Revenue - Summary of Revenue from Contracts with Customers on a Disaggregated Basis (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Disaggregation Of Revenue [Line Items]
Total revenues from contracts with customers	$ 6,458
Other operating revenues (a)	(135)
Total sales and other operating revenues	6,323	$ 5,466	$ 4,762
United States
Disaggregation Of Revenue [Line Items]
Total sales and other operating revenues	4,842	3,692	3,085
Intercompany Revenue
Disaggregation Of Revenue [Line Items]
Total revenues from contracts with customers	0
Crude Oil Revenue
Disaggregation Of Revenue [Line Items]
Total revenues from contracts with customers	3,523
Natural Gas Liquids Revenue
Disaggregation Of Revenue [Line Items]
Total revenues from contracts with customers	308
Natural Gas Revenue
Disaggregation Of Revenue [Line Items]
Total revenues from contracts with customers	859
Sales of Purchased Oil and Gas
Disaggregation Of Revenue [Line Items]
Total revenues from contracts with customers	1,768
Operating Segments | Europe
Disaggregation Of Revenue [Line Items]
Total sales and other operating revenues	164	629	610
Operating Segments | Africa
Disaggregation Of Revenue [Line Items]
Total sales and other operating revenues	548	675	601
Operating Segments | Exploration and Production
Disaggregation Of Revenue [Line Items]
Total revenues from contracts with customers	6,458
Other operating revenues (a)	(135)
Total sales and other operating revenues	6,323	5,460	4,755
Operating Segments | Exploration and Production | United States
Disaggregation Of Revenue [Line Items]
Total revenues from contracts with customers	4,977
Other operating revenues (a)	(135)
Total sales and other operating revenues	4,842
Operating Segments | Exploration and Production | Europe
Disaggregation Of Revenue [Line Items]
Total revenues from contracts with customers	164
Other operating revenues (a)	0
Total sales and other operating revenues	164
Operating Segments | Exploration and Production | Africa
Disaggregation Of Revenue [Line Items]
Total revenues from contracts with customers	548
Other operating revenues (a)	0
Total sales and other operating revenues	548
Operating Segments | Exploration and Production | Asia
Disaggregation Of Revenue [Line Items]
Total revenues from contracts with customers	769
Other operating revenues (a)	0
Total sales and other operating revenues	769
Operating Segments | Midstream
Disaggregation Of Revenue [Line Items]
Total revenues from contracts with customers	713
Other operating revenues (a)	0
Total sales and other operating revenues	713	617	569
Operating Segments | Intercompany Revenue | Exploration and Production
Disaggregation Of Revenue [Line Items]
Total revenues from contracts with customers	0
Operating Segments | Intercompany Revenue | Exploration and Production | United States
Disaggregation Of Revenue [Line Items]
Total revenues from contracts with customers	0
Operating Segments | Intercompany Revenue | Exploration and Production | Europe
Disaggregation Of Revenue [Line Items]
Total revenues from contracts with customers	0
Operating Segments | Intercompany Revenue | Exploration and Production | Africa
Disaggregation Of Revenue [Line Items]
Total revenues from contracts with customers	0
Operating Segments | Intercompany Revenue | Exploration and Production | Asia
Disaggregation Of Revenue [Line Items]
Total revenues from contracts with customers	0
Operating Segments | Intercompany Revenue | Midstream
Disaggregation Of Revenue [Line Items]
Total revenues from contracts with customers	713
Operating Segments | Crude Oil Revenue | Exploration and Production
Disaggregation Of Revenue [Line Items]
Total revenues from contracts with customers	3,523
Operating Segments | Crude Oil Revenue | Exploration and Production | United States
Disaggregation Of Revenue [Line Items]
Total revenues from contracts with customers	2,832
Operating Segments | Crude Oil Revenue | Exploration and Production | Europe
Disaggregation Of Revenue [Line Items]
Total revenues from contracts with customers	153
Operating Segments | Crude Oil Revenue | Exploration and Production | Africa
Disaggregation Of Revenue [Line Items]
