Intangible Assets (Schedule Of Intangible Assets) (Detail) (USD $) In Millions, unless otherwise specified	Jun. 30, 2013		Dec. 31, 2012
Finite And Indefinite Lived Intangible Assets [Line Items]
Amortized Intangible Assets, Gross Carrying Amount	$ 420		$ 345
Amortized Intangible Assets, Accumulated Amortization	72		59
Amortized Intangible Assets, Net Carrying Amount	348		286
Unamortized Intangible Assets, Goodwill, Gross Carrying Amount	652		375
License Agreements [Member]
Finite And Indefinite Lived Intangible Assets [Line Items]
Amortized Intangible Assets, Gross Carrying Amount	254		257
Amortized Intangible Assets, Accumulated Amortization	45		39
Amortized Intangible Assets, Net Carrying Amount	209		218
Customer Relationships [Member]
Finite And Indefinite Lived Intangible Assets [Line Items]
Amortized Intangible Assets, Gross Carrying Amount	164	[1]	86	[1]
Amortized Intangible Assets, Accumulated Amortization	26	[1]	19	[1]
Amortized Intangible Assets, Net Carrying Amount	138	[1]	67	[1]
Other Intangible Assets [Member]
Finite And Indefinite Lived Intangible Assets [Line Items]
Amortized Intangible Assets, Gross Carrying Amount	2		2
Amortized Intangible Assets, Accumulated Amortization	1		1
Amortized Intangible Assets, Net Carrying Amount	1		1
Goodwill [Member]
Finite And Indefinite Lived Intangible Assets [Line Items]
Unamortized Intangible Assets, Goodwill, Gross Carrying Amount	652	[1]	375	[1]
Trademarks [Member]
Finite And Indefinite Lived Intangible Assets [Line Items]
Unamortized Intangible Assets, Trademarks, Gross Carrying Amount	$ 554	[1]	$ 445	[1]

[1] The increases in carrying amounts primarily relate to the acquisition of Zipcar.