Derivative Fair Value (Detail) (USD $) In Millions, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Other current liabilities:
Total	$ 22	$ 34
Designated as Hedging Instrument | Derivative Assets Included Other Current Assets
Other current assets:
Derivative assets	26	64
Designated as Hedging Instrument | Derivative Liabilities Included Other Current Liabilities
Other current liabilities:
Derivative liabilities	(18)	(33)
Not Designated as Hedging Instrument | Derivative Assets Included Other Current Assets
Other current assets:
Derivative assets	21	20
Not Designated as Hedging Instrument | Derivative Liabilities Included Other Current Liabilities
Other current liabilities:
Derivative liabilities	$ (7)	$ (17)