Fair Value Measurements - Assets Recognized in Consolidated Balance Sheets Measured at Fair Value on Recurring Basis (Details) - Fair Value, Measurements, Recurring - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
U.S. government agencies
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Fair value of asset, recurring basis		$ 10,053
State and municipal obligations
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Fair value of asset, recurring basis	$ 119,610	143,509
Subordinated notes
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Fair value of asset, recurring basis	15,930	4,505
Fair Value, Inputs, Level 1 | U.S. government agencies
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Fair value of asset, recurring basis		0
Fair Value, Inputs, Level 1 | State and municipal obligations
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Fair value of asset, recurring basis	0	0
Fair Value, Inputs, Level 1 | Subordinated notes
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Fair value of asset, recurring basis	0	0
Fair Value, Inputs, Level 2 | U.S. government agencies
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Fair value of asset, recurring basis		10,053
Fair Value, Inputs, Level 2 | State and municipal obligations
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Fair value of asset, recurring basis	119,610	143,509
Fair Value, Inputs, Level 2 | Subordinated notes
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Fair value of asset, recurring basis	15,930	4,505
Fair Value, Inputs, Level 3 | U.S. government agencies
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Fair value of asset, recurring basis		0
Fair Value, Inputs, Level 3 | State and municipal obligations
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Fair value of asset, recurring basis	0	0
Fair Value, Inputs, Level 3 | Subordinated notes
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Fair value of asset, recurring basis	$ 0	$ 0