Intangible Assets (Amortization Expense Related To Intangible Assets By Major Class) (Details) (USD $) In Millions	3 Months Ended				6 Months Ended
	Jun. 30, 2011		Jun. 30, 2010		Jun. 30, 2011		Jun. 30, 2010
Amortization expense	$ 8	[1]	$ 7	[1]	$ 16	[1]	$ 14	[1]
Franchise Agreements [Member]
Amortization expense	5		5		10		10
Other Intangible Assets [Member]
Amortization expense	$ 3		$ 2		$ 6		$ 4

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