Derivative Instruments And Hedging Activities (Fair Values Of The Companies' Commodity Derivatives) (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2011		Dec. 31, 2010
Derivative Asset [Member]
Derivatives, Fair Value [Line Items]
Fair value of derivative assets	$ 165	[1]	$ 235	[1]
Impact of netting	(95)	[1]	(129)	[1]
Net derivatives asset	70	[1]	106	[1]
Derivative Asset [Member] | Other Current Assets [Member]
Derivatives, Fair Value [Line Items]
Fair value of derivative assets	139	[1]	184	[1]
Derivative Asset [Member] | Other Deferred Charges And Non-Current Assets [Member]
Derivatives, Fair Value [Line Items]
Fair value of derivative assets	26	[1]	51	[1]
Derivative Liability [Member]
Derivatives, Fair Value [Line Items]
Impact of netting	(205)	[1]	(305)	[1]
Fair value of derivative liabilities	414	[1]	496	[1]
Net derivatives liability	209	[1]	191	[1]
Derivative Liability [Member] | Fair Value Of Derivative Liabilities, Current [Member]
Derivatives, Fair Value [Line Items]
Fair value of derivative liabilities	331	[1]	385	[1]
Derivative Liability [Member] | Fair Value Of Derivative Liabilities, Long Term [Member]
Derivatives, Fair Value [Line Items]
Fair value of derivative liabilities	$ 83	[1]	$ 111	[1]

[1] Qualifying derivative contracts, which have been designated as normal purchases or normal sales contracts, are not reported at fair value under the accounting rules for derivatives and hedging and, therefore, are excluded from the table.