REDEMABLE NONCONTROLLING INTEREST - ALTUS - Activity Related to Preferred Units (Details) $ in Millions	3 Months Ended		12 Months Ended
	Mar. 31, 2021 USD ($) shares	Mar. 31, 2020 USD ($) shares	Dec. 31, 2020 USD ($) shares
Increase (Decrease) in Temporary Equity [Roll Forward]
Beginning balance	$ 608
Ending balance	605		$ 608
Recurring
Increase (Decrease) in Temporary Equity [Roll Forward]
Preferred Units embedded derivative	209		192
Preferred Units embedded derivative | Recurring
Increase (Decrease) in Temporary Equity [Roll Forward]
Preferred Units embedded derivative			139
Altus Preferred Unit limited partners
Increase (Decrease) in Temporary Equity [Roll Forward]
Beginning balance	608	$ 555	555
Dividends payable to Altus Preferred Unit limited partners	(11)
Allocation of Altus Midstream LP net income	19	18
Ending balance	605	$ 573	$ 608
Altus Midstream LP
Increase (Decrease) in Temporary Equity [Roll Forward]
Preferred Units embedded derivative	156
Redeemable noncontrolling interest, net of embedded derivative liability	$ 761
Preferred units, redemption terms, internal rate of return	11.50%
Preferred units, invested capital	$ 813
Preferred units, redemption value	$ 713
Altus Midstream LP | Altus Preferred Unit limited partners
Movement In Preferred Units [Roll Forward]
Preferred units: beginning of period (in shares) | shares	660,694	638,163	638,163
Distribution of in-kind additional preferred units (in shares) | shares			22,531
Preferred units: end of period (in shares) | shares	660,694		660,694
Increase (Decrease) in Temporary Equity [Roll Forward]
Beginning balance	$ 608	$ 555	$ 555
Distribution of in-kind additional Preferred Units			0
Cash distributions to Altus Preferred Unit limited partners	(11)		(23)
Dividends payable to Altus Preferred Unit limited partners	(11)
Allocation of Altus Midstream LP net income	19		76
Ending balance	$ 605		$ 608
Preferred units, redemption terms, multiple of invested capital	1.3