Regulatory Matters - Additional Information (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Jul. 31, 2013
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Tier 1 Capital to Risk Weighted Assets	11.03%	10.88%
Total Capital to Risk Weighted Assets	13.78%	13.70%
Amount available for dividend distribution without prior approval from Regulatory Agency	$ 73.0
Percentage of Bank's capital and surplus of which extensions of credit to a single affiliate are limited	10.00%
Percentage of Bank's capital and surplus of which extensions of credit to all affiliates are limited	20.00%
Basel III New Requirements [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Common Equity Tier 1 capital minimum buffer percent			2.50%
Minimum [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Tier 1 Capital to Risk Weighted Assets	8.50%
Total Capital to Risk Weighted Assets	10.50%