Price Risk Management Activities, Hedging Instruments by Consolidated Balance Sheet Location (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Derivatives Designated as Hedging Instruments [Member] | Commodity Contracts [Member] | Receivables, Net [Member]
Fair Values of Derivative Instruments
Derivative asset, fair value, gross asset	$ 4	$ 9
Derivative asset, fair value, gross liability	17	20
Derivatives Not Designated as Hedging Instruments [Member]
Fair Values of Derivative Instruments
Derivative asset, fair value, gross asset	412	635
Derivative liability, fair value, gross liability	392	661
Derivatives Not Designated as Hedging Instruments [Member] | Commodity Contracts [Member] | Receivables, Net [Member]
Fair Values of Derivative Instruments
Derivative asset, fair value, gross asset	399	608
Derivative asset, fair value, gross liability	388	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	13	0
Derivative asset, fair value, gross liability	0	3
Derivatives Not Designated as Hedging Instruments [Member] | Foreign Currency Contracts [Member] | Receivables, Net [Member]
Fair Values of Derivative Instruments
Derivative asset, fair value, gross asset	0	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	$ 4	$ 10