ALLOWANCE FOR CREDIT LOSSES AND CREDIT QUALITY INFORMATION - Schedule of Credit Quality Indicators (Details) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans	$ 12,980,281	$ 12,143,268	$ 12,766,518
Total charge offs	11,859	13,666
Commercial | Commercial and industrial
Financing Receivable, Credit Quality Indicator [Line Items]
Year one, originated, current fiscal year	221,928		797,050
Year two, originated, fiscal year before current fiscal year	819,383		556,818
Year three, originated, two years before current fiscal year	499,883		189,098
Year four, originated, three years before current fiscal year	173,272		221,838
Year five, originated, four years before current fiscal year	197,141		113,303
Prior	421,420		402,258
Revolving loans amortized cost basis	9,218		8,785
Revolving loans converted to term	249,616		250,920
Total Loans	2,591,861	2,568,742	2,540,070
Year one, current fiscal year charge offs	0		0
Year two, current fiscal year charge offs	0		568
Year three, current fiscal year charge offs	109		5,214
Year four, current fiscal year charge offs	143		1,747
Year five, current fiscal year charge offs	156		7,567
Prior year charge offs	68		11,557
Revolving loans amortized cost basis charge offs	0		0
Revolving loans converted to term gross charge offs	0		0
Total charge offs	476	6,563	26,653
Commercial | Commercial and industrial | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Year one, originated, current fiscal year	176,858		716,848
Year two, originated, fiscal year before current fiscal year	762,244		490,934
Year three, originated, two years before current fiscal year	450,439		180,343
Year four, originated, three years before current fiscal year	163,071		211,151
Year five, originated, four years before current fiscal year	191,450		90,522
Prior	385,731		383,609
Revolving loans amortized cost basis	9,218		8,785
Revolving loans converted to term	233,340		237,786
Total Loans	2,372,351		2,319,978
Commercial | Commercial and industrial | Special mention
Financing Receivable, Credit Quality Indicator [Line Items]
Year one, originated, current fiscal year	1,662		7,209
Year two, originated, fiscal year before current fiscal year	4,485		11,860
Year three, originated, two years before current fiscal year	8,443		2,804
Year four, originated, three years before current fiscal year	3,228		463
Year five, originated, four years before current fiscal year	218		735
Prior	2,526		743
Revolving loans amortized cost basis	0		0
Revolving loans converted to term	1,589		1,649
Total Loans	22,151		25,463
Commercial | Commercial and industrial | Substandard or Lower
Financing Receivable, Credit Quality Indicator [Line Items]
Year one, originated, current fiscal year	43,408		72,993
Year two, originated, fiscal year before current fiscal year	52,654		54,024
Year three, originated, two years before current fiscal year	41,001		5,951
Year four, originated, three years before current fiscal year	6,973		10,224
Year five, originated, four years before current fiscal year	5,473		22,046
Prior	33,163		17,906
Revolving loans amortized cost basis	0		0
Revolving loans converted to term	14,687		11,485
Total Loans	197,359		194,629
Commercial | Owner-occupied commercial
Financing Receivable, Credit Quality Indicator [Line Items]
Year one, originated, current fiscal year	59,845		350,789
Year two, originated, fiscal year before current fiscal year	345,238		286,875
Year three, originated, two years before current fiscal year	263,769		267,790
Year four, originated, three years before current fiscal year	256,337		220,257
Year five, originated, four years before current fiscal year	212,968		213,174
Prior	542,063		354,690
Revolving loans amortized cost basis	0		0
Revolving loans converted to term	202,656		192,512
Total Loans	1,882,876	1,846,661	1,886,087
Year one, current fiscal year charge offs	0		0
Year two, current fiscal year charge offs	0		0
Year three, current fiscal year charge offs	0		0
Year four, current fiscal year charge offs	0		0
Year five, current fiscal year charge offs	0		184
Prior year charge offs	0		0
Revolving loans amortized cost basis charge offs	0		0
Revolving loans converted to term gross charge offs	0		0
Total charge offs	0	0	184
Commercial | Owner-occupied commercial | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Year one, originated, current fiscal year	59,845		346,908
Year two, originated, fiscal year before current fiscal year	340,919		264,895
Year three, originated, two years before current fiscal year	242,775		251,262
