Segment Information, Total Assets by Reportable Segments (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2010
Total Assets by Reportable Segments
Reportable segment assets	$ 42,783	$ 37,621
Refining [Member]
Total Assets by Reportable Segments
Reportable segment assets	38,164	30,363
Retail [Member]
Total Assets by Reportable Segments
Reportable segment assets	1,999	1,925
Ethanol [Member]
Total Assets by Reportable Segments
Reportable segment assets	943	953
Corporate [Member]
Total Assets by Reportable Segments
Reportable segment assets	$ 1,677	$ 4,380