Price Risk Management Activities, Gain (Loss) by Income Statement Location (Details) - Cost of Materials and Other [Member] - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Economic Hedges [Member] | Commodity Contracts [Member]
Effect of Derivative Instruments on Income
Gain (loss) recognized in income on derivatives	$ (66)	$ 25	$ (114)	$ (72)
Economic Hedges [Member] | Foreign Currency Contracts [Member]
Effect of Derivative Instruments on Income
Gain (loss) recognized in income on derivatives	17	(20)	14	(26)
Trading Derivatives [Member] | Commodity Contracts [Member]
Effect of Derivative Instruments on Income
Gain (loss) recognized in income on derivatives	$ 51	$ (3)	$ 87	$ (2)