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Basis of Presentation and Significant Accounting Policies - Asset Retirement Obligation (Details) - USD ($)
$ in Thousands
12 Months Ended
Dec. 31, 2019
Dec. 31, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]    
Asset retirement obligation, noncurrent $ 124,019 $ 89,176
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]    
Beginning balance 95,548 97,422
Liabilities incurred 11,534 4,901
Settlements and payments (22,036) (3,555)
Accretion expense 7,570 6,258
Reduction due to property sales 0 (4,145)
Revisions 56,611 (5,333)
Ending balance $ 149,227 $ 95,548