Price Risk Management Activities, Hedging Instruments by Consolidated Balance Sheet Location (Details) - USD ($) $ in Millions	Mar. 31, 2020	Dec. 31, 2019
Derivatives Designated as Hedging Instruments [Member] | Commodity Contracts [Member] | Receivable, Net [Member]
Fair Values of Derivative Instruments
Derivative asset, fair value, gross asset	$ 86	$ 9
Derivative asset, fair value, gross liability	45	20
Derivatives Not Designated as Hedging Instruments [Member]
Fair Values of Derivative Instruments
Derivative asset, fair value, gross asset	4,168	635
Derivative liability, fair value, gross liability	4,505	661
Derivatives Not Designated as Hedging Instruments [Member] | Commodity Contracts [Member] | Receivable, Net [Member]
Fair Values of Derivative Instruments
Derivative asset, fair value, gross asset	4,166	608
Derivative asset, fair value, gross liability	4,423	648
Derivatives Not Designated as Hedging Instruments [Member] | Physical Purchase Contracts [Member] | Inventories [Member]
Fair Values of Derivative Instruments
Derivative asset, fair value, gross asset	0	0
Derivative asset, fair value, gross liability	10	3
Derivatives Not Designated as Hedging Instruments [Member] | Foreign Currency Contracts [Member] | Receivable, Net [Member]
Fair Values of Derivative Instruments
Derivative asset, fair value, gross asset	2	27
Derivative asset, fair value, gross liability	0	0
Derivatives Not Designated as Hedging Instruments [Member] | Foreign Currency Contracts [Member] | Accrued Expenses [Member]
Fair Values of Derivative Instruments
Derivative liability, fair value, gross asset	0	0
Derivative liability, fair value, gross liability	$ 72	$ 10