Year four, originated, three years before current fiscal year	239,418		212,365
Year five, originated, four years before current fiscal year	206,450		194,153
Prior	473,877		313,801
Revolving loans amortized cost basis	0		0
Revolving loans converted to term	188,984		178,150
Total Loans	1,752,268		1,761,534
Commercial | Owner-occupied commercial | Special mention
Financing Receivable, Credit Quality Indicator [Line Items]
Year one, originated, current fiscal year	0		2,885
Year two, originated, fiscal year before current fiscal year	3,123		3,115
Year three, originated, two years before current fiscal year	3,037		5,419
Year four, originated, three years before current fiscal year	5,369		1,105
Year five, originated, four years before current fiscal year	1,088		11,002
Prior	22,524		5,559
Revolving loans amortized cost basis	0		0
Revolving loans converted to term	1,571		1,393
Total Loans	36,712		30,478
Commercial | Owner-occupied commercial | Substandard or Lower
Financing Receivable, Credit Quality Indicator [Line Items]
Year one, originated, current fiscal year	0		996
Year two, originated, fiscal year before current fiscal year	1,196		18,865
Year three, originated, two years before current fiscal year	17,957		11,109
Year four, originated, three years before current fiscal year	11,550		6,787
Year five, originated, four years before current fiscal year	5,430		8,019
Prior	45,662		35,330
Revolving loans amortized cost basis	0		0
Revolving loans converted to term	12,101		12,969
Total Loans	93,896		94,075
Commercial | Commercial mortgages
Financing Receivable, Credit Quality Indicator [Line Items]
Year one, originated, current fiscal year	131,704		877,631
Year two, originated, fiscal year before current fiscal year	839,148		466,048
Year three, originated, two years before current fiscal year	462,767		527,394
Year four, originated, three years before current fiscal year	490,430		481,028
Year five, originated, four years before current fiscal year	454,649		511,873
Prior	1,087,463		631,660
Revolving loans amortized cost basis	0		0
Revolving loans converted to term	410,695		305,546
Total Loans	3,876,856	3,473,083	3,801,180
Year one, current fiscal year charge offs	0		0
Year two, current fiscal year charge offs	25		83
Year three, current fiscal year charge offs	0		0
Year four, current fiscal year charge offs	0		217
Year five, current fiscal year charge offs	0		0
Prior year charge offs	0		0
Revolving loans amortized cost basis charge offs	0		0
Revolving loans converted to term gross charge offs	0		0
Total charge offs	25	0	300
Commercial | Commercial mortgages | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Year one, originated, current fiscal year	126,380		847,137
Year two, originated, fiscal year before current fiscal year	806,552		464,895
Year three, originated, two years before current fiscal year	461,038		526,280
Year four, originated, three years before current fiscal year	488,314		465,354
Year five, originated, four years before current fiscal year	431,554		486,855
Prior	1,051,552		619,448
Revolving loans amortized cost basis	0		0
Revolving loans converted to term	395,234		290,083
Total Loans	3,760,624		3,700,052
Commercial | Commercial mortgages | Special mention
Financing Receivable, Credit Quality Indicator [Line Items]
Year one, originated, current fiscal year	5,324		20,632
Year two, originated, fiscal year before current fiscal year	22,437		0
Year three, originated, two years before current fiscal year	576		67
Year four, originated, three years before current fiscal year	1,107		1,837
Year five, originated, four years before current fiscal year	1,810		10,666
Prior	5,117		0
Revolving loans amortized cost basis	0		0
Revolving loans converted to term	0		0
Total Loans	36,371		33,202
Commercial | Commercial mortgages | Substandard or Lower
Financing Receivable, Credit Quality Indicator [Line Items]
Year one, originated, current fiscal year	0		9,862
Year two, originated, fiscal year before current fiscal year	10,159		1,153
Year three, originated, two years before current fiscal year	1,153		1,047
Year four, originated, three years before current fiscal year	1,009		13,837
Year five, originated, four years before current fiscal year	21,285		14,352
Prior	30,794		12,212
Revolving loans amortized cost basis	0		0
Revolving loans converted to term	15,461		15,463
Total Loans	79,861		67,926
Commercial | Construction
Financing Receivable, Credit Quality Indicator [Line Items]
Year one, originated, current fiscal year	89,107		463,471
Year two, originated, fiscal year before current fiscal year	408,579		339,727
