Price Risk Management Activities, Gain (Loss) by Income Statement Location (Details) - Not Designated as Hedging Instrument [Member] - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Commodity Contracts [Member] | Cost of Materials and Other [Member]
Effect of Derivative Instruments on Income
Gain (loss) recognized in income on derivatives	$ (71)	$ (12)
Foreign Currency Contracts [Member] | Cost of Materials and Other [Member]
Effect of Derivative Instruments on Income
Gain (loss) recognized in income on derivatives	(9)	(3)
Foreign Currency Contracts [Member] | Other Income, Net [Member]
Effect of Derivative Instruments on Income
Gain (loss) recognized in income on derivatives	$ 7	$ 0