Fair Value of Financial Instruments - Quantitative Information about Unobservable Inputs Used in Recurring and Nonrecurring Level 3 Fair Value Measurements (Detail) $ in Thousands	Mar. 31, 2025 USD ($)	Dec. 31, 2024 USD ($)
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair Value	$ 438,568	$ 426,556
State and Local Governments [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair Value	63,102	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	$ 1,460	$ 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	$ 4,113	$ 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	$ (6)	$ (4)
Valuation Technique	us-gaap:ValuationTechniqueDiscountedCashFlowMember	us-gaap:ValuationTechniqueDiscountedCashFlowMember
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	0.0342	(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	0.098	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	0.0415	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	0.2664	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	1.1489	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	0.0426	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	0.30	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	5.50	6.187