Securities - Additional Information (Detail) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Schedule of Available-for-sale Securities [Line Items]
Fair value of securities	$ 3,500	$ 11,100
Debt Securities, Available-for-sale, Restriction Type [Extensible List]	us-gaap:CollateralPledgedMember	us-gaap:CollateralPledgedMember
Securities sold under repurchase agreements	$ 1,117	$ 6,525	[1]
Amortized cost	85,868	98,894
Unrealized losses	107	181
Company's investment in Federal Home Loan Bank stock	2,100	2,900
Company's investment in Federal Reserve Bank stock	2,700	2,600
Investment in primary correspondent bank stock	220	220
Corporate Bonds
Schedule of Available-for-sale Securities [Line Items]
Amortized cost	20,154	$ 15,165
Unrealized losses	91
Corporate Bonds | Subordinated Debt | Blue Ridge
Schedule of Available-for-sale Securities [Line Items]
Amortized cost	1,800
Unrealized losses	$ 68

[1] Derived from audited December 31, 2019 Consolidated Financial Statements.