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	6 Months Ended
	Jun. 30, 2013
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Options Outstanding, Beginning balance	8,654
Options Outstanding, Granted	1,562
Options Outstanding, Exercised	875
Options Outstanding, Cancelled	321
Options Outstanding, Ending balance	9,020
Options Outstanding, Exercisable, Ending balance	3,756
Options Outstanding, Vested and expected to vest, Ending balance	8,439
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	$ 46.35
Options Exercised, Weighted Average Exercise Price	$ 22.69
Options Cancelled, Weighted Average Exercise Price	$ 36.23
Options Outstanding, Weighted Average Exercise Price, Ending balance	$ 34.67
Options Exercisable, Weighted Average Exercise Price, Ending balance	$ 29.03
Options Vested and expected to vest, Weighted Average Exercise Price, Ending balance	$ 34.12
Options Outstanding, Weighted Average Remaining Contractual Life, Ending balance	6 years
Options Exercisable, Weighted Average Remaining Contractual Life, Ending balance	3 years 6 months
Options Vested and expected to vest, Weighted Average Remaining Contractual Life, Ending balance	6 years
Options Exercised, Aggregate Intrinsic Value,	$ 26,740
Options Outstanding, Aggregate Intrinsic Value, Ending balance	236,321
Options Exercisable, Aggregate Intrinsic Value, Ending balance	119,593
Options Vested and expected to vest, Aggregate Intrinsic Value, Ending balance	$ 223,343