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Asset Retirement Obligations (Details) - USD ($)
$ in Millions
12 Months Ended
Dec. 31, 2019
Dec. 31, 2018
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]    
Asset retirement obligations, beginning of period $ 166 $ 177
Additions(a) 21 3
Revisions 18 11
Settlements and disposals (5) (35)
Accretion expense 11 10
Asset retirement obligations, end of period 211 166
Less current portion 11 11
Asset retirement obligation, long-term 200 155
Business Acquisition [Line Items]    
Additions 21 $ 3
Wildhorse resource development corporation    
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]    
Additions(a) 17  
Business Acquisition [Line Items]    
Additions $ 17