SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Additional Information (Details) - USD ($)	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	Dec. 31, 2016
Schedule Of Significant Accounting Policies [Line Items]
Asset impairments	$ 1,400,000,000				$ 639,000,000	$ 49,000,000	$ 21,000,000	$ 16,000,000	$ 2,949,000,000	$ 511,000,000	$ 8,000,000
Asset impairments for property and equipment		$ 9,000,000
Capitalized exploratory well costs, impairment										10,000,000
Impairment on equity method investment										113,000,000
Inventory write-downs										4,000,000
UK Petroleum Revenue Tax (PRT) rate											0.00%	35.00%
Cash and cash equivalent	247,000,000				714,000,000				247,000,000	714,000,000
Restricted cash	0				0				0	0
Allowance for doubtful accounts	88,000,000				92,000,000				88,000,000	92,000,000	$ 84,000,000	$ 93,000,000
Oil and gas property impaired, fair value	628,000,000				323,000,000				628,000,000	323,000,000
Impairment of leasehold	3,200,000,000	21,000,000	$ 279,000,000	$ 23,000,000
Gathering, processing, and transmission facilities	799,000,000				1,856,000,000				799,000,000	1,856,000,000
Accumulated depreciation	28,987,000,000				28,335,000,000				28,987,000,000	28,335,000,000
Changes of goodwill									0	0	0
Goodwill	$ 87,000,000				87,000,000				$ 87,000,000	87,000,000	87,000,000
Percentage of production available to recover these operating and capital costs over contractually defined periods (up to)	40.00%								40.00%
Impairment of GTP assets										56,000,000	0
Property and equipment, net	$ 14,158,000,000				18,421,000,000				$ 14,158,000,000	18,421,000,000	17,759,000,000
Cost of oil and gas purchased									306,000,000	348,000,000	195,000,000
Receivables from contracts with customers, net of allowance for doubtful accounts	945,000,000				1,000,000,000.0				945,000,000	1,000,000,000.0
Other foreign currency losses									1,000,000	1,000,000	11,000,000
North Sea
Schedule Of Significant Accounting Policies [Line Items]
Gain (loss) on sale of oil and gas properties											$ 6,000,000
Scottish Area Gas Evacuation System | North Sea
Schedule Of Significant Accounting Policies [Line Items]
Equity method investment, ownership percentage											30.28%
Beryl Pipeline | North Sea
Schedule Of Significant Accounting Policies [Line Items]
Equity method investment, ownership percentage											60.56%
Alpine High Play
Schedule Of Significant Accounting Policies [Line Items]
Oil and gas property impaired, fair value	203,000,000								203,000,000
Oil and gas proved property
Schedule Of Significant Accounting Policies [Line Items]
Asset impairments									1,484,000,000	328,000,000	$ 0
Asset impairments for property and equipment									1,484,000,000	328,000,000	0
Oil And Gas Properties, Unproved
Schedule Of Significant Accounting Policies [Line Items]
Asset impairments for property and equipment									768,000,000	224,000,000	246,000,000
Impairment of leasehold											0
Oil And Gas Properties, Unproved | Oklahoma And Texas
Schedule Of Significant Accounting Policies [Line Items]
Impairment of leasehold									149,000,000
Oil And Gas Properties, Unproved | North Sea
Schedule Of Significant Accounting Policies [Line Items]
Asset impairments for property and equipment									0	128,000,000	$ 0
Impairment of leasehold										10,000,000
GTC facilities
Schedule Of Significant Accounting Policies [Line Items]
Asset impairments for property and equipment	1,300,000,000									56,000,000
Gathering, processing, and transmission facilities	799,000,000				1,900,000,000				799,000,000	1,900,000,000
Accumulated depreciation	310,000,000				264,000,000				310,000,000	264,000,000
Gain (loss) on sale of oil and gas properties									0	0
Other Property and Equipment
Schedule Of Significant Accounting Policies [Line Items]
Accumulated depreciation	817,000,000				786,000,000				817,000,000	786,000,000
Property and equipment, net	$ 1,100,000,000				1,100,000,000				$ 1,100,000,000	1,100,000,000
Minimum
Schedule Of Significant Accounting Policies [Line Items]
Voting interest required for consolidation of investments	50.00%								50.00%
Minimum | Other Property and Equipment
Schedule Of Significant Accounting Policies [Line Items]
Useful lives of gas gathering, transmission and processing facilities									3 years
Maximum
Schedule Of Significant Accounting Policies [Line Items]
Voting interest required for consolidation of investments	50.00%								50.00%
Maximum | Other Property and Equipment
Schedule Of Significant Accounting Policies [Line Items]
Useful lives of gas gathering, transmission and processing facilities									20 years
Oil and Gas, Purchased
Schedule Of Significant Accounting Policies [Line Items]
Cost of oil and gas purchased									$ 142,000,000	340,000,000
ALTM
Schedule Of Significant Accounting Policies [Line Items]
Cash and cash equivalent	$ 6,000,000				$ 450,000,000				$ 6,000,000	$ 450,000,000
Apache Egypt | Sinopec
Schedule Of Significant Accounting Policies [Line Items]
Ownership percentage by noncontrolling owners	33.33%								33.33%
ALTM
Schedule Of Significant Accounting Policies [Line Items]
Ownership percentage by noncontrolling owners	21.00%								21.00%
Disposal Group, Disposed of by Sale, Not Discontinued Operations | Oklahoma And Texas
Schedule Of Significant Accounting Policies [Line Items]
Asset impairments for property and equipment			$ 240,000,000						$ 255,000,000
Gain (loss) on sale of oil and gas properties		(7,000,000)
Disposal Group, Disposed of by Sale, Not Discontinued Operations | Oil and gas proved property | Oklahoma And Texas
Schedule Of Significant Accounting Policies [Line Items]
Asset impairments for property and equipment									101,000,000
Disposal Group, Disposed of by Sale, Not Discontinued Operations | Oil And Gas Properties, Unproved | Oklahoma And Texas
Schedule Of Significant Accounting Policies [Line Items]
Asset impairments for property and equipment									149,000,000
Disposal Group, Disposed of by Sale, Not Discontinued Operations | Other Working Capital | Oklahoma And Texas
Schedule Of Significant Accounting Policies [Line Items]
Asset impairments for property and equipment									$ 5,000,000
Altus Midstream
Schedule Of Significant Accounting Policies [Line Items]
Asset impairments		$ 9,000,000