Derivatives (Schedule Of Fair Value Of Derivative Assets And Liabilities) (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2011		Dec. 31, 2010
Derivatives, Fair Value [Line Items]
Asset Derivatives	$ 306		$ 507
Liability Derivatives	(2,820.0)		(2,474.0)
Other Current Assets [Member] | Commodity Derivatives [Member] | Designated As Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Asset Derivatives			14
Liability Derivatives			(191.0)	[1]
Other Current Assets [Member] | Commodity Derivatives [Member] | Not Designated As Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Asset Derivatives	306		493
Liability Derivatives	$ (2,820.0)	[1]	$ (2,283.0)	[1]

[1] These derivative liabilities have been funded with margin deposits recorded in our Consolidated Balance Sheets in other current assets.