Segment Information (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011	Dec. 31, 2011
Segment information for our reportable segments
Operating revenues from external customers	$ 34,726	$ 33,713	$ 104,555	$ 91,314
Intersegment revenues	2,363	2,283	6,881	6,691
Operating income (loss)	1,309	1,979	2,426	3,513
Total assets by reportable segment
Reportable segment assets	43,792		43,792		42,783
Refining [Member]
Segment information for our reportable segments
Operating revenues from external customers	30,543	29,177	92,181	78,660
Intersegment revenues	2,348	2,258	6,806	6,566
Operating income (loss)	1,528	1,947	2,773	3,476
Total assets by reportable segment
Reportable segment assets	38,198		38,198		38,164
Retail [Member]
Segment information for our reportable segments
Operating revenues from external customers	3,092	3,053	9,089	8,865
Intersegment revenues	0	0	0	0
Operating income (loss)	41	97	253	298
Total assets by reportable segment
Reportable segment assets	2,098		2,098		1,999
Ethanol [Member]
Segment information for our reportable segments
Operating revenues from external customers	1,091	1,483	3,285	3,789
Intersegment revenues	15	25	75	125
Operating income (loss)	(73)	107	(59)	215
Total assets by reportable segment
Reportable segment assets	900		900		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)	(187)	(172)	(541)	(476)
Total assets by reportable segment
Reportable segment assets	$ 2,596		$ 2,596		$ 1,677