LOANS AND LEASES - Schedule of Loan and Lease Portfolio by Category (Details) - USD ($) $ in Thousands	Sep. 30, 2025	Jun. 30, 2025	Dec. 31, 2024	Sep. 30, 2024	Jun. 30, 2024	Dec. 31, 2023
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for credit losses	$ 183,230	$ 186,304	$ 195,281	$ 197,490	$ 198,253	$ 186,126
Net loans and leases	12,777,336		12,996,218
Reverse mortgage, fair value	5,300		3,600	3,200
Financing Receivable Portfolio Segment, Including Reverse Mortgages
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross loans	12,960,566		13,191,499
Commercial | Commercial and industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross loans	2,625,152		2,656,174
Allowance for credit losses	49,629	52,121	57,131	56,795	56,516	49,394
Commercial | Owner-occupied commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross loans	1,922,767		1,973,645
Allowance for credit losses	8,311	8,584	9,139	9,787	9,668	10,719
Commercial | Commercial mortgages
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross loans	3,855,971		4,030,627
Allowance for credit losses	48,610	54,775	48,962	48,989	46,831	36,055
Commercial | Construction
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross loans	1,003,986		832,093
Allowance for credit losses	17,174	10,696	9,185	8,348	9,198	10,762
Commercial | Commercial Small Business Leases
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross loans	617,256		647,516
Allowance for credit losses	17,265	18,301	15,965	15,374	16,218	15,170
Residential
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross loans	1,038,656		965,051
Allowance for credit losses	6,452	5,815	5,566	5,463	5,057	5,483
Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross loans	1,896,778		2,086,393
Allowance for credit losses	$ 35,789	$ 36,012	$ 49,333	$ 52,734	$ 54,765	$ 58,543