FAIR VALUE DISCLOSURES OF FINANCIAL ASSETS AND LIABILITIES - Book Value and Estimated Fair Value of Financial Instruments (Details) - USD ($) $ in Thousands	Dec. 31, 2024	Dec. 31, 2023
Financial assets:
Investment securities, available for sale	$ 3,510,648	$ 3,846,537
Loans and leases, net	12,996,218	12,583,202
Stock in FHLB of Pittsburgh	11,805	15,398
Accrued interest receivable	84,671	85,979
Financial liabilities:
Deposits	17,029,808	16,474,086
Accrued interest payable	38,173	46,684
Level 3
Financial assets:
Other investments	15,516	15,206
Other assets	25	78
Book Value | Level 1
Financial assets:
Cash, cash equivalents and restricted cash	1,154,818	1,092,900
Book Value | Level 2
Financial assets:
Investment securities, available for sale	3,510,648	3,846,537
Investment securities, held to maturity, net	1,015,161	1,058,557
Loans, held for sale	49,699	29,268
Stock in FHLB of Pittsburgh	11,805	15,398
Accrued interest receivable	84,671	85,979
Financial liabilities:
Deposits	17,029,808	16,474,086
Borrowed funds	383,607	895,076
Accrued interest payable	38,173	46,684
Book Value | Level 3
Financial assets:
Other investments	18,184	17,434
Loans and leases, net	12,996,218	12,583,202
Financial liabilities:
Standby letters of credit	776	814
Book Value | Levels 2, 3
Financial assets:
Other assets	170,489	153,647
Financial liabilities:
Other liabilities	160,512	151,642
Fair Value | Level 1
Financial assets:
Cash, cash equivalents and restricted cash	1,154,818	1,092,900
Fair Value | Level 2
Financial assets:
Investment securities, available for sale	3,510,648	3,846,537
Investment securities, held to maturity, net	895,511	985,931
Loans, held for sale	49,699	29,268
Stock in FHLB of Pittsburgh	11,805	15,398
Accrued interest receivable	84,671	85,979
Financial liabilities:
Deposits	17,016,839	16,449,198
Borrowed funds	379,154	912,760
Accrued interest payable	38,173	46,684
Fair Value | Level 3
Financial assets:
Other investments	18,184	17,434
Loans and leases, net	13,100,492	12,514,431
Financial liabilities:
Standby letters of credit	776	814
Fair Value | Levels 2, 3
Financial assets:
Other assets	170,489	153,647
Financial liabilities:
Other liabilities	$ 160,512	$ 151,642