Price Risk Management Activities, Gain (Loss) by Income Statement Location (Details) - Cost of Sales [Member] - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Economic Hedging [Member] | Commodity Contracts [Member]
Effect of Derivative Instruments on Income and OCI
Gain (loss) recognized in income on derivatives	$ (113)	$ (27)	$ (252)	$ 37
Economic Hedging [Member] | Foreign Currency Contracts [Member]
Effect of Derivative Instruments on Income and OCI
Gain (loss) recognized in income on derivatives	4	(15)	1	7
Trading Derivatives [Member] | Commodity Contracts [Member]
Effect of Derivative Instruments on Income and OCI
Gain (loss) recognized in income on derivatives	$ (3)	$ 1	$ 38	$ 21