Loans - Summary of Internal Risk Ratings of Loans (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Financing Receivable, Recorded Investment [Line Items]
Loans and leases receivable gross carrying amount	$ 331,598	$ 312,370
Commercial Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases receivable gross carrying amount	189,291	178,882
Commercial Land Development [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases receivable gross carrying amount	1,492	1,623
Commercial Other [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases receivable gross carrying amount	46,184	34,072
Internal Credit Risk Rating [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases receivable gross carrying amount	236,967	214,577
Internal Credit Risk Rating [Member] | Commercial Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases receivable gross carrying amount	189,291	178,882
Internal Credit Risk Rating [Member] | Commercial Land Development [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases receivable gross carrying amount	1,492	1,623
Internal Credit Risk Rating [Member] | Commercial Other [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases receivable gross carrying amount	46,184	34,072
Pass [Member] | Internal Credit Risk Rating [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases receivable gross carrying amount	201,636	196,356
Pass [Member] | Internal Credit Risk Rating [Member] | Commercial Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases receivable gross carrying amount	163,961	168,834
Pass [Member] | Internal Credit Risk Rating [Member] | Commercial Other [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases receivable gross carrying amount	37,675	27,522
Watch and Special Mention [Member] | Internal Credit Risk Rating [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases receivable gross carrying amount	24,977	11,558
Watch and Special Mention [Member] | Internal Credit Risk Rating [Member] | Commercial Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases receivable gross carrying amount	19,272	4,418
Watch and Special Mention [Member] | Internal Credit Risk Rating [Member] | Commercial Land Development [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases receivable gross carrying amount		1,623
Watch and Special Mention [Member] | Internal Credit Risk Rating [Member] | Commercial Other [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases receivable gross carrying amount	5,705	5,517
Substandard [Member] | Internal Credit Risk Rating [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases receivable gross carrying amount	10,354	6,663
Substandard [Member] | Internal Credit Risk Rating [Member] | Commercial Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases receivable gross carrying amount	6,058	5,630
Substandard [Member] | Internal Credit Risk Rating [Member] | Commercial Land Development [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases receivable gross carrying amount	1,492
Substandard [Member] | Internal Credit Risk Rating [Member] | Commercial Other [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases receivable gross carrying amount	$ 2,804	$ 1,033