Receivables (Schedule Of Allowance For Doubtful Accounts) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010
Customer Receivables [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Balance at beginning of year	$ 46	$ 72
Provision for doubtful accounts	19	(8)
Write off of uncollectible accounts	(14)	(10)
Recoveries of prior write-offs	(3)	(4)
Other	(2)	(4)
Balance at end of year	46	46
Other Receivables [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Balance at beginning of year	87	90
Provision for doubtful accounts	7	1
Write off of uncollectible accounts	(3)	(1)
Recoveries of prior write-offs	(5)	(3)
Other	(7)
Balance at end of year	$ 79	$ 87