Property, Plant and Equipment - Components of Property, Plant and Equipment (Detail) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Property Plant And Equipment [Line Items]
Total — at cost	$ 32,504	$ 46,907
Less: Reserves for depreciation, depletion, amortization and lease impairment	16,312	23,312
Property, plant and equipment — net	16,192	23,595	[1]
Exploration and Production
Property Plant And Equipment [Line Items]
Unproved properties	520	710
Proved properties	3,162	4,249
Wells, equipment and related facilities	25,550	38,250
Total — at cost	29,232	43,209
Midstream
Property Plant And Equipment [Line Items]
Total — at cost	3,219	3,598
Corporate and Other
Property Plant And Equipment [Line Items]
Total — at cost	$ 53	$ 100

[1] Of the total Europe, Property, plant and equipment (net), Norway represented $3,893 million in 2016.