Loans - Summary of Internal Risk Ratings of Loans (Detail) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Financing Receivable, Recorded Investment [Line Items]
Loans and leases receivable gross carrying amount	$ 312,370	$ 372,589
Commercial Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases receivable gross carrying amount	178,882	191,645
Commercial Land Development [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases receivable gross carrying amount	1,623	2,187
Commercial Other [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases receivable gross carrying amount	34,072	30,508
Internal Credit Risk Rating [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases receivable gross carrying amount	214,577	224,340
Internal Credit Risk Rating [Member] | Commercial Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases receivable gross carrying amount	178,882	191,645
Internal Credit Risk Rating [Member] | Commercial Land Development [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases receivable gross carrying amount	1,623	2,187
Internal Credit Risk Rating [Member] | Commercial Other [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases receivable gross carrying amount	34,072	30,508
Internal Credit Risk Rating [Member] | Pass [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases receivable gross carrying amount	196,356	212,400
Internal Credit Risk Rating [Member] | Pass [Member] | Commercial Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases receivable gross carrying amount	168,834	186,303
Internal Credit Risk Rating [Member] | Pass [Member] | Commercial Land Development [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases receivable gross carrying amount		158
Internal Credit Risk Rating [Member] | Pass [Member] | Commercial Other [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases receivable gross carrying amount	27,522	25,939
Internal Credit Risk Rating [Member] | Watch and Special Mention [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases receivable gross carrying amount	11,558	10,537
Internal Credit Risk Rating [Member] | Watch and Special Mention [Member] | Commercial Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases receivable gross carrying amount	4,418	4,403
Internal Credit Risk Rating [Member] | Watch and Special Mention [Member] | Commercial Land Development [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases receivable gross carrying amount	1,623	1,726
Internal Credit Risk Rating [Member] | Watch and Special Mention [Member] | Commercial Other [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases receivable gross carrying amount	5,517	4,408
Internal Credit Risk Rating [Member] | Substandard [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases receivable gross carrying amount	6,663	1,403
Internal Credit Risk Rating [Member] | Substandard [Member] | Commercial Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases receivable gross carrying amount	5,630	939
Internal Credit Risk Rating [Member] | Substandard [Member] | Commercial Land Development [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases receivable gross carrying amount		303
Internal Credit Risk Rating [Member] | Substandard [Member] | Commercial Other [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases receivable gross carrying amount	$ 1,033	$ 161