Basic and Diluted Earnings Per Share (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended				9 Months Ended
	Sep. 30, 2012		Sep. 30, 2011		Sep. 30, 2012		Sep. 30, 2011
Earnings Per Share [Abstract]
Income from Continuing Operations	$ 164		$ 491		$ 687		$ 727
Earnings Adjustment from Assumed Conversion of Dilutive Shares of Common Stock in Rabbi Trust	0	[1]	(12)	[1]	(1)	[1]	(10)	[1]
Income from Continuing Operations Used for Diluted Earnings Per Share Calculation	$ 164		$ 479		$ 686		$ 717
Weighted Average Number of Shares Outstanding, Basic (in shares)	178		177		178		176
Incremental Shares from Assumed Conversion of Dilutive Stock Options, Restricted Stock and Shares of Common Stock in Rabbi Trust (in shares)	2		3		2		3
Weighted Average Number of Shares Outstanding, Diluted (in shares)	180		180		180		179
Earnings from Continuing Operations Per Share, Basic (in dollars per share)	$ 0.92		$ 2.78		$ 3.87		$ 4.11
Earnings from Continuing Operations Per Share, Diluted (in dollars per share)	$ 0.91		$ 2.67		$ 3.81		$ 3.99
Number of antidilutive stock options, shares of restricted stock and shares of common stock in rabbi trust excluded from calculation above (in shares)	3		1		2		2

[1] Consistent with GAAP, when dilutive, deferred compensation gains or losses, net of tax, are excluded from net income while our common shares held in the rabbi trust are included in the diluted share count. For this reason, the diluted earnings per share calculations for the three months ended September 30, 2011 and for the nine months ended September 30, 2012 and 2011 exclude deferred compensation gains, net of tax.