Derivatives (Schedule Of Fair Value Of Derivative Assets And Liabilities) (Details) (USD $) In Millions, unless otherwise specified	Mar. 31, 2012		Dec. 31, 2011
Derivatives, Fair Value [Line Items]
Asset Derivatives	$ 425		$ 306
Liability Derivatives	(947)		(2,820)
Other Current Assets [Member] | Total Commodity Derivatives [Member] | Not Designated As Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Asset Derivatives	425		306
Liability Derivatives	$ (947)	[1]	$ (2,820)	[1]

[1] These derivative liabilities have been funded with margin deposits recorded in our Unaudited Condensed Consolidated Balance Sheets in Other Current Assets.