Loans - Summary of Loans by Credit Quality Indicator (Detail) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Financing Receivable, Recorded Investment [Line Items]
Total Loans	$ 508,929	$ 474,968
Commercial [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	137,459	134,268
Commercial Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	177,588	159,475
Residential Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	153,281	144,489
Construction & Land Development [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	23,915	23,428
Consumer [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	16,686	13,308
Pass [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	294,357	283,768
Pass [Member] | Commercial [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	115,301	116,739
Pass [Member] | Commercial Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	160,677	149,630
Pass [Member] | Residential Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	208	216
Pass [Member] | Construction & Land Development [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	18,171	17,183
Special Mention [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	27,510	12,023
Special Mention [Member] | Commercial [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	16,167	6,874
Special Mention [Member] | Commercial Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	9,933	4,168
Special Mention [Member] | Construction & Land Development [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	1,410	981
Substandard [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	12,057	15,149
Substandard [Member] | Commercial [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	5,130	9,704
Substandard [Member] | Commercial Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	6,744	4,766
Substandard [Member] | Residential Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	183	175
Substandard [Member] | Construction & Land Development [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans		504
Not Rated [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	175,005	164,028
Not Rated [Member] | Commercial [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	861	951
Not Rated [Member] | Commercial Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	234	911
Not Rated [Member] | Residential Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	152,890	144,098
Not Rated [Member] | Construction & Land Development [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	4,334	4,760
Not Rated [Member] | Consumer [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	$ 16,686	$ 13,308