Equity (Details) (USD $) In Millions, except Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Common Stock, Shares, Outstanding beginning of period	75,556,272
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest	$ 1,730
Net Income (Loss) Attributable to Parent	49	49
Net Income (Loss) Attributable to Noncontrolling Interest	(1)	0
Common Stock, Shares, Outstanding end of period	75,677,181
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest	1,758
Common Stock [Member]
Stock Issued During Period, Shares, Share-based Compensation, Net of Forfeitures	120,909	141,624
Common Stock, Shares, Outstanding beginning of period	75,556,272	75,362,956
Common Stock, Shares, Outstanding end of period	75,677,181	75,504,580
Common Stock Including Additional Paid in Capital [Member]
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest	841	836
Dividends, Common Stock	0	0
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest	841	836
Accumulated Other Comprehensive Income (Loss) [Member]
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest	(6)	(6)
Dividends, Common Stock	0	0
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest	(6)	(6)
Retained Earnings [Member]
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest	893	833
Dividends, Common Stock	(20)	(20)
Net Income (Loss) Attributable to Parent		49
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest	922	862
Noncontrolling Interest [Member]
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest	2	3
Dividends, Common Stock	0	0
Net Income (Loss) Attributable to Noncontrolling Interest		0
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest	$ 1	$ 3