Segment Information (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011	Dec. 31, 2011
Segment information for our reportable segments
Operating revenues from external customers	$ 34,662	$ 31,293	$ 69,829	$ 57,601
Intersegment revenues	2,249	2,363	4,518	4,408
Operating income (loss)	1,361	1,290	1,117	1,534
Total assets by reportable segment
Reportable segment assets	41,188		41,188		42,783
Refining [Member]
Segment information for our reportable segments
Operating revenues from external customers	30,488	26,921	61,638	49,483
Intersegment revenues	2,203	2,311	4,458	4,308
Operating income (loss)	1,364	1,253	1,245	1,529
Total assets by reportable segment
Reportable segment assets	36,602		36,602		38,164
Retail [Member]
Segment information for our reportable segments
Operating revenues from external customers	3,062	3,128	5,997	5,812
Intersegment revenues	0	0	0	0
Operating income (loss)	172	135	212	201
Total assets by reportable segment
Reportable segment assets	1,973		1,973		1,999
Ethanol [Member]
Segment information for our reportable segments
Operating revenues from external customers	1,112	1,244	2,194	2,306
Intersegment revenues	46	52	60	100
Operating income (loss)	5	64	14	108
Total assets by reportable segment
Reportable segment assets	926		926		943
Corporate [Member]
Segment information for our reportable segments
Operating revenues from external customers	0	0	0	0
Intersegment revenues	0	0	0	0
Operating income (loss)	(180)	(162)	(354)	(304)
Total assets by reportable segment
Reportable segment assets	$ 1,687		$ 1,687		$ 1,677