CREDIT QUALITY ASSESSMENT - Information about Credit Quality Indicator by Year of Origination (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]
Current year	$ 353,255		$ 1,245,085
Year one	1,132,101		2,958,596
Year two	2,964,521		2,375,873
Year three	2,305,753		1,175,656
Year four	1,106,848		870,390
Prior	2,549,494		1,776,440
Revolving Loans	952,312		964,949
Total loans	11,364,284		11,366,989
Current period gross charge-offs, Total	1,620	$ 171	2,614
Commercial investor real estate
Financing Receivable, Credit Quality Indicator [Line Items]
Current year	134,604		445,782
Year one	377,493		1,396,438
Year two	1,345,678		1,226,951
Year three	1,196,965		634,361
Year four	600,295		511,146
Prior	1,316,366		865,346
Revolving Loans	26,478		24,401
Total loans	4,997,879		5,104,425
Current period gross charge-offs, current year	0		0
Current period gross charge-offs, year one	0		0
Current period gross charge-offs, year two	0		0
Current period gross charge-offs, year three	1		0
Current period gross charge-offs, year four	0		0
Current period gross charge-offs, prior	0		0
Current period gross charge-offs, revolving	0		0
Current period gross charge-offs, Total	1		0
Commercial investor real estate | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Current year	109,352		405,740
Year one	361,098		1,395,973
Year two	1,345,217		1,195,708
Year three	1,168,206		634,361
Year four	599,290		511,146
Prior	1,294,814		848,958
Revolving Loans	26,478		23,653
Total loans	4,904,455		5,015,539
Commercial investor real estate | Special Mention
Financing Receivable, Credit Quality Indicator [Line Items]
Current year	861		9,250
Year one	6,229		0
Year two	0		316
Year three	723		0
Year four	1,005		0
Prior	7,148		1,978
Revolving Loans	0		0
Total loans	15,966		11,544
Commercial investor real estate | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Current year	24,391		30,792
Year one	10,166		465
Year two	461		30,927
Year three	28,036		0
Year four	0		0
Prior	14,404		14,410
Revolving Loans	0		748
Total loans	77,458		77,342
Commercial investor real estate | Doubtful
Financing Receivable, Credit Quality Indicator [Line Items]
Current year	0		0
Year one	0		0
Year two	0		0
Year three	0		0
Year four	0		0
Prior	0		0
Revolving Loans	0		0
Total loans	0		0
Commercial owner-occupied real estate
Financing Receivable, Credit Quality Indicator [Line Items]
Current year	35,074		139,040
Year one	124,507		364,951
Year two	358,306		321,310
Year three	314,985		239,979
Year four	237,255		243,278
Prior	665,342		441,056
Revolving Loans	5,644		5,621
Total loans	1,741,113		1,755,235
Current period gross charge-offs, current year	0		0
Current period gross charge-offs, year one	0		0
Current period gross charge-offs, year two	0		0
Current period gross charge-offs, year three	0		0
Current period gross charge-offs, year four	0		0
Current period gross charge-offs, prior	0		0
Current period gross charge-offs, revolving	0		0
Current period gross charge-offs, Total	0		0
Commercial owner-occupied real estate | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Current year	35,074		136,072
Year one	121,759		361,247
Year two	355,379		318,269
Year three	311,954		238,761
Year four	236,043		235,145
Prior	649,493		428,846
Revolving Loans	5,644		5,621
Total loans	1,715,346		1,723,961
Commercial owner-occupied real estate | Special Mention
Financing Receivable, Credit Quality Indicator [Line Items]
Current year	0		406
Year one	2,162		70
Year two	69		2,240
Year three	2,234		875
Year four	872		2,267
Prior	5,108		8,616
Revolving Loans	0		0
Total loans	10,445		14,474
Commercial owner-occupied real estate | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Current year	0		2,562
Year one	586		3,634
Year two	2,858		801
Year three	797		343
Year four	340		5,866
Prior	10,741		3,594
Revolving Loans	0		0
Total loans	15,322		16,800
Commercial owner-occupied real estate | Doubtful
Financing Receivable, Credit Quality Indicator [Line Items]
Current year	0		0
Year one	0		0
Year two	0		0
Year three	0		0
Year four	0		0
Prior	0		0
Revolving Loans	0		0
Total loans	0		0
Commercial AD&C
Financing Receivable, Credit Quality Indicator [Line Items]
Current year	93,033		335,934
Year one	328,011		289,301
Year two	357,299		178,889
Year three	172,284		28,954
Year four	5,429		0
