Schedule II Valuation And Qualifying Accounts (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011		Dec. 31, 2010		Dec. 31, 2009
Schedule II Valuation And Qualifying Accounts [Abstract]
Balance at Beginning of Period	$ 84	[1]	$ 75	[1]	$ 64	[1]
Charged To Costs And Expenses	99	[1]	91	[1]	98	[1]
Charged To Other Accounts		[1]		[1]		[1]
Deductions	86	[1],[2]	82	[1],[2]	87	[1],[2]
Balance At End of Period	$ 97	[1]	$ 84	[1]	$ 75	[1]

[1] This is a valuation account deducted in the balance sheet from the assets (Accounts receivable-customers) to which they apply.

[2] Accounts written off less cash collections, miscellaneous adjustments and amounts reinstated as receivables previously written off.