Stock Option Activities (Detail) (USD $)	9 Months Ended	12 Months Ended
	Sep. 30, 2013	Dec. 31, 2012	Dec. 31, 2011
Number of shares
Beginning Balance	45,600	45,600
Options granted	0	0
Options exercised	0	0
Options expired	(600)	0
Ending Balance	45,000	45,600	45,600
Weighted Average Exercise Price per Share
Beginning Balance	$ 14.75	$ 14.75
Options granted	$ 0	$ 0
Options exercised	$ 0	$ 0
Options expired	$ (0.05)	$ 0
Ending Balance	$ 14.90	$ 14.75	$ 14.75
Weighted Average Fair Value at Grant Date
Options granted	$ 0	$ 0
Weighted Average Remaining Contractual Life
Weighted Average Remaining Contractual Life	1 year 3 months 18 days	1 year 3 months 18 days	1 year 3 months 18 days
Intrinsic Value
Beginning Balance	$ 0	$ 0
Options granted	0	0
Options exercised	0	0
Options expired	0	0
Ending Balance	$ 0	$ 0	$ 0