Fair Value Measurement and Fair Value of Financial Instruments - Fair Value of Financial Assets Measured on Non-recurring Basis (Detail) - Fair Value, Measurements, Non-recurring - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired loans	$ 5,789	$ 8,966
Loans held for sale	1,743	1,113
Other real estate owned and other repossessed assets	563	830
Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired loans	0	0
Loans held for sale	0	0
Other real estate owned and other repossessed assets	0	0
Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired loans	0	0
Loans held for sale	1,743	1,113
Other real estate owned and other repossessed assets	0	0
Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired loans	5,789	8,966
Loans held for sale	0	0
Other real estate owned and other repossessed assets	$ 563	$ 830