132,942
Total Loans	1,748,938		1,748,938		1,693,932
Commercial | Owner-occupied commercial | Special mention
Financing Receivable, Credit Quality Indicator [Line Items]
Year one, originated, current fiscal year	2,929		2,929		17,376
Year two, originated, fiscal year before current fiscal year	652		652		0
Year three, originated, two years before current fiscal year	5,436		5,436		0
Year four, originated, three years before current fiscal year	5,931		5,931		0
Year five, originated, four years before current fiscal year	8,824		8,824		0
Prior	5,747		5,747		2,166
Revolving loans amortized cost basis	0		0		0
Revolving loans converted to term	1,209		1,209		3,351
Total Loans	30,728		30,728		22,893
Commercial | Owner-occupied commercial | Substandard or Lower
Financing Receivable, Credit Quality Indicator [Line Items]
Year one, originated, current fiscal year	8,606		8,606		2,981
Year two, originated, fiscal year before current fiscal year	18,378		18,378		1,500
Year three, originated, two years before current fiscal year	3,820		3,820		23,284
Year four, originated, three years before current fiscal year	8,538		8,538		4,401
Year five, originated, four years before current fiscal year	2,872		2,872		11,864
Prior	42,916		42,916		35,311
Revolving loans amortized cost basis	0		0		0
Revolving loans converted to term	18,259		18,259		13,416
Total Loans	103,389		103,389		92,757
Commercial | Commercial mortgages
Financing Receivable, Credit Quality Indicator [Line Items]
Year one, originated, current fiscal year	399,547		399,547		520,094
Year two, originated, fiscal year before current fiscal year	526,314		526,314		601,511
Year three, originated, two years before current fiscal year	584,932		584,932		542,712
Year four, originated, three years before current fiscal year	515,240		515,240		558,818
Year five, originated, four years before current fiscal year	527,599		527,599		289,583
Prior	745,311		745,311		627,247
Revolving loans amortized cost basis	0		0		0
Revolving loans converted to term	253,857		253,857		211,119
Total Loans	3,552,800	3,321,654	3,552,800	3,321,654	3,351,084
Year one, current fiscal year charge offs			0
Year two, current fiscal year charge offs			0
Year three, current fiscal year charge offs			0
Year four, current fiscal year charge offs			0
Year five, current fiscal year charge offs			0
Prior year charge offs			0
Revolving loans amortized cost basis charge offs			0
Revolving loans converted to term gross charge offs			0
Total charge offs	0	0	0	37
Commercial | Commercial mortgages | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Year one, originated, current fiscal year	380,749		380,749		516,783
Year two, originated, fiscal year before current fiscal year	509,272		509,272		600,226
Year three, originated, two years before current fiscal year	580,119		580,119		526,312
Year four, originated, three years before current fiscal year	502,722		502,722		549,788
Year five, originated, four years before current fiscal year	519,953		519,953		276,414
Prior	735,252		735,252		594,024
Revolving loans amortized cost basis	0		0		0
Revolving loans converted to term	253,328		253,328		210,550
Total Loans	3,481,395		3,481,395		3,274,097
Commercial | Commercial mortgages | Special mention
Financing Receivable, Credit Quality Indicator [Line Items]
Year one, originated, current fiscal year	9,328		9,328		1,450
Year two, originated, fiscal year before current fiscal year	0		0		75
Year three, originated, two years before current fiscal year	71		71		3,848
Year four, originated, three years before current fiscal year	2,438		2,438		6,121
Year five, originated, four years before current fiscal year	6,032		6,032		9,596
Prior	5,367		5,367		32,014
Revolving loans amortized cost basis	0		0		0
Revolving loans converted to term	301		301		0
Total Loans	23,537		23,537		53,104
Commercial | Commercial mortgages | Substandard or Lower
Financing Receivable, Credit Quality Indicator [Line Items]
Year one, originated, current fiscal year	9,470		9,470		1,861