Prior	0		0
Revolving Loans	134,203		155,889
Total loans	1,090,259		988,967
Current period gross charge-offs, current year	0		0
Current period gross charge-offs, year one	0		0
Current period gross charge-offs, year two	0		0
Current period gross charge-offs, year three	0		0
Current period gross charge-offs, year four	0		0
Current period gross charge-offs, prior	0		0
Current period gross charge-offs, revolving	0		0
Current period gross charge-offs, Total	0		0
Commercial AD&C | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Current year	92,911		334,918
Year one	327,688		288,732
Year two	356,865		178,889
Year three	172,284		28,954
Year four	5,429		0
Prior	0		0
Revolving Loans	133,678		155,889
Total loans	1,088,855		987,382
Commercial AD&C | Special Mention
Financing Receivable, Credit Quality Indicator [Line Items]
Current year	0		0
Year one	0		0
Year two	0		0
Year three	0		0
Year four	0		0
Prior	0		0
Revolving Loans	525		0
Total loans	525		0
Commercial AD&C | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Current year	122		1,016
Year one	323		569
Year two	434		0
Year three	0		0
Year four	0		0
Prior	0		0
Revolving Loans	0		0
Total loans	879		1,585
Commercial AD&C | Doubtful
Financing Receivable, Credit Quality Indicator [Line Items]
Current year	0		0
Year one	0		0
Year two	0		0
Year three	0		0
Year four	0		0
Prior	0		0
Revolving Loans	0		0
Total loans	0		0
Residential mortgage
Financing Receivable, Credit Quality Indicator [Line Items]
Current year	7,795		32,863
Year one	40,495		487,240
Year two	516,187		418,747
Year three	420,041		173,191
Year four	171,192		47,779
Prior	355,914		314,701
Revolving Loans	0		0
Total loans	1,511,624		1,474,521
Current period gross charge-offs, current year	0		0
Current period gross charge-offs, year one	0		0
Current period gross charge-offs, year two	0		43
Current period gross charge-offs, year three	0		0
Current period gross charge-offs, year four	0		10
Current period gross charge-offs, prior	0		107
Current period gross charge-offs, revolving	0		0
Current period gross charge-offs, Total	0		160
Residential mortgage | 660-850
Financing Receivable, Credit Quality Indicator [Line Items]
Current year	7,224		31,853
Year one	38,452		476,631
Year two	498,423		394,414
Year three	394,110		166,387
Year four	162,827		41,473
Prior	304,763		266,927
Revolving Loans	0		0
Total loans	1,405,799		1,377,685
Residential mortgage | 600-659
Financing Receivable, Credit Quality Indicator [Line Items]
Current year	293		781
Year one	613		7,022
Year two	15,375		18,284
Year three	17,473		2,009
Year four	4,305		1,882
Prior	24,462		24,040
Revolving Loans	0		0
Total loans	62,521		54,018
Residential mortgage | 540-599
Financing Receivable, Credit Quality Indicator [Line Items]
Current year	0		0
Year one	1,203		1,545
Year two	357		2,698
Year three	3,566		2,371
Year four	2,437		1,891
Prior	9,714		9,377
Revolving Loans	0		0
Total loans	17,277		17,882
Residential mortgage | less than 540
Financing Receivable, Credit Quality Indicator [Line Items]
Current year	278		229
Year one	227		2,042
Year two	2,032		3,351
Year three	4,892		2,424
Year four	1,623		2,533
Prior	16,975		14,357
Revolving Loans	0		0
Total loans	26,027		24,936
Residential construction
Financing Receivable, Credit Quality Indicator [Line Items]
Current year	2,353		24,059
Year one	25,939		68,773
Year two	44,607		23,216
Year three	19,872		3,978
Year four	3,456		150
Prior	1,458		1,243
Revolving Loans	0		0
Total loans	97,685		121,419
Current period gross charge-offs, current year	0		0
Current period gross charge-offs, year one	0		0
Current period gross charge-offs, year two	0		0
Current period gross charge-offs, year three	0		0
Current period gross charge-offs, year four	0		0
Current period gross charge-offs, prior	0		0
Current period gross charge-offs, revolving	0		0
Current period gross charge-offs, Total	0		0
Residential construction | 660-850
Financing Receivable, Credit Quality Indicator [Line Items]
Current year	1,768		21,975
Year one	25,593		68,273
Year two	42,790		21,897
Year three	19,872		2,478
Year four	1,956		150
Prior	1,458		0
Revolving Loans	0		0
Total loans	93,437		114,773
Residential construction | 600-659
Financing Receivable, Credit Quality Indicator [Line Items]
Current year	542		1,641
