Capital Stock (Details) (USD $) In Millions, except Per Share data	3 Months Ended		9 Months Ended
	Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2011	Sep. 30, 2010
Basic:
Income attributable to common stock	$ 983	$ 765	$ 3,338	$ 2,330
Income attributable to common stock, shares	384	357	384	344
Income attributable to common stock, per share	$ 2.56	$ 2.14	$ 8.70	$ 6.78
Effect of Dilutive Securities:
Mandatory Convertible Preferred Stock	14	9	14	3
Mandatory Convertible Preferred Stock, Income	19	13	57	13
Stock options and other	2	1	2	2
Diluted:
Income attributable to common stock, including assumed conversions, Amount	$ 1,002	$ 778	$ 3,395	$ 2,343
Income attributable to common stock, including assumed conversions, Shares	400	367	400	349
Income attributable to common stock, including assumed conversions, per share	$ 2.50	$ 2.12	$ 8.49	$ 6.72