Intangible Assets (Amortization Expense Related To Intangible Assets By Major Class) (Details) (USD $) In Millions	3 Months Ended				9 Months Ended
	Sep. 30, 2011		Sep. 30, 2010		Sep. 30, 2011		Sep. 30, 2010
Amortization expense	$ 8	[1]	$ 6	[1]	$ 24	[1]	$ 20	[1]
Franchise Agreements [Member]
Amortization expense	5		5		15		15
Other Intangible Assets [Member]
Amortization expense	$ 3		$ 1		$ 9		$ 5

[1] Included as a component of depreciation and amortization on the Consolidated Statements of Income.