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Loans and Allowance for Credit Losses on Loans - Additional Information (Detail) - USD ($) | 9 Months Ended |
--- | --- | ---
Sep. 30, 2025 | Dec. 31, 2024
Accrued interest receivable | $ 1,400,000 | $ 1,300,000
Loans outstanding | 3,800,000 | 4,300,000
Loans past due over 90 days still accruing interest | 0 | 0
Maximum [Member] |  |
Reduced credit administration process for commercial relationships | 500,000 |
Residential Real Estate [Member] |  |
Loans collateralized by real estate | $ 0 | $ 0

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