ALLOWANCE FOR CREDIT LOSSES AND CREDIT QUALITY INFORMATION - Schedule of Credit Quality Indicators (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended		12 Months Ended
	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024	Dec. 31, 2024
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans	$ 13,318,988	$ 12,955,253	$ 13,318,988	$ 13,187,874
Total charge offs	23,101		52,532
Commercial | Commercial and industrial
Financing Receivable, Credit Quality Indicator [Line Items]
Year one, current fiscal year amortized cost		573,352		749,866
Year two, current fiscal year amortized cost		632,836		571,748
Year three, current fiscal year amortized cost		392,231		369,477
Year four, current fiscal year amortized cost		270,490		131,936
Year five, current fiscal year amortized cost		79,762		179,216
Prior		355,944		339,837
Revolving loans amortized cost basis		7,914		8,771
Revolving loans converted to term		312,623		305,323
Total Loans	2,639,266	2,625,152	2,639,266	2,656,174
Year one, current fiscal year charge offs		20		102
Year two, current fiscal year charge offs		5,888		1,303
Year three, current fiscal year charge offs		1,635		4,276
Year four, current fiscal year charge offs		1,664		706
Year five, current fiscal year charge offs		13,390		275
Prior year charge offs		6,469		8,828
Revolving loans amortized cost basis charge offs		0		0
Revolving loans converted to term gross charge offs		0		0
Total charge offs	11,277	29,066	13,659	15,490
Commercial | Commercial and industrial | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Year one, current fiscal year amortized cost		512,106		662,723
Year two, current fiscal year amortized cost		599,556		542,655
Year three, current fiscal year amortized cost		376,825		345,370
Year four, current fiscal year amortized cost		249,644		126,173
Year five, current fiscal year amortized cost		75,397		155,137
Prior		320,403		309,445
Revolving loans amortized cost basis		7,889		8,744
Revolving loans converted to term		277,683		252,524
Total Loans		2,419,503		2,402,771
Commercial | Commercial and industrial | Special mention
Financing Receivable, Credit Quality Indicator [Line Items]
Year one, current fiscal year amortized cost		8,755		18,861
Year two, current fiscal year amortized cost		2,904		386
Year three, current fiscal year amortized cost		6,690		4,147
Year four, current fiscal year amortized cost		14,414		1,176
Year five, current fiscal year amortized cost		826		2,490
Prior		4,149		607
Revolving loans amortized cost basis		0		0
Revolving loans converted to term		3,133		1,868
Total Loans		40,871		29,535
Commercial | Commercial and industrial | Substandard or Lower
Financing Receivable, Credit Quality Indicator [Line Items]
Year one, current fiscal year amortized cost		52,491		68,282
Year two, current fiscal year amortized cost		30,376		28,707
Year three, current fiscal year amortized cost		8,716		19,960
Year four, current fiscal year amortized cost		6,432		4,587
Year five, current fiscal year amortized cost		3,539		21,589
Prior		31,392		29,785
Revolving loans amortized cost basis		25		27
Revolving loans converted to term		31,807		50,931
Total Loans		164,778		223,868
Commercial | Owner-occupied commercial
Financing Receivable, Credit Quality Indicator [Line Items]
Year one, current fiscal year amortized cost		190,891		288,647
Year two, current fiscal year amortized cost		252,755		305,383
Year three, current fiscal year amortized cost		272,075		247,208
Year four, current fiscal year amortized cost		194,823		233,971
Year five, current fiscal year amortized cost		202,419		198,395
Prior		525,836		445,559
Revolving loans amortized cost basis		0		0
Revolving loans converted to term		283,968		254,482
Total Loans	2,003,722	1,922,767	2,003,722	1,973,645
Year one, current fiscal year charge offs		0		0
Year two, current fiscal year charge offs		0		114
Year three, current fiscal year charge offs		4		0
Year four, current fiscal year charge offs		0		0
Year five, current fiscal year charge offs		0		0
Prior year charge offs		0		63
Revolving loans amortized cost basis charge offs		0		0
Revolving loans converted to term gross charge offs		0		0
