Earnings Per Share (Details) (USD $) In Millions, except Per Share data	3 Months Ended		6 Months Ended
	Jun. 30, 2011	Jun. 30, 2010	Jun. 30, 2011	Jun. 30, 2010
Numerator:
Net income, as reported	$ 291	$ 263	$ 539	$ 495
Less: Net income attributable to participating securities	(1)		(1)
Net income available to common shareholders	$ 290	$ 263	$ 538	$ 495
Denominator:
Basic EPS- weighted average shares	141.79	152.04	143.28	153.29
Effect of dilutive securities:
Stock Options and SARS	0.17	0.18	0.29	0.17
Diluted EPS- adjusted weighted average shares and assumed conversions	141.96	152.22	143.57	153.46
Earning Per Share
Basic	$ 2.05	$ 1.73	$ 3.75	$ 3.23
Diluted	$ 2.05	$ 1.73	$ 3.75	$ 3.22
Earnings Per Share (Textuals) [Abstract]
Common stock excluded from the diluted earnings per share		0.7		0.7