CREDIT QUALITY ASSESSMENT - Allowance for Credit or Loan Losses by Respective Loan Portfolio Segment (Details) - USD ($) $ in Thousands	9 Months Ended		12 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Dec. 31, 2021
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Balance at beginning of period	$ 109,145	$ 165,367	$ 165,367
Provision/ (credit) for credit losses - loans	18,773	(47,141)	(45,556)
Charge-offs	(1,029)	(11,496)	(12,313)
Recoveries	1,379	1,190	1,647
Net recoveries (charge-offs)	(350)	10,306	10,666
Balance at period end	128,268	107,920	109,145
Total loans	$ 11,218,813		$ 9,967,091
Allowance for credit losses on loans to total loans ratio	1.14%		1.10%
Average loans	$ 10,431,024		$ 10,034,866
Annualized net charge-offs/ (recoveries) to average loans	0.00%		0.11%
Balance of loans individually evaluated for credit loss	$ 29,948		$ 33,534
Allowance related to loans evaluated individually	$ 6,548		$ 6,593
Individual allowance to loans evaluated individually ratio	21.86%		19.66%
Balance of loans collectively evaluated for credit loss	$ 11,188,865		$ 9,933,557
Allowance related to loans evaluated collectively	$ 121,720		$ 102,552
Collective allowance to loans evaluated collectively ratio	1.09%		1.03%
Commercial investor real estate
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Charge-offs	$ 0		$ (5,802)
Total loans	5,066,843		4,141,346
Commercial owner-occupied real estate
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Charge-offs	0		(136)
Total loans	1,743,724		1,690,881
Commercial AD&C
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Charge-offs	0		(2,007)
Total loans	1,143,783		1,088,094
Residential mortgage
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Charge-offs	(130)		0
Total loans	1,218,552		937,570
Residential construction
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Charge-offs	0		0
Total loans	229,243		197,652
Commercial real estate: | Commercial investor real estate
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Balance at beginning of period	45,289	57,404	57,404
Provision/ (credit) for credit losses - loans	18,561		(6,598)
Charge-offs	0		(5,802)
Recoveries	319		285
Net recoveries (charge-offs)	(319)		5,517
Balance at period end	64,169		45,289
Total loans	$ 5,066,843		$ 4,141,346
Allowance for credit losses on loans to total loans ratio	1.27%		1.09%
Average loans	$ 4,546,440		$ 3,689,769
Annualized net charge-offs/ (recoveries) to average loans	(0.01%)		0.15%
Balance of loans individually evaluated for credit loss	$ 14,038		$ 12,489
Allowance related to loans evaluated individually	$ 134		$ 213
Individual allowance to loans evaluated individually ratio	0.95%		1.71%
Balance of loans collectively evaluated for credit loss	$ 5,052,805		$ 4,128,857
Allowance related to loans evaluated collectively	$ 64,035		$ 45,076
Collective allowance to loans evaluated collectively ratio	1.27%		1.09%
Commercial real estate: | Commercial owner-occupied real estate
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Balance at beginning of period	$ 11,687	20,061	$ 20,061
Provision/ (credit) for credit losses - loans	(610)		(8,238)
Charge-offs	0		(136)
Recoveries	22		0
Net recoveries (charge-offs)	(22)		136
Balance at period end	11,099		11,687
Total loans	$ 1,743,724		$ 1,690,881
Allowance for credit losses on loans to total loans ratio	0.64%		0.69%
Average loans	$ 1,722,522		$ 1,661,015
Annualized net charge-offs/ (recoveries) to average loans	0.00%		0.01%
Balance of loans individually evaluated for credit loss	$ 6,294		$ 9,306
Allowance related to loans evaluated individually	$ 1,122		$ 79
Individual allowance to loans evaluated individually ratio	17.83%		0.85%
Balance of loans collectively evaluated for credit loss	$ 1,737,430		$ 1,681,575
Allowance related to loans evaluated collectively	$ 9,977		$ 11,608
Collective allowance to loans evaluated collectively ratio	0.57%		0.69%
Commercial real estate: | Commercial AD&C
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Balance at beginning of period	$ 20,322	22,157	$ 22,157
Provision/ (credit) for credit losses - loans	(3,475)		172
Charge-offs	0		(2,007)
Recoveries	0		0
Net recoveries (charge-offs)	0		2,007
Balance at period end	16,847		20,322
Total loans	$ 1,143,783		$ 1,088,094
Allowance for credit losses on loans to total loans ratio	1.47%		1.87%
Average loans	$ 1,104,901		$ 1,110,420
Annualized net charge-offs/ (recoveries) to average loans	0.00%		0.18%
