Franchises, Goodwill and Other Intangible Assets Franchises, Goodwill and Other Intangible Assets (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011
Goodwill [Line Items]
Finite-lived intangible assets, amortization expense	$ 74	$ 79
Franchise Rights [Member]
Goodwill [Line Items]
Indefinite-lived Intangible Assets, Acquired During Period	3
Customer Relationships [Member]
Goodwill [Line Items]
Indefinite-lived Intangible Assets, Acquired During Period	$ 1