Leases - Additional Information (Detail) $ in Thousands	12 Months Ended
	Dec. 31, 2018 USD ($) RealEstate Office	Dec. 31, 2017 USD ($) Branch
Operating Leased Assets [Line Items]
Number of retail branches | Branch		4
Number of additional long-term real estate leases | RealEstate	6
Lease expense | $	$ 577	$ 377
Virginia [Member]
Operating Leased Assets [Line Items]
Number of additional office suites | Office	2