BUSINESS SEGMENT INFORMATION - Financial Segment Information (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Segment Reporting Information [Line Items]
Oil and gas production revenues									$ 6,315	$ 7,348	$ 5,887
Operating Expenses:
Lease operating expenses									1,447	1,439	1,384
Gathering, processing, and transmission									306	348	195
Taxes other than income									207	215	151
Exploration									805	503	549
Depreciation, depletion, and amortization									2,680	2,405	2,280
Asset retirement obligation accretion									107	108	130
Impairments	$ 1,400				$ 639	$ 49	$ 21	$ 16	2,949	511	8
Total operating expenses									8,501	5,529	4,697
Operating Income (Loss)	(2,893)	$ 175	$ 124	$ 408	(204)	698	738	587	(2,186)	1,819	1,190
Other Income (Expense):
Gain on divestitures									43	23	627
Other									53	53	(91)
General and administrative									(406)	(431)	(395)
Transaction, reorganization, and separation									(50)	(28)	(16)
Financing costs, net									(462)	(478)	(397)
NET INCOME (LOSS) BEFORE INCOME TAXES	(3,035)	14	$ (152)	$ 165	(344)	$ 406	$ 508	$ 388	(3,008)	958	918
Net Property and Equipment	14,158				18,421				14,158	18,421	17,759
Total Assets(5)	18,107				21,582				18,107	21,582	21,922
Additions to Net Property and Equipment	2,734				3,914				2,734	3,914	3,302
Revenue from non-customers									451	652
Altus Midstream
Operating Expenses:
Impairments		$ 9
Operating Segments | Egypt
Segment Reporting Information [Line Items]
Oil and gas production revenues									2,276	2,748	2,307
Operating Expenses:
Lease operating expenses									484	428	362
Gathering, processing, and transmission									40	47	44
Taxes other than income									0	0	0
Exploration									100	88	62
Depreciation, depletion, and amortization									708	745	758
Asset retirement obligation accretion									0	0	0
Impairments									0	63	0
Total operating expenses									1,332	1,371	1,226
Operating Income (Loss)									944	1,377	1,081
Other Income (Expense):
Net Property and Equipment	2,573				2,856				2,573	2,856	3,099
Total Assets(5)	3,700				4,260				3,700	4,260	4,658
Additions to Net Property and Equipment	454				594				454	594	517
Operating Segments | North Sea
Segment Reporting Information [Line Items]
Oil and gas production revenues									1,276	1,321	1,078
Operating Expenses:
Lease operating expenses									320	341	335
Gathering, processing, and transmission									45	42	30
Taxes other than income									0	0	(14)
Exploration									2	192	86
Depreciation, depletion, and amortization									366	375	446
Asset retirement obligation accretion									76	75	72
Impairments									0	10	8
Total operating expenses									809	1,035	963
Operating Income (Loss)									467	286	115
Other Income (Expense):
Net Property and Equipment	1,956				2,148				1,956	2,148	2,553
Total Assets(5)	2,473				2,456				2,473	2,456	2,977
Additions to Net Property and Equipment	183				223				183	223	374
Operating Segments | U.S.
Segment Reporting Information [Line Items]
Oil and gas production revenues									2,763	3,279	2,271
Operating Expenses:
Lease operating expenses									645	670	584
Gathering, processing, and transmission									299	282	86
Taxes other than income									194	207	153
Exploration									688	219	363
Depreciation, depletion, and amortization									1,566	1,266	994
Asset retirement obligation accretion									29	32	31
Impairments									1,648	438	0
Total operating expenses									5,069	3,114	2,211
Operating Income (Loss)									(2,306)	165	60
Other Income (Expense):
Net Property and Equipment	9,385				12,145				9,385	12,145	11,370
Total Assets(5)	10,388				12,962				10,388	12,962	13,522
Additions to Net Property and Equipment	1,696				2,544				1,696	2,544	1,847
Operating Segments | Altus Midstream
Segment Reporting Information [Line Items]
Oil and gas production revenues									0	0	0
Operating Expenses:
Lease operating expenses									0	0	0
Gathering, processing, and transmission									56	54	16
Taxes other than income									13	8	0
Exploration									0	0	0
Depreciation, depletion, and amortization									40	19	6
Asset retirement obligation accretion									2	1	0
Impairments									1,301	0	0
Total operating expenses									1,412	82	22
Operating Income (Loss)									(1,276)	(5)	(7)
Other Income (Expense):
Net Property and Equipment	206				1,227				206	1,227	700
Total Assets(5)	1,479				1,857				1,479	1,857	706
Additions to Net Property and Equipment	308				545				308	545	550
Operating Segments | Canada
Segment Reporting Information [Line Items]
Oil and gas production revenues											231
Operating Expenses:
Lease operating expenses											103
Gathering, processing, and transmission											34
Taxes other than income											12
Exploration											11
Depreciation, depletion, and amortization											76
Asset retirement obligation accretion											27
Impairments											0
Total operating expenses											263
Operating Income (Loss)											(32)
Other Income (Expense):
Net Property and Equipment											0
Total Assets(5)											0
Additions to Net Property and Equipment											0
Intersegment Eliminations & Other
Segment Reporting Information [Line Items]
Oil and gas production revenues									(136)	(77)	(15)
Operating Expenses:
Lease operating expenses									(2)	0	0
Gathering, processing, and transmission									(134)	(77)	(15)
Taxes other than income									0	0	0
Exploration									15	4	27
Depreciation, depletion, and amortization									0	0	0
Asset retirement obligation accretion									0	0	0
Impairments									0	0	0
Total operating expenses									(121)	(73)	12
Operating Income (Loss)									(15)	(4)	(27)
Other Income (Expense):
Net Property and Equipment	38				45				38	45	37
Total Assets(5)	67				47				67	47	59
Additions to Net Property and Equipment	$ 93				$ 8				93	8	14
Intersegment Eliminations & Other | Egypt
Segment Reporting Information [Line Items]
Oil and gas production revenues									0	0	0
Intersegment Eliminations & Other | North Sea
Segment Reporting Information [Line Items]
Oil and gas production revenues									0	0	0
Intersegment Eliminations & Other | U.S.
