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, 2014	$ 4,330	$ 2	$ 2,418	$ 5,723	$ (27)	$ (3,815)	$ 29
Balance, shares at Dec. 31, 2014		144.0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	552			521			31
Other comprehensive loss, net of taxes	(4)				(4)
Dividends declared	(164)			(164)
Distributions to noncontrolling interests	(28)						(28)
Issuance of common stock under benefit plans, value	17		5			12
Issuance of common stock under benefit plans, shares		1.0
Stock-based compensation expense	39		37			2
Exercise of stock options, value	58					58
Exercise of stock options, shares		1.0
Shares to cover employee payroll tax withholdings on stock issued under stock-based compensation plans	(6)		(6)
Tax benefits associated with stock-based compensation plans	4		4
Purchases of treasury stock, value	(174)					$ (174)
Purchases of treasury stock, shares		(2.0)				(2.4)
Sale of redeembable noncontrolling interest	11		11
Adjustment to fair value	(14)			(14)
Balance, value at Sep. 30, 2015	4,621	$ 2	2,469	6,066	(31)	$ (3,917)	32
Balance, shares at Sep. 30, 2015		144.0
Balance, Value at Dec. 31, 2014	0
Redeemable Non-controlling Interest [Abstract]
Net income	1
Sale of redeembable noncontrolling interest	54
Adjustment to fair value	14
Balance, Value at Sep. 30, 2015	69
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	523			490			33
Other comprehensive loss, net of taxes	(23)				(23)
Dividends declared	(169)			(169)
Distributions to noncontrolling interests	(31)						(31)
Issuance of common stock under benefit plans, value	16		5			11
Issuance of common stock under benefit plans, shares		1.0
Stock-based compensation expense	52		49			3
Exercise of stock options, value	63		1			62
Exercise of stock options, shares		1.0
Shares to cover employee payroll tax withholdings on stock issued under stock-based compensation plans	(10)		(10)
Purchases of treasury stock, value	(440)					$ (440)
Purchases of treasury stock, shares		(6.0)				(5.7)
Balance, value at Sep. 30, 2016	4,694	$ 2	$ 2,526	$ 6,520	$ (61)	$ (4,324)	$ 31
Balance, shares at Sep. 30, 2016		139.0
Balance, Value at Dec. 31, 2015	70
Redeemable Non-controlling Interest [Abstract]
Net income	6
Balance, Value at Sep. 30, 2016	$ 76