CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) shares in Millions, $ in Millions	Total	Common Stock	Additional Paid-In Capital	Retained Earnings	Accumulated Other Comprehensive Loss	Treasury Stock, at Cost	Non-controlling Interests
Balance, value at Dec. 31, 2016	$ 4,660	$ 2	$ 2,545	$ 6,613	$ (72)	$ (4,460)	$ 32
Balance, shares at Dec. 31, 2016		137.0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	552			518			34
Other comprehensive loss, net of taxes	24				24
Dividends declared	(185)			(185)
Distributions to noncontrolling interests	(34)						(34)
Issuance of common stock under benefit plans	18		9			9
Stock-based compensation expense	54		51			3
Exercise of stock options, value	125		3			122
Exercise of stock options, shares		3.0
Shares to cover employee payroll tax withholdings on stock issued under stock-based compensation plans, value	(23)		(23)
Purchases of treasury stock, value	(365)					$ (365)
Purchases of treasury stock, shares		(4.0)				(3.6)
Other	2						2
Balance, value at Sep. 30, 2017	4,828	$ 2	2,585	6,946	(48)	$ (4,691)	34
Balance, shares at Sep. 30, 2017		136.0
Balance, Value at Dec. 31, 2016	77
Redeemable Non-controlling Interest [Abstract]
Net income	5
Distributions to noncontrolling interests	(4)
Balance, Value at Sep. 30, 2017	78
Balance, value at Dec. 31, 2017	4,955	$ 2	2,612	7,138	(48)	(4,783)	34
Balance, shares at Dec. 31, 2017		135.0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	643			609			34
Other comprehensive loss, net of taxes	(8)				(8)
Dividends declared	(203)			(203)
Distributions to noncontrolling interests	(32)						(32)
Issuance of common stock under benefit plans	20		10			10
Stock-based compensation expense	53		49			4
Exercise of stock options, value	95		5			90
Exercise of stock options, shares		2.0
Shares to cover employee payroll tax withholdings on stock issued under stock-based compensation plans, value	(20)		(20)
Purchases of treasury stock, value	(150)					$ (150)
Purchases of treasury stock, shares		(1.0)				(1.4)
Sale of noncontrolling interest in subsidiaries	12						12
Reclassification of stranded tax effects resulting from enactment of the Tax Cuts and Jobs Act	0			2	(2)
Balance, value at Sep. 30, 2018	5,365	$ 2	$ 2,656	$ 7,546	$ (58)	$ (4,829)	$ 48
Balance, shares at Sep. 30, 2018		136.0
Balance, Value at Dec. 31, 2017	80
Redeemable Non-controlling Interest [Abstract]
Net income	6
Distributions to noncontrolling interests	(9)
Balance, Value at Sep. 30, 2018	$ 77