Revenues and Segment Information, Assets (Details) - USD ($) $ in Millions	Mar. 31, 2021	Dec. 31, 2020
Total Assets by Reportable Segment
Reportable segment assets	$ 53,614	$ 51,774
Corporate and Eliminations [Member]
Total Assets by Reportable Segment
Reportable segment assets	4,281	5,448
Refining [Member] | Operating Segments [Member]
Total Assets by Reportable Segment
Reportable segment assets	45,649	42,939
Renewable Diesel [Member] | Operating Segments [Member]
Total Assets by Reportable Segment
Reportable segment assets	1,948	1,659
Ethanol [Member] | Operating Segments [Member]
Total Assets by Reportable Segment
Reportable segment assets	$ 1,736	$ 1,728