Allowance for Loan Losses - Allowance for Loan Losses Disaggregated Based on Loan Receivables Evaluated for Impairment Individually and Collectively by Segment (Detail) - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014
Accounts, Notes, Loans and Financing Receivable [Line Items]
Individually evaluated for impairment	$ 830	$ 676
Collectively evaluated for impairment	2,544	2,529
Total allowance for loan losses	3,374	3,205	[1]
Mortgage Loans on Real Estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Individually evaluated for impairment	711	665
Collectively evaluated for impairment	2,103	2,113
Total allowance for loan losses	2,814	2,778
Commercial and Industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Individually evaluated for impairment	119
Collectively evaluated for impairment	314	323
Total allowance for loan losses	433	323
Consumer and Other Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Individually evaluated for impairment		11
Collectively evaluated for impairment	127	93
Total allowance for loan losses	$ 127	$ 104

[1] Derived from the audited consolidated financial statements.