Year two, originated, fiscal year before current fiscal year	17,042		17,042		1,210
Year three, originated, two years before current fiscal year	4,742		4,742		12,552
Year four, originated, three years before current fiscal year	10,080		10,080		2,909
Year five, originated, four years before current fiscal year	1,614		1,614		3,573
Prior	4,692		4,692		1,209
Revolving loans amortized cost basis	0		0		0
Revolving loans converted to term	228		228		569
Total Loans	47,868		47,868		23,883
Commercial | Construction
Financing Receivable, Credit Quality Indicator [Line Items]
Year one, originated, current fiscal year	290,686		290,686		448,581
Year two, originated, fiscal year before current fiscal year	378,299		378,299		303,819
Year three, originated, two years before current fiscal year	206,930		206,930		124,597
Year four, originated, three years before current fiscal year	31,039		31,039		9,502
Year five, originated, four years before current fiscal year	2,609		2,609		26,553
Prior	8,118		8,118		7,539
Revolving loans amortized cost basis	0		0		0
Revolving loans converted to term	37,543		37,543		123,458
Total Loans	955,224	934,324	955,224	934,324	1,044,049
Year one, current fiscal year charge offs			0
Year two, current fiscal year charge offs			0
Year three, current fiscal year charge offs			0
Year four, current fiscal year charge offs			0
Year five, current fiscal year charge offs			0
Prior year charge offs			0
Revolving loans amortized cost basis charge offs			0
Revolving loans converted to term gross charge offs			0
Total charge offs	0	0	0	0
Commercial | Construction | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Year one, originated, current fiscal year	277,159		277,159		448,581
Year two, originated, fiscal year before current fiscal year	378,299		378,299		299,619
Year three, originated, two years before current fiscal year	206,930		206,930		115,667
Year four, originated, three years before current fiscal year	22,097		22,097		9,319
Year five, originated, four years before current fiscal year	2,441		2,441		26,553
Prior	8,118		8,118		7,539
Revolving loans amortized cost basis	0		0		0
Revolving loans converted to term	36,970		36,970		122,116
Total Loans	932,014		932,014		1,029,394
Commercial | Construction | Special mention
Financing Receivable, Credit Quality Indicator [Line Items]
Year one, originated, current fiscal year	13,527		13,527		0
Year two, originated, fiscal year before current fiscal year	0		0		0
Year three, originated, two years before current fiscal year	0		0		0
Year four, originated, three years before current fiscal year	0		0		0
Year five, originated, four years before current fiscal year	0		0		0
Prior	0		0		0
Revolving loans amortized cost basis	0		0		0
Revolving loans converted to term	0		0		581
Total Loans	13,527		13,527		581
Commercial | Construction | Substandard or Lower
Financing Receivable, Credit Quality Indicator [Line Items]
Year one, originated, current fiscal year	0		0		0
Year two, originated, fiscal year before current fiscal year	0		0		4,200
Year three, originated, two years before current fiscal year	0		0		8,930
Year four, originated, three years before current fiscal year	8,942		8,942		183
Year five, originated, four years before current fiscal year	168		168		0
Prior	0		0		0
Revolving loans amortized cost basis	0		0		0
Revolving loans converted to term	573		573		761
Total Loans	9,683		9,683		14,074
Residential
Financing Receivable, Credit Quality Indicator [Line Items]
Year one, originated, current fiscal year	104,143		104,143		64,500
Year two, originated, fiscal year before current fiscal year	70,338		70,338		111,237
Year three, originated, two years before current fiscal year	106,206		106,206		61,127
Year four, originated, three years before current fiscal year	59,249		59,249		37,117
Year five, originated, four years before current fiscal year	35,672		35,672		47,077
Prior	451,142		451,142		438,407
Revolving loans amortized cost basis	0		0		0
Revolving loans converted to term	0		0		0
Total Loans	826,750	770,575	826,750	770,575	759,465
