Allowance for Loan Losses - Additional Information (Detail) (USD $)	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014	Dec. 31, 2014
Accounts, Notes, Loans and Financing Receivable [Line Items]
Period of nonperforming loans	90 days
Non-accruing loans excluded from impaired loan	$ 489,000		$ 663,000
Non-accruing loans accrued interest	9,000	4,000
Residential First Mortgages
Accounts, Notes, Loans and Financing Receivable [Line Items]
Minimum balance in order to assign a risk rating grade	1,000,000
Consumer Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Minimum balance in order to assign a risk rating grade	$ 250,000