v3.26.3
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, 2026
USD ($)
Dec. 31, 2025
USD ($)
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Fair Value $ 455,977 $ 422,072
State and Local Governments [Member]    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Fair Value 54,022 56,876
Level 3 [Member] | State and Local Governments [Member]    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Fair Value $ 1,445 $ 1,455
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 $ 3,145 $ 715
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 $ 1,585 $ 1,556
Valuation Technique us-gaap:ValuationTechniqueDiscountedCashFlowMember us-gaap:MarketApproachValuationTechniqueMember
Unobservable Inputs us-gaap:MeasurementInputDiscountRateMember 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 0.0383 0.0326
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 0.0122 0.2272
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 0.0388 0.0368
Level 3 [Member] | Weighted Average | Collateral Dependent Loans [Member]    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Discount rate 0.2458 0.2468
Level 3 [Member] | Weighted Average | Loan Servicing Rights [Member]    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Discount rate 0.4741 0.3621
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 0.0389 0.0375
Level 3 [Member] | Maximum [Member] | Collateral Dependent Loans [Member]    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Discount rate 0.25 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 6.0581 5.8371