Goodwill and Other Intangible Assets - Schedule of Other Intangible Assets (Detail) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Finite-Lived Intangible Assets [Line Items]
Other intangible assets, net	$ 1,019	$ 1,563
Core deposits [Member]
Finite-Lived Intangible Assets [Line Items]
Other intangible assets, net	845	1,296
Customer relationships [Member]
Finite-Lived Intangible Assets [Line Items]
Other intangible assets, net	$ 174	$ 267