Stock Based Awards and Other Equity Instruments - Summary of Status and Activity for Stock Option Awards Relating to Common Stock (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2014
Options Outstanding
Options Outstanding, Beginning balance	9,470
Options Outstanding, Granted	477
Options Outstanding, Exercised	(599)
Options Outstanding, Cancelled or expired	(78)
Options Outstanding, Ending balance	9,270
Options Outstanding, Exercisable	4,184
Options Outstanding, Vested and expected to vest	8,516
Weighted Average Exercise Price per share
Options Outstanding, Weighted Average Exercise Price, Beginning Balance	$ 40.18
Options Granted, Weighted Average Exercise Price	$ 96.62
Options Exercised, Weighted Average Exercise Price	$ 34.63
Options Cancelled or expired, Weighted Average Exercise Price	$ 44.98
Options Outstanding, Weighted Average Exercise Price, Ending balance	$ 43.40
Options Exercisable, Weighted Average Exercise Price	$ 31.54
Options Vested and expected to vest, Weighted Average Exercise Price	$ 42.57
Weighted Average Remaining Contractual Life and Aggregate Intrinsic Value
Options Outstanding, Weighted Average Remaining Contractual Life	5 years 9 months 18 days
Options Exercisable, Weighted Average Remaining Contractual Life	3 years 6 months
Options Vested and expected to vest, Weighted Average Remaining Contractual Life	5 years 6 months
Options Outstanding, Aggregate Intrinsic Value	$ 440
Options Exercisable, Aggregate Intrinsic Value	247
Options Vested and expected to vest, Aggregate Intrinsic Value	$ 411