Schedule of Assets and Liabilities Measured at Fair Value on Recurring Basis (Detail) (Fair Value, Measurements, Recurring, USD $) In Millions, unless otherwise specified	Sep. 30, 2013
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of assets measured on a recurring basis	$ 4,674
Cash and Cash Equivalents | Fixed Income Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of assets measured on a recurring basis	3,000
Short-term Investments | Fixed Income Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of assets measured on a recurring basis	264
Short-term Investments | Equity Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of assets measured on a recurring basis	367
Other Current Assets | Interest Rate Swaps
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of assets measured on a recurring basis	16
Other Assets | Fixed Income Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of assets measured on a recurring basis	885
Other Assets | Cross Currency Swaps
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of assets measured on a recurring basis	142
Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of assets measured on a recurring basis	3,367	[1]
Level 1 | Cash and Cash Equivalents | Fixed Income Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of assets measured on a recurring basis	3,000	[1]
Level 1 | Short-term Investments | Equity Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of assets measured on a recurring basis	367	[1]
Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of assets measured on a recurring basis	1,307	[2]
Level 2 | Short-term Investments | Fixed Income Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of assets measured on a recurring basis	264	[2]
Level 2 | Other Current Assets | Interest Rate Swaps
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of assets measured on a recurring basis	16	[2]
Level 2 | Other Assets | Fixed Income Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of assets measured on a recurring basis	885	[2]
Level 2 | Other Assets | Cross Currency Swaps
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of assets measured on a recurring basis	$ 142	[2]

[1] quoted prices in active markets for identical assets or liabilities

[2] observable inputs other than quoted prices in active markets for identical assets and liabilities