Quarterly report pursuant to Section 13 or 15(d)

Asset Retirement Obligations (Details)

v3.10.0.1
Asset Retirement Obligations (Details) - USD ($)
$ in Thousands
3 Months Ended 9 Months Ended
Sep. 30, 2018
Sep. 30, 2017
Sep. 30, 2018
Sep. 30, 2017
Dec. 31, 2017
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]          
Asset retirement obligations at January 1, 2018     $ 6,020    
Accretion expense $ 202 $ 131 626 $ 523  
Liabilities incurred     729    
Liabilities settled     (989)    
Sales     (612)    
Revisions to estimate     4,118    
Asset retirement obligations at end of period 9,892   9,892    
Less: Current asset retirement obligations (4,464)   (4,464)   $ (1,295)
Long-term asset retirement obligations at September 30, 2018 5,428   5,428   4,725
Restricted Investments          
Restricted investments $ 3,413   $ 3,413   $ 3,372