Loans Receivable and Allowance for Loan Losses - Additional Information (Detail) (USD $)	12 Months Ended
	Dec. 31, 2014 Loan Commitment	Dec. 31, 2013 Loan Commitment
Financing Receivable, Modifications [Line Items]
Troubled debt restructurings loans	$ 5,000,000	$ 4,600,000
Financing receivable impairment modification	6 months
Commitments to lend additional funds to debtors	0	0
Loans receivables gross troubled debt restructurings performing amount	1,100,000	1,200,000
Number of TDR loans	6	5
Recorded investment	400,000	400,000
Specific allowances resulting from TDR modifications	0
Loss estimates of loan minimum percentage	30.00%
Available funds for reimbursement	$ 3,000,000	$ 3,100,000
Troubled Debt Restructurings
Financing Receivable, Modifications [Line Items]
Financing receivable impairment modification	9 months