Fair Value Measurement - Schedule of Assets Measured at Fair Value on Nonrecurring Basis (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Fair Value Inputs Asset Quantitative Information [Line Items]
Other real estate owned and repossessed assets	$ 549	$ 4,178
Fair Value, Measurements, Nonrecurring [Member]
Fair Value Inputs Asset Quantitative Information [Line Items]
Individually-evaluated nonperforming loans	1,958
Other real estate owned and repossessed assets	549	4,178
Impaired loans		2,362
Fair Value, Measurements, Nonrecurring [Member] | Significant Unobservable Inputs (Level 3) [Member]
Fair Value Inputs Asset Quantitative Information [Line Items]
Individually-evaluated nonperforming loans	1,958
Other real estate owned and repossessed assets	$ 549	4,178
Impaired loans		$ 2,362
Individually-evaluated nonperforming loans, Appraisal adjustments	(30.00%)
Individually-evaluated nonperforming loans, Liquidation expenses	(5.60%)
Impaired loans, Appraisal adjustments		(29.80%)
Impaired Loans Liquidation Expenses		(5.30%)
Fair Value, Measurements, Nonrecurring [Member] | Significant Unobservable Inputs (Level 3) [Member] | Weighted Average [Member]
Fair Value Inputs Asset Quantitative Information [Line Items]
Individually-evaluated nonperforming loans, Appraisal adjustments	(30.00%)
Individually-evaluated nonperforming loans, Liquidation expenses	(5.60%)
Impaired loans, Appraisal adjustments		(29.80%)
Impaired Loans Liquidation Expenses		(5.30%)