Income Taxes - Additional Information (Detail) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2014
Income Tax [Line Items]
Accrued unrecognized tax benefits interest and penalties	$ 51	$ 84	$ 10
Unrecognized tax benefits interest and penalties reflected in current year	3	8	2
Undistributed earnings of foreign subsidiaries	8,700
Tax reductions related to tax holidays	122	102	108
Income taxes paid, net	218	240	330
New Accounting Pronouncement, Early Adoption, Effect
Income Tax [Line Items]
Deferred Tax Assets, Net, Current		$ (387)	$ (355)
Deferred Income Taxes and Other
Income Tax [Line Items]
Indemnification liability, non-current	$ 126