Stock Based Awards and Other Equity Instruments - Summary of Status and Activity for Stock Option Awards Relating to Common Stock (Detail) (USD $) In Thousands, except Per Share data, unless otherwise specified	9 Months Ended
	Sep. 30, 2013
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Options Outstanding, Beginning balance	8,654
Options Outstanding, Granted	2,776
Options Outstanding, Exercised	1,273
Options Outstanding, Cancelled	481
Options Outstanding, Ending balance	9,676
Options Outstanding, Exercisable, Ending balance	3,499
Options Outstanding, Vested and expected to vest, Ending balance	8,813
Weighted Average Exercise Price, Remaining Contractual Life and Aggregate Intrinsic Value
Options Outstanding, Weighted Average Exercise Price, Beginning Balance	$ 31.41
Options Granted, Weighted Average Exercise Price	$ 57.66
Options Exercised, Weighted Average Exercise Price	$ 23.53
Options Cancelled, Weighted Average Exercise Price	$ 37.34
Options Outstanding, Weighted Average Exercise Price, Ending balance	$ 39.69
Options Exercisable, Weighted Average Exercise Price, Ending balance	$ 29.83
Options Vested and expected to vest, Weighted Average Exercise Price, Ending balance	$ 39.46
Options Outstanding, Weighted Average Remaining Contractual Life, Ending balance	6 years 1 month 6 days
Options Exercisable, Weighted Average Remaining Contractual Life, Ending balance	3 years 2 months 12 days
Options Vested and expected to vest, Weighted Average Remaining Contractual Life, Ending balance	5 years 10 months 24 days
Options Exercised, Aggregate Intrinsic Value,	$ 45,300
Options Outstanding, Aggregate Intrinsic Value, Ending balance	349,716
Options Exercisable, Aggregate Intrinsic Value, Ending balance	160,963
Options Vested and expected to vest, Aggregate Intrinsic Value, Ending balance	$ 320,645