Total charge offs	177	4	177	177
Commercial | Owner-occupied commercial | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Year one, current fiscal year amortized cost		185,776		285,146
Year two, current fiscal year amortized cost		247,043		296,339
Year three, current fiscal year amortized cost		255,409		224,797
Year four, current fiscal year amortized cost		182,827		225,086
Year five, current fiscal year amortized cost		191,648		168,368
Prior		468,775		404,515
Revolving loans amortized cost basis		0		0
Revolving loans converted to term		266,597		238,356
Total Loans		1,798,075		1,842,607
Commercial | Owner-occupied commercial | Special mention
Financing Receivable, Credit Quality Indicator [Line Items]
Year one, current fiscal year amortized cost		2,126		0
Year two, current fiscal year amortized cost		0		0
Year three, current fiscal year amortized cost		691		498
Year four, current fiscal year amortized cost		1,384		0
Year five, current fiscal year amortized cost		1,249		25,220
Prior		26,218		0
Revolving loans amortized cost basis		0		0
Revolving loans converted to term		7,859		756
Total Loans		39,527		26,474
Commercial | Owner-occupied commercial | Substandard or Lower
Financing Receivable, Credit Quality Indicator [Line Items]
Year one, current fiscal year amortized cost		2,989		3,501
Year two, current fiscal year amortized cost		5,712		9,044
Year three, current fiscal year amortized cost		15,975		21,913
Year four, current fiscal year amortized cost		10,612		8,885
Year five, current fiscal year amortized cost		9,522		4,807
Prior		30,843		41,044
Revolving loans amortized cost basis		0		0
Revolving loans converted to term		9,512		15,370
Total Loans		85,165		104,564
Commercial | Commercial mortgages
Financing Receivable, Credit Quality Indicator [Line Items]
Year one, current fiscal year amortized cost		416,309		605,582
Year two, current fiscal year amortized cost		417,380		768,096
Year three, current fiscal year amortized cost		560,269		412,786
Year four, current fiscal year amortized cost		363,606		418,585
Year five, current fiscal year amortized cost		371,089		402,873
Prior		1,123,454		879,045
Revolving loans amortized cost basis		0		0
Revolving loans converted to term		603,864		543,660
Total Loans	4,149,049	3,855,971	4,149,049	4,030,627
Year one, current fiscal year charge offs		0		0
Year two, current fiscal year charge offs		34		62
Year three, current fiscal year charge offs		9		0
Year four, current fiscal year charge offs		0		0
Year five, current fiscal year charge offs		0		97
Prior year charge offs		197		5,590
Revolving loans amortized cost basis charge offs		0		0
Revolving loans converted to term gross charge offs		0		0
Total charge offs	205	240	5,137	5,749
Commercial | Commercial mortgages | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Year one, current fiscal year amortized cost		381,971		546,404
Year two, current fiscal year amortized cost		408,112		740,711
Year three, current fiscal year amortized cost		556,056		396,458
Year four, current fiscal year amortized cost		348,303		414,546
Year five, current fiscal year amortized cost		365,412		379,637
Prior		1,025,437		858,744
Revolving loans amortized cost basis		0		0
Revolving loans converted to term		569,406		506,394
Total Loans		3,654,697		3,842,894
Commercial | Commercial mortgages | Special mention
Financing Receivable, Credit Quality Indicator [Line Items]
Year one, current fiscal year amortized cost		18,921		15,606
Year two, current fiscal year amortized cost		739		3,389
Year three, current fiscal year amortized cost		1,611		0
Year four, current fiscal year amortized cost		0		1,962
Year five, current fiscal year amortized cost		4,159		2,356
Prior		46,134		2,136
Revolving loans amortized cost basis		0		0
Revolving loans converted to term		23,740		36,738
Total Loans		95,304		62,187
Commercial | Commercial mortgages | Substandard or Lower
Financing Receivable, Credit Quality Indicator [Line Items]
Year one, current fiscal year amortized cost		15,417		43,572
Year two, current fiscal year amortized cost		8,529		23,996
Year three, current fiscal year amortized cost		2,602		16,328
Year four, current fiscal year amortized cost		15,303		2,077
