Loans - Summary of Loans by Credit Quality Indicator (Detail) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Financing Receivable, Recorded Investment [Line Items]
Total Loans	$ 534,861	$ 516,300
Commercial [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	142,019	140,273
Commercial Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	182,034	179,663
Residential Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	162,184	157,172
Construction & Land Development [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	30,706	22,886
Consumer [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	17,918	16,306
Pass [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	310,553	297,543
Pass [Member] | Commercial [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	119,590	116,833
Pass [Member] | Commercial Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	164,149	162,012
Pass [Member] | Residential Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	200	205
Pass [Member] | Construction & Land Development [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	26,614	18,493
Special Mention [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	13,684	22,785
Special Mention [Member] | Commercial [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	4,850	13,685
Special Mention [Member] | Commercial Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	8,834	8,220
Special Mention [Member] | Construction & Land Development [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans		880
Substandard [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	24,709	17,988
Substandard [Member] | Commercial [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	16,564	8,841
Substandard [Member] | Commercial Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	7,858	8,620
Substandard [Member] | Residential Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	266	470
Substandard [Member] | Consumer [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	21	57
Not Rated [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	185,915	177,984
Not Rated [Member] | Commercial [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	1,015	914
Not Rated [Member] | Commercial Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	1,193	811
Not Rated [Member] | Residential Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	161,718	156,497
Not Rated [Member] | Construction & Land Development [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	4,092	3,513
Not Rated [Member] | Consumer [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	$ 17,897	$ 16,249