Fair Value Measurement - Assets and Liabilities Measured at Fair Value (Detail) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total securities available for sale	$ 498,149	$ 363,464
Equity securities	1,077	886
(Level 2) [Member] \| Assets Measured at Fair Value on a Recurring Basis [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total securities available for sale	498,149	363,464
Equity securities	1,077	886
(Level 2) [Member] \| Assets Measured at Fair Value on a Recurring Basis [Member] \| Swap [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Swap asset	12,858	21,700
Swap liability	12,858	21,764
(Level 2) [Member] \| Assets Measured at Fair Value on a Recurring Basis [Member] \| U.S. Treasury Securities and Obligations of U.S. Government Agencies [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total securities available for sale	53,277	21,693
(Level 2) [Member] \| Assets Measured at Fair Value on a Recurring Basis [Member] \| Obligations of States and Political Subdivisions [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total securities available for sale	256,715	229,012
(Level 2) [Member] \| Assets Measured at Fair Value on a Recurring Basis [Member] \| Mortgage-backed Securities in Government Sponsored Entities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total securities available for sale	188,157	112,759
(Level 3) [Member] \| Assets Measured at Fair Value on a Nonrecurring Basis [Member] \| Mortgage Servicing Rights [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	2,576	2,246
(Level 3) [Member] \| Assets Measured at Fair Value on a Nonrecurring Basis [Member] \| Impaired Loans [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	11	1
(Level 3) [Member] \| Assets Measured at Fair Value on a Nonrecurring Basis [Member] \| Other Real Estate Owned [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	$ 26	$ 31

Fair value portion of probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.

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Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Fair value of liability associated with financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset.

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Fair value, before effects of master netting arrangements, of a financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes assets elected not to be offset. Excludes assets not subject to a master netting arrangement.

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Amount of investment in equity security measured at fair value with change in fair value recognized in net income (FV-NI), classified as current.

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