Allowance for Loan Losses - Loan Receivables Evaluated for Impairment Individually and Collectively by Segment (Detail) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Accounts, Notes, Loans and Financing Receivable [Line Items]
Individually evaluated for impairment	$ 10,415	$ 10,826
Collectively evaluated for impairment	374,594	336,396
Total Gross Loans	385,009	347,222
Mortgage Loans on Real Estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Individually evaluated for impairment	10,323	10,542
Collectively evaluated for impairment	328,118	296,561
Total Gross Loans	338,441	307,103
Commercial and Industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Individually evaluated for impairment	92	284
Collectively evaluated for impairment	42,932	34,820
Total Gross Loans	43,024	35,104
Consumer and Other Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Collectively evaluated for impairment	3,544	5,015
Total Gross Loans	$ 3,544	$ 5,015