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INVESTMENT SECURITIES - Summary of Held-to-Maturity Debt Securities by Stated Maturity (Detail) $ in Thousands	Sep. 30, 2025 USD ($)
Schedule of Held-to-Maturity Securities [Line Items]
Amortized Cost	$ 801,324
Fair Value	757,130
Asset-backed securities
Schedule of Held-to-Maturity Securities [Line Items]
Amortized Cost	301,284
Fair Value	300,675
Agency-guaranteed residential mortgage-backed securities
Schedule of Held-to-Maturity Securities [Line Items]
Amortized Cost	6,750
Fair Value	6,010
Agency-guaranteed commercial mortgage-backed securities
Schedule of Held-to-Maturity Securities [Line Items]
Amortized Cost	1,708
Fair Value	1,493
Agency-guaranteed residential collateralized mortgage obligations
Schedule of Held-to-Maturity Securities [Line Items]
Amortized Cost	157,231
Fair Value	146,113
Agency-guaranteed commercial collateralized mortgage obligations
Schedule of Held-to-Maturity Securities [Line Items]
Amortized Cost	179,333
Fair Value	157,365
Private label collateralized mortgage obligations
Schedule of Held-to-Maturity Securities [Line Items]
Amortized Cost	155,018
Fair Value	$ 145,474

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- Definition

Amount excluding accrued interest, after allowance for credit loss, of investment in debt security measured at amortized cost (held-to-maturity) without single maturity date and not allocated over maturity grouping.

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