Share Based Compensation - Summary of Stock Option Activity (Detail)	6 Months Ended
	Jun. 30, 2017 USD ($) $ / shares shares
Stockholders Equity Note [Abstract]
Number of Shares Outstanding, Beginning Balance | shares	11,313,909
Number of Shares Granted | shares	2,803,667
Number of Shares Exercised | shares	(969,108)
Number of Shares Cancelled/Forfeited | shares	(674,619)
Number of Shares Outstanding, Ending Balance | shares	12,473,849
Number of Shares Exercisable, Ending Balance | shares	7,614,437
Weighted Average Exercise Price Outstanding, Beginning Balance | $ / shares	$ 1.84
Weighted Average Exercise Price Granted | $ / shares	2.65
Weighted Average Exercise Price Exercised | $ / shares	1.64
Weighted Average Exercise Price Cancelled/Forfeited | $ / shares	2.49
Weighted Average Exercise Price Outstanding, Ending Balance | $ / shares	2.01
Weighted Average Exercise Price Exercisable, Ending Balance | $ / shares	$ 1.94
Weighted Average Remaining Contractual Term (Years) Outstanding, Ending Balance	7 years 4 months 24 days
Weighted Average Remaining Contractual Term (Years) Exercisable, Ending Balance	6 years 2 months 12 days
Aggregate Intrinsic Value Outstanding, Ending Balance | $	$ 15,597,050
Aggregate Intrinsic Value Exercisable, Ending Balance | $	$ 10,232,347