XML 44 R29.htm IDEA: XBRL DOCUMENT v3.10.0.1
Asset Retirement Obligations (Details) - USD ($)
$ in Thousands
3 Months Ended 6 Months Ended
Jun. 30, 2018
Jun. 30, 2017
Jun. 30, 2018
Jun. 30, 2017
Dec. 31, 2017
Changes in the Company's asset retirement obligations          
Beginning asset retirement obligations     $ 26,256    
Liabilities incurred during period     1,589    
Liabilities settled during period     (459)    
Accretion expense $ 375 $ 314 739 $ 614  
Ending asset retirement obligations 28,125   28,125    
Less: current asset retirement obligations [1] (1,235)   (1,235)    
Long-term asset retirement obligations $ 26,890   $ 26,890   $ 25,080
[1] Included in accrued liabilities in the Company’s interim unaudited condensed consolidated balance sheet at June 30, 2018.