Revenue - Summary of Revenue from Contracts with Customers on a Disaggregated Basis (Detail) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Disaggregation Of Revenue [Line Items]
Total revenues from contracts with customers	$ 1,671	$ 1,581	$ 3,228	$ 2,961
Other operating revenues (a)	(11)	(47)	4	(81)
Total sales and other operating revenues	1,660	1,534	3,232	2,880
Intercompany Revenue
Disaggregation Of Revenue [Line Items]
Total revenues from contracts with customers	0	0	0	0
Crude Oil Revenue
Disaggregation Of Revenue [Line Items]
Total revenues from contracts with customers	967	849	1,777	1,617
Natural Gas Liquids Revenue
Disaggregation Of Revenue [Line Items]
Total revenues from contracts with customers	48	75	116	146
Natural Gas Revenue
Disaggregation Of Revenue [Line Items]
Total revenues from contracts with customers	195	211	426	389
Sales of Purchased Oil and Gas
Disaggregation Of Revenue [Line Items]
Total revenues from contracts with customers	461	446	909	809
Operating Segments | Exploration and Production
Disaggregation Of Revenue [Line Items]
Total revenues from contracts with customers	1,671	1,581	3,228	2,961
Other operating revenues (a)	(11)	(47)	4	(81)
Total sales and other operating revenues	1,660	1,534	3,232	2,880
Operating Segments | Exploration and Production | Intercompany Revenue
Disaggregation Of Revenue [Line Items]
Total revenues from contracts with customers	0	0	0	0
Operating Segments | Exploration and Production | United States
Disaggregation Of Revenue [Line Items]
Total revenues from contracts with customers	1,282	1,228	2,500	2,256
Other operating revenues (a)	(11)	(47)	4	(81)
Total sales and other operating revenues	1,271	1,181	2,504	2,175
Operating Segments | Exploration and Production | United States | Intercompany Revenue
Disaggregation Of Revenue [Line Items]
Total revenues from contracts with customers	0	0	0	0
Operating Segments | Exploration and Production | Denmark
Disaggregation Of Revenue [Line Items]
Total revenues from contracts with customers	53	21	72	57
Other operating revenues (a)	0	0	0	0
Total sales and other operating revenues	53	21	72	57
Operating Segments | Exploration and Production | Denmark | Intercompany Revenue
Disaggregation Of Revenue [Line Items]
Total revenues from contracts with customers	0	0	0	0
Operating Segments | Exploration and Production | Libya
Disaggregation Of Revenue [Line Items]
Total revenues from contracts with customers	158	139	277	270
Other operating revenues (a)	0	0	0	0
Total sales and other operating revenues	158	139	277	270
Operating Segments | Exploration and Production | Libya | Intercompany Revenue
Disaggregation Of Revenue [Line Items]
Total revenues from contracts with customers	0	0	0	0
Operating Segments | Exploration and Production | Malaysia & JDA
Disaggregation Of Revenue [Line Items]
Total revenues from contracts with customers	178	193	379	378
Other operating revenues (a)	0	0	0	0
Total sales and other operating revenues	178	193	379	378
Operating Segments | Exploration and Production | Malaysia & JDA | Intercompany Revenue
Disaggregation Of Revenue [Line Items]
Total revenues from contracts with customers	0	0	0	0
Operating Segments | Exploration and Production | Crude Oil Revenue
Disaggregation Of Revenue [Line Items]
Total revenues from contracts with customers	967	849	1,777	1,617
Operating Segments | Exploration and Production | Crude Oil Revenue | United States
Disaggregation Of Revenue [Line Items]
Total revenues from contracts with customers	762	692	1,444	1,285
Operating Segments | Exploration and Production | Crude Oil Revenue | Denmark
Disaggregation Of Revenue [Line Items]
Total revenues from contracts with customers	51	19	67	52
Operating Segments | Exploration and Production | Crude Oil Revenue | Libya
Disaggregation Of Revenue [Line Items]
Total revenues from contracts with customers	130	110	221	209
Operating Segments | Exploration and Production | Crude Oil Revenue | Malaysia & JDA
Disaggregation Of Revenue [Line Items]
Total revenues from contracts with customers	24	28	45	71
Operating Segments | Exploration and Production | Natural Gas Liquids Revenue
Disaggregation Of Revenue [Line Items]
Total revenues from contracts with customers	48	75	116	146
Operating Segments | Exploration and Production | Natural Gas Liquids Revenue | United States
