Loans - Summary of Loans (Detail) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans before deferred costs	$ 508,929	$ 474,968
Deferred loan costs	529	481
Total Loans	509,458	475,449
Commercial [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans before deferred costs	137,459	134,268
Commercial Real Estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans before deferred costs	177,588	159,475
Residential Real Estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans before deferred costs	153,281	144,489
Construction & Land Development [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans before deferred costs	23,915	23,428
Consumer [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans before deferred costs	$ 16,686	$ 13,308