Intangible Assets - Amortization Expense (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Finite-Lived Intangible Assets [Line Items]
Intangible asset amortization expense	$ 27	$ 28	$ 83	$ 84
Amortization expense for remainder of 2012	27		27
Finite-Lived Intangible Assets, Amortization Expense, Year Two	105		105
Finite-Lived Intangible Assets, Amortization Expense, Year Three	105		105
Finite-Lived Intangible Assets, Amortization Expense, Year Four	95		95
Finite-Lived Intangible Assets, Amortization Expense, Year Five	94		94
Finite-Lived Intangible Assets, Amortization Expense, after Year Five	1,618		1,618
Franchise agreements [Member]
Finite-Lived Intangible Assets [Line Items]
Intangible asset amortization expense	17	17	51	51
License agreements [Member]
Finite-Lived Intangible Assets [Line Items]
Intangible asset amortization expense	0	0	1	0
Customer relationships [Member]
Finite-Lived Intangible Assets [Line Items]
Intangible asset amortization expense	10	9	29	28
Other [Member]
Finite-Lived Intangible Assets [Line Items]
Intangible asset amortization expense	$ 0	$ 2	$ 2	$ 5