ALLOWANCE FOR CREDIT LOSSES AND CREDIT QUALITY INFORMATION - Nonaccrual and Past Due Loans (Details) - USD ($) $ in Thousands	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Financing Receivable, Recorded Investment, Past Due [Line Items]
Nonaccrual loans with no allowance	$ 103,578	$ 58,441
Nonaccrual loans with an allowance	18,603	5,568
Total Loans	$ 13,187,874	$ 12,766,518	$ 11,909,436
Percent of nonaccrual loans with no allowance	0.79%	0.46%
Percent of nonaccrual loans with allowance	0.14%	0.04%
% of Total Loans	100.00%	100.00%
Reverse mortgage, fair value	$ 3,600	$ 2,800	2,400
Total Past Due And Still Accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Gross loans	$ 44,768	$ 47,397
Percent past due	0.34%	0.37%
30–89 Days Past Due and Still Accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Gross loans	$ 35,566	$ 35,813
Percent past due	0.27%	0.28%
Greater Than 90 Days Past Due and Still Accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Gross loans	$ 9,202	$ 11,584
Percent past due	0.07%	0.09%
Accruing Current Balances
Financing Receivable, Recorded Investment, Past Due [Line Items]
Gross loans	$ 13,020,925	$ 12,655,112
Percent of accruing current balances	98.73%	99.13%
Residential
Financing Receivable, Recorded Investment, Past Due [Line Items]
Gross loans	$ 965,051	$ 870,705
Nonaccrual loans with no allowance	5,011	2,579
Nonaccrual loans with an allowance	0	0
Total Loans	961,426	867,895	759,465
Residential | Total Past Due And Still Accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Gross loans	4,277	9,261
Residential | 30–89 Days Past Due and Still Accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Gross loans	4,262	9,261
Residential | Greater Than 90 Days Past Due and Still Accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Gross loans	15	0
Residential | Accruing Current Balances
Financing Receivable, Recorded Investment, Past Due [Line Items]
Gross loans	952,138	856,055
Consumer
Financing Receivable, Recorded Investment, Past Due [Line Items]
Gross loans	2,086,393	2,012,134
Nonaccrual loans with no allowance	2,828	2,446
Nonaccrual loans with an allowance	0	0
Total Loans	2,086,393	2,012,134	1,810,930
Consumer | Total Past Due And Still Accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Gross loans	25,461	25,281
Consumer | 30–89 Days Past Due and Still Accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Gross loans	18,086	15,249
Consumer | Greater Than 90 Days Past Due and Still Accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Gross loans	7,375	10,032
Consumer | Accruing Current Balances
Financing Receivable, Recorded Investment, Past Due [Line Items]
Gross loans	2,058,104	1,984,407
Commercial and industrial | Commercial
Financing Receivable, Recorded Investment, Past Due [Line Items]
Gross loans	2,656,174	2,540,070
Nonaccrual loans with no allowance	43,206	13,645
Nonaccrual loans with an allowance	18,603	5,568
Total Loans	2,656,174	2,540,070	2,575,345
Commercial and industrial | Commercial | Total Past Due And Still Accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Gross loans	1,970	1,923
Commercial and industrial | Commercial | 30–89 Days Past Due and Still Accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Gross loans	1,482	1,630
Commercial and industrial | Commercial | Greater Than 90 Days Past Due and Still Accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Gross loans	488	293
Commercial and industrial | Commercial | Accruing Current Balances
Financing Receivable, Recorded Investment, Past Due [Line Items]
Gross loans	2,592,395	2,518,934
Owner-occupied commercial | Commercial
Financing Receivable, Recorded Investment, Past Due [Line Items]
Gross loans	1,973,645	1,886,087
Nonaccrual loans with no allowance	4,710	4,862
Nonaccrual loans with an allowance	0	0
Total Loans	1,973,645	1,886,087	1,809,582
Owner-occupied commercial | Commercial | Total Past Due And Still Accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Gross loans	902	2,273
Owner-occupied commercial | Commercial | 30–89 Days Past Due and Still Accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Gross loans	706	1,786
Owner-occupied commercial | Commercial | Greater Than 90 Days Past Due and Still Accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Gross loans	196	487
Owner-occupied commercial | Commercial | Accruing Current Balances
Financing Receivable, Recorded Investment, Past Due [Line Items]
Gross loans	1,968,033	1,878,952
Commercial mortgages | Commercial
Financing Receivable, Recorded Investment, Past Due [Line Items]
Gross loans	4,030,627	3,801,180
Nonaccrual loans with no allowance	22,223	22,292
Nonaccrual loans with an allowance	0	0
Total Loans	4,030,627	3,801,180	3,351,084
Commercial mortgages | Commercial | Total Past Due And Still Accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Gross loans	3,183	1,190
Commercial mortgages | Commercial | 30–89 Days Past Due and Still Accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Gross loans	2,621	1,190
Commercial mortgages | Commercial | Greater Than 90 Days Past Due and Still Accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Gross loans	562	0
Commercial mortgages | Commercial | Accruing Current Balances
Financing Receivable, Recorded Investment, Past Due [Line Items]
Gross loans	4,005,221	3,777,698
Construction | Commercial
Financing Receivable, Recorded Investment, Past Due [Line Items]
Gross loans	832,093	1,035,530
Nonaccrual loans with no allowance	25,600	12,617
Nonaccrual loans with an allowance	0	0
Total Loans	832,093	1,035,530	1,044,049
Construction | Commercial | Total Past Due And Still Accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Gross loans	0	0
Construction | Commercial | 30–89 Days Past Due and Still Accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Gross loans	0	0
Construction | Commercial | Greater Than 90 Days Past Due and Still Accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Gross loans	0	0
Construction | Commercial | Accruing Current Balances
Financing Receivable, Recorded Investment, Past Due [Line Items]
Gross loans	806,493	1,022,913
Commercial small business leases | Commercial
Financing Receivable, Recorded Investment, Past Due [Line Items]
Gross loans	647,516	623,622
Nonaccrual loans with no allowance	0	0
Nonaccrual loans with an allowance	0	0
Total Loans	647,516	623,622	$ 558,981
Commercial small business leases | Commercial | Total Past Due And Still Accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Gross loans	8,975	7,469
Commercial small business leases | Commercial | 30–89 Days Past Due and Still Accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Gross loans	8,409	6,697
Commercial small business leases | Commercial | Greater Than 90 Days Past Due and Still Accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Gross loans	566	772
Commercial small business leases | Commercial | Accruing Current Balances
Financing Receivable, Recorded Investment, Past Due [Line Items]
Gross loans	638,541	616,153
Student loans | Consumer | Total Past Due And Still Accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Gross loans	$ 15,600	$ 14,500