Derivative Instruments And Hedging Activities (Fair Values Of The Companies' Commodity Derivatives) (Detail) (USD $) In Millions, unless otherwise specified	Jun. 30, 2012		Dec. 31, 2011
Derivatives Assets [Member]
Current Other current assets	$ 140	[1]	$ 165	[1]
Impact of netting	(79)	[1]	(95)	[1]
Net derivative assets	61	[1]	70	[1]
Derivatives Assets [Member] | Other Current Assets [Member]
Current Other current assets	118	[1]	139	[1]
Derivatives Assets [Member] | Other Deferred Charges And Non-Current Assets [Member]
Current Other current assets	22	[1]	26	[1]
Derivatives Liabilities [Member]
Current Fair value of derivative liabilities	335	[1]	414	[1]
Impact of netting	(181)	[1]	(205)	[1]
Net derivative liabilities	154	[1]	209	[1]
Derivatives Liabilities [Member] | Fair Value Of Derivative Liabilities, Current [Member]
Current Fair value of derivative liabilities	253	[1]	331	[1]
Derivatives Liabilities [Member] | Fair Value Of Derivative Liabilities, Long-Term [Member]
Current Fair value of derivative liabilities	$ 82	[1]	$ 83	[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.