Earnings Per Share (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended				12 Months Ended
	Sep. 30, 2011	Sep. 30, 2010	Jun. 30, 2010	Dec. 31, 2009	Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2009
Income Available to Common Shareholders
Basic income (loss) available to common shareholders					$ 1,624	$ 1,491	$ (338)
Interest expense, net of tax					3	5
Diluted income (loss) available to common shareholders					$ 1,627	$ 1,496	$ (338)
Weighted Average Shares Outstanding
Basic weighted average shares outstanding					677.7	672.0	595.3
Effect of dilutive securities:
Stock options					8.1	5.9
Equity units					4.1	4.5
Convertible senior notes						0.1
Diluted weighted average shares outstanding					689.9	682.5	595.3
Antidilutive Securities
Options to purchase common shares							47.8
Earnings Per Share (Textuals)
Total weighted average of potential dilutive shares due to stock options, Equity Units and convertible senior notes							47.8
Interest rate on convertible senior notes			6.50%	6.50%	6.50%
Dividend declared	$ 0.16	$ 0.13			$ 0.64	$ 0.52	$ 0.52
Options [Member]
Antidilutive Securities
Options to purchase common shares					0.4	0.8	2.5
Earnings Per Share (Textuals)
Total weighted average of potential dilutive shares due to stock options, Equity Units and convertible senior notes					0.4	0.8	2.5