Schedule Of Effect Of Derivatives Recognized (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012		Dec. 31, 2011		Dec. 31, 2010
Schedule of Cost-method Investments [Line Items]
Derivatives not designated as hedging instruments	$ (30)		$ 11		$ 45
Designated as Hedging Instrument | Interest Rate Swap
Schedule of Cost-method Investments [Line Items]
Interest rate swaps	13	[1]	33	[1]	36	[1]
Not Designated as Hedging Instrument | Currency Exchange Forward
Schedule of Cost-method Investments [Line Items]
Derivatives not designated as hedging instruments	(31)	[2]	(19)	[2]	12	[2]
Not Designated as Hedging Instrument | Interest Rate Contract
Schedule of Cost-method Investments [Line Items]
Derivatives not designated as hedging instruments	(15)	[3]	(3)	[3]	(4)	[3]
Not Designated as Hedging Instrument | Commodity Contract
Schedule of Cost-method Investments [Line Items]
Derivatives not designated as hedging instruments	$ 3	[4]			$ 1	[4]

[1] Recognized, net of tax, as a component of other comprehensive income within stockholders' equity.

[2] For the year ended December 31, 2012, included a $32 million loss included in interest expense, and included a $1 million gain included in operating expenses. For the year ended December 31, 2011, included a $46 million loss in transaction-related costs and a $27 million gain in operating expenses. For the year ended December 31, 2010, amounts were included in operating expenses.

[3] For the year ended December 31, 2011, $2 million of expense is included in vehicle interest, net and $1 million of expense is included in interest expense. For the years ended December 31, 2012 and 2010 amounts are included in vehicle interest, net.

[4] Included in operating expenses.