DIVESTITURES AND OTHER TRANSACTIONS - SUMMARY OF REVENUES AND COSTS FROM DISCONTINUED OPERATIONS (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Costs and other deductions
Discontinued operations, net of tax		$ (1,298)	$ (15)	$ 0
Algeria Africa Assets | Reclassifications
Revenues and other income
Net sales			518
Costs and other deductions
Oil and gas lease operating expense			36
Transportation expense			14
Taxes other than on income			133
Depreciation, depletion and amortization			159
Other			9
Total costs and other deductions			351
Income (loss) before income taxes			167
Income tax benefit (expense)			(167)
Discontinued operations, net of tax			$ 0
Anadarko's Africa Assets | Disposed of by sale
Revenues and other income
Net sales	$ 221	419
Costs and other deductions
Oil and gas lease operating expense	45	117
Fair value adjustment on assets held for sale	85	2,263
Other	45	48
Total costs and other deductions	175	2,428
Income (loss) before income taxes	46	(2,009)
Income tax benefit (expense)	(61)	711
Discontinued operations, net of tax	$ (15)	$ (1,298)