Revenue (Disaggregated by Product Line) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Sales and other operating revenues	$ 15,024	$ 33,529	$ 40,239	$ 61,782
Refining & Marketing
Sales and other operating revenues	9,441	23,654	26,969	43,574
Retail
Sales and other operating revenues	4,778	8,944	11,547	16,320
Midstream
Sales and other operating revenues	805	931	1,723	1,888
Refined products
Sales and other operating revenues	11,621	29,714	33,618	54,627
Refined products | Refining & Marketing
Sales and other operating revenues	8,341	22,221	24,880	40,971
Refined products | Retail
Sales and other operating revenues	3,160	7,303	8,449	13,250
Refined products | Midstream
Sales and other operating revenues	120	190	289	406
Merchandise
Sales and other operating revenues	1,599	1,614	3,056	3,024
Merchandise | Refining & Marketing
Sales and other operating revenues	0	1	1	2
Merchandise | Retail
Sales and other operating revenues	1,599	1,613	3,055	3,022
Merchandise | Midstream
Sales and other operating revenues	0	0	0	0
Crude oil
Sales and other operating revenues	1,003	1,310	1,878	2,381
Crude oil | Refining & Marketing
Sales and other operating revenues	1,003	1,310	1,878	2,381
Crude oil | Retail
Sales and other operating revenues	0	0	0	0
Crude oil | Midstream
Sales and other operating revenues	0	0	0	0
Midstream services and other
Sales and other operating revenues	801	891	1,687	1,750
Midstream services and other | Refining & Marketing
Sales and other operating revenues	97	122	210	220
Midstream services and other | Retail
Sales and other operating revenues	19	28	43	48
Midstream services and other | Midstream
Sales and other operating revenues	$ 685	$ 741	$ 1,434	$ 1,482