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, 2022 USD ($)	Dec. 31, 2021 USD ($)
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair Value	$ 395,485	$ 429,931
State and Local Governments [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair Value	72,039	65,941
Level 3 [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair Value	3,366	4,773
Level 3 [Member] | State and Local Governments [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair Value	$ 3,366	$ 4,773
Valuation Technique	us-gaap:ValuationTechniqueDiscountedCashFlowMember	us-gaap:ValuationTechniqueDiscountedCashFlowMember
Unobservable Inputs	us-gaap:MeasurementInputDiscountRateMember	us-gaap:MeasurementInputDiscountRateMember
Level 3 [Member] | Collateral Dependent Impaired Loans [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair Value	$ 2,482	$ 8,527
Valuation Technique	us-gaap:MarketApproachValuationTechniqueMember	us-gaap:MarketApproachValuationTechniqueMember
Level 3 [Member] | Mortgage Servicing Rights [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair Value	$ 52	$ 3,157
Valuation Technique	us-gaap:ValuationTechniqueDiscountedCashFlowMember	us-gaap:ValuationTechniqueDiscountedCashFlowMember
Unobservable Inputs	us-gaap:MeasurementInputDiscountRateMember	us-gaap:MeasurementInputDiscountRateMember
Level 3 [Member] | Other Real Estate Owned-Residential [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair Value		$ 99
Valuation Technique		us-gaap:MarketApproachValuationTechniqueMember
Unobservable Inputs		us-gaap:MeasurementInputAppraisedValueMember
Discount rate		32.72
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	2.13	0.21
Level 3 [Member] | Minimum [Member] | Collateral Dependent Impaired Loans [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Discount rate	20.00	20.00
Level 3 [Member] | Minimum [Member] | Mortgage Servicing Rights [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Discount rate	0.09	1.94
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	3.96	1.33
Level 3 [Member] | Weighted Average | Collateral Dependent Impaired Loans [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Discount rate	23.80	34.78
Level 3 [Member] | Weighted Average | Mortgage Servicing Rights [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Discount rate	1.81	18.44
Level 3 [Member] | Weighted Average | Other Real Estate Owned-Residential [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Discount rate		32.72
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	4.59	1.77
Level 3 [Member] | Maximum [Member] | Collateral Dependent Impaired Loans [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Discount rate	23.87	53.95
Level 3 [Member] | Maximum [Member] | Mortgage Servicing Rights [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Discount rate	1.85	27.70