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 [Abstract]
Balance at Beginning of Period	$ 51		$ 44		$ 35
Charged to Costs and Expenses	45		53		52
Charged to Other Accounts	8	[1]	6	[1]	6	[1]
Deductions	(55)	[2]	(52)	[2]	(49)	[2]
Balance at End of Period	$ 49		$ 51		$ 44

[1] Collection of accounts previously written off.

[2] Uncollectible accounts written off.