Segment Information, Revenue by Product (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended									12 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013		Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Revenue from External Customer [Line Items]
Operating revenues	$ 27,859	$ 34,408	$ 34,914	$ 33,663	$ 34,429	$ 36,137	$ 34,034	[1]	$ 33,474	$ 130,844	$ 138,074	$ 138,393
Refining [Member]
Revenue from External Customer [Line Items]
Operating revenues										126,004	129,064	122,068
Refining [Member] | Gasoline and Blendstocks [Member]
Revenue from External Customer [Line Items]
Operating revenues										56,846	57,806	55,647
Refining [Member] | Distillates [Member]
Revenue from External Customer [Line Items]
Operating revenues										57,521	56,921	51,095
Refining [Member] | Petrochemicals [Member]
Revenue from External Customer [Line Items]
Operating revenues										3,759	4,281	3,908
Refining [Member] | Lubes and Asphalts [Member]
Revenue from External Customer [Line Items]
Operating revenues										1,397	1,643	2,033
Refining [Member] | Other Product Revenues [Member]
Revenue from External Customer [Line Items]
Operating revenues										6,481	8,413	9,385
Ethanol [Member]
Revenue from External Customer [Line Items]
Operating revenues										4,840	5,114	4,317
Ethanol [Member] | Ethanol Product [Member]
Revenue from External Customer [Line Items]
Operating revenues										4,192	4,245	3,545
Ethanol [Member] | Distillers Grains [Member]
Revenue from External Customer [Line Items]
Operating revenues										648	869	772
Retail [Member]
Revenue from External Customer [Line Items]
Operating revenues										0	3,896	12,008
Retail [Member] | Fuel Sales Gasoline and Diesel [Member]
Revenue from External Customer [Line Items]
Operating revenues										0	3,226	10,045
Retail [Member] | Merchandise Sales and Other [Member]
Revenue from External Customer [Line Items]
Operating revenues										0	524	1,649
Retail [Member] | Heating Oil [Member]
Revenue from External Customer [Line Items]
Operating revenues										$ 0	$ 146	$ 314

[1] The separation of our retail business was completed on May 1, 2013.