Stockholders' Equity - Additional Information (Details) $ / shares in Units, $ in Millions		12 Months Ended
	Feb. 08, 2019 $ / shares	Dec. 31, 2018 USD ($) vote $ / shares shares	Dec. 31, 2017 USD ($) $ / shares shares	Dec. 31, 2016 USD ($) $ / shares shares	Dec. 30, 2018 shares	Dec. 31, 2015 shares	Dec. 31, 2012 shares	Dec. 31, 2006 shares
Class of Stock [Line Items]
Preferred stock outstanding		0	0
Authorized share repurchase		85,000,000			15,000,000	10,000,000	20,000,000	20,000,000
Shares authorized and remaining under the repurchase program		12,200,000
Number of shares repurchased		7,720,194	2,317,617	3,979,170
Cost of stock repurchases | $		$ 904	$ 294	$ 436
Average price per share (in dollars per share) | $ / shares		$ 117.02	$ 127.04	$ 109.64
Class B Common Stock
Class of Stock [Line Items]
Common stock, shares authorized		400,000,000	400,000,000
Common stock, par value (in dollars per share) | $ / shares		$ 0.0001	$ 0.0001
Number of voting rights to each shareholder, per share | vote		10
Common stock
Class of Stock [Line Items]
Common stock, shares authorized		1,600,000,000	1,600,000,000
Common stock, par value (in dollars per share) | $ / shares		$ 0.0001	$ 0.0001
Number of voting rights to each shareholder, per share | vote		1
Total number of directors elected by holders of common stock, voting as single class, percentage		25.00%
Subsequent Event
Class of Stock [Line Items]
Dividend Per Share | $ / shares	$ 0.32