Share-Based Payments - Summary of Stock Option Activity and Related Information (Detail)	6 Months Ended
	Jun. 30, 2016 $ / shares shares
Shares
Outstanding at beginning of period (in shares) | shares	1,803,574
Granted (in shares) | shares	981,352
Exercised (in shares) | shares	(281,441)
Cancelled or forfeited (in shares) | shares	(297,711)
Outstanding at end of period (in shares) | shares	2,205,774
Exercisable at June 30, 2016 (in shares) | shares	891,327
Vested and expected to vest at June 30, 2016 (in shares) | shares	1,923,413
Weighted-Average Exercise Price
Outstanding at beginning of period (in USD per share) | $ / shares	$ 6.28
Granted (in USD per share) | $ / shares	0.39
Exercised (in USD per share) | $ / shares	0.29
Cancelled or forfeited (in USD per share) | $ / shares	3.60
Outstanding at end of period (in USD per share) | $ / shares	4.78
Exercisable at end of period (in USD per share) | $ / shares	6.05
Vested and expected to vest at end of period | $ / shares	$ 5.20