Loans - Summary of Allowance for Loan and Lease Losses for Loans Evaluated Individually and Collectively for Impairment (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Loans and Leases Receivable Disclosure [Line Items]
Individually evaluated for impairment	$ 11,005	$ 8,041
Collectively evaluated for impairment	320,593	304,329
Total loans	331,598	312,370
Individually evaluated for impairment		67
Collectively evaluated for impairment	2,703	1,933
Total allowance for loan losses	2,703	2,000	$ 3,262
Commercial [Member]
Loans and Leases Receivable Disclosure [Line Items]
Individually evaluated for impairment	10,573	6,931
Collectively evaluated for impairment	226,394	207,646
Total loans	236,967	214,577
Collectively evaluated for impairment	1,609	1,235
Total allowance for loan losses	1,609	1,235	1,448
Residential [Member]
Loans and Leases Receivable Disclosure [Line Items]
Individually evaluated for impairment	411	1,078
Collectively evaluated for impairment	71,511	66,413
Total loans	71,922	67,491
Individually evaluated for impairment		62
Collectively evaluated for impairment	745	511
Total allowance for loan losses	745	573	1,250
Consumer [Member]
Loans and Leases Receivable Disclosure [Line Items]
Individually evaluated for impairment	21	32
Collectively evaluated for impairment	22,688	30,270
Total loans	22,709	30,302
Individually evaluated for impairment		5
Collectively evaluated for impairment	349	187
Total allowance for loan losses	$ 349	$ 192	$ 564

The valuation allowance for financing receivables that are expected to be uncollectible that were collectively evaluated for impairment.

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Amount of valuation allowance for financing receivables that are expected to be uncollectible that were individually evaluated for impairment.

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The balance of financing receivables that were collectively evaluated for impairment.

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Amount of allowance to cover probable credit losses on loans and leases. Includes carryover of or adjustments to the allowance for loan losses in connection with business combinations. Excludes allowance for loans and leases covered under loss sharing agreements.

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Amount, after allowance for credit loss, of financing receivable. Excludes financing receivable covered under loss sharing agreement.

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Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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