Loans and Allowance For Credit Losses - Summary of Allowance for Loan Losses (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Loans and Leases Receivable Disclosure [Line Items]
Beginning balance	$ 13,240	$ 12,524	$ 14,111	$ 11,075
Provision for loan losses	300	850	(500)	4,180
Charge-offs	0	0	(278)	(1,976)
Recoveries	31	11	238	106
Ending balance	13,571	13,385	13,571	13,385
Commercial And Industrial [Member]
Loans and Leases Receivable Disclosure [Line Items]
Beginning balance	8,133	7,851	8,923	6,708
Provision for loan losses	45	772	(952)	3,688
Charge-offs		0		(1,868)
Recoveries	31	11	238	106
Ending balance	8,209	8,634	8,209	8,634
Real Estate, Other [Member]
Loans and Leases Receivable Disclosure [Line Items]
Beginning balance	4,069	3,332	3,877	3,281
Provision for loan losses	324	276	516	327
Ending balance	4,393	3,608	4,393	3,608
Real Estate Construction And Land [Member]
Loans and Leases Receivable Disclosure [Line Items]
Beginning balance	697	956	681	1,022
Provision for loan losses	(22)	(280)	(6)	(346)
Ending balance	675	676	675	676
SBA [Member]
Loans and Leases Receivable Disclosure [Line Items]
Beginning balance	317	366	604	50
Provision for loan losses	(44)	79	(53)	503
Charge-offs	0	0	(278)	(108)
Ending balance	273	445	273	445
Other Loans [Member]
Loans and Leases Receivable Disclosure [Line Items]
Beginning balance	24	19	26	14
Provision for loan losses	(3)	3	(5)	8
Ending balance	$ 21	$ 22	$ 21	$ 22