Basic and Diluted Earnings Per Share (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Earnings Per Share [Abstract]
Income from Continuing Operations	$ 232	$ 249
Weighted Average Number of Shares Outstanding, Basic (in shares)	179	177
Incremental Shares from Assumed Conversion of Dilutive Stock Options, Restricted Stock and Shares of Common Stock in Rabbi Trust (in shares)	2	3
Weighted Average Number of Shares Outstanding, Diluted (in shares)	181	180
Earnings from Continuing Operations Per Share, Basic (in dollars per share)	$ 1.29	$ 1.40
Income from Continuing Operations (in dollars per share)	$ 1.28	$ 1.39
Number of antidilutive stock options, shares of restricted stock and shares of common stock in rabbi trust excluded from calculation above (in shares)	3	2