Revenue (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers	$ 4,094	$ 6,456	$ 6,458
Other operating revenues	573	39	(135)
Total sales and other operating revenues	4,667	6,495	6,323
Gain (loss) on commodity derivatives	547	1	(183)
Crude Oil Revenue
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers	2,363	3,660	3,523
Natural Gas Liquids Revenue
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers	253	229	308
Natural Gas Revenue
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers	631	829	859
Sales of Purchased Oil and Gas
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers	847	1,738	1,768
Exploration and Production
Disaggregation of Revenue [Line Items]
Total sales and other operating revenues	4,667	6,495	6,323
Exploration and Production | Crude Oil Revenue
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers	2,363	3,660	3,523
Exploration and Production | Natural Gas Liquids Revenue
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers	253	229	308
Exploration and Production | Natural Gas Revenue
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers	631	829	859
Exploration and Production | Sales of Purchased Oil and Gas
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers	847	1,738	1,768
Exploration and Production | United States | Crude Oil Revenue
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers	1,898	2,981	2,832
Exploration and Production | United States | Natural Gas Liquids Revenue
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers	253	229	308
Exploration and Production | United States | Natural Gas Revenue
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers	144	150	176
Exploration and Production | United States | Sales of Purchased Oil and Gas
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers	831	1,644	1,661
Exploration and Production | Guyana | Crude Oil Revenue
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers	278	0	0
Exploration and Production | Guyana | Natural Gas Liquids Revenue
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers	0	0	0
Exploration and Production | Guyana | Natural Gas Revenue
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers	0	0	0
Exploration and Production | Guyana | Sales of Purchased Oil and Gas
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers	5	0	0
Exploration and Production | Malaysia and JDA | Crude Oil Revenue
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers	34	113	104
Exploration and Production | Malaysia and JDA | Natural Gas Liquids Revenue
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers	0	0	0
Exploration and Production | Malaysia and JDA | Natural Gas Revenue
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers	477	646	651
Exploration and Production | Malaysia and JDA | Sales of Purchased Oil and Gas
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers	0	3	14
Exploration and Production | Other | Crude Oil Revenue
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers	153	566	587
Exploration and Production | Other | Natural Gas Liquids Revenue
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers	0	0	0
Exploration and Production | Other | Natural Gas Revenue
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers	10	33	32
Exploration and Production | Other | Sales of Purchased Oil and Gas
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers	11	91	93
Midstream
Disaggregation of Revenue [Line Items]
Total sales and other operating revenues	0	0	0
Midstream | Crude Oil Revenue
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers	0	0	0
Midstream | Natural Gas Liquids Revenue
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers	0	0	0
Midstream | Natural Gas Revenue
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers	0	0	0
Midstream | Sales of Purchased Oil and Gas
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers	0	0	0
Operating Segments | United States
Disaggregation of Revenue [Line Items]
Total sales and other operating revenues	3,604	5,043	4,842
Operating Segments | Guyana
Disaggregation of Revenue [Line Items]
Total sales and other operating revenues	350	0	0
Operating Segments | Other
Disaggregation of Revenue [Line Items]
Total sales and other operating revenues	202	690	712
Operating Segments | Exploration and Production
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers	4,094	6,456	6,458
Other operating revenues	573	39	(135)
Total sales and other operating revenues	4,667	6,495	6,323
Operating Segments | Exploration and Production | United States
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers	3,126	5,004	4,977
Other operating revenues	478	39	(135)
Total sales and other operating revenues	3,604	5,043	4,842
Operating Segments | Exploration and Production | Guyana
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers	283	0	0
Other operating revenues	67	0	0
Total sales and other operating revenues	350	0	0
Operating Segments | Exploration and Production | Malaysia and JDA
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers	511	762	769
Other operating revenues	0	0	0
Total sales and other operating revenues	511	762	769
Operating Segments | Exploration and Production | Other
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers	174	690	712
Other operating revenues	28	0	0
Total sales and other operating revenues	202	690	712
Operating Segments | Midstream
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers	1,092	848	713
Other operating revenues	0	0	0
Total sales and other operating revenues	1,092	848	713
Eliminations
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers	(1,092)	(848)	(713)
Other operating revenues	0	0	0
Total sales and other operating revenues	(1,092)	(848)	(713)
Eliminations | Exploration and Production
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers	0	0	0
Total sales and other operating revenues	0	0	0
Eliminations | Exploration and Production | United States
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers	0	0	0
Eliminations | Exploration and Production | Guyana
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers	0	0	0
Eliminations | Exploration and Production | Malaysia and JDA
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers	0	0	0
Eliminations | Exploration and Production | Other
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers	0	0	0
Eliminations | Midstream
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers	1,092	848	713
Total sales and other operating revenues	$ 1,092	$ 848	$ 713