Loans Receivable - Additional Information (Detail) (USD $)	9 Months Ended	12 Months Ended
	Sep. 30, 2013 Office	Dec. 31, 2012 Office
Receivables [Abstract]
Number of offices of company	23	23
Historical loss calculation period	3 years
Allowance for loan losses	$ 6,713,000	$ 6,709,000
Borrowers sustained repayment period	6 months
Non-performing loans, including non-accrual loans and TDRs	6,665,000	7,393,000
Troubled debt restructuring (TDRs)	112,000	368,000
TDR with modified terms	$ 10,600,000	$ 8,200,000
Maturity period of impaired loans	90 days
Maturity period of Larger commercial loans	60 days
Description of Loans	Loans are considered nonaccrual upon reaching 90 days delinquency