Segment Information (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011	Dec. 31, 2011
Segment information for our three reportable segments
Operating revenues from external customers	$ 35,167	$ 26,308
Intersegment revenues	2,269	2,045
Operating income (loss)	(244)	244
Total assets by reportable segment
Reportable segment assets	42,634		42,783
Refining [Member]
Segment information for our three reportable segments
Operating revenues from external customers	31,150	22,562
Intersegment revenues	2,255	1,997
Operating income (loss)	(119)	276
Total assets by reportable segment
Reportable segment assets	37,600		38,164
Retail [Member]
Segment information for our three reportable segments
Operating revenues from external customers	2,935	2,684
Intersegment revenues	0	0
Operating income (loss)	40	66
Total assets by reportable segment
Reportable segment assets	2,049		1,999
Ethanol [Member]
Segment information for our three reportable segments
Operating revenues from external customers	1,082	1,062
Intersegment revenues	14	48
Operating income (loss)	9	44
Total assets by reportable segment
Reportable segment assets	982		943
Corporate [Member]
Segment information for our three reportable segments
Operating revenues from external customers	0	0
Intersegment revenues	0	0
Operating income (loss)	(174)	(142)
Total assets by reportable segment
Reportable segment assets	$ 2,003		$ 1,677