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Fair Value Measurements - Summary of Assets and Liabilities Classified as Level 3 and Measured at Fair Value on Nonrecurring Basis (Details) | 6 Months Ended | 9 Months Ended
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Jun. 30, 2026 | Sep. 30, 2025
Level 3 | Measurement Input, Discount Rate | Valuation, Market Approach |  |
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items] |  |
Impaired loans, measurement input | 8.40% | 8.10%

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