Inventories (Details) (USD $)	Mar. 31, 2013	Dec. 31, 2012
Schedule of Inventories
Refinery feedstocks	$ 2,580,000,000	$ 2,458,000,000
Refined products and blendstocks	3,832,000,000	2,995,000,000
Ethanol feedstocks and products	190,000,000	191,000,000
Convenience store merchandise	111,000,000	112,000,000
Materials and supplies	224,000,000	217,000,000
Inventories	6,937,000,000	5,973,000,000
Inventories (Textual)
Excess of market value over carrying amount of LIFO inventories	$ 7,500,000,000	$ 6,700,000,000