Property, Plant And Equipment (Summary Of Property, Plant And Equipment) (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 61,213	$ 40,538
Less accumulated depreciation	16,155	14,095
Net property, plant and equipment	45,058	26,443
Operating Segments | Refining & Marketing
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	27,590	19,490
Operating Segments | Retail
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	6,637	5,358
Operating Segments | Midstream
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	25,692	14,898
Corporate and Other
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 1,294	$ 792
Minimum
Property, Plant and Equipment [Line Items]
Estimated useful lives (in years)	3 years
Minimum | Operating Segments | Refining & Marketing
Property, Plant and Equipment [Line Items]
Estimated useful lives (in years)	4 years
Minimum | Operating Segments | Retail
Property, Plant and Equipment [Line Items]
Estimated useful lives (in years)	4 years
Minimum | Operating Segments | Midstream
Property, Plant and Equipment [Line Items]
Estimated useful lives (in years)	3 years
Minimum | Corporate and Other
Property, Plant and Equipment [Line Items]
Estimated useful lives (in years)	4 years
Maximum
Property, Plant and Equipment [Line Items]
Estimated useful lives (in years)	51 years
Maximum | Operating Segments | Refining & Marketing
Property, Plant and Equipment [Line Items]
Estimated useful lives (in years)	30 years
Maximum | Operating Segments | Retail
Property, Plant and Equipment [Line Items]
Estimated useful lives (in years)	25 years
Maximum | Operating Segments | Midstream
Property, Plant and Equipment [Line Items]
Estimated useful lives (in years)	51 years
Maximum | Corporate and Other
Property, Plant and Equipment [Line Items]
Estimated useful lives (in years)	40 years