Revenue - Summary of Revenue from Contracts with Customers on a Disaggregated Basis (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Disaggregation Of Revenue [Line Items]
Total revenues from contracts with customers	$ 1,380
Other operating revenue, includes gains (losses) on commodity derivatives	(34)
Total sales and other operating revenues	1,346	$ 1,258
Exploration and Production
Disaggregation Of Revenue [Line Items]
Total revenues from contracts with customers	1,380
Other operating revenue, includes gains (losses) on commodity derivatives	(34)
Total sales and other operating revenues	1,346
Exploration and Production | United States
Disaggregation Of Revenue [Line Items]
Total revenues from contracts with customers	1,028
Other operating revenue, includes gains (losses) on commodity derivatives	(34)
Total sales and other operating revenues	994
Exploration and Production | Europe
Disaggregation Of Revenue [Line Items]
Total revenues from contracts with customers	36
Total sales and other operating revenues	36
Exploration and Production | Africa
Disaggregation Of Revenue [Line Items]
Total revenues from contracts with customers	131
Total sales and other operating revenues	131
Exploration and Production | Asia
Disaggregation Of Revenue [Line Items]
Total revenues from contracts with customers	185
Total sales and other operating revenues	185
Midstream
Disaggregation Of Revenue [Line Items]
Total revenues from contracts with customers	167
Total sales and other operating revenues	167
Midstream | Intercompany Revenue
Disaggregation Of Revenue [Line Items]
Total revenues from contracts with customers	167
Crude Oil Revenue
Disaggregation Of Revenue [Line Items]
Total revenues from contracts with customers	768
Crude Oil Revenue | Exploration and Production
Disaggregation Of Revenue [Line Items]
Total revenues from contracts with customers	768
Crude Oil Revenue | Exploration and Production | United States
Disaggregation Of Revenue [Line Items]
Total revenues from contracts with customers	593
Crude Oil Revenue | Exploration and Production | Europe
Disaggregation Of Revenue [Line Items]
Total revenues from contracts with customers	33
Crude Oil Revenue | Exploration and Production | Africa
Disaggregation Of Revenue [Line Items]
Total revenues from contracts with customers	99
Crude Oil Revenue | Exploration and Production | Asia
Disaggregation Of Revenue [Line Items]
Total revenues from contracts with customers	43
Natural Gas Liquids Revenue
Disaggregation Of Revenue [Line Items]
Total revenues from contracts with customers	71
Natural Gas Liquids Revenue | Exploration and Production
Disaggregation Of Revenue [Line Items]
Total revenues from contracts with customers	71
Natural Gas Liquids Revenue | Exploration and Production | United States
Disaggregation Of Revenue [Line Items]
Total revenues from contracts with customers	71
Natural Gas Revenue
Disaggregation Of Revenue [Line Items]
Total revenues from contracts with customers	178
Natural Gas Revenue | Exploration and Production
Disaggregation Of Revenue [Line Items]
Total revenues from contracts with customers	178
Natural Gas Revenue | Exploration and Production | United States
Disaggregation Of Revenue [Line Items]
Total revenues from contracts with customers	39
Natural Gas Revenue | Exploration and Production | Europe
Disaggregation Of Revenue [Line Items]
Total revenues from contracts with customers	3
Natural Gas Revenue | Exploration and Production | Africa
Disaggregation Of Revenue [Line Items]
Total revenues from contracts with customers	8
Natural Gas Revenue | Exploration and Production | Asia
Disaggregation Of Revenue [Line Items]
Total revenues from contracts with customers	128
Revenue from Sale of Third Party Purchased Volumes
Disaggregation Of Revenue [Line Items]
Total revenues from contracts with customers	363
Revenue from Sale of Third Party Purchased Volumes | Exploration and Production
Disaggregation Of Revenue [Line Items]
Total revenues from contracts with customers	363
Revenue from Sale of Third Party Purchased Volumes | Exploration and Production | United States
Disaggregation Of Revenue [Line Items]
Total revenues from contracts with customers	325
Revenue from Sale of Third Party Purchased Volumes | Exploration and Production | Africa
Disaggregation Of Revenue [Line Items]
Total revenues from contracts with customers	24
Revenue from Sale of Third Party Purchased Volumes | Exploration and Production | Asia
Disaggregation Of Revenue [Line Items]
Total revenues from contracts with customers	14
Eliminations
Disaggregation Of Revenue [Line Items]
Total revenues from contracts with customers	(167)
Total sales and other operating revenues	(167)	$ (147)
Eliminations | Intercompany Revenue
Disaggregation Of Revenue [Line Items]
Total revenues from contracts with customers	$ (167)