Schedule of Equity (Details) (USD $) In Millions, except Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Common Stock, Shares, Outstanding beginning of period	78,228,339
Stockholders' Equity	$ 1,911
Net Income	50	58
Common Stock, Shares, Outstanding end of period	78,344,691
Stockholders' Equity	1,939
Common Stock [Member]
Common Stock, Shares, Outstanding beginning of period	78,228,339	78,085,559
Issuances of shares pursuant to equity-based plans	116,352	96,497
Common Stock, Shares, Outstanding end of period	78,344,691	78,182,056
Common Stock Including Additional Paid in Capital [Member]
Issuance of shares pursuant to equity-based plans	1	0
Adjustments Related to Tax Withholding for Share-based Compensation	(1)
Stockholders' Equity	918	911
Stock-based compensation		1
Dividends declared	0	0
Stockholders' Equity	918	912
Accumulated Other Comprehensive Income (Loss) [Member]
Stockholders' Equity	(7)	(5)
Stock-based compensation	0	0
Dividends declared	0	0
Stockholders' Equity	(7)	(5)
Retained Earnings [Member]
Stockholders' Equity	1,000	913
Stock-based compensation	0	0
Dividends declared	(22)	(22)
Net Income	50	58
Stockholders' Equity	$ 1,028	$ 949