SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Non-Cash Impairments of Proved and Unproved Property and Equipment (Details) - USD ($) $ in Millions	3 Months Ended			6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Mar. 31, 2020	Jun. 30, 2021	Jun. 30, 2020
Oil and gas proved property
Schedule Of Significant Accounting Policies [Line Items]
Asset impairments for property and equipment	$ 0	$ 20		$ 0	$ 4,319
Oil and gas unproved properties
Schedule Of Significant Accounting Policies [Line Items]
Asset impairments for property and equipment	3	31		21	50
U.S. | Oil and gas proved property
Schedule Of Significant Accounting Policies [Line Items]
Asset impairments for property and equipment	0	0	$ 3,900	0	3,938
U.S. | Oil and gas unproved properties
Schedule Of Significant Accounting Policies [Line Items]
Asset impairments for property and equipment	1	29		17	46
Egypt | Oil and gas proved property
Schedule Of Significant Accounting Policies [Line Items]
Asset impairments for property and equipment	0	20	354	0	374
Egypt | Oil and gas unproved properties
Schedule Of Significant Accounting Policies [Line Items]
Asset impairments for property and equipment	2	2		4	4
North Sea | Oil and gas proved property
Schedule Of Significant Accounting Policies [Line Items]
Asset impairments for property and equipment	$ 0	$ 0	$ 7	$ 0	$ 7