Stock Plans - Summary of RSU Activity Outstanding and Weighted Average Grant Date Fair Value (Detail) (USD $)	3 Months Ended
	Mar. 31, 2014
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Number of Restricted Stock Units Outstanding, Unvested - Beginning Balance	1,044,651
Number of Restricted Stock Units Outstanding, Granted	582,952
Number of Restricted Stock Units Outstanding, Granted, performance RSUs	16,000
Number of Restricted Stock Units Outstanding, Released	(106,952)
Number of Restricted Stock Units Outstanding, Cancelled or expired	(22,926)
Number of Restricted Stock Units Outstanding, RSUs assumed in acquisition	204,828
Number of Restricted Stock Units Outstanding, Unvested - Ending balance	1,718,553
Weighted-Average Grant Date Fair Value, Unvested - Beginning Balance	$ 31.64
Weighted-Average Grant Date Fair Value, Granted	$ 55.79
Weighted-Average Grant Date Fair Value, Granted, performance RSUs	$ 58.02
Weighted-Average Grant Date Fair Value, Released	$ 34.04
Weighted-Average Grant Date Fair Value, Cancelled or expired	$ 40.63
Weighted-Average Grant Date Fair Value, RSUs assumed in acquisition	$ 61.40
Weighted-Average Grant Date Fair Value, Unvested - Ending balance	$ 43.35