Loans - Additional Information (Detail) (USD $)	9 Months Ended		12 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Dec. 31, 2012
Receivables [Abstract]
Minimum percentage of concentrations of loans	10.00%		10.00%
Concentrations of loans	$ 0		$ 0
Allowance for loan losses	9,418,000	10,500,000	10,648,000
Ratio of the allowance for loan losses to total loans	1.74%	1.91%	1.99%
Company's annualized net charge off ratios	0.61%	0.61%	0.52%
Ratios of allowance for loan losses to non-accrual loans	77.67%	106.78%	138.99%
Annual reviews of loan to ascertain the borrowers continued ability to service	1,000,000
Loans past due period for classify to risk grade	60 days
Loans past due period for classify to substandard grade	12 months
Company's impaired loans	45,277,000	75,800,000	66,604,000
Related Allowance	$ 3,402,000	$ 3,600,000	$ 3,841,000