Goodwill and Intangible Assets - Information on Intangible Assets, Other than Goodwill (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Schedule Of Goodwill And Purchased Intangible Assets [Line Items]
Gross Carrying Value	$ 4,647	$ 4,669
Accumulated Amortization	1,477	679
Net Carrying Value	3,170	3,990
Mortgage Servicing Rights
Schedule Of Goodwill And Purchased Intangible Assets [Line Items]
Net Carrying Value	977	999
Core Deposits
Schedule Of Goodwill And Purchased Intangible Assets [Line Items]
Gross Carrying Value	3,670	3,670
Accumulated Amortization	1,477	679
Net Carrying Value	$ 2,193	$ 2,991