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Asset Retirement Obligations - Summary of Changes in Asset Retirement Obligations (Detail) - USD ($)
$ in Thousands
3 Months Ended 6 Months Ended
Jun. 30, 2021
Jun. 30, 2020
Jun. 30, 2021
Jun. 30, 2020
Dec. 31, 2020
Asset Retirement Obligation Disclosure [Abstract]          
Asset retirement obligations at beginning of period     $ 97,149    
Liabilities added from acquisition or drilling     29    
Liabilities settled     (162)    
Liabilities removed upon sale of wells     (113)    
Accretion expense $ 1,638 $ 1,539 3,253 $ 3,052  
Revision of estimates     3    
Asset retirement obligation at end of period 100,159   100,159    
Less: Current portion (747)   (747)   $ (424)
Asset retirement obligations - long-term portion $ 99,412   $ 99,412   $ 96,725