Quarterly report pursuant to Section 13 or 15(d)

ASSET RETIREMENT OBLIGATIONS - Asset Retirement Obligation Disclosure (Details)

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ASSET RETIREMENT OBLIGATIONS - Asset Retirement Obligation Disclosure (Details) - USD ($)
$ in Millions
3 Months Ended
Mar. 31, 2021
Mar. 31, 2020
Asset Retirement Obligation [Roll Forward]    
Asset retirement obligation at beginning of period $ 342 $ 165
Increase (decrease) from Acquisitions (34) 14
Accretion expense 3 2
Remediation payments (1) 0
Asset retirement obligation at end of period $ 310 $ 181