Property, Plant and Equipment - Components of Property, Plant and Equipment (Detail) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Property Plant And Equipment [Line Items]
Total — at cost	$ 35,820	$ 33,222
Less: Reserves for depreciation, depletion, amortization and lease impairment	19,006	17,139
Property, plant and equipment — net	16,814	16,083
Exploration and Production
Property Plant And Equipment [Line Items]
Unproved properties	168	394
Proved properties	3,304	3,124
Wells, equipment and related facilities	28,404	26,173
Total — at cost	31,876	29,691
Midstream
Property Plant And Equipment [Line Items]
Total — at cost	3,904	3,492
Corporate and Other
Property Plant And Equipment [Line Items]
Total — at cost	$ 40	$ 39