Year one, current fiscal year charge offs			33
Year two, current fiscal year charge offs			0
Year three, current fiscal year charge offs			0
Year four, current fiscal year charge offs			0
Year five, current fiscal year charge offs			0
Prior year charge offs			0
Revolving loans amortized cost basis charge offs			0
Revolving loans converted to term gross charge offs			0
Total charge offs	33	0	33	186
Residential | Performing
Financing Receivable, Credit Quality Indicator [Line Items]
Year one, originated, current fiscal year	104,143		104,143		64,500
Year two, originated, fiscal year before current fiscal year	70,167		70,167		110,508
Year three, originated, two years before current fiscal year	105,199		105,199		60,625
Year four, originated, three years before current fiscal year	58,757		58,757		36,118
Year five, originated, four years before current fiscal year	34,406		34,406		45,859
Prior	447,587		447,587		434,175
Revolving loans amortized cost basis	0		0		0
Revolving loans converted to term	0		0		0
Total Loans	820,259		820,259		751,785
Residential | Nonperforming
Financing Receivable, Credit Quality Indicator [Line Items]
Year one, originated, current fiscal year	0		0		0
Year two, originated, fiscal year before current fiscal year	171		171		729
Year three, originated, two years before current fiscal year	1,007		1,007		502
Year four, originated, three years before current fiscal year	492		492		999
Year five, originated, four years before current fiscal year	1,266		1,266		1,218
Prior	3,555		3,555		4,232
Revolving loans amortized cost basis	0		0		0
Revolving loans converted to term	0		0		0
Total Loans	6,491		6,491		7,680
Consumer
Financing Receivable, Credit Quality Indicator [Line Items]
Year one, originated, current fiscal year	159,097		159,097		595,158
Year two, originated, fiscal year before current fiscal year	629,797		629,797		195,397
Year three, originated, two years before current fiscal year	174,387		174,387		126,806
Year four, originated, three years before current fiscal year	113,970		113,970		54,449
Year five, originated, four years before current fiscal year	49,271		49,271		220,518
Prior	251,167		251,167		71,478
Revolving loans amortized cost basis	522,680		522,680		541,563
Revolving loans converted to term	4,850		4,850		5,561
Total Loans	1,905,219	1,522,596	1,905,219	1,522,596	1,810,930
Year one, current fiscal year charge offs			482
Year two, current fiscal year charge offs			6,361
Year three, current fiscal year charge offs			2,122
Year four, current fiscal year charge offs			207
Year five, current fiscal year charge offs			99
Prior year charge offs			231
Revolving loans amortized cost basis charge offs			0
Revolving loans converted to term gross charge offs			0
Total charge offs	5,298	$ 1,418	9,502	$ 2,228
Consumer | Performing
Financing Receivable, Credit Quality Indicator [Line Items]
Year one, originated, current fiscal year	159,097		159,097		595,158
Year two, originated, fiscal year before current fiscal year	629,797		629,797		195,397
Year three, originated, two years before current fiscal year	174,387		174,387		126,456
Year four, originated, three years before current fiscal year	113,970		113,970		54,449
Year five, originated, four years before current fiscal year	49,228		49,228		220,039
Prior	250,979		250,979		71,478
Revolving loans amortized cost basis	521,054		521,054		540,308
Revolving loans converted to term	4,532		4,532		5,232
Total Loans	1,903,044		1,903,044		1,808,517
Consumer | Nonperforming
Financing Receivable, Credit Quality Indicator [Line Items]
Year one, originated, current fiscal year	0		0		0
Year two, originated, fiscal year before current fiscal year	0		0		0
Year three, originated, two years before current fiscal year	0		0		350
Year four, originated, three years before current fiscal year	0		0		0
Year five, originated, four years before current fiscal year	43		43		479
Prior	188		188		0
Revolving loans amortized cost basis	1,626		1,626		1,255
Revolving loans converted to term	318		318		329
Total Loans	$ 2,175		$ 2,175		$ 2,413