Financial and Derivative Instruments - Fair Value of Derivatives Not Designated as Hedging Instruments (Details) - Commodity - USD ($) $ in Millions	Sep. 30, 2020	Dec. 31, 2019
Consolidated Balance Sheet: Fair Value of Derivatives not Designated as Hedging Instruments
Total Assets at Fair Value	$ 104	$ 11
Total Liabilities at Fair Value	8	74
Accounts and notes receivable, net
Consolidated Balance Sheet: Fair Value of Derivatives not Designated as Hedging Instruments
Total Assets at Fair Value	90	11
Long-term receivables, net
Consolidated Balance Sheet: Fair Value of Derivatives not Designated as Hedging Instruments
Total Assets at Fair Value	14	0
Accounts payable
Consolidated Balance Sheet: Fair Value of Derivatives not Designated as Hedging Instruments
Total Liabilities at Fair Value	3	74
Deferred credits and other noncurrent obligations
Consolidated Balance Sheet: Fair Value of Derivatives not Designated as Hedging Instruments
Total Liabilities at Fair Value	$ 5	$ 0