Balance of loans individually evaluated for credit loss	$ 0		$ 650
Allowance related to loans evaluated individually	$ 0		$ 504
Individual allowance to loans evaluated individually ratio	0.00%		77.54%
Balance of loans collectively evaluated for credit loss	$ 1,143,783		$ 1,087,444
Allowance related to loans evaluated collectively	$ 16,847		$ 19,818
Collective allowance to loans evaluated collectively ratio	1.47%		1.82%
Commercial Business
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Total loans	$ 9,347,984		$ 8,402,155
Balance of loans individually evaluated for credit loss	7,769		9,033
Allowance related to loans evaluated individually	5,292		5,797
Commercial Business | Commercial business
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Balance at beginning of period	23,170	46,806	46,806
Provision/ (credit) for credit losses - loans	1,586		(20,132)
Charge-offs	(716)		(4,069)
Recoveries	786		565
Net recoveries (charge-offs)	(70)		3,504
Balance at period end	24,826		23,170
Total loans	$ 1,393,634		$ 1,481,834
Allowance for credit losses on loans to total loans ratio	1.78%		1.56%
Average loans	$ 1,344,608		$ 1,952,537
Annualized net charge-offs/ (recoveries) to average loans	(0.01%)		0.18%
Balance of loans individually evaluated for credit loss	$ 7,769		$ 9,033
Allowance related to loans evaluated individually	$ 5,292		$ 5,797
Individual allowance to loans evaluated individually ratio	68.12%		64.18%
Balance of loans collectively evaluated for credit loss	$ 1,385,865		$ 1,472,801
Allowance related to loans evaluated collectively	$ 19,534		$ 17,373
Collective allowance to loans evaluated collectively ratio	1.41%		1.18%
Residential real estate: | Residential mortgage
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Balance at beginning of period	$ 5,384	11,295	$ 11,295
Provision/ (credit) for credit losses - loans	2,782		(6,321)
Charge-offs	(130)		0
Recoveries	27		410
Net recoveries (charge-offs)	103		(410)
Balance at period end	8,063		5,384
Total loans	$ 1,218,552		$ 937,570
Allowance for credit losses on loans to total loans ratio	0.66%		0.57%
Average loans	$ 1,071,634		$ 979,754
Annualized net charge-offs/ (recoveries) to average loans	0.01%		(0.04%)
Balance of loans individually evaluated for credit loss	$ 1,506		$ 1,704
Allowance related to loans evaluated individually	$ 0		$ 0
Individual allowance to loans evaluated individually ratio	0.00%		0.00%
Balance of loans collectively evaluated for credit loss	$ 1,217,046		$ 935,866
Allowance related to loans evaluated collectively	$ 8,063		$ 5,384
Collective allowance to loans evaluated collectively ratio	0.66%		0.58%
Residential real estate: | Residential construction
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Balance at beginning of period	$ 1,048	1,502	$ 1,502
Provision/ (credit) for credit losses - loans	170		(459)
Charge-offs	0		0
Recoveries	8		5
Net recoveries (charge-offs)	(8)		(5)
Balance at period end	1,226		1,048
Total loans	$ 229,243		$ 197,652
Allowance for credit losses on loans to total loans ratio	0.53%		0.53%
Average loans	$ 217,978		$ 178,171
Annualized net charge-offs/ (recoveries) to average loans	0.00%		0.00%
Balance of loans individually evaluated for credit loss	$ 0		$ 0
Allowance related to loans evaluated individually	$ 0		$ 0
Individual allowance to loans evaluated individually ratio	0.00%		0.00%
Balance of loans collectively evaluated for credit loss	$ 229,243		$ 197,652
Allowance related to loans evaluated collectively	$ 1,226		$ 1,048
Collective allowance to loans evaluated collectively ratio	0.53%		0.53%
Consumer
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Balance at beginning of period	$ 2,245	$ 6,142	$ 6,142
Provision/ (credit) for credit losses - loans	(241)		(3,980)
Charge-offs	(183)		(299)
Recoveries	217		382
Net recoveries (charge-offs)	(34)		(83)
Balance at period end	2,038		2,245
Total loans	$ 423,034		$ 429,714
Allowance for credit losses on loans to total loans ratio	0.48%		0.52%
Average loans	$ 422,941		$ 463,200
Annualized net charge-offs/ (recoveries) to average loans	(0.01%)		(0.02%)
Balance of loans individually evaluated for credit loss	$ 341		$ 352
Allowance related to loans evaluated individually	$ 0		$ 0
Individual allowance to loans evaluated individually ratio	0.00%		0.00%
Balance of loans collectively evaluated for credit loss	$ 422,693		$ 429,362
Allowance related to loans evaluated collectively	$ 2,038		$ 2,245
Collective allowance to loans evaluated collectively ratio	0.48%		0.52%