Inventories (Details) - USD ($) $ in Millions	3 Months Ended			12 Months Ended
	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Schedule of Inventories
Refinery feedstocks			$ 2,404	$ 2,068	$ 2,404
Refined petroleum products and blendstocks			3,774	3,153	3,774
Ethanol feedstocks and products			242	238	242
Materials and supplies			244	250	244
Inventories, before lower of cost or market inventory valuation reserve			6,664	5,709	6,664
Lower of cost or market inventory valuation reserve			(766)	0	(766)
Inventories			5,898	5,709	5,898
Inventories (Textual)
Lower of cost or market inventory valuation reserve			766	0	766
Lower of cost or market inventory valuation adjustment	$ 454	$ 293	(790)	747	(790)	$ 0
Effect of LIFO inventory liquidation on income				120
Excess of market value over carrying amount of LIFO inventories				1,900
Inventory not valued at LIFO			$ 668	$ 641	$ 668