Consolidated Balance Sheets (Parenthetical) (USD $) In Millions, except Share data, unless otherwise specified	Dec. 31, 2011	Sep. 30, 2011
Consolidated Balance Sheets [Abstract]
Allowance for doubtful accounts receivable, current	$ 99	$ 104
Preferred stock, par value per share	$ 2.5	$ 2.5
Preferred stock, shares authorized	5,400,000	5,400,000
Preferred stock, shares issued	0	0
Common stock, par value per share	$ 0.5	$ 0.5
Common stock, shares authorized	1,200,000,000	1,200,000,000
Common stock, shares issued	953,354,012	953,354,012
Common stock, shares outstanding	734,739,727	738,877,768
Treasury stock, shares	218,614,285	214,476,244