BUSINESS SEGMENT INFORMATION - Financial Segment Information (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Operating Expenses:
Lease operating expenses		$ 1,127	$ 1,447	$ 1,439
Taxes other than income		123	207	215
Exploration		274	805	503
Depreciation, depletion, and amortization		1,772	2,680	2,405
Asset retirement obligation accretion		109	107	108
Impairments	$ 1,400	4,501	2,949	511
Total operating expenses		8,537	8,643	5,869
Operating Income (Loss)		(4,102)	(2,152)	1,836
Other Income (Expense):
Gain on divestitures, net		32	43	23
Derivative instrument losses, net		(223)	(35)	(17)
Other		64	54	53
General and administrative		(290)	(406)	(431)
Transaction, reorganization, and separation		(54)	(50)	(28)
Financing costs, net		(267)	(462)	(478)
NET INCOME (LOSS) BEFORE INCOME TAXES		(4,840)	(3,008)	958
Total assets	18,107	12,746	18,107	21,582
Net Property and Equipment	14,158	8,819	14,158	18,421
Additions to Net Property and Equipment	2,734	1,162	2,734	3,914
Operating Segments | Egypt
Segment Reporting Information [Line Items]
Oil and gas production revenues		0	0	0
Operating Expenses:
Lease operating expenses		424	484	428
Taxes other than income		0	0	0
Exploration		63	100	88
Depreciation, depletion, and amortization		601	708	745
Asset retirement obligation accretion		0	0	0
Impairments		529	0	63
Total operating expenses		1,655	1,332	1,371
Operating Income (Loss)		(265)	944	1,377
Other Income (Expense):
Total assets	3,700	3,003	3,700	4,260
Net Property and Equipment	2,573	1,955	2,573	2,856
Additions to Net Property and Equipment	454	454	454	594
Operating Segments | North Sea
Segment Reporting Information [Line Items]
Oil and gas production revenues		0	0	0
Operating Expenses:
Lease operating expenses		305	320	341
Taxes other than income		0	0	0
Exploration		28	2	192
Depreciation, depletion, and amortization		380	366	375
Asset retirement obligation accretion		73	76	75
Impairments		7	0	10
Total operating expenses		843	809	1,035
Operating Income (Loss)		40	467	286
Other Income (Expense):
Total assets	2,473	2,220	2,473	2,456
Net Property and Equipment	1,956	1,773	1,956	2,148
Additions to Net Property and Equipment	183	215	183	223
Operating Segments | U.S.
Segment Reporting Information [Line Items]
Oil and gas production revenues		0	0	0
Operating Expenses:
Lease operating expenses		400	645	670
Taxes other than income		108	194	207
Exploration		168	688	219
Depreciation, depletion, and amortization		779	1,566	1,266
Asset retirement obligation accretion		32	29	32
Impairments		3,963	1,648	438
Total operating expenses		6,095	5,211	3,454
Operating Income (Loss)		(3,937)	(2,272)	182
Other Income (Expense):
Total assets	10,388	5,540	10,388	12,962
Net Property and Equipment	9,385	4,760	9,385	12,145
Additions to Net Property and Equipment	1,696	345	1,696	2,544
Operating Segments | Altus Midstream
Segment Reporting Information [Line Items]
Oil and gas production revenues		145	136	77
Operating Expenses:
Lease operating expenses		0	0	0
Taxes other than income		15	13	8
Exploration		0	0	0
Depreciation, depletion, and amortization		12	40	19
Asset retirement obligation accretion		4	2	1
Impairments		2	1,301	0
Total operating expenses		74	1,412	82
Operating Income (Loss)		75	(1,276)	(5)
Other Income (Expense):
Total assets	1,479	1,786	1,479	1,857
Net Property and Equipment	206	196	206	1,227
Additions to Net Property and Equipment	308	12	308	545
Intersegment Eliminations & Other
Segment Reporting Information [Line Items]
Oil and gas production revenues		(145)	(136)	(77)
Operating Expenses:
Lease operating expenses		(2)	(2)	0
Taxes other than income		0	0	0
Exploration		15	15	4
Depreciation, depletion, and amortization		0	0	0
Asset retirement obligation accretion		0	0	0
Impairments		0	0	0
Total operating expenses		(130)	(121)	(73)
Operating Income (Loss)		(15)	(15)	(4)
Other Income (Expense):
Total assets	67	197	67	47
Net Property and Equipment	38	135	38	45
Additions to Net Property and Equipment	$ 93	136	93	8
Oil and gas, excluding purchased
Segment Reporting Information [Line Items]
Oil and gas production revenues		4,037	6,315	7,348
Operating Expenses:
Gathering, processing, and transmission		274	306	348
Oil and gas, excluding purchased | Operating Segments | Egypt
Segment Reporting Information [Line Items]
Oil and gas production revenues		1,390	2,276	2,748
Operating Expenses:
Gathering, processing, and transmission		38	40	47
Oil and gas, excluding purchased | Operating Segments | North Sea
Segment Reporting Information [Line Items]
Oil and gas production revenues		883	1,276	1,321
Operating Expenses:
Gathering, processing, and transmission		50	45	42
Oil and gas, excluding purchased | Operating Segments | U.S.
