LOANS AND LEASES - Schedule of Loan and Lease Portfolio by Category (Details) - USD ($) $ in Thousands	Jun. 30, 2025	Mar. 31, 2025	Dec. 31, 2024	Jun. 30, 2024	Mar. 31, 2024	Dec. 31, 2023
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for credit losses	$ 186,304	$ 187,515	$ 195,281	$ 198,253	$ 192,629	$ 186,126
Net loans and leases	12,807,920		12,996,218
Reverse mortgage, fair value	4,700		3,600	2,800
Financing Receivable Portfolio Segment, Including Reverse Mortgages
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross loans	12,994,224		13,191,499
Commercial | Commercial and industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross loans	2,744,392		2,656,174
Allowance for credit losses	52,121	50,736	57,131	56,516	55,902	49,394
Commercial | Owner-occupied commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross loans	1,947,594		1,973,645
Allowance for credit losses	8,584	8,410	9,139	9,668	10,569	10,719
Commercial | Commercial mortgages
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross loans	3,911,537		4,030,627
Allowance for credit losses	54,775	49,792	48,962	46,831	36,797	36,055
Commercial | Construction
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross loans	857,631		832,093
Allowance for credit losses	10,696	9,691	9,185	9,198	10,959	10,762
Commercial | Commercial Small Business Leases
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross loans	630,127		647,516
Allowance for credit losses	18,301	17,109	15,965	16,218	15,459	15,170
Residential
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross loans	981,140		965,051
Allowance for credit losses	5,815	5,697	5,566	5,057	5,407	5,483
Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross loans	1,921,803		2,086,393
Allowance for credit losses	$ 36,012	$ 46,080	$ 49,333	$ 54,765	$ 57,536	$ 58,543