Accrued Litigation for Both Covered and Other Non-Covered Litigation (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Sep. 30, 2012		Sep. 30, 2011		Sep. 30, 2010	Oct. 29, 2012
Settlement payable	$ 719		$ 449			$ 350
Beginning balance	425		697
Provision for legal matters	4,100		7		(45)
Reclassification of settled matters	0		12
Interest accretion on settled matters	1		11
Payments on settled matters	(140)		(302)
Ending balance	4,386		425		697
Settled [Member]
Provision for legal matters	0	[1]	7	[1]
Unsettled
Provision for legal matters	$ 4,100

[1] Reclassification of amount previously recorded in accrued liabilities.