FAIR VALUE DISCLOSURES OF FINANCIAL ASSETS AND LIABILITIES - Schedule of Book Value and Estimated Fair Value of Financial Instruments (Details) - USD ($) $ in Thousands	Jun. 30, 2025	Dec. 31, 2024
Financial assets:
Investment securities available-for-sale	$ 3,494,783	$ 3,510,648
Stock in FHLB of Pittsburgh	21,940	11,805
Accrued interest receivable	79,769	84,671
Financial liabilities:
Deposits	17,121,469	17,029,808
Accrued interest payable	29,134	38,173
Level 1 | Book Value
Financial assets:
Cash, cash equivalents, and restricted cash	1,331,498	1,154,818
Level 1 | Fair Value
Financial assets:
Cash, cash equivalents, and restricted cash	1,331,498	1,154,818
Level 2 | Book Value
Financial assets:
Investment securities available-for-sale	3,494,783	3,510,648
Investment securities held-to-maturity, net	994,340	1,015,161
Loans, held for sale	157,905	49,699
Stock in FHLB of Pittsburgh	21,940	11,805
Accrued interest receivable	79,769	84,671
Financial liabilities:
Deposits	17,121,469	17,029,808
Borrowed funds	303,459	383,607
Accrued interest payable	29,134	38,173
Level 2 | Fair Value
Financial assets:
Investment securities available-for-sale	3,494,783	3,510,648
Investment securities held-to-maturity, net	884,260	895,511
Loans, held for sale	157,905	49,699
Stock in FHLB of Pittsburgh	21,940	11,805
Accrued interest receivable	79,769	84,671
Financial liabilities:
Deposits	17,109,531	17,016,839
Borrowed funds	310,670	379,154
Accrued interest payable	29,134	38,173
Level 3
Financial assets:
Other investments	15,493	15,516
Other assets	52	25
Level 3 | Book Value
Financial assets:
Other investments	17,767	18,184
Loans and leases, net	12,807,920	12,996,218
Financial liabilities:
Standby letters of credit	712	776
Level 3 | Fair Value
Financial assets:
Other investments	17,767	18,184
Loans and leases, net	12,885,457	13,100,492
Financial liabilities:
Standby letters of credit	712	776
Levels 2, 3 | Book Value
Financial assets:
Other assets	146,942	170,489
Financial liabilities:
Other liabilities	129,700	160,512
Levels 2, 3 | Fair Value
Financial assets:
Other assets	146,942	170,489
Financial liabilities:
Other liabilities	$ 129,700	$ 160,512