SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Additional Information (Details) - USD ($)	3 Months Ended			12 Months Ended
	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Nov. 30, 2018
Schedule Of Significant Accounting Policies [Line Items]
Asset impairments		$ 1,400,000,000		$ 4,501,000,000	$ 2,949,000,000	$ 511,000,000
Goodwill impairment				87,000,000	0	0
Impairment for early termination of drilling rig leases	$ 13,000,000
Inventory write-downs	5,000,000					4,000,000
Other asset impairments	9,000,000
Capitalized exploratory well costs, impairment						10,000,000
Equity method investment				0	0	113,000,000
Cash and cash equivalent		247,000,000		262,000,000	247,000,000
Restricted cash		0		0	0
Oil and gas property impaired, fair value		628,000,000		1,900,000,000	628,000,000
Divested unproved properties and leasehold				0	149,000,000	10,000,000
Gathering, processing, and transmission facilities ($206 and $203 related to Altus VIE)		799,000,000		670,000,000	799,000,000
Other property and equipment		1,140,000,000		$ 1,140,000,000	1,140,000,000
Percentage of production available to recover these operating and capital costs over contractually defined periods (up to)				40.00%
Receivables from contracts with customers, net of allowance for doubtful accounts		945,000,000		$ 670,000,000	945,000,000
Restructuring cumulative cost incurred to date				79,000,000
Transaction, reorganization, and separation				54,000,000	50,000,000	28,000,000
Egypt
Schedule Of Significant Accounting Policies [Line Items]
Goodwill impairment	87,000,000			87,000,000	0	0
Employee Severance
Schedule Of Significant Accounting Policies [Line Items]
Transaction, reorganization, and separation				51,000,000	26,000,000	6,000,000
Consulting and Legal Fees
Schedule Of Significant Accounting Policies [Line Items]
Transaction, reorganization, and separation				2,000,000	2,000,000	22,000,000
Office closure
Schedule Of Significant Accounting Policies [Line Items]
Transaction, reorganization, and separation				1,000,000
Employee Termination and Office Closures
Schedule Of Significant Accounting Policies [Line Items]
Transaction, reorganization, and separation					15,000,000
Other restructuring
Schedule Of Significant Accounting Policies [Line Items]
Transaction, reorganization, and separation					7,000,000
Oil and gas, purchased
Schedule Of Significant Accounting Policies [Line Items]
Oil and gas production revenues				398,000,000	176,000,000	357,000,000
Gathering, processing, and transmission				357,000,000	142,000,000	340,000,000
Oil and gas, purchased | Revision of Prior Period, Reclassification, Adjustment
Schedule Of Significant Accounting Policies [Line Items]
Oil and gas production revenues					176,000,000	357,000,000
Gathering, processing, and transmission					142,000,000	340,000,000
Alpine High Play
Schedule Of Significant Accounting Policies [Line Items]
Oil and gas property impaired, fair value		203,000,000			203,000,000
Oklahoma And Texas | Disposal Group, Disposed of by Sale, Not Discontinued Operations
Schedule Of Significant Accounting Policies [Line Items]
Asset impairments for property and equipment			$ 240,000,000		255,000,000
(Loss) gain on sale of oil and gas properties			$ (7,000,000)
Oil and gas proved property
Schedule Of Significant Accounting Policies [Line Items]
Asset impairments for property and equipment				$ 4,319,000,000	1,484,000,000	328,000,000
Oil and gas proved property | Significant Unobservable Inputs (Level 3) | Measurement Input, Discount Rate
Schedule Of Significant Accounting Policies [Line Items]
Oil and gas properties, measurement inputs				10.00%
Oil and gas proved property | United States
Schedule Of Significant Accounting Policies [Line Items]
Asset impairments for property and equipment	3,900,000,000			$ 3,938,000,000	1,484,000,000	265,000,000
Oil and gas proved property | Egypt
Schedule Of Significant Accounting Policies [Line Items]
Asset impairments for property and equipment	354,000,000			374,000,000	0	63,000,000
Oil and gas proved property | North Sea
Schedule Of Significant Accounting Policies [Line Items]
Asset impairments for property and equipment	7,000,000			7,000,000	0	0
Oil and gas proved property | Oklahoma And Texas | Disposal Group, Disposed of by Sale, Not Discontinued Operations
Schedule Of Significant Accounting Policies [Line Items]
Asset impairments for property and equipment					101,000,000
Gathering, processing, and transmission facilities
Schedule Of Significant Accounting Policies [Line Items]
Asset impairments for property and equipment						56,000,000
Oil and gas property impaired, fair value	46,000,000
Gathering, processing, and transmission facilities ($206 and $203 related to Altus VIE)		799,000,000		670,000,000	799,000,000
Accumulated depreciation		310,000,000		323,000,000	310,000,000
(Loss) gain on sale of oil and gas properties					0	0
Gathering, processing, and transmission facilities | Egypt
Schedule Of Significant Accounting Policies [Line Items]
Asset impairments	$ 68,000,000
Oil And Gas Properties, Unproved
Schedule Of Significant Accounting Policies [Line Items]
Asset impairments for property and equipment				101,000,000	768,000,000	224,000,000
Oil And Gas Properties, Unproved | United States
Schedule Of Significant Accounting Policies [Line Items]
Asset impairments for property and equipment				92,000,000	760,000,000	96,000,000
Oil And Gas Properties, Unproved | Egypt
Schedule Of Significant Accounting Policies [Line Items]
Asset impairments for property and equipment				8,000,000	8,000,000	0
Oil And Gas Properties, Unproved | North Sea
Schedule Of Significant Accounting Policies [Line Items]
Asset impairments for property and equipment				1,000,000	0	128,000,000
Divested unproved properties and leasehold						$ 10,000,000
Oil And Gas Properties, Unproved | Oklahoma And Texas
Schedule Of Significant Accounting Policies [Line Items]
Divested unproved properties and leasehold					149,000,000
Oil And Gas Properties, Unproved | Oklahoma And Texas | Disposal Group, Disposed of by Sale, Not Discontinued Operations
Schedule Of Significant Accounting Policies [Line Items]
Asset impairments for property and equipment					149,000,000
Other Working Capital | Oklahoma And Texas | Disposal Group, Disposed of by Sale, Not Discontinued Operations
Schedule Of Significant Accounting Policies [Line Items]
Asset impairments for property and equipment					5,000,000
Power Generators
Schedule Of Significant Accounting Policies [Line Items]
(Loss) gain on sale of oil and gas properties				(2,000,000)
Other Property and Equipment
Schedule Of Significant Accounting Policies [Line Items]
Accumulated depreciation		817,000,000		$ 864,000,000	817,000,000
Other Property and Equipment | Minimum
Schedule Of Significant Accounting Policies [Line Items]
Useful lives of gas gathering, transmission and processing facilities				3 years
Other Property and Equipment | Maximum
Schedule Of Significant Accounting Policies [Line Items]
Useful lives of gas gathering, transmission and processing facilities				20 years
ALTM
Schedule Of Significant Accounting Policies [Line Items]
Cash and cash equivalent		6,000,000		$ 24,000,000	$ 6,000,000
ALTM | Gathering, processing, and transmission facilities
Schedule Of Significant Accounting Policies [Line Items]
Asset impairments for property and equipment		$ 1,300,000,000
Apache Egypt | Sinopec
Schedule Of Significant Accounting Policies [Line Items]
Ownership percentage by noncontrolling owners				33.33%
ALTM | Third-party investors
Schedule Of Significant Accounting Policies [Line Items]
Ownership percentage by noncontrolling owners				21.00%			21.00%