Segment Reporting Information [Line Items]
Oil and gas production revenues									0	0	0
Intersegment Eliminations & Other | Altus Midstream
Segment Reporting Information [Line Items]
Oil and gas production revenues									136	77	15
Intersegment Eliminations & Other | Canada
Segment Reporting Information [Line Items]
Oil and gas production revenues											0
Oil
Segment Reporting Information [Line Items]
Oil and gas production revenues									5,230	5,846	4,598
Other Income (Expense):
Revenue from non-customers									410	592
Oil | Operating Segments | Egypt
Segment Reporting Information [Line Items]
Oil and gas production revenues									1,969	2,396	1,901
Oil | Operating Segments | North Sea
Segment Reporting Information [Line Items]
Oil and gas production revenues									1,163	1,179	971
Oil | Operating Segments | U.S.
Segment Reporting Information [Line Items]
Oil and gas production revenues									2,098	2,271	1,616
Oil | Operating Segments | Altus Midstream
Segment Reporting Information [Line Items]
Oil and gas production revenues									0	0	0
Oil | Operating Segments | Canada
Segment Reporting Information [Line Items]
Oil and gas production revenues											110
Oil | Intersegment Eliminations & Other
Segment Reporting Information [Line Items]
Oil and gas production revenues									0	0	0
Natural Gas
Segment Reporting Information [Line Items]
Oil and gas production revenues									678	919	959
Other Income (Expense):
Revenue from non-customers									40	58
Natural Gas | Operating Segments | Egypt
Segment Reporting Information [Line Items]
Oil and gas production revenues									295	339	395
Natural Gas | Operating Segments | North Sea
Segment Reporting Information [Line Items]
Oil and gas production revenues									90	122	92
Natural Gas | Operating Segments | U.S.
Segment Reporting Information [Line Items]
Oil and gas production revenues									293	458	368
Natural Gas | Operating Segments | Altus Midstream
Segment Reporting Information [Line Items]
Oil and gas production revenues									0	0	0
Natural Gas | Operating Segments | Canada
Segment Reporting Information [Line Items]
Oil and gas production revenues											104
Natural Gas | Intersegment Eliminations & Other
Segment Reporting Information [Line Items]
Oil and gas production revenues									0	0	0
Natural Gas Liquids
Segment Reporting Information [Line Items]
Oil and gas production revenues									407	583	330
Other Income (Expense):
Revenue from non-customers									1	2
Natural Gas Liquids | Operating Segments | Egypt
Segment Reporting Information [Line Items]
Oil and gas production revenues									12	13	11
Natural Gas Liquids | Operating Segments | North Sea
Segment Reporting Information [Line Items]
Oil and gas production revenues									23	20	15
Natural Gas Liquids | Operating Segments | U.S.
Segment Reporting Information [Line Items]
Oil and gas production revenues									372	550	287
Natural Gas Liquids | Operating Segments | Altus Midstream
Segment Reporting Information [Line Items]
Oil and gas production revenues									0	0	0
Natural Gas Liquids | Operating Segments | Canada
Segment Reporting Information [Line Items]
Oil and gas production revenues											17
Natural Gas Liquids | Intersegment Eliminations & Other
Segment Reporting Information [Line Items]
Oil and gas production revenues									0	0	$ 0
Oil and Gas, Purchased
Segment Reporting Information [Line Items]
Oil and gas production revenues									176	357
Operating Expenses:
Gathering, processing, and transmission									$ 142	$ 340