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SECURITIES - Additional Information (Details) $ in Thousands | 3 Months Ended | 12 Months Ended |  |
--- | --- | --- | --- | ---
Mar. 31, 2017 security | Dec. 31, 2024 USD ($) item security | Dec. 31, 2023 USD ($) | Dec. 31, 2022 USD ($) | Sep. 30, 2024 USD ($) | Sep. 30, 2023 USD ($)
Debt Securities, Available-for-sale [Line Items] |  |  |  |  |  |
Securities pledged as collateral |  | $ 929,800 | $ 992,100 |  |  |
Gain on sale of investments |  | 133 | 1 | $ 6 |  |
Loss on sale of investments |  | $ 30 | 2 | 3 |  |
Number of CDO other-than-temporary impaired | security |  | 3 |  |  |  |
Number of CDO called | security | 1 |  |  |  |  |
Cumulative credit loss charges recorded through earnings to date |  | $ 2,974 | 2,974 | $ 2,974 | $ 2,974 | $ 2,974
Number of Investment securities with an amortized cost greater than fair value | item |  | 962 |  |  |  |
Unrealized losses |  | $ 168,934 | $ 157,845 |  |  |
Collateralized Debt Obligations [Member] |  |  |  |  |  |
Debt Securities, Available-for-sale [Line Items] |  |  |  |  |  |
Contractual balance |  | 3,700 |  |  |  |
Reduced balance |  | 3,000 |  |  |  |
Interest payment received |  | 750 |  |  |  |
Other comprehensive income net |  | 2,900 |  |  |  |
Cumulative credit loss charges recorded through earnings to date |  | $ 3,000 |  |  |  |

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