Stockholders' Equity (Stock Option Activity) (Details) - Jun. 30, 2015 - USD ($) $ / shares in Units, $ in Millions	Total
Options Outstanding - Number of Shares
Balance as of December 31, 2014 (in shares)	7,240,419
Granted (in shares)	0
Exercised (in shares)	(1,142,926)
Forfeited/canceled (in shares)	(132,858)
Balance as of June 30, 2015 (in shares)	5,964,635
Exercisable as of June 30, 2015 (in shares)	5,331,727
Exercisable as of June 30, 2015 and expected to vest thereafter (in shares)	5,781,735
Options Outstanding - Weighted-Average Exercise Price
Balance as of December 31, 2014 (in dollars per share)	$ 215.56
Exercised (in dollars per share)	193.38
Forfeited/canceled (in dollars per share)	310.78
Balance as of June 30, 2015 (in dollars per share)	217.69
Exercisable as of June 30, 2015 (in dollars per share)	206.15
Exercisable as of June 30, 2015 and expected to vest thereafter (in dollars per share)	$ 214.59
Options Outstanding - Weighted-Average Remaining Contractual Term
Balance as of June 30, 2015	3 years 9 months 22 days
Exercisable as of June 30, 2015	3 years 8 months 15 days
Exercisable as of June 30, 2015 and expected to vest thereafter	3 years 10 months 29 days
Options Outstanding - Aggregate Intrinsic Value
Balance as of June 30, 2015	$ 1,865
Exercisable as of June 30, 2015	1,729
Exercisable as of June 30, 2015 and expected to vest thereafter	$ 1,826