Fair Value Measurement - Assets and Liabilities Measured at Fair Value (Detail) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total securities available for sale	$ 356,824	$ 363,464
Equity securities	974	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	356,824	363,464
Equity securities	974	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	12,609	21,700
Swap liability	12,653	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	26,505	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	228,732	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	101,587	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	$ 2,224	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		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		$ 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).

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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