Year one	346		500
Year two	1,817		1,319
Year three	0		1,500
Year four	1,500		0
Prior	0		1,243
Revolving Loans	0		0
Total loans	4,205		6,203
Residential construction | 540-599
Financing Receivable, Credit Quality Indicator [Line Items]
Current year	43		443
Year one	0		0
Year two	0		0
Year three	0		0
Year four	0		0
Prior	0		0
Revolving Loans	0		0
Total loans	43		443
Residential construction | less than 540
Financing Receivable, Credit Quality Indicator [Line Items]
Current year	0		0
Year one	0		0
Year two	0		0
Year three	0		0
Year four	0		0
Prior	0		0
Revolving Loans	0		0
Total loans	0		0
Commercial Business
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans	9,338,843		9,353,507
Commercial Business | Commercial business
Financing Receivable, Credit Quality Indicator [Line Items]
Current year	78,887		254,338
Year one	223,063		346,152
Year two	336,995		204,481
Year three	179,424		94,152
Year four	88,089		65,378
Prior	175,486		119,926
Revolving Loans	427,648		420,453
Total loans	1,509,592		1,504,880
Current period gross charge-offs, current year	0		0
Current period gross charge-offs, year one	0		9
Current period gross charge-offs, year two	612		324
Current period gross charge-offs, year three	0		0
Current period gross charge-offs, year four	0		0
Current period gross charge-offs, prior	939		116
Current period gross charge-offs, revolving	0		0
Current period gross charge-offs, Total	1,551		449
Commercial Business | Commercial business | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Current year	78,623		247,081
Year one	217,077		344,034
Year two	335,793		202,020
Year three	176,699		92,198
Year four	86,378		62,413
Prior	171,698		118,061
Revolving Loans	418,680		410,856
Total loans	1,484,948		1,476,663
Commercial Business | Commercial business | Special Mention
Financing Receivable, Credit Quality Indicator [Line Items]
Current year	177		532
Year one	647		45
Year two	130		180
Year three	491		1,037
Year four	762		1,040
Prior	1,198		294
Revolving Loans	3,350		3,635
Total loans	6,755		6,763
Commercial Business | Commercial business | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Current year	87		6,725
Year one	5,339		2,073
Year two	1,072		2,281
Year three	2,234		917
Year four	949		1,925
Prior	2,590		1,571
Revolving Loans	5,618		5,962
Total loans	17,889		21,454
Commercial Business | Commercial business | Doubtful
Financing Receivable, Credit Quality Indicator [Line Items]
Current year	0		0
Year one	0		0
Year two	0		0
Year three	0		0
Year four	0		0
Prior	0		0
Revolving Loans	0		0
Total loans	0		0
Consumer
Financing Receivable, Credit Quality Indicator [Line Items]
Current year	1,509		13,069
Year one	12,593		5,741
Year two	5,449		2,279
Year three	2,182		1,041
Year four	1,132		2,659
Prior	34,928		34,168
Revolving Loans	358,339		358,585
Total loans	416,132		417,542
Current period gross charge-offs, current year	0		0
Current period gross charge-offs, year one	0		20
Current period gross charge-offs, year two	0		28
Current period gross charge-offs, year three	5		0
Current period gross charge-offs, year four	0		15
Current period gross charge-offs, prior	11		1,735
Current period gross charge-offs, revolving	52		207
Current period gross charge-offs, Total	68		2,005
Consumer | 660-850
Financing Receivable, Credit Quality Indicator [Line Items]
Current year	1,409		11,452
Year one	10,606		4,960
Year two	4,476		1,823
Year three	1,717		519
Year four	740		1,662
Prior	25,997		24,543
Revolving Loans	331,206		333,382
Total loans	376,151		378,341
Consumer | 600-659
Financing Receivable, Credit Quality Indicator [Line Items]
Current year	11		1,209
Year one	1,154		192
Year two	357		237
Year three	94		425
Year four	241		209
Prior	3,873		3,954
Revolving Loans	14,047		12,668
Total loans	19,777		18,894
Consumer | 540-599
Financing Receivable, Credit Quality Indicator [Line Items]
Current year	13		24
Year one	477		374
Year two	284		87
Year three	73		47
Year four	34		500
Prior	2,298		2,868
Revolving Loans	4,460		5,920
Total loans	7,639		9,820
Consumer | less than 540
Financing Receivable, Credit Quality Indicator [Line Items]
Current year	76		384
Year one	356		215
Year two	332		132
Year three	298		50
Year four	117		288
Prior	2,760		2,803
Revolving Loans	8,626		6,615
Total loans	$ 12,565		$ 10,487