Fair Value Measurement - Assets and Liabilities Measured at Fair Value (Detail) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total securities available for sale	$ 593,487	$ 615,402
Equity securities	2,021	2,190
Assets Measured at Fair Value on a Recurring Basis [Member] | (Level 2) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total securities available for sale	593,487	615,402
Equity securities	2,021	2,190
Assets Measured at Fair Value on a Recurring Basis [Member] | (Level 2) [Member] | Swap [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Swap asset	19,784	16,579
Swap liability	19,784	16,579
Assets Measured at Fair Value on a Recurring Basis [Member] | (Level 2) [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	71,295	61,029
Assets Measured at Fair Value on a Recurring Basis [Member] | (Level 2) [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	310,535	317,248
Assets Measured at Fair Value on a Recurring Basis [Member] | (Level 2) [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	211,657	237,125
Assets Measured at Fair Value on a Nonrecurring Basis [Member] | (Level 3) [Member] | Mortgage Servicing Rights [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	$ 3,046	$ 2,689