XML 172 R71.htm IDEA: XBRL DOCUMENT v3.20.4
ASSET RETIREMENT OBLIGATION - Schedule of changes to Asset Retirement Obligation (Details) - USD ($)
$ in Millions
12 Months Ended
Dec. 31, 2020
Dec. 31, 2019
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]    
Asset retirement obligation at beginning of year $ 1,858 $ 1,932
Liabilities incurred 10 41
Liabilities divested (26) (56)
Liabilities settled (30) (56)
Accretion expense 109 107
Revisions in estimated liabilities 23 (110)
Asset retirement obligation at end of year 1,944 1,858
Less current portion (56) (47)
Asset retirement obligation, long-term $ 1,888 $ 1,811