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	174			164			10
Other comprehensive income, net of taxes	4				4
Dividends declared	(62)			(62)
Distributions to noncontrolling interests	(9)						(9)
Issuance of common stock under benefit plans, value	5		2			3
Issuance of common stock under benefit plans, shares		1.0
Stock-based compensation expense	17		16			1
Exercise of stock options, value	46		1			45
Exercise of stock options, shares		1.0
Shares to cover employee payroll tax withholdings on stock issued under stock-based compensation plans, value	(22)		(22)
Purchases of treasury stock, value	(150)					$ (150)
Purchases of treasury stock, shares		(2.0)				(1.6)
Balance, value at Mar. 31, 2017	4,663	$ 2	2,542	6,715	(68)	$ (4,561)	33
Balance, shares at Mar. 31, 2017		137.0
Balance, Value at Dec. 31, 2016	77
Redeemable Non-controlling Interest [Abstract]
Net income	1
Balance, Value at Mar. 31, 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	188			177			11
Other comprehensive income, net of taxes	7				7
Dividends declared	(66)			(66)
Distributions to noncontrolling interests	(11)						(11)
Issuance of common stock under benefit plans, value	8		4			4
Stock-based compensation expense	19		18			1
Exercise of stock options, value	34		2			32
Exercise of stock options, shares		1.0
Shares to cover employee payroll tax withholdings on stock issued under stock-based compensation plans, value	(20)		(20)
Purchases of treasury stock, value	(50)					$ (50)
Purchases of treasury stock, shares		0.0				(0.5)
Sale of noncontrolling interest in subsidiaries	2						2
Balance, value at Mar. 31, 2018	5,066	$ 2	$ 2,616	$ 7,249	$ (41)	$ (4,796)	$ 36
Balance, shares at Mar. 31, 2018		136.0
Balance, Value at Dec. 31, 2017	80
Redeemable Non-controlling Interest [Abstract]
Net income	1
Distributions to noncontrolling interests	(4)
Balance, Value at Mar. 31, 2018	$ 77