Stockholders' Equity - Summary of Stock Option Activity (Detail)	6 Months Ended
	Jun. 30, 2016 $ / shares shares
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Number of Outstanding Options, Beginning Balance | shares	2,625,280
Number of Outstanding Options, Granted | shares	1,691,619
Number of Outstanding Options, Exercised | shares	(15,045)
Number of Outstanding Options, Canceled | shares	(479,148)
Number of Outstanding Options, Ending Balance | shares	3,822,706
Weighted Average Price, Beginning Balance | $ / shares	$ 8.83
Weighted Average Price, Granted | $ / shares	6.39
Weighted Average Price, Exercised | $ / shares	1.27
Weighted Average Price, Canceled | $ / shares	11.07
Weighted Average Price, Ending Balance | $ / shares	$ 7.50