Derivative Financial Instruments - Narrative (Details)	3 Months Ended		9 Months Ended
	Sep. 30, 2021 USD ($) bblPerDay	Sep. 30, 2020 USD ($)	Sep. 30, 2021 USD ($) bblPerDay	Sep. 30, 2020 USD ($)
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Purchase contract, amount of barrel to be purchased and sold | bblPerDay	50,000		50,000
Long-term purchase commitment, period			6 years
Gain (loss) on derivative, net	$ 6,000,000	$ (85,000,000)	$ 3,000,000	$ (100,000,000)
Cash payments or receipts from marketing derivatives	$ (11,000,000)	$ 0	$ (31,000,000)	$ 0