Allowance for Loan Losses - Summary of Performing and Nonperforming Loans by Class (Detail) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Financing Receivable Recorded Investment [Line Items]
Loans	$ 349,919	$ 341,829
Real Estate - Commercial [Member]
Financing Receivable Recorded Investment [Line Items]
Loans	116,178	109,752
Other Real Estate Construction [Member]
Financing Receivable Recorded Investment [Line Items]
Loans	32,511	26,718
Real Estate 1 - 4 Family Construction [Member]
Financing Receivable Recorded Investment [Line Items]
Loans	4,360	5,625
Real Estate - Residential [Member]
Financing Receivable Recorded Investment [Line Items]
Loans	77,427	81,769
Home Equity [Member]
Financing Receivable Recorded Investment [Line Items]
Loans	49,840	50,815
Other Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Loans	2,703	1,687
Commercial Loan [Member]
Financing Receivable Recorded Investment [Line Items]
Loans	56,469	55,752
Consumer Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Loans	10,431	9,711
Performing [Member]
Financing Receivable Recorded Investment [Line Items]
Loans	349,159	340,379
Performing [Member] | Real Estate - Commercial [Member]
Financing Receivable Recorded Investment [Line Items]
Loans	115,721	109,360
Performing [Member] | Other Real Estate Construction [Member]
Financing Receivable Recorded Investment [Line Items]
Loans	32,458	26,528
Performing [Member] | Real Estate 1 - 4 Family Construction [Member]
Financing Receivable Recorded Investment [Line Items]
Loans	4,360	5,625
Performing [Member] | Real Estate - Residential [Member]
Financing Receivable Recorded Investment [Line Items]
Loans	77,238	80,923
Performing [Member] | Home Equity [Member]
Financing Receivable Recorded Investment [Line Items]
Loans	49,781	50,793
Performing [Member] | Other Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Loans	2,703	1,687
Performing [Member] | Commercial Loan [Member]
Financing Receivable Recorded Investment [Line Items]
Loans	56,469	55,752
Performing [Member] | Consumer Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Loans	10,429	9,711
Non-Performing [Member]
Financing Receivable Recorded Investment [Line Items]
Loans	760	1,450
Non-Performing [Member] | Real Estate - Commercial [Member]
Financing Receivable Recorded Investment [Line Items]
Loans	457	392
Non-Performing [Member] | Other Real Estate Construction [Member]
Financing Receivable Recorded Investment [Line Items]
Loans	53	190
Non-Performing [Member] | Real Estate - Residential [Member]
Financing Receivable Recorded Investment [Line Items]
Loans	190	846
Non-Performing [Member] | Home Equity [Member]
Financing Receivable Recorded Investment [Line Items]
Loans	58	$ 22
Non-Performing [Member] | Consumer Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Loans	$ 2