Total revenues from contracts with customers	434
Operating Segments | Crude Oil Revenue | Exploration and Production | Asia
Disaggregation Of Revenue [Line Items]
Total revenues from contracts with customers	104
Operating Segments | Crude Oil Revenue | Midstream
Disaggregation Of Revenue [Line Items]
Total revenues from contracts with customers	0
Operating Segments | Natural Gas Liquids Revenue | Exploration and Production
Disaggregation Of Revenue [Line Items]
Total revenues from contracts with customers	308
Operating Segments | Natural Gas Liquids Revenue | Exploration and Production | United States
Disaggregation Of Revenue [Line Items]
Total revenues from contracts with customers	308
Operating Segments | Natural Gas Liquids Revenue | Exploration and Production | Europe
Disaggregation Of Revenue [Line Items]
Total revenues from contracts with customers	0
Operating Segments | Natural Gas Liquids Revenue | Exploration and Production | Africa
Disaggregation Of Revenue [Line Items]
Total revenues from contracts with customers	0
Operating Segments | Natural Gas Liquids Revenue | Exploration and Production | Asia
Disaggregation Of Revenue [Line Items]
Total revenues from contracts with customers	0
Operating Segments | Natural Gas Liquids Revenue | Midstream
Disaggregation Of Revenue [Line Items]
Total revenues from contracts with customers	0
Operating Segments | Natural Gas Revenue | Exploration and Production
Disaggregation Of Revenue [Line Items]
Total revenues from contracts with customers	859
Operating Segments | Natural Gas Revenue | Exploration and Production | United States
Disaggregation Of Revenue [Line Items]
Total revenues from contracts with customers	176
Operating Segments | Natural Gas Revenue | Exploration and Production | Europe
Disaggregation Of Revenue [Line Items]
Total revenues from contracts with customers	11
Operating Segments | Natural Gas Revenue | Exploration and Production | Africa
Disaggregation Of Revenue [Line Items]
Total revenues from contracts with customers	21
Operating Segments | Natural Gas Revenue | Exploration and Production | Asia
Disaggregation Of Revenue [Line Items]
Total revenues from contracts with customers	651
Operating Segments | Natural Gas Revenue | Midstream
Disaggregation Of Revenue [Line Items]
Total revenues from contracts with customers	0
Operating Segments | Sales of Purchased Oil and Gas | Exploration and Production
Disaggregation Of Revenue [Line Items]
Total revenues from contracts with customers	1,768
Operating Segments | Sales of Purchased Oil and Gas | Exploration and Production | United States
Disaggregation Of Revenue [Line Items]
Total revenues from contracts with customers	1,661
Operating Segments | Sales of Purchased Oil and Gas | Exploration and Production | Europe
Disaggregation Of Revenue [Line Items]
Total revenues from contracts with customers	0
Operating Segments | Sales of Purchased Oil and Gas | Exploration and Production | Africa
Disaggregation Of Revenue [Line Items]
Total revenues from contracts with customers	93
Operating Segments | Sales of Purchased Oil and Gas | Exploration and Production | Asia
Disaggregation Of Revenue [Line Items]
Total revenues from contracts with customers	14
Operating Segments | Sales of Purchased Oil and Gas | Midstream
Disaggregation Of Revenue [Line Items]
Total revenues from contracts with customers	0
Eliminations
Disaggregation Of Revenue [Line Items]
Total revenues from contracts with customers	(713)
Other operating revenues (a)	0
Total sales and other operating revenues	(713)	$ (611)	$ (562)
Eliminations | Intercompany Revenue
Disaggregation Of Revenue [Line Items]
Total revenues from contracts with customers	(713)
Eliminations | Crude Oil Revenue
Disaggregation Of Revenue [Line Items]
Total revenues from contracts with customers	0
Eliminations | Natural Gas Liquids Revenue
Disaggregation Of Revenue [Line Items]
Total revenues from contracts with customers	0
Eliminations | Natural Gas Revenue
Disaggregation Of Revenue [Line Items]
Total revenues from contracts with customers	0
Eliminations | Sales of Purchased Oil and Gas
Disaggregation Of Revenue [Line Items]
Total revenues from contracts with customers	$ 0