Derivative Instruments and Hedging Activities - Effects on Consolidated Balance Sheets (Detail) - USD ($) $ in Millions	Jun. 30, 2016	Sep. 30, 2015
Derivatives, Fair Value [Line Items]
Asset derivatives	$ 39	$ 32
Liability derivatives	30	30
Derivatives Designated as Hedging Instruments | Interest rate swaps
Derivatives, Fair Value [Line Items]
Asset derivatives	27	19
Liability derivatives	19	0
Derivatives Designated as Hedging Instruments | Commodity forward contracts
Derivatives, Fair Value [Line Items]
Liability derivatives	2	10
Derivatives Not Designated as Hedging Instruments | Forward exchange contracts
Derivatives, Fair Value [Line Items]
Asset derivatives	12	13
Liability derivatives	$ 8	$ 21