Year five, current fiscal year amortized cost		1,518		20,880
Prior		51,883		18,165
Revolving loans amortized cost basis		0		0
Revolving loans converted to term		10,718		528
Total Loans		105,970		125,546
Commercial | Construction
Financing Receivable, Credit Quality Indicator [Line Items]
Year one, current fiscal year amortized cost		363,574		338,122
Year two, current fiscal year amortized cost		279,265		277,130
Year three, current fiscal year amortized cost		214,966		182,296
Year four, current fiscal year amortized cost		73,666		3,903
Year five, current fiscal year amortized cost		4,384		87
Prior		10,909		3,319
Revolving loans amortized cost basis		0		0
Revolving loans converted to term		57,222		27,236
Total Loans	805,857	1,003,986	805,857	832,093
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		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	0	0
Commercial | Construction | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Year one, current fiscal year amortized cost		330,722		318,363
Year two, current fiscal year amortized cost		273,830		277,130
Year three, current fiscal year amortized cost		192,867		161,517
Year four, current fiscal year amortized cost		73,666		3,112
Year five, current fiscal year amortized cost		4,384		87
Prior		10,909		3,319
Revolving loans amortized cost basis		0		0
Revolving loans converted to term		54,602		22,416
Total Loans		940,980		785,944
Commercial | Construction | Special mention
Financing Receivable, Credit Quality Indicator [Line Items]
Year one, current fiscal year amortized cost		0		0
Year two, current fiscal year amortized cost		0		0
Year three, current fiscal year amortized cost		0		0
Year four, current fiscal year amortized cost		0		0
Year five, current fiscal year amortized cost		0		0
Prior		0		0
Revolving loans amortized cost basis		0		0
Revolving loans converted to term		0		0
Total Loans		0		0
Commercial | Construction | Substandard or Lower
Financing Receivable, Credit Quality Indicator [Line Items]
Year one, current fiscal year amortized cost		32,852		19,759
Year two, current fiscal year amortized cost		5,435		0
Year three, current fiscal year amortized cost		22,099		20,779
Year four, current fiscal year amortized cost		0		791
Year five, current fiscal year amortized cost		0		0
Prior		0		0
Revolving loans amortized cost basis		0		0
Revolving loans converted to term		2,620		4,820
Total Loans		63,006		46,149
Commercial | Commercial Small Business Leases
Financing Receivable, Credit Quality Indicator [Line Items]
Year one, current fiscal year amortized cost		147,082		247,583
Year two, current fiscal year amortized cost		200,265		189,509
Year three, current fiscal year amortized cost		138,961		121,990
Year four, current fiscal year amortized cost		80,540		56,998
Year five, current fiscal year amortized cost		29,661		14,569
Prior		20,747		16,867
Revolving loans amortized cost basis		0		0
Revolving loans converted to term		0		0
Total Loans	645,421	617,256	645,421	647,516
Year one, current fiscal year charge offs		357		1,018
Year two, current fiscal year charge offs		2,148		5,442
Year three, current fiscal year charge offs		3,980		8,216
Year four, current fiscal year charge offs		3,143		3,645
Year five, current fiscal year charge offs		1,343		1,235
Prior year charge offs		232		477
Revolving loans amortized cost basis charge offs		0		0
Revolving loans converted to term gross charge offs		0		0
Total charge offs	5,451	11,203	15,191	20,033
Commercial | Commercial Small Business Leases | Performing
Financing Receivable, Credit Quality Indicator [Line Items]
Year one, current fiscal year amortized cost		147,082		247,583
Year two, current fiscal year amortized cost		200,265		189,509
Year three, current fiscal year amortized cost		138,961		121,990
Year four, current fiscal year amortized cost		80,540		56,998
Year five, current fiscal year amortized cost		29,661		14,569
Prior		20,747		16,867
Revolving loans amortized cost basis		0		0
Revolving loans converted to term		0		0
Total Loans		617,256		647,516
Commercial | Commercial Small Business Leases | Nonperforming
Financing Receivable, Credit Quality Indicator [Line Items]
