Stockholders' Equity - Stock Option Award Activity (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Number of Shares
Ending balance (in shares)	8,443,000
Aggregate Intrinsic Value
Aggregate intrinsic value of the options exercised	$ 403	$ 624	$ 4,580
Total grant date fair value of stock options vested	$ 5	$ 7	$ 7
Employee Stock Option
Number of Shares
Beginning balance (in shares)	12,984,000
Stock options exercised (in shares)	(4,541,000)
Ending balance (in shares)	8,443,000	12,984,000
Stock options vested and expected to vest as of period end (in shares)	8,441,000
Stock options exercisable as of period end (in shares)	6,250,000
Weighted Average Exercise Price
Beginning Balance (in dollars per share)	$ 4.78
Stock options exercised (in dollars per share)	0.48
Ending Balance (in dollars per share)	7.10	$ 4.78
Stock options vested and expected to vest as of period end (in dollars per share)	7.10
Stock options exercisable as of period end (in dollars per share)	$ 5.19
Weighted Average Remaining Contractual Term
Balance at period end (in years)	3 years 7 months 25 days
Stock options vested and expected to vest as of period end (in years)	3 years 7 months 25 days
Stock options exercisable as of period end (in years)	3 years 3 months 14 days
Aggregate Intrinsic Value
Balance at period end	$ 824
Stock options vested and expected to vest as of period end	824
Stock options exercisable as of period end	$ 622
Options granted in period	0
Options forfeited or canceled in period	0
Class A Common Stock
Aggregate Intrinsic Value
Share price	$ 104.66		$ 55.05