Loans - Summary of Activity in Allowance for Loan and Lease Losses (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Loans and Leases Receivable Disclosure [Line Items]
Beginning balance	$ 2,000	$ 3,262
Provision (credit) for loan losses	500	(1,032)
Loans charged-off	(68)	(566)
Recoveries of loans previously charged off	271	336
Ending balance	2,703	2,000
Commercial [Member]
Loans and Leases Receivable Disclosure [Line Items]
Beginning balance	1,235	1,448
Provision (credit) for loan losses	360	(222)
Loans charged-off		(214)
Recoveries of loans previously charged off	14	223
Ending balance	1,609	1,235
Residential [Member]
Loans and Leases Receivable Disclosure [Line Items]
Beginning balance	573	1,250
Provision (credit) for loan losses	100	(599)
Loans charged-off	(60)	(83)
Recoveries of loans previously charged off	132	5
Ending balance	745	573
Consumer [Member]
Loans and Leases Receivable Disclosure [Line Items]
Beginning balance	192	564
Provision (credit) for loan losses	40	(211)
Loans charged-off	(8)	(269)
Recoveries of loans previously charged off	125	108
Ending balance	$ 349	$ 192