Stockholders' Equity - Summary of Stock Option Activity (Detail) (USD $)	9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013
Stockholders' Equity Note [Abstract]
Number of Shares Outstanding, Beginning	7,697,892
Number of Shares Granted	1,957,701
Number of Shares Exercised	(1,991,728)	(707,285)
Number of Shares canceled/Forfeited	(556,675)
Number of Shares Outstanding, Ending	7,107,190
Number of Shares Exercisable, Ending	4,893,821
Weighted Average Exercise Price Outstanding, Beginning Balance	$ 1.89
Weighted Average Exercise Price Granted	$ 3.08
Weighted Average Exercise Price Exercised	$ 1.19	$ 0.72
Weighted Average Exercise Price Cancelled/Forfeited	$ 3.36
Weighted Average Exercise Price Outstanding, Ending Balance	$ 2.30
Weighted Average Exercise Price Exercisable, Ending Balance	$ 1.85
Weighted Average Remaining Contractual Term Outstanding, Ending	6 years 3 months 18 days
Weighted Average Remaining Contractual Term Exercisable, Ending	5 years
Aggregate Intrinsic Value, Exercised	$ 3,499,052
Aggregate Intrinsic Value Outstanding, Ending	2,050,397
Aggregate Intrinsic Value Exercisable, Ending	$ 2,050,397