Year three, originated, two years before current fiscal year	363,893		122,868
Year four, originated, three years before current fiscal year	78,913		11,628
Year five, originated, four years before current fiscal year	2,704		2,522
Prior	2,240		7,016
Revolving loans amortized cost basis	0		0
Revolving loans converted to term	110,913		88,298
Total Loans	1,056,349	1,023,711	1,035,530
Year one, current fiscal year charge offs	0		0
Year two, current fiscal year charge offs	0		0
Year three, current fiscal year charge offs	0		794
Year four, current fiscal year charge offs	0		0
Year five, current fiscal year charge offs	0		0
Prior year charge offs	0		0
Revolving loans amortized cost basis charge offs	0		0
Revolving loans converted to term gross charge offs	0		0
Total charge offs	0	0	794
Commercial | Construction | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Year one, originated, current fiscal year	81,959		429,055
Year two, originated, fiscal year before current fiscal year	357,747		319,958
Year three, originated, two years before current fiscal year	344,241		111,333
Year four, originated, three years before current fiscal year	75,655		3,030
Year five, originated, four years before current fiscal year	2,704		388
Prior	2,088		7,016
Revolving loans amortized cost basis	0		0
Revolving loans converted to term	110,361		87,741
Total Loans	974,755		958,521
Commercial | Construction | Special mention
Financing Receivable, Credit Quality Indicator [Line Items]
Year one, originated, current fiscal year	7,148		28,718
Year two, originated, fiscal year before current fiscal year	35,402		19,769
Year three, originated, two years before current fiscal year	5,257		8,227
Year four, originated, three years before current fiscal year	0		0
Year five, originated, four years before current fiscal year	0		0
Prior	0		0
Revolving loans amortized cost basis	0		0
Revolving loans converted to term	0		0
Total Loans	47,807		56,714
Commercial | Construction | Substandard or Lower
Financing Receivable, Credit Quality Indicator [Line Items]
Year one, originated, current fiscal year	0		5,698
Year two, originated, fiscal year before current fiscal year	15,430		0
Year three, originated, two years before current fiscal year	14,395		3,308
Year four, originated, three years before current fiscal year	3,258		8,598
Year five, originated, four years before current fiscal year	0		2,134
Prior	152		0
Revolving loans amortized cost basis	0		0
Revolving loans converted to term	552		557
Total Loans	33,787		20,295
Commercial | Commercial Small Business Leases
Financing Receivable, Credit Quality Indicator [Line Items]
Year one, originated, current fiscal year	68,659		260,348
Year two, originated, fiscal year before current fiscal year	244,037		191,746
Year three, originated, two years before current fiscal year	174,415		103,428
Year four, originated, three years before current fiscal year	91,029		40,697
Year five, originated, four years before current fiscal year	33,350		15,411
Prior	22,313		11,992
Revolving loans amortized cost basis	0		0
Revolving loans converted to term	0		0
Total Loans	633,803	576,584	623,622
Year one, current fiscal year charge offs	0		1,528
Year two, current fiscal year charge offs	1,347		7,250
Year three, current fiscal year charge offs	1,656		4,447
Year four, current fiscal year charge offs	1,253		1,454
Year five, current fiscal year charge offs	429		735
Prior year charge offs	167		227
Revolving loans amortized cost basis charge offs	0		0
Revolving loans converted to term gross charge offs	0		0
Total charge offs	4,852	2,899	15,641
Commercial | Commercial Small Business Leases | Performing
Financing Receivable, Credit Quality Indicator [Line Items]
Year one, originated, current fiscal year	68,659		260,348
Year two, originated, fiscal year before current fiscal year	244,037		191,746
Year three, originated, two years before current fiscal year	174,415		103,428
Year four, originated, three years before current fiscal year	91,029		40,697
Year five, originated, four years before current fiscal year	33,350		15,411
Prior	22,313		11,992
Revolving loans amortized cost basis	0		0
Revolving loans converted to term	0		0
Total Loans	633,803		623,622
Commercial | Commercial Small Business Leases | Nonperforming
Financing Receivable, Credit Quality Indicator [Line Items]
Year one, originated, current fiscal year	0		0
Year two, originated, fiscal year before current fiscal year	0		0
Year three, originated, two years before current fiscal year	0		0
