Stock-Based Compensation - Summary of Share-Based Option Activity (Detail) (USD $)	6 Months Ended
	Jun. 30, 2014
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Shares Outstanding, Beginning of Period	8,463,811
Shares Granted	1,500,000
Shares Exercised	(98,026)
Shares Canceled	(121,862)
Shares Expired	(6,946)
Shares Outstanding, End of Period	9,736,977
Shares Vested and expected to vest at June 30, 2014	9,298,209
Shares Exercisable at June 30, 2014	2,956,822
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Abstract]
Weighted Average Exercise Price Outstanding, Beginning of Period	$ 12.09
Weighted Average Exercise Price Granted	$ 21.18
Weighted Average Exercise Price Exercised	$ 11.00
Weighted Average Exercise Price Canceled	$ 8.78
Weighted Average Exercise Price Expired	$ 12.51
Weighted Average Exercise Price Outstanding, End of Period	$ 13.53
Weighted Average Exercise Price Vested and expected to vest at June 30, 2014	$ 13.27
Weighted Average Exercise Price Exercisable at June 30, 2014	$ 14.04