Segment Reporting Information [Line Items]
Oil and gas production revenues		1,764	2,763	3,279
Operating Expenses:
Gathering, processing, and transmission		291	299	282
Oil and gas, excluding purchased | Operating Segments | Altus Midstream
Segment Reporting Information [Line Items]
Oil and gas production revenues		0	0	0
Operating Expenses:
Gathering, processing, and transmission		38	56	54
Oil and gas, excluding purchased | Intersegment Eliminations & Other
Operating Expenses:
Gathering, processing, and transmission		(143)	(134)	(77)
Oil and gas, purchased
Segment Reporting Information [Line Items]
Oil and gas production revenues		398	176	357
Operating Expenses:
Gathering, processing, and transmission		357	142	340
Oil and gas, purchased | Operating Segments | Egypt
Segment Reporting Information [Line Items]
Oil and gas production revenues		0	0	0
Operating Expenses:
Gathering, processing, and transmission		0	0	0
Oil and gas, purchased | Operating Segments | North Sea
Segment Reporting Information [Line Items]
Oil and gas production revenues		0	0	0
Operating Expenses:
Gathering, processing, and transmission		0	0	0
Oil and gas, purchased | Operating Segments | U.S.
Segment Reporting Information [Line Items]
Oil and gas production revenues		394	176	357
Operating Expenses:
Gathering, processing, and transmission		354	142	340
Oil and gas, purchased | Operating Segments | Altus Midstream
Segment Reporting Information [Line Items]
Oil and gas production revenues		4	0	0
Operating Expenses:
Gathering, processing, and transmission		3	0	0
Oil and gas, purchased | Intersegment Eliminations & Other
Segment Reporting Information [Line Items]
Oil and gas production revenues		0	0	0
Operating Expenses:
Gathering, processing, and transmission		0	0	0
Oil and gas
Segment Reporting Information [Line Items]
Oil and gas production revenues		4,435	6,491	7,705
Oil and gas | Operating Segments | Egypt
Segment Reporting Information [Line Items]
Oil and gas production revenues		1,390	2,276	2,748
Oil and gas | Operating Segments | North Sea
Segment Reporting Information [Line Items]
Oil and gas production revenues		883	1,276	1,321
Oil and gas | Operating Segments | U.S.
Segment Reporting Information [Line Items]
Oil and gas production revenues		2,158	2,939	3,636
Oil and gas | Operating Segments | Altus Midstream
Segment Reporting Information [Line Items]
Oil and gas production revenues		149	136	77
Oil and gas | Intersegment Eliminations & Other
Segment Reporting Information [Line Items]
Oil and gas production revenues		(145)	(136)	(77)
Oil
Other Income (Expense):
Revenue from non-customers		95	410	592
Oil | Oil and gas, excluding purchased
Segment Reporting Information [Line Items]
Oil and gas production revenues		3,106	5,230	5,846
Oil | Oil and gas, excluding purchased | Operating Segments | Egypt
Segment Reporting Information [Line Items]
Oil and gas production revenues		1,102	1,969	2,396
Oil | Oil and gas, excluding purchased | Operating Segments | North Sea
Segment Reporting Information [Line Items]
Oil and gas production revenues		795	1,163	1,179
Oil | Oil and gas, excluding purchased | Operating Segments | U.S.
Segment Reporting Information [Line Items]
Oil and gas production revenues		1,209	2,098	2,271
Oil | Oil and gas, excluding purchased | Operating Segments | Altus Midstream
Segment Reporting Information [Line Items]
Oil and gas production revenues		0	0	0
Oil | Oil and gas, excluding purchased | Intersegment Eliminations & Other
Segment Reporting Information [Line Items]
Oil and gas production revenues		0	0	0
Natural Gas
Other Income (Expense):
Revenue from non-customers		14	40	58
Natural Gas | Oil and gas, excluding purchased
Segment Reporting Information [Line Items]
Oil and gas production revenues		598	678	919
Natural Gas | Oil and gas, excluding purchased | Operating Segments | Egypt
Segment Reporting Information [Line Items]
Oil and gas production revenues		280	295	339
Natural Gas | Oil and gas, excluding purchased | Operating Segments | North Sea
Segment Reporting Information [Line Items]
Oil and gas production revenues		67	90	122
Natural Gas | Oil and gas, excluding purchased | Operating Segments | U.S.
Segment Reporting Information [Line Items]
Oil and gas production revenues		251	293	458
Natural Gas | Oil and gas, excluding purchased | Operating Segments | Altus Midstream
Segment Reporting Information [Line Items]
Oil and gas production revenues		0	0	0
Natural Gas | Oil and gas, excluding purchased | Intersegment Eliminations & Other
Segment Reporting Information [Line Items]
Oil and gas production revenues		0	0	0
Natural Gas Liquids
Other Income (Expense):
Revenue from non-customers		0	1	2
Natural Gas Liquids | Oil and gas, excluding purchased
Segment Reporting Information [Line Items]
Oil and gas production revenues		333	407	583
Natural Gas Liquids | Oil and gas, excluding purchased | Operating Segments | Egypt
Segment Reporting Information [Line Items]
Oil and gas production revenues		8	12	13
Natural Gas Liquids | Oil and gas, excluding purchased | Operating Segments | North Sea
Segment Reporting Information [Line Items]
Oil and gas production revenues		21	23	20
Natural Gas Liquids | Oil and gas, excluding purchased | Operating Segments | U.S.
Segment Reporting Information [Line Items]
Oil and gas production revenues		304	372	550
Natural Gas Liquids | Oil and gas, excluding purchased | Operating Segments | Altus Midstream
Segment Reporting Information [Line Items]
Oil and gas production revenues		0	0	0
Natural Gas Liquids | Oil and gas, excluding purchased | Intersegment Eliminations & Other
Segment Reporting Information [Line Items]
Oil and gas production revenues		$ 0	$ 0	$ 0