Derivatives Derivatives (Details 5-Non Hedges) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Derivative Instruments, Gain (Loss) [Line Items]
Net cash received (paid) in settlement of derivative instruments	$ 14	$ 4	$ 46	$ 4
Not Designated as Hedging Instrument [Member] | Commodity [Member] | Sales and other operating revenues [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Gain (Loss) on Derivative, Net	$ (88)	$ (43)	$ (90)	$ (17)