Accrued Litigation for Both Covered and Non-Covered Litigation (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Mar. 31, 2012	Mar. 31, 2011	Mar. 31, 2012		Mar. 31, 2011
Loss Contingency Accrual [Roll Forward]
Beginning Balance			$ 425		$ 697
Provision for settled matters		6			6
Reclassification of settled matters				[1]	12	[1]
Interest accretion on settled matters			1		7
Payments on settled matters			(140)		(142)
Ending Balance	$ 286	$ 580	$ 286		$ 580

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