Price Risk Management Activities, Hedging Instruments by Consolidated Balance Sheet Location (Details) - USD ($) $ in Millions	Mar. 31, 2021	Dec. 31, 2020
Derivatives Designated as Hedging Instruments [Member] | Commodity Contracts [Member] | Receivable, Net [Member]
Fair Values of Derivative Instruments
Derivative asset, fair value, gross asset	$ 5	$ 4
Derivative asset, fair value, gross liability	10	17
Derivatives Not Designated as Hedging Instruments [Member]
Fair Values of Derivative Instruments
Derivative asset, fair value, gross asset	401	412
Derivative liability, fair value, gross liability	434	392
Derivatives Not Designated as Hedging Instruments [Member] | Commodity Contracts [Member] | Receivable, Net [Member]
Fair Values of Derivative Instruments
Derivative asset, fair value, gross asset	381	399
Derivative asset, fair value, gross liability	434	388
Derivatives Not Designated as Hedging Instruments [Member] | Physical Purchase Contracts [Member] | Inventories [Member]
Fair Values of Derivative Instruments
Derivative asset, fair value, gross asset	10	13
Derivative asset, fair value, gross liability	0	0
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	10	0
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	$ 0	$ 4