Property, Plant And Equipment - Summary Of Property, Plant And Equipment (Detail) - USD ($) $ in Millions	Jun. 30, 2019	Dec. 31, 2018
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 62,902	$ 61,213
Less accumulated depreciation	17,567	16,155
Property, plant and equipment, net	45,335	45,058
Operating Segments | Refining & Marketing
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	28,429	27,590
Operating Segments | Retail
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	6,767	6,637
Operating Segments | Midstream
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	26,472	25,692
Corporate and Other
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 1,234	$ 1,294