Derivative Instruments and Hedging Activities - Location and Fair Values of Derivative Instruments and Hedging Activities (Detail) (USD $) In Millions, unless otherwise specified	Mar. 31, 2013	Sep. 30, 2012	Mar. 31, 2012
Designated as Hedging Instrument
Derivative Instruments [Line Items]
Derivatives Assets under ASC 815	$ 21	$ 34	$ 39
Derivatives Liabilities under ASC 815	778	874	884
Designated as Hedging Instrument | Other Current Assets | Foreign Currency Exchange Derivatives
Derivative Instruments [Line Items]
Derivatives Assets under ASC 815	14	14	13
Designated as Hedging Instrument | Other Current Assets | Commodity Derivatives
Derivative Instruments [Line Items]
Derivatives Assets under ASC 815	2	11	1
Designated as Hedging Instrument | Other Current Assets | Interest Rate Swaps
Derivative Instruments [Line Items]
Derivatives Assets under ASC 815	5	2
Designated as Hedging Instrument | Other Current Assets | Cross-Currency Interest Rate Swaps
Derivative Instruments [Line Items]
Derivatives Assets under ASC 815		1	16
Designated as Hedging Instrument | Other Noncurrent Assets | Interest Rate Swaps
Derivative Instruments [Line Items]
Derivatives Assets under ASC 815		6	9
Designated as Hedging Instrument | Other Current Liabilities | Foreign Currency Exchange Derivatives
Derivative Instruments [Line Items]
Derivatives Liabilities under ASC 815	13	17	21
Designated as Hedging Instrument | Other Current Liabilities | Commodity Derivatives
Derivative Instruments [Line Items]
Derivatives Liabilities under ASC 815	7		4
Designated as Hedging Instrument | Other Liabilities | Cross-Currency Interest Rate Swaps
Derivative Instruments [Line Items]
Derivatives Liabilities under ASC 815	2
Designated as Hedging Instrument | Current Portion of Long-Term Debt | Fixed Rate Debt Swapped to Floating
Derivative Instruments [Line Items]
Derivatives Liabilities under ASC 815	754	401	100
Designated as Hedging Instrument | Long-Term Debt | Fixed Rate Debt Swapped to Floating
Derivative Instruments [Line Items]
Derivatives Liabilities under ASC 815		456	759
Designated as Hedging Instrument | Other Noncurrent Liabilities | Cross-Currency Interest Rate Swaps
Derivative Instruments [Line Items]
Derivatives Liabilities under ASC 815	2
Not Designated as Hedging Instrument
Derivative Instruments [Line Items]
Derivatives Assets under ASC 815	171	131	150
Derivatives Liabilities under ASC 815	4	9	10
Not Designated as Hedging Instrument | Other Current Assets | Foreign Currency Exchange Derivatives
Derivative Instruments [Line Items]
Derivatives Assets under ASC 815	2	8	12
Not Designated as Hedging Instrument | Other Noncurrent Assets | Equity swap
Derivative Instruments [Line Items]
Derivatives Assets under ASC 815	169	123	138
Not Designated as Hedging Instrument | Other Current Liabilities | Foreign Currency Exchange Derivatives
Derivative Instruments [Line Items]
Derivatives Liabilities under ASC 815	$ 4	$ 9	$ 10