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ASSET RETIREMENT OBLIGATIONS - SCHEDULE OF ROLL FORWARD ACTIVITY (Details)
$ in Thousands
6 Months Ended
Jun. 30, 2021
USD ($)
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]  
Beginning balance as of December 31, 2020 $ 28,699
Liabilities settled (2,902)
Additions 24,633
Accretion expense 764
Ending balance as of June 30, 2021 $ 51,194