Share-Based Payments - Summary of Stock Option Activity and Related Information (Detail)	3 Months Ended
	Mar. 31, 2017 $ / shares shares
Shares
Outstanding at December 31, 2016 (in shares) | shares	2,024,468
Granted (in shares) | shares	0
Exercised (in shares) | shares	(140,400)
Cancelled or forfeited (in shares) | shares	(166,887)
Outstanding at March 31, 2017 (in shares) | shares	1,717,181
Exercisable at March 31, 2017 (in shares) | shares	863,767
Vested and expected to vest at March 31, 2017 (in shares) | shares	1,717,181
Weighted-Average Exercise Price
Outstanding at December 31, 2016 (in USD per share) | $ / shares	$ 4.41
Granted (in USD per share) | $ / shares	0.00
Exercised (in USD per share) | $ / shares	0.28
Cancelled or forfeited (in USD per share) | $ / shares	9.85
Outstanding at March 31, 2017 (in USD per share) | $ / shares	4.22
Exercisable at March 31, 2017 (in USD per share) | $ / shares	4.93
Vested and expected to vest at March 31, 2017 (in USD per share) | $ / shares	$ 4.22