Segment Information (Details) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2016	Mar. 31, 2015	Dec. 31, 2015
Segment information for our reportable segments
Operating revenues	[1]	$ 15,714	$ 21,330
Lower of cost or market inventory valuation adjustment		(293)	0
Operating income (loss)		829	1,495
Total assets by reportable segment
Reportable segment assets		44,259		$ 44,227
Refining [Member]
Segment information for our reportable segments
Operating revenues		14,920	20,529
Total assets by reportable segment
Reportable segment assets		38,427		38,068
Ethanol [Member]
Segment information for our reportable segments
Operating revenues		794	801
Total assets by reportable segment
Reportable segment assets		1,040		1,016
Corporate and Other [Member]
Total assets by reportable segment
Reportable segment assets		4,792		$ 5,143
Operating Segments [Member]
Segment information for our reportable segments
Operating revenues		15,748	21,358
Operating Segments [Member] | Refining [Member]
Segment information for our reportable segments
Operating revenues		14,920	20,529
Lower of cost or market inventory valuation adjustment		(263)
Operating income (loss)		958	1,641
Operating Segments [Member] | Ethanol [Member]
Segment information for our reportable segments
Operating revenues		828	829
Lower of cost or market inventory valuation adjustment		(30)
Operating income (loss)		39	12
Intersegment Eliminations [Member]
Segment information for our reportable segments
Operating revenues		34	28
Intersegment Eliminations [Member] | Refining [Member]
Segment information for our reportable segments
Operating revenues		0	0
Intersegment Eliminations [Member] | Ethanol [Member]
Segment information for our reportable segments
Operating revenues		34	28
Corporate, Non-Segment [Member] | Corporate and Other [Member]
Segment information for our reportable segments
Operating income (loss)		$ (168)	$ (158)

[1] Includes excise taxes on sales by certain of our international operations of $1,395 million and $1,426 million for the three months ended March 31, 2016 and 2015, respectively.