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Asset Retirement Obligations - Summary of Changes in Asset Retirement Obligations (Detail) - USD ($)
$ in Thousands
12 Months Ended
Dec. 31, 2020
Dec. 31, 2019
Asset Retirement Obligation Disclosure [Abstract]    
Asset retirement obligations at beginning of period $ 91,089 $ 76,344
Liabilities added from acquisition or drilling [1] 79 9,497
Liabilities removed upon sale of wells 0 0
Liabilities settled (327) (259)
Accretion expense 6,206 5,559
Revision of estimates 102 (52)
Asset retirement obligation at end of period 97,149 91,089
Less: Current Portion 424 623
Asset retirement obligations - long-term portion $ 96,725 $ 90,466
[1] The increase in liabilities added from acquisition or drilling for the year ended December 31, 2019, is primarily due to the Merger with Midstates.