Derivative Instruments and Hedging Activities - Effects on Consolidated Balance Sheets (Detail) - USD ($) $ in Millions	Mar. 31, 2016	Sep. 30, 2015
Derivatives, Fair Value [Line Items]
Asset derivatives	$ 46	$ 32
Liability derivatives	16	30
Derivatives Designated as Hedging Instruments | Interest rate swaps
Derivatives, Fair Value [Line Items]
Asset derivatives	24	19
Liability derivatives	3	0
Derivatives Designated as Hedging Instruments | Commodity forward contracts
Derivatives, Fair Value [Line Items]
Liability derivatives	5	10
Derivatives Not Designated as Hedging Instruments | Forward exchange contracts
Derivatives, Fair Value [Line Items]
Asset derivatives	22	13
Liability derivatives	$ 9	$ 21