Loans - Summary of Internal Risk Ratings of Loans (Detail) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Financing Receivable, Recorded Investment [Line Items]
Loans and leases receivable gross carrying amount	$ 343,224	$ 372,589
Commercial Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases receivable gross carrying amount	190,173	191,645
Commercial Land Development [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases receivable gross carrying amount	1,851	2,187
Commercial Other [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases receivable gross carrying amount	38,546	30,508
Internal Credit Risk Rating [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases receivable gross carrying amount	230,570	224,340
Internal Credit Risk Rating [Member] | Commercial Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases receivable gross carrying amount	190,173	191,645
Internal Credit Risk Rating [Member] | Commercial Land Development [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases receivable gross carrying amount	1,851	2,187
Internal Credit Risk Rating [Member] | Commercial Other [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases receivable gross carrying amount	38,546	30,508
Pass [Member] | Internal Credit Risk Rating [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases receivable gross carrying amount	219,486	212,400
Pass [Member] | Internal Credit Risk Rating [Member] | Commercial Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases receivable gross carrying amount	184,168	186,303
Pass [Member] | Internal Credit Risk Rating [Member] | Commercial Land Development [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases receivable gross carrying amount	176	158
Pass [Member] | Internal Credit Risk Rating [Member] | Commercial Other [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases receivable gross carrying amount	35,142	25,939
Watch and Special Mention [Member] | Internal Credit Risk Rating [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases receivable gross carrying amount	10,465	10,537
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	5,632	4,403
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	1,675	1,726
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	3,158	4,408
Substandard [Member] | Internal Credit Risk Rating [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases receivable gross carrying amount	619	1,403
Substandard [Member] | Internal Credit Risk Rating [Member] | Commercial Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases receivable gross carrying amount	373	939
Substandard [Member] | Internal Credit Risk Rating [Member] | Commercial Land Development [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases receivable gross carrying amount		303
Substandard [Member] | Internal Credit Risk Rating [Member] | Commercial Other [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases receivable gross carrying amount	$ 246	$ 161