Price Risk Management Activities, Gain (Loss) by Income Statement Location (Details) - Derivatives Not Designated as Hedging Instruments [Member] - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Commodity Contracts [Member] | Revenues [Member]
Effect of Derivative Instruments on Income
Gain (loss) recognized in income on derivatives	$ 5	$ 0	$ 0
Commodity Contracts [Member] | Cost of Materials and Other [Member]
Effect of Derivative Instruments on Income
Gain (loss) recognized in income on derivatives	(68)	(165)	(278)
Commodity Contracts [Member] | Operating Expenses (Excluding Depreciation and Amortization Expense) [Member]
Effect of Derivative Instruments on Income
Gain (loss) recognized in income on derivatives	0	7	0
Foreign Currency Contracts [Member] | Cost of Materials and Other [Member]
Effect of Derivative Instruments on Income
Gain (loss) recognized in income on derivatives	(21)	56	(40)
Foreign Currency Contracts [Member] | Other Income, Net [Member]
Effect of Derivative Instruments on Income
Gain (loss) recognized in income on derivatives	$ 75	$ (43)	$ 0