SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Non-Cash Impairments of Proved and Unproved Property and Equipment (Details) - USD ($) $ in Millions	3 Months Ended			9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Mar. 31, 2020	Sep. 30, 2021	Sep. 30, 2020
Oil and gas proved property
Schedule Of Significant Accounting Policies [Line Items]
Impairments	$ 0	$ 0		$ 0	$ 4,319
Oil and gas proved property | U.S.
Schedule Of Significant Accounting Policies [Line Items]
Impairments	0	0	$ 3,900	0	3,938
Oil and gas proved property | Egypt
Schedule Of Significant Accounting Policies [Line Items]
Impairments	0	0		0	374
Oil and gas proved property | North Sea
Schedule Of Significant Accounting Policies [Line Items]
Impairments	0	0	$ 7	0	7
Oil and gas unproved properties
Schedule Of Significant Accounting Policies [Line Items]
Impairments	5	36		26	86
Oil and gas unproved properties | U.S.
Schedule Of Significant Accounting Policies [Line Items]
Impairments	2	34		19	80
Oil and gas unproved properties | Egypt
Schedule Of Significant Accounting Policies [Line Items]
Impairments	2	2		6	6
Oil and gas unproved properties | North Sea
Schedule Of Significant Accounting Policies [Line Items]
Impairments	$ 1	$ 0		$ 1	$ 0