Allowance for Loan Losses - Additional Information (Detail) (USD $)	12 Months Ended
	Dec. 31, 2014 Loan Contract	Dec. 31, 2013 Contract
Accounts, Notes, Loans and Financing Receivable [Line Items]
Period of nonperforming loans	90 days
Non-accruing loans excluded from impaired loan	$ 663,000	$ 724,000
Non-accruing loans accrued interest	32,000	23,000
Subsequently defaulted number of loans	3
Number of trouble debt restructurings	14	14
Aggregate balance of trouble debt restructuring	2,500,000	2,500,000
Charge off of loan default	$ 75,000