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Fair Value Measurements - Additional Information (Detail) - USD ($) | 9 Months Ended | 12 Months Ended
--- | --- | ---
Sep. 30, 2025 | Dec. 31, 2024
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items] |  |
Days from origination after which mortgage loans are sold | 30 days |
Amount of non-financial assets (liabilities) measured at fair value on a recurring basis | $ 0 | $ 0
Non-financial assets for which no impairment was provided | $ 0 | $ 0

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