Derivative Instruments and Hedging Activities (Details 2) (USD $) In Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2011	Jun. 30, 2010	Jun. 30, 2011	Jun. 30, 2010
Oil and Gas Production Revenues [Member]
Commodity Derivative Activity Recorded in Statement of Consolidated Operations
Gain (loss) reclassified from accumulated other comprehensive income (loss) into operations (effective portion)	$ (53)	$ 52	$ (47)	$ 51
Revenues [Member]
Commodity Derivative Activity Recorded in Statement of Consolidated Operations
Gain (loss) derivatives recognized in operations (ineffective portion and basis swaps)	$ 4		$ 1