Stockholders' Equity - Stock Option Activity (Details) $ / shares in Units, shares in Thousands, $ in Millions	3 Months Ended
	Mar. 31, 2017 USD ($) $ / shares shares
Class A Common Stock
Aggregate Intrinsic Value
Common stock, closing share price (in usd per share)	$ 142.05
Employee Stock Options
Number of Shares
Beginning balance (in shares) | shares	5,687
Stock options exercised (in shares) | shares	(1,547)
Ending balance (in shares) | shares	4,140
Stock options exercisable as of period end (in shares) | shares	3,122
Weighted Average Exercise Price
Beginning balance (in dollars per share)	$ 7.78
Stock options exercised (in dollars per share)	5.12
Ending balance (in dollars per share)	8.78
Stock options exercisable as of period end (in dollars per share)	$ 6.85
Weighted Average Remaining Contractual Term
Balance at period end	2 years 10 months 25 days
Stock options exercisable as of period end	2 years 8 months 12 days
Aggregate Intrinsic Value
Balance at period end | $	$ 552	[1]
Stock options exercisable as of period end | $	$ 422	[1]

[1] The aggregate intrinsic value is calculated as the difference between the exercise price of the underlying stock option awards and the official closing price of our Class A common stock of $142.05, as reported on the NASDAQ Global Select Market on March 31, 2017.