Revenue (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers	$ 1,015	$ 1,578	$ 2,911	$ 4,806
Other operating revenues	144	2	435	6
Total sales and other operating revenues	1,159	1,580	3,346	4,812
Crude oil revenue
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers	575	924	1,616	2,701
Natural gas liquids revenue
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers	68	46	159	162
Natural gas revenue
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers	151	201	455	627
Sales of purchased oil and gas
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers	221	407	681	1,316
Exploration and Production
Disaggregation of Revenue [Line Items]
Total sales and other operating revenues	1,159	1,580	3,346	4,812
Exploration and Production | Crude oil revenue
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers	575	924	1,616	2,701
Exploration and Production | Crude oil revenue | United States
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers	471	749	1,390	2,193
Exploration and Production | Crude oil revenue | Guyana
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers	80	0	149	0
Exploration and Production | Crude oil revenue | Malaysia & JDA
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers	13	22	16	67
Exploration and Production | Crude oil revenue | Denmark
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers	11	31	61	98
Exploration and Production | Crude oil revenue | Libya
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers	0	122	0	343
Exploration and Production | Natural gas liquids revenue
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers	68	46	159	162
Exploration and Production | Natural gas liquids revenue | United States
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers	68	46	159	162
Exploration and Production | Natural gas liquids revenue | Guyana
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers	0	0	0	0
Exploration and Production | Natural gas liquids revenue | Malaysia & JDA
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers	0	0	0	0
Exploration and Production | Natural gas liquids revenue | Denmark
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers	0	0	0	0
Exploration and Production | Natural gas liquids revenue | Libya
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers	0	0	0	0
Exploration and Production | Natural gas revenue
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers	151	201	455	627
Exploration and Production | Natural gas revenue | United States
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers	34	34	104	109
Exploration and Production | Natural gas revenue | Guyana
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers	0	0	0	0
Exploration and Production | Natural gas revenue | Malaysia & JDA
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers	116	160	344	494
Exploration and Production | Natural gas revenue | Denmark
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers	1	2	5	7
Exploration and Production | Natural gas revenue | Libya
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers	0	5	2	17
Exploration and Production | Sales of purchased oil and gas
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers	221	407	681	1,316
Exploration and Production | Sales of purchased oil and gas | United States
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers	220	381	679	1,246
Exploration and Production | Sales of purchased oil and gas | Guyana
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers	1	0	2	0
Exploration and Production | Sales of purchased oil and gas | Malaysia & JDA
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers	0	3	0	3
Exploration and Production | Sales of purchased oil and gas | Denmark
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers	0	0	0	0
Exploration and Production | Sales of purchased oil and gas | Libya
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers	0	23	0	67
Midstream
Disaggregation of Revenue [Line Items]
Total sales and other operating revenues	0	0	0	0
Midstream | Crude oil revenue
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers	0	0	0	0
Midstream | Natural gas liquids revenue
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers	0	0	0	0
Midstream | Natural gas revenue
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers	0	0	0	0
Midstream | Sales of purchased oil and gas
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers	0	0	0	0
Operating Segments | Exploration and Production
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers	1,015	1,578	2,911	4,806
Other operating revenues	144	2	435	6
Total sales and other operating revenues	1,159	1,580	3,346	4,812
Operating Segments | Exploration and Production | United States
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers	793	1,210	2,332	3,710
Other operating revenues	125	2	368	6
Total sales and other operating revenues	918	1,212	2,700	3,716
Operating Segments | Exploration and Production | Guyana
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers	81	0	151	0
Other operating revenues	18	0	51	0
Total sales and other operating revenues	99	0	202	0
Operating Segments | Exploration and Production | Malaysia & JDA
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers	129	185	360	564
Other operating revenues	0	0	1	0
Total sales and other operating revenues	129	185	361	564
Operating Segments | Exploration and Production | Denmark
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers	12	33	66	105
Other operating revenues	1	0	15	0
Total sales and other operating revenues	13	33	81	105
Operating Segments | Exploration and Production | Libya
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers	0	150	2	427
Other operating revenues	0	0	0	0
Total sales and other operating revenues	0	150	2	427
Operating Segments | Midstream
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers	264	215	825	595
Other operating revenues	0	0	0	0
Total sales and other operating revenues	264	215	825	595
Eliminations
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers	(264)	(215)	(825)	(595)
Other operating revenues	0	0	0	0
Total sales and other operating revenues	(264)	(215)	(825)	(595)
Eliminations | Exploration and Production
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers	0	0	0	0
Total sales and other operating revenues	0	0	0	0
Eliminations | Exploration and Production | United States
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers	0	0	0	0
Eliminations | Exploration and Production | Guyana
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers	0	0	0	0
Eliminations | Exploration and Production | Malaysia & JDA
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers	0	0	0	0
Eliminations | Exploration and Production | Denmark
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers	0	0	0	0
Eliminations | Exploration and Production | Libya
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers	0	0	0	0
Eliminations | Midstream
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers	264	215	825	595
Total sales and other operating revenues	$ 264	$ 215	$ 825	$ 595