Earnings Per Share (Calculation of our Basic and Diluted EPS) (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2011		Dec. 31, 2010		Dec. 31, 2009
Earnings Per Share [Abstract]
Net income	$ 1,408		$ 2,808		$ 1,287
Average shares of common stock outstanding - Basic	573.1		588.9		593.3
Net effect of potentially dilutive securities	1.5	[1]	1.2	[1]	0.4	[1]
Average shares of common stock outstanding - Diluted	574.6		590.1		593.7
Earnings Per Common Share - Basic	$ 2.46		$ 4.77		$ 2.17
Earnings Per Common Share - Diluted	$ 2.45		$ 4.76		$ 2.17

[1] Potentially dilutive securities consist of options, goal-based stock and contingently convertible senior notes.