Year four, originated, three years before current fiscal year	0		0
Year five, originated, four years before current fiscal year	0		0
Prior	0		0
Revolving loans amortized cost basis	0		0
Revolving loans converted to term	0		0
Total Loans	0		0
Residential
Financing Receivable, Credit Quality Indicator [Line Items]
Year one, originated, current fiscal year	23,516		188,644
Year two, originated, fiscal year before current fiscal year	188,880		67,528
Year three, originated, two years before current fiscal year	67,207		103,695
Year four, originated, three years before current fiscal year	100,270		57,759
Year five, originated, four years before current fiscal year	57,314		34,750
Prior	435,478		415,519
Revolving loans amortized cost basis	0		0
Revolving loans converted to term	0		0
Total Loans	872,665	786,060	867,895
Year one, current fiscal year charge offs	0		33
Year two, current fiscal year charge offs	0		0
Year three, current fiscal year charge offs	0		0
Year four, current fiscal year charge offs	0		0
Year five, current fiscal year charge offs	0		0
Prior year charge offs	50		8
Revolving loans amortized cost basis charge offs	0		0
Revolving loans converted to term gross charge offs	0		0
Total charge offs	50	0	41
Residential | Performing
Financing Receivable, Credit Quality Indicator [Line Items]
Year one, originated, current fiscal year	23,516		188,644
Year two, originated, fiscal year before current fiscal year	188,880		67,358
Year three, originated, two years before current fiscal year	67,040		102,982
Year four, originated, three years before current fiscal year	96,732		57,273
Year five, originated, four years before current fiscal year	56,831		33,499
Prior	431,193		412,099
Revolving loans amortized cost basis	0		0
Revolving loans converted to term	0		0
Total Loans	864,192		861,855
Residential | Nonperforming
Financing Receivable, Credit Quality Indicator [Line Items]
Year one, originated, current fiscal year	0		0
Year two, originated, fiscal year before current fiscal year	0		170
Year three, originated, two years before current fiscal year	167		713
Year four, originated, three years before current fiscal year	3,538		486
Year five, originated, four years before current fiscal year	483		1,251
Prior	4,285		3,420
Revolving loans amortized cost basis	0		0
Revolving loans converted to term	0		0
Total Loans	8,473		6,040
Consumer
Financing Receivable, Credit Quality Indicator [Line Items]
Year one, originated, current fiscal year	54,669		391,580
Year two, originated, fiscal year before current fiscal year	423,471		568,919
Year three, originated, two years before current fiscal year	538,009		154,065
Year four, originated, three years before current fiscal year	144,852		104,600
Year five, originated, four years before current fiscal year	100,293		45,172
Prior	296,127		245,879
Revolving loans amortized cost basis	502,621		496,025
Revolving loans converted to term	5,829		5,894
Total Loans	2,065,871	1,868,427	2,012,134
Year one, current fiscal year charge offs	286		1,790
Year two, current fiscal year charge offs	677		15,227
Year three, current fiscal year charge offs	4,239		4,411
Year four, current fiscal year charge offs	774		313
Year five, current fiscal year charge offs	380		198
Prior year charge offs	100		455
Revolving loans amortized cost basis charge offs	0		0
Revolving loans converted to term gross charge offs	0		0
Total charge offs	6,456	$ 4,204	22,394
Consumer | Performing
Financing Receivable, Credit Quality Indicator [Line Items]
Year one, originated, current fiscal year	54,669		391,580
Year two, originated, fiscal year before current fiscal year	423,471		568,919
Year three, originated, two years before current fiscal year	538,009		153,930
Year four, originated, three years before current fiscal year	144,717		104,248
Year five, originated, four years before current fiscal year	99,941		44,996
Prior	296,127		245,849
Revolving loans amortized cost basis	500,904		494,663
Revolving loans converted to term	5,329		5,662
Total Loans	2,063,167		2,009,847
Consumer | Nonperforming
Financing Receivable, Credit Quality Indicator [Line Items]
Year one, originated, current fiscal year	0		0
Year two, originated, fiscal year before current fiscal year	0		0
Year three, originated, two years before current fiscal year	0		135
Year four, originated, three years before current fiscal year	135		352
Year five, originated, four years before current fiscal year	352		176
Prior	0		30
Revolving loans amortized cost basis	1,717		1,362
Revolving loans converted to term	500		232
Total Loans	$ 2,704		$ 2,287