Disaggregation Of Revenue [Line Items]
Total revenues from contracts with customers	48	75	116	146
Operating Segments | Exploration and Production | Natural Gas Liquids Revenue | Denmark
Disaggregation Of Revenue [Line Items]
Total revenues from contracts with customers	0	0	0	0
Operating Segments | Exploration and Production | Natural Gas Liquids Revenue | Libya
Disaggregation Of Revenue [Line Items]
Total revenues from contracts with customers	0	0	0	0
Operating Segments | Exploration and Production | Natural Gas Liquids Revenue | Malaysia & JDA
Disaggregation Of Revenue [Line Items]
Total revenues from contracts with customers	0	0	0	0
Operating Segments | Exploration and Production | Natural Gas Revenue
Disaggregation Of Revenue [Line Items]
Total revenues from contracts with customers	195	211	426	389
Operating Segments | Exploration and Production | Natural Gas Revenue | United States
Disaggregation Of Revenue [Line Items]
Total revenues from contracts with customers	33	37	75	76
Operating Segments | Exploration and Production | Natural Gas Revenue | Denmark
Disaggregation Of Revenue [Line Items]
Total revenues from contracts with customers	2	2	5	5
Operating Segments | Exploration and Production | Natural Gas Revenue | Libya
Disaggregation Of Revenue [Line Items]
Total revenues from contracts with customers	6	7	12	15
Operating Segments | Exploration and Production | Natural Gas Revenue | Malaysia & JDA
Disaggregation Of Revenue [Line Items]
Total revenues from contracts with customers	154	165	334	293
Operating Segments | Exploration and Production | Sales of Purchased Oil and Gas
Disaggregation Of Revenue [Line Items]
Total revenues from contracts with customers	461	446	909	809
Operating Segments | Exploration and Production | Sales of Purchased Oil and Gas | United States
Disaggregation Of Revenue [Line Items]
Total revenues from contracts with customers	439	424	865	749
Operating Segments | 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
Operating Segments | Exploration and Production | Sales of Purchased Oil and Gas | Libya
Disaggregation Of Revenue [Line Items]
Total revenues from contracts with customers	22	22	44	46
Operating Segments | Exploration and Production | Sales of Purchased Oil and Gas | Malaysia & JDA
Disaggregation Of Revenue [Line Items]
Total revenues from contracts with customers	0	0	0	14
Operating Segments | Midstream
Disaggregation Of Revenue [Line Items]
Total revenues from contracts with customers	190	176	380	343
Other operating revenues (a)	0	0	0	0
Total sales and other operating revenues	190	176	380	343
Operating Segments | Midstream | Intercompany Revenue
Disaggregation Of Revenue [Line Items]
Total revenues from contracts with customers	190	176	380	343
Operating Segments | Midstream | Crude Oil Revenue
Disaggregation Of Revenue [Line Items]
Total revenues from contracts with customers	0	0	0	0
Operating Segments | Midstream | Natural Gas Liquids Revenue
Disaggregation Of Revenue [Line Items]
Total revenues from contracts with customers	0	0	0	0
Operating Segments | Midstream | Natural Gas Revenue
Disaggregation Of Revenue [Line Items]
Total revenues from contracts with customers	0	0	0	0
Operating Segments | Midstream | Sales of Purchased Oil and Gas
Disaggregation Of Revenue [Line Items]
Total revenues from contracts with customers	0	0	0	0
Eliminations
Disaggregation Of Revenue [Line Items]
Total revenues from contracts with customers	(190)	(176)	(380)	(343)
Other operating revenues (a)	0	0	0	0
Total sales and other operating revenues	(190)	(176)	(380)	(343)
Eliminations | Intercompany Revenue
Disaggregation Of Revenue [Line Items]
Total revenues from contracts with customers	(190)	(176)	(380)	(343)
Eliminations | Crude Oil Revenue
Disaggregation Of Revenue [Line Items]
Total revenues from contracts with customers	0	0	0	0
Eliminations | Natural Gas Liquids Revenue
Disaggregation Of Revenue [Line Items]
Total revenues from contracts with customers	0	0	0	0
Eliminations | Natural Gas Revenue
Disaggregation Of Revenue [Line Items]
Total revenues from contracts with customers	0	0	0	0
Eliminations | Sales of Purchased Oil and Gas
Disaggregation Of Revenue [Line Items]
Total revenues from contracts with customers	$ 0	$ 0	$ 0	$ 0