Sales and Other Operating Revenues Sales and Other Operating Revenues (Disaggregated) (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018		Dec. 31, 2017		Dec. 31, 2016
Revenue from External Customer [Line Items]
Sales and other operating revenues	$ 29,098	$ 29,788	$ 28,980	$ 23,595					$ 111,461	[1]
Sales and other operating revenues					$ 29,746	$ 25,627	$ 24,087	$ 22,894			$ 102,354	[1]	$ 84,279	[1]
United States
Revenue from External Customer [Line Items]
Sales and other operating revenues									86,401
Sales and other operating revenues											75,684		59,742
United Kingdom
Revenue from External Customer [Line Items]
Sales and other operating revenues									11,054
Sales and other operating revenues											10,626		9,895
Germany
Revenue from External Customer [Line Items]
Sales and other operating revenues									4,352
Sales and other operating revenues											6,692		6,128
Other foreign countries
Revenue from External Customer [Line Items]
Sales and other operating revenues									9,654
Sales and other operating revenues											9,352		8,514
Refined petroleum products
Revenue from External Customer [Line Items]
Sales and other operating revenues									87,967
Sales and other operating revenues											85,405		73,385
Crude oil resales
Revenue from External Customer [Line Items]
Sales and other operating revenues									16,419
Sales and other operating revenues											11,808		7,594
NGL
Revenue from External Customer [Line Items]
Sales and other operating revenues									6,161
Sales and other operating revenues											4,670		3,107
Services and other
Revenue from External Customer [Line Items]
Sales and other operating revenues									$ 914
Sales and other operating revenues											$ 471		$ 193

[1] Includes excise taxes on petroleum products sales: $13,054 million