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Fair Value of Financial Instruments - Quantitative Information about Unobservable Inputs Used in Recurring and Nonrecurring Level 3 Fair Value Measurements (Detail) $ in Thousands | Sep. 30, 2025 USD ($) | Dec. 31, 2024 USD ($)
--- | --- | ---
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items] |  |
Fair Value | $ 422,773 | $ 426,556
State and Local Governments [Member] |  |
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items] |  |
Fair Value | 61,960 | 64,760
Level 3 [Member] | State and Local Governments [Member] |  |
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items] |  |
Fair Value | $ 1,458 | $ 1,627
Valuation Technique | us-gaap:ValuationTechniqueDiscountedCashFlowMember | us-gaap:ValuationTechniqueDiscountedCashFlowMember
Unobservable Inputs | us-gaap:MeasurementInputDiscountRateMember | us-gaap:MeasurementInputDiscountRateMember
Level 3 [Member] | Collateral Dependent Loans [Member] |  |
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items] |  |
Fair Value | $ 4,646 | $ 2,988
Valuation Technique | us-gaap:MarketApproachValuationTechniqueMember | us-gaap:MarketApproachValuationTechniqueMember
Unobservable Inputs | us-gaap:MeasurementInputAppraisedValueMember | us-gaap:MeasurementInputAppraisedValueMember
Level 3 [Member] | Loan Servicing Rights [Member] |  |
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items] |  |
Fair Value | $ 1,982 |
Valuation Technique | us-gaap:ValuationTechniqueDiscountedCashFlowMember |
Unobservable Inputs | us-gaap:MeasurementInputDiscountRateMember |
Fair Value |  | $ (4)
Valuation Technique |  | us-gaap:MarketApproachValuationTechniqueMember
Unobservable Inputs |  | us-gaap:MeasurementInputDiscountRateMember
Level 3 [Member] | Minimum [Member] | State and Local Governments [Member] |  |
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items] |  |
Discount rate | 0.0312 | (0.0361)
Level 3 [Member] | Minimum [Member] | Collateral Dependent Loans [Member] |  |
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items] |  |
Discount rate | 0.2000 | 0.2000
Level 3 [Member] | Minimum [Member] | Loan Servicing Rights [Member] |  |
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items] |  |
Discount rate | 0.151 |
Discount rate |  | 0.0936
Level 3 [Member] | Weighted Average | State and Local Governments [Member] |  |
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items] |  |
Discount rate | 0.0381 | 0.0433
Level 3 [Member] | Weighted Average | Collateral Dependent Loans [Member] |  |
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items] |  |
Discount rate | 0.20 | 0.2078
Level 3 [Member] | Weighted Average | Loan Servicing Rights [Member] |  |
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items] |  |
Discount rate | 0.1879 |
Discount rate |  | 1.079
Level 3 [Member] | Maximum [Member] | State and Local Governments [Member] |  |
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items] |  |
Discount rate | 0.0391 | 0.0452
Level 3 [Member] | Maximum [Member] | Collateral Dependent Loans [Member] |  |
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items] |  |
Discount rate | 0.20 | 0.3000
Level 3 [Member] | Maximum [Member] | Loan Servicing Rights [Member] |  |
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items] |  |
Discount rate | 5.4099 |
Discount rate |  | 6.187

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