Summary Of Significant Accounting Policies (Supplemental Disclosure Of Cash Flow Information) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012		Dec. 31, 2011		Dec. 31, 2010
Summary Of Significant Accounting Policies [Abstract]
Issued credit memoranda for settlement of customer receivables			$ 28	[1]	$ 83	[1]
Accruals for capital expenditures	240		472		382
Interest	178	[2]	140	[2]	125	[2]
Income taxes, net of refunds received	355		215		170
Interest costs capitalized as part of property	$ 74		$ 46		$ 20

[1] Amounts represent credits applied to customer receivable balances for customers that made advance cash deposits under long-term purchase and supply agreements.

[2] Included in this amount are approximately $74 million, $46 million and $20 million of interest costs that were capitalized as part of property, net in 2012, 2011 and 2010, respectively.