Price Risk Management Activities, Gain (Loss) by Income Statement Location (Details) - Cost of Sales [Member] - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Economic Hedging [Member] | Commodity Contracts [Member]
Effect of Derivative Instruments on Income and OCI
Gain (loss) recognized in income on derivatives	$ 42	$ 122	$ (210)	$ 159
Economic Hedging [Member] | Foreign Currency Contracts [Member]
Effect of Derivative Instruments on Income and OCI
Gain (loss) recognized in income on derivatives	4	24	5	31
Trading Derivatives [Member] | Commodity Contracts [Member]
Effect of Derivative Instruments on Income and OCI
Gain (loss) recognized in income on derivatives	$ 13	$ 20	$ 51	$ 41