Stock Based Compensation - Summary of Changes in Number of Shares of Common Stock Under Option (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Shares, Outstanding, Beginning Balance	5,131	5,331	6,565
Shares, Granted	654	1,544	307
Shares, Exercised	(586)	(1,429)	(1,425)
Shares, Forfeited	(196)	(315)	(116)
Shares, Outstanding, Ending Balance	5,003	5,131	5,331
Weighted Average Exercise Price, Outstanding, Beginning balance	$ 58.71	$ 25.68	$ 22.17
Shares, Expected to vest	5,003
Weighted Average Exercise Price, Granted	$ 154.56	135.16	80.77
Weighted Average Exercise Price, Exercised	33.97	20.75	21.13
Weighted Average Exercise Price, Forfeited	95.16	41.72	28.68
Weighted Average Exercise Price, Outstanding, Ending balance	$ 72.72	$ 58.71	$ 25.68
Options Exercisable at End of Period, Outstanding, Beginning Balance	2,370	2,589	2,666
Weighted Average Exercise Price, Expected to vest	$ 72.72
Options Exercisable at End of Period, Outstanding, Ending Balance	2,545	2,370	2,589
Weighted Average Exercise Price of Exercisable Options, Outstanding, Beginning Balance	$ 21.75	$ 16.57	$ 14.71
Weighted Average Exercise Price of Exercisable Options, Outstanding, Ending Balance	$ 26.82	$ 21.75	$ 16.57
Aggregate Intrinsic Value, Outstanding, Beginning Balance	$ 461,770	$ 487,673	$ 206,636
Weighted Average Fair Value of Options Granted During the Period, Granted	$ 35.32	$ 42.77	$ 23.00
Aggregate Intrinsic Value, Exercised	$ 63,863	$ 182,904	$ 136,807
Aggregate Intrinsic Value, Outstanding, Ending Balance	$ 351,277	$ 461,770	$ 487,673