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INVESTMENT SECURITIES - Summary of Amortized Cost and Approximate Fair Value of Investment Securities (Detail) - USD ($) | Sep. 30, 2025 | Dec. 31, 2024
--- | --- | ---
Schedule of Held-to-Maturity Securities [Line Items] |  |
Amortized Cost | $ 801,324,000 | $ 991,937,000
Allowance for Credit Losses | 0 | 0
Net Carrying Value | 801,324,000 | 991,937,000
Gross Unrealized Gains | 947,000 | 2,349,000
Gross Unrealized Losses | (45,141,000) | (59,609,000)
Fair Value | 757,130,000 | 934,677,000
Debt securities, held to maturity, accrued interest | 1,800,000 | 2,400,000
Asset-backed securities |  |
Schedule of Held-to-Maturity Securities [Line Items] |  |
Amortized Cost | 301,284,000 | 471,996,000
Allowance for Credit Losses | 0 | 0
Net Carrying Value | 301,284,000 | 471,996,000
Gross Unrealized Gains | 942,000 | 1,775,000
Gross Unrealized Losses | (1,551,000) | (401,000)
Fair Value | 300,675,000 | 473,370,000
Agency-guaranteed residential mortgage-backed securities |  |
Schedule of Held-to-Maturity Securities [Line Items] |  |
Amortized Cost | 6,750,000 | 6,880,000
Allowance for Credit Losses | 0 | 0
Net Carrying Value | 6,750,000 | 6,880,000
Gross Unrealized Gains | 0 | 0
Gross Unrealized Losses | (740,000) | (940,000)
Fair Value | 6,010,000 | 5,940,000
Agency-guaranteed commercial mortgage-backed securities |  |
Schedule of Held-to-Maturity Securities [Line Items] |  |
Amortized Cost | 1,708,000 | 1,770,000
Allowance for Credit Losses | 0 | 0
Net Carrying Value | 1,708,000 | 1,770,000
Gross Unrealized Gains | 0 | 0
Gross Unrealized Losses | (215,000) | (146,000)
Fair Value | 1,493,000 | 1,624,000
Agency-guaranteed residential collateralized mortgage obligations |  |
Schedule of Held-to-Maturity Securities [Line Items] |  |
Amortized Cost | 157,231,000 | 169,754,000
Allowance for Credit Losses | 0 | 0
Net Carrying Value | 157,231,000 | 169,754,000
Gross Unrealized Gains | 0 | 0
Gross Unrealized Losses | (11,118,000) | (21,984,000)
Fair Value | 146,113,000 | 147,770,000
Agency-guaranteed commercial collateralized mortgage obligations |  |
Schedule of Held-to-Maturity Securities [Line Items] |  |
Amortized Cost | 179,333,000 | 158,320,000
Allowance for Credit Losses | 0 | 0
Net Carrying Value | 179,333,000 | 158,320,000
Gross Unrealized Gains | 0 | 0
Gross Unrealized Losses | (21,968,000) | (22,689,000)
Fair Value | 157,365,000 | 135,631,000
Private label collateralized mortgage obligations |  |
Schedule of Held-to-Maturity Securities [Line Items] |  |
Amortized Cost | 155,018,000 | 183,217,000
Allowance for Credit Losses | 0 | 0
Net Carrying Value | 155,018,000 | 183,217,000
Gross Unrealized Gains | 5,000 | 574,000
Gross Unrealized Losses | (9,549,000) | (13,449,000)
Fair Value | $ 145,474,000 | $ 170,342,000

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