Loans - Summary of Activity in Allowance for Loan and Lease Losses (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Loans and Leases Receivable Disclosure [Line Items]
Beginning balance	$ 3,262	$ 3,093
Provision (credit) for loan losses	(1,032)
Loans charged off	(566)	(124)
Recoveries of loans previously charged off	336	293
Total ending allowance balance	2,000	3,262
Commercial [Member]
Loans and Leases Receivable Disclosure [Line Items]
Beginning balance	1,448	1,369
Provision (credit) for loan losses	(222)
Loans charged off	(214)	(1)
Recoveries of loans previously charged off	223	80
Total ending allowance balance	1,235	1,448
Residential [Member]
Loans and Leases Receivable Disclosure [Line Items]
Beginning balance	1,250	1,246
Provision (credit) for loan losses	(599)
Loans charged off	(83)
Recoveries of loans previously charged off	5	4
Total ending allowance balance	573	1,250
Consumer [Member]
Loans and Leases Receivable Disclosure [Line Items]
Beginning balance	564	478
Provision (credit) for loan losses	(211)
Loans charged off	(269)	(123)
Recoveries of loans previously charged off	108	209
Total ending allowance balance	$ 192	$ 564