Loans - Summary of Company's Loans by Risk Rating (Detail) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	$ 335,086	$ 287,102
Construction [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	23,629	7,807
Pass [Member] | Construction [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	23,286	7,807
Special Mention [Member] | Construction [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	343
Commercial Real Estate Loans [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	88,394	74,911
Commercial Real Estate Loans [Member] | Pass [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	88,186	73,517
Commercial Real Estate Loans [Member] | Special Mention [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans		1,145
Commercial Real Estate Loans [Member] | Substandard [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	208	249
Commercial and Industrial [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	2,067	2,040
Commercial and Industrial [Member] | Pass [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	$ 2,067	2,006
Commercial and Industrial [Member] | Substandard [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans		$ 34