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, 2015	$ 4,713	$ 2	$ 2,481	$ 6,199	$ (38)	$ (3,960)	$ 29
Balance, shares at Dec. 31, 2015		143.0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	320			298			22
Other comprehensive income (loss), net of taxes	(18)				(18)
Dividends declared	(113)			(113)
Distributions to noncontrolling interests	(19)						(19)
Issuance of common stock under benefit plans, value	11		3			8
Stock-based compensation expense	36		34			2
Exercise of stock options, value	38		1			37
Exercise of stock options, shares		1.0
Shares to cover employee payroll tax withholdings on stock issued under stock-based compensation plans	(9)		(9)
Purchases of treasury stock, value	(390)		(38)			$ (352)
Purchases of treasury stock, shares		(5.0)				(4.8)
Balance, value at Jun. 30, 2016	4,569	$ 2	2,472	6,384	(56)	$ (4,265)	32
Balance, shares at Jun. 30, 2016		139.0
Balance, Value at Dec. 31, 2015	70
Redeemable Non-controlling Interest [Abstract]
Net income	4
Balance, Value at Jun. 30, 2016	74
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	379			357			22
Other comprehensive income (loss), net of taxes	12				12
Dividends declared	(123)			(123)
Distributions to noncontrolling interests	(20)						(20)
Issuance of common stock under benefit plans, value	12		6			6
Issuance of common stock under benefit plans, shares		0.0
Stock-based compensation expense	37		35			2
Exercise of stock options, value	97		2			95
Exercise of stock options, shares		2.0
Shares to cover employee payroll tax withholdings on stock issued under stock-based compensation plans	(23)		(23)
Purchases of treasury stock, value	(300)					$ (300)
Purchases of treasury stock, shares		(3.0)				(3.0)
Other	2						2
Balance, value at Jun. 30, 2017	4,733	$ 2	$ 2,565	$ 6,847	$ (60)	$ (4,657)	$ 36
Balance, shares at Jun. 30, 2017		136.0
Balance, Value at Dec. 31, 2016	77
Redeemable Non-controlling Interest [Abstract]
Net income	3
Balance, Value at Jun. 30, 2017	$ 80