Derivatives Derivatives (Details 5-Non Hedges) (Details) (Not Designated as Hedging Instrument [Member], Sales and other operating revenues [Member], Commodity [Member], USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Mar. 31, 2012	Jun. 30, 2013	Jun. 30, 2012
Not Designated as Hedging Instrument [Member] | Sales and other operating revenues [Member] | Commodity [Member]
Derivative Instruments not Designated as Hedges Gain (Loss) by Hedging Relationship, by Income Statement Location, by Derivative Instrument Risk [Line Items]
Derivative Instruments, Gain (Loss) Recognized in Income, Net	$ 67	$ (1)	$ 13	$ 2