FAIR VALUE DISCLOSURES OF FINANCIAL ASSETS AND LIABILITIES - Book Value and Estimated Fair Value of Financial Instruments (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Financial assets:
Loans and leases, net	$ 12,583,202	$ 11,759,992
Stock in FHLB of Pittsburgh	15,398	24,116
Accrued interest receivable	85,979	74,448
Financial liabilities:
Deposits	16,474,086	16,203,569
Accrued interest payable	46,684	5,174
Book Value | Level 1
Financial assets:
Cash, cash equivalents and restricted cash	1,092,900	837,258
Book Value | Level 2
Financial assets:
Investment securities, available for sale	3,846,537	4,093,060
Investment securities, held to maturity, net	1,058,557	1,111,619
Loans, held for sale	29,268	42,985
Stock in FHLB of Pittsburgh	15,398	24,116
Accrued interest receivable	85,979	74,448
Financial liabilities:
Deposits	16,474,086	16,203,569
Borrowed funds	895,076	726,894
Accrued interest payable	46,684	5,174
Book Value | Level 3
Financial assets:
Other investments	17,434	26,120
Loans and leases, net	12,583,202	11,759,992
Financial liabilities:
Standby letters of credit	814	739
Book Value | Levels 2, 3
Financial assets:
Other assets	153,647	156,993
Financial liabilities:
Other liabilities	151,642	173,622
Fair Value | Level 1
Financial assets:
Cash, cash equivalents and restricted cash	1,092,900	837,258
Fair Value | Level 2
Financial assets:
Investment securities, available for sale	3,846,537	4,093,060
Investment securities, held to maturity, net	985,931	1,040,104
Loans, held for sale	29,268	42,985
Stock in FHLB of Pittsburgh	15,398	24,116
Accrued interest receivable	85,979	74,448
Financial liabilities:
Deposits	16,449,198	16,156,124
Borrowed funds	912,760	709,014
Accrued interest payable	46,684	5,174
Fair Value | Level 3
Financial assets:
Other investments	17,434	26,120
Loans and leases, net	12,514,431	11,567,888
Financial liabilities:
Standby letters of credit	814	739
Fair Value | Levels 2, 3
Financial assets:
Other assets	153,647	156,993
Financial liabilities:
Other liabilities	$ 151,642	$ 173,622