LOANS AND LEASES - Schedule of Loan and Lease Portfolio by Category (Details) - USD ($) $ in Thousands	Sep. 30, 2026	Jun. 30, 2026	Dec. 31, 2025	Sep. 30, 2025	Jun. 30, 2025	Dec. 31, 2024
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for credit losses	$ 185,238	$ 177,263	$ 179,647	$ 183,230	$ 186,304	$ 195,281
Net loans and leases	13,457,002		13,082,027
Reverse mortgage, fair value	3,500		3,700	5,300
Financing Receivable Portfolio Segment, Including Reverse Mortgages
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross loans	13,642,240		13,261,674
Commercial \| Commercial and Industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross loans	2,975,080		2,796,654
Allowance for credit losses	60,683	51,883	52,927	49,629	52,121	57,131
Commercial \| Owner-occupied commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross loans	2,040,299		1,937,339
Allowance for credit losses	9,034	8,717	7,626	8,311	8,584	9,139
Commercial \| Commercial mortgages
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross loans	3,884,727		3,916,159
Allowance for credit losses	49,082	49,451	48,047	48,610	54,775	48,962
Commercial \| Construction
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross loans	1,004,871		1,023,911
Allowance for credit losses	13,242	13,541	13,264	17,174	10,696	9,185
Commercial \| Commercial Small Business Leases
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross loans	593,112		603,321
Allowance for credit losses	16,065	17,424	16,449	17,265	18,301	15,965
Residential
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross loans	1,331,351		1,089,830
Allowance for credit losses	5,983	6,260	6,764	6,452	5,815	5,566
Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross loans	1,812,800		1,894,460
Allowance for credit losses	$ 31,149	$ 29,987	$ 34,570	$ 35,789	$ 36,012	$ 49,333