XML 79 R68.htm IDEA: XBRL DOCUMENT v3.8.0.1
Asset Retirement Obligations - Asset Retirement Obligations (Detail) - USD ($)
$ in Thousands
9 Months Ended
Sep. 30, 2017
Dec. 31, 2016
Asset Retirement Obligation [Abstract]    
Beginning of period $ 257,943  
Liabilities incurred 5,597  
Liabilities settled (6,125)  
Disposition of wells (2,427)  
Accretion expense 11,022  
Change in estimate 862  
End of period 266,872  
Less current portion (7,271) $ (7,271)
Long-term asset retirement obligations $ 259,601