Stockholders' Equity - Summary of Stock Option Activity (Detail) - USD ($) $ / shares in Units, $ in Thousands	6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Outstanding, Number of shares, beginning balance	3,137,529
Granted, Number of shares	462,600
Exercised, Number of share	(2,444)	(2,595)
Forfeited or expired, Number of share	(173,586)
Outstanding, Number of shares, ending balance	3,424,099
Vested and expected to vest, Number of shares	3,424,099
Exercisable, Number of shares	702,649
Outstanding, Weighted Average Exercise Price, beginning balance	$ 25.81
Granted, Weighted Average Exercise Price	19.99
Exercised, Weighted Average Exercise Price	11.82
Forfeited or expired, Weighted Average Exercise price	25.39
Outstanding, Weighted Average Exercise Price, ending balance	25.12
Stock options vested and expected to vest, Weighted Average Exercise Price	25.12
Exercisable, Weighted Average Exercise Price	$ 22.36
Outstanding, Weighted Average Remaining Contractual Term	6 years 15 days
Stock options vested and expected to vest, Weighted Average Remaining Contractual Term	6 years 15 days
Exercisable, Weighted Average Remaining Contractual Term	5 years 7 months 6 days
Aggregate intrinsic value	$ 7,120
Vested and expected to vest, Aggregate Intrinsic Value	7,120
Exercisable, Aggregate Intrinsic Value	$ 2,451