Year one, current fiscal year amortized cost		0		0
Year two, current fiscal year amortized cost		0		0
Year three, current fiscal year amortized cost		0		0
Year four, current fiscal year amortized cost		0		0
Year five, current fiscal year amortized cost		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, current fiscal year amortized cost		158,264		170,647
Year two, current fiscal year amortized cost		162,100		177,043
Year three, current fiscal year amortized cost		151,360		63,193
Year four, current fiscal year amortized cost		60,257		96,042
Year five, current fiscal year amortized cost		90,542		50,977
Prior		410,820		403,524
Revolving loans amortized cost basis		0		0
Revolving loans converted to term		0		0
Total Loans	937,594	1,033,343	937,594	961,426
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		0
Prior year charge offs		0		125
Revolving loans amortized cost basis charge offs		0		0
Revolving loans converted to term gross charge offs		0		0
Total charge offs	8	0	109	125
Residential | Performing
Financing Receivable, Credit Quality Indicator [Line Items]
Year one, current fiscal year amortized cost		158,264		170,647
Year two, current fiscal year amortized cost		162,100		176,923
Year three, current fiscal year amortized cost		151,244		62,833
Year four, current fiscal year amortized cost		60,257		92,574
Year five, current fiscal year amortized cost		87,089		49,994
Prior		406,084		399,981
Revolving loans amortized cost basis		0		0
Revolving loans converted to term		0		0
Total Loans		1,025,038		952,952
Residential | Nonperforming
Financing Receivable, Credit Quality Indicator [Line Items]
Year one, current fiscal year amortized cost		0		0
Year two, current fiscal year amortized cost		0		120
Year three, current fiscal year amortized cost		116		360
Year four, current fiscal year amortized cost		0		3,468
Year five, current fiscal year amortized cost		3,453		983
Prior		4,736		3,543
Revolving loans amortized cost basis		0		0
Revolving loans converted to term		0		0
Total Loans		8,305		8,474
Consumer
Financing Receivable, Credit Quality Indicator [Line Items]
Year one, current fiscal year amortized cost		49,579		282,465
Year two, current fiscal year amortized cost		229,171		350,854
Year three, current fiscal year amortized cost		247,582		446,797
Year four, current fiscal year amortized cost		338,294		117,155
Year five, current fiscal year amortized cost		90,955		85,825
Prior		260,475		229,340
Revolving loans amortized cost basis		670,571		566,536
Revolving loans converted to term		10,151		7,421
Total Loans	2,138,079	1,896,778	2,138,079	2,086,393
Year one, current fiscal year charge offs		9,212		1,282
Year two, current fiscal year charge offs		558		3,942
Year three, current fiscal year charge offs		1,758		13,955
Year four, current fiscal year charge offs		3,647		2,837
Year five, current fiscal year charge offs		1,082		863
Prior year charge offs		731		670
Revolving loans amortized cost basis charge offs		0		0
Revolving loans converted to term gross charge offs		0		0
Total charge offs	$ 5,983	16,988	$ 18,259	23,549
Consumer | Performing
Financing Receivable, Credit Quality Indicator [Line Items]
Year one, current fiscal year amortized cost		49,579		282,465
Year two, current fiscal year amortized cost		229,171		350,605
Year three, current fiscal year amortized cost		247,427		446,701
Year four, current fiscal year amortized cost		338,060		116,890
Year five, current fiscal year amortized cost		90,955		85,633
Prior		260,397		229,340
Revolving loans amortized cost basis		668,228		564,839
Revolving loans converted to term		9,937		7,124
Total Loans		1,893,754		2,083,597
Consumer | Nonperforming
Financing Receivable, Credit Quality Indicator [Line Items]
Year one, current fiscal year amortized cost		0		0
Year two, current fiscal year amortized cost		0		249
Year three, current fiscal year amortized cost		155		96
Year four, current fiscal year amortized cost		234		265
Year five, current fiscal year amortized cost		0		192
Prior		78		0
Revolving loans amortized cost basis		2,343		1,697
Revolving loans converted to term		214		297
Total Loans		$ 3,024		$ 2,796