Revenue - Disaggregated by Product Line (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Sales and other operating revenues	$ 31,043	$ 22,988	$ 92,857	$ 64,171
Refined products
Sales and other operating revenues	27,462	19,925	81,762	55,604
Merchandise
Sales and other operating revenues	1,698	1,340	4,722	3,756
Crude oil and refinery feedstocks
Sales and other operating revenues	986	1,069	3,827	3,025
Midstream services and other
Sales and other operating revenues	897	654	2,546	1,786
Refining & Marketing
Sales and other operating revenues	21,437	16,751	65,043	46,635
Refining & Marketing \| Refined products
Sales and other operating revenues	20,330	15,636	60,963	43,493
Refining & Marketing \| Merchandise
Sales and other operating revenues	1	1	3	3
Refining & Marketing \| Crude oil and refinery feedstocks
Sales and other operating revenues	945	1,009	3,682	2,871
Refining & Marketing \| Midstream services and other
Sales and other operating revenues	161	105	395	268
Retail
Sales and other operating revenues	8,677	5,395	24,997	15,231
Retail \| Refined products
Sales and other operating revenues	6,956	4,051	20,206	11,462
Retail \| Merchandise
Sales and other operating revenues	1,697	1,339	4,719	3,753
Retail \| Crude oil and refinery feedstocks
Sales and other operating revenues	0	0	0	0
Retail \| Midstream services and other
Sales and other operating revenues	24	5	72	16
Midstream
Sales and other operating revenues	929	842	2,817	2,305
Midstream \| Refined products
Sales and other operating revenues	176	238	593	649
Midstream \| Merchandise
Sales and other operating revenues	0	0	0	0
Midstream \| Crude oil and refinery feedstocks
Sales and other operating revenues	41	60	145	154
Midstream \| Midstream services and other
Sales and other operating revenues	$ 712	$ 544	$ 2,079	$ 1,502