Stockholder's Equity - Summary of Activity Related to Options Granted (Detail) (USD $)	9 Months Ended	12 Months Ended
	Sep. 30, 2013	Dec. 31, 2012
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Number of options outstanding, beginning balance	3,640,324	2,674,324
Number of options granted	446,000	1,014,000
Number of options exercised	(5,000)
Number of options forfeited		(33,000)
Number of options expired		(15,000)
Number of options outstanding, ending balance	4,081,324	3,640,324
Number of options exercisable	3,226,658
Weighted average exercise price, options outstanding, beginning balance	$ 1.76	$ 1.59
Number of options available for grant ending balance	854,666
Weighted average exercise price, options granted	$ 2.61	$ 2.30
Weighted average exercise price, options exercised	$ 2.75
Weighted average exercise price, options forfeited		$ 2.47
Weighted average exercise price, options expired		$ 2.68
Weighted average exercise price, options outstanding, ending balance	$ 1.85	$ 1.76
Weighted average remaining contractual term, options outstanding, beginning balance	2 years 8 months 9 days	2 years 5 months 5 days
Weighted average exercise price, options exercisable	$ 1.70
Weighted average remaining contractual term, options outstanding, ending balance		2 years 8 months 9 days
Weighted average remaining contractual term, exercisable options, ending Balance	2 years 3 months 22 days
Aggregate fair value, beginning balance	$ 6,406,970	$ 4,252,175
Aggregate fair value, ending balance	7,550,449	6,406,970
Aggregate fair value, exercisable	$ 5,485,319