Allowance for Loan Losses - Summary of Risk Grades of Portfolio by Class (Detail) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Financing Receivable Recorded Investment [Line Items]
Loans	$ 368,252	$ 357,950
Real Estate - Commercial [Member]
Financing Receivable Recorded Investment [Line Items]
Loans	133,618	130,998
Other Real Estate Construction [Member]
Financing Receivable Recorded Investment [Line Items]
Loans	29,136	23,043
Real Estate 1 - 4 Family Construction [Member]
Financing Receivable Recorded Investment [Line Items]
Loans	8,882	7,600
Real Estate - Residential [Member]
Financing Receivable Recorded Investment [Line Items]
Loans	70,675	71,122
Home Equity [Member]
Financing Receivable Recorded Investment [Line Items]
Loans	52,801	51,216
Other Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Loans	2,691	1,939
Commercial Loan [Member]
Financing Receivable Recorded Investment [Line Items]
Loans	58,180	59,075
Consumer Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Loans	12,269	12,957
Pass [Member]
Financing Receivable Recorded Investment [Line Items]
Loans	355,190	344,220
Pass [Member] | Real Estate - Commercial [Member]
Financing Receivable Recorded Investment [Line Items]
Loans	129,525	126,498
Pass [Member] | Other Real Estate Construction [Member]
Financing Receivable Recorded Investment [Line Items]
Loans	27,349	21,253
Pass [Member] | Real Estate 1 - 4 Family Construction [Member]
Financing Receivable Recorded Investment [Line Items]
Loans	8,882	7,600
Pass [Member] | Real Estate - Residential [Member]
Financing Receivable Recorded Investment [Line Items]
Loans	67,198	67,647
Pass [Member] | Home Equity [Member]
Financing Receivable Recorded Investment [Line Items]
Loans	51,739	50,255
Pass [Member] | Other Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Loans	2,691	1,939
Pass [Member] | Commercial Loan [Member]
Financing Receivable Recorded Investment [Line Items]
Loans	55,632	56,151
Pass [Member] | Consumer Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Loans	12,174	12,877
Watch [Member]
Financing Receivable Recorded Investment [Line Items]
Loans	7,520	9,014
Watch [Member] | Real Estate - Commercial [Member]
Financing Receivable Recorded Investment [Line Items]
Loans	1,177	1,194
Watch [Member] | Other Real Estate Construction [Member]
Financing Receivable Recorded Investment [Line Items]
Loans	394	1,477
Watch [Member] | Real Estate - Residential [Member]
Financing Receivable Recorded Investment [Line Items]
Loans	2,377	2,464
Watch [Member] | Home Equity [Member]
Financing Receivable Recorded Investment [Line Items]
Loans	982	879
Watch [Member] | Commercial Loan [Member]
Financing Receivable Recorded Investment [Line Items]
Loans	2,508	2,921
Watch [Member] | Consumer Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Loans	82	79
Sub-standard [Member]
Financing Receivable Recorded Investment [Line Items]
Loans	5,542	4,716
Sub-standard [Member] | Real Estate - Commercial [Member]
Financing Receivable Recorded Investment [Line Items]
Loans	2,916	3,306
Sub-standard [Member] | Other Real Estate Construction [Member]
Financing Receivable Recorded Investment [Line Items]
Loans	1,393	313
Sub-standard [Member] | Real Estate - Residential [Member]
Financing Receivable Recorded Investment [Line Items]
Loans	1,100	1,011
Sub-standard [Member] | Home Equity [Member]
Financing Receivable Recorded Investment [Line Items]
Loans	80	82
Sub-standard [Member] | Commercial Loan [Member]
Financing Receivable Recorded Investment [Line Items]
Loans	40	3
Sub-standard [Member] | Consumer Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Loans	$ 13	$ 1