Classification and Fair Value Amounts of Derivative Instruments (Detail) (USD $) In Millions, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012
Derivatives, Fair Value [Line Items]
Derivative asset, fair value	$ 96	$ 142
Derivative liability, fair value	8	37
Designated as Hedging Instrument
Derivatives, Fair Value [Line Items]
Derivative asset, fair value	96	95
Derivative liability, fair value	7	26
Designated as Hedging Instrument | Interest Rate Contract | Accounts Payable And Accrued Liabilities
Derivatives, Fair Value [Line Items]
Derivative liability, fair value		21
Designated as Hedging Instrument | Interest Rate Contract | Other Long -Term Assets
Derivatives, Fair Value [Line Items]
Derivative asset, fair value	42	67
Designated as Hedging Instrument | Foreign Exchange Contract | Accounts Payable And Accrued Liabilities
Derivatives, Fair Value [Line Items]
Derivative liability, fair value	6	5
Designated as Hedging Instrument | Foreign Exchange Contract | Other Long -Term Assets
Derivatives, Fair Value [Line Items]
Derivative asset, fair value	8
Designated as Hedging Instrument | Foreign Exchange Contract | Prepaid Expense And Other
Derivatives, Fair Value [Line Items]
Derivative asset, fair value	46	28
Designated as Hedging Instrument | Foreign Exchange Contract | Other Long -Term Liabilities
Derivatives, Fair Value [Line Items]
Derivative liability, fair value	1
Not Designated as Hedging Instrument | Foreign Exchange Contract | Accounts Payable And Accrued Liabilities
Derivatives, Fair Value [Line Items]
Derivative liability, fair value	1	11
Not Designated as Hedging Instrument | Foreign Exchange Contract | Prepaid Expense And Other
Derivatives, Fair Value [Line Items]
Derivative asset, fair value		$ 47