Valuation And Qualifying Accounts (Schedule Of Valuation And Qualifying Accounts) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011		Dec. 31, 2010		Dec. 31, 2009
Allowance For Doubtful Accounts [Member]
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at Beginning of Period	$ 68		$ 79		$ 66
Additions, Charged to cost and expenses	102		99		110
Additions, Charged to other accounts-describe	0		0		0
Deductions-describe	114	[1]	110	[1]	97	[1]
Balance at End of Period	56		68		79
Materials And Supplies Valuation Reserve [Member]
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at Beginning of Period	4		5		5
Additions, Charged to cost and expenses	2		0		1
Additions, Charged to other accounts-describe	0		0		0
Deductions-describe	3	[2]	1	[2]	1	[2]
Balance at End of Period	3		4		5
Other Valuation Allowances [Member]
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at Beginning of Period			8		8
Additions, Charged to cost and expenses			0		0
Additions, Charged to other accounts-describe			0		0
Deductions-describe			8	[3]	0
Balance at End of Period			$ 0		$ 8

[1] Accounts Receivable written off.

[2] Reduced reserve to appropriate level and to remove obsolete inventory.

[3] Valuation Allowance written off.