Allowances for Loan Losses - Summary of Allowances for Loan Losses by Loan Class (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Loans and Leases Receivable Disclosure [Line Items]
Beginning balance	$ 4,386	$ 3,644	$ 4,177	$ 1,689
Charge-offs	0	0	0	0
Recoveries	4	5	6	12
Provision	410	115	617	2,065
Ending balance	4,800	3,766	4,800	3,766
Commercial and Industrial [Member]
Loans and Leases Receivable Disclosure [Line Items]
Beginning balance	901	904	1,002	623
Charge-offs	0	0	0	0
Recoveries	2	4	3	6
Provision	73	32	(29)	311
Ending balance	976	940	976	940
Construction and Land Development [Member]
Loans and Leases Receivable Disclosure [Line Items]
Beginning balance	408	226	397	170
Charge-offs	0	0	0	0
Recoveries	0	0	0	0
Provision	84	100	95	156
Ending balance	492	326	492	326
Real Estate Commercial [Member]
Loans and Leases Receivable Disclosure [Line Items]
Beginning balance	2,343	1,638	2,082	598
Charge-offs	0	0	0	0
Recoveries	0	0	0	0
Provision	177	127	438	1,167
Ending balance	2,520	1,765	2,520	1,765
Real Estate Residential [Member]
Loans and Leases Receivable Disclosure [Line Items]
Beginning balance	484	526	418	214
Charge-offs	0	0	0	0
Recoveries	2	3	3	6
Provision	24	(32)	89	277
Ending balance	510	497	510	497
Real Estate Home Equity [Member]
Loans and Leases Receivable Disclosure [Line Items]
Beginning balance	219	103	242	45
Charge-offs	0	0	0	0
Recoveries	0	0	0	0
Provision	36	(6)	13	52
Ending balance	255	97	255	97
Consumer Other [Member]
Loans and Leases Receivable Disclosure [Line Items]
Beginning balance	31	76	35	9
Charge-offs	0	0	0	0
Recoveries	0	0	0	0
Provision	16	(62)	12	5
Ending balance	47	14	47	14
Unallocated [Member]
Loans and Leases Receivable Disclosure [Line Items]
Beginning balance	0	171	1	30
Charge-offs	0	0	0	0
Recoveries	0	0	0	0
Provision	0	(44)	(1)	97
Ending balance	$ 0	$ 127	$ 0	$ 127