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, 2013	$ 3,973	$ 2	$ 2,379	$ 5,358	$ (8)	$ (3,783)	$ 25
Balance, shares at Dec. 31, 2013		144
Net income	253			237			16
Other comprehensive income, net of tax	0				0
Dividends declared	(95)			(95)
Distributions to noncontrolling interests	(14)						(14)
Issuance of common stock under benefit plans, value	9					9
Issuance of common stock under benefit plans, shares		1
Stock-based compensation expense	25		$ 23			2
Exercise of stock options, value	30		(3)			33
Shares to cover employee payroll tax withholdings on stock issued under benefit plans, value	(5)		$ (5)
Purchases of treasury stock, value	(57)					(57)
Purchases of treasury stock, shares		(1)
Balance, value at Jun. 30, 2014	4,119	$ 2	$ 2,394	5,500	(8)	(3,796)	27
Balance, shares at Jun. 30, 2014		144
Balance, value at Dec. 31, 2014	4,330	$ 2	2,418	5,723	(27)	(3,815)	29
Balance, shares at Dec. 31, 2014		144
Net income	199			179			20
Other comprehensive income, net of tax	2				2
Dividends declared	(109)			(109)
Distributions to noncontrolling interests	(19)						(19)
Issuance of common stock under benefit plans, value	11		4			7
Issuance of common stock under benefit plans, shares		1
Stock-based compensation expense	27		$ 25			2
Exercise of stock options, value	55					55
Exercise of stock options, shares		1
Shares to cover employee payroll tax withholdings on stock issued under benefit plans, value	(6)		$ (6)
Tax benefits associated with stock-based compensation plans	3		3
Purchases of treasury stock, value	(149)					(149)
Purchases of treasury stock, shares		(2)
Balance, value at Jun. 30, 2015	$ 4,344	$ 2	$ 2,444	$ 5,793	$ (25)	$ (3,900)	$ 30
Balance, shares at Jun. 30, 2015		144