XML 41 R30.htm IDEA: XBRL DOCUMENT 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
Changes in the Company's asset retirement obligations          
Beginning asset retirement obligations     $ 26,256    
Liabilities incurred during period     2,473    
Liabilities settled during period     (663)    
Revisions in estimated cash flows     442    
Accretion expense $ 387 $ 323 1,126 $ 937  
Ending asset retirement obligations 29,634   29,634    
Less: current asset retirement obligations [1] (928)   (928)    
Long-term asset retirement obligations $ 28,706   $ 28,706   $ 25,080
[1] Included in accrued liabilities in the Company’s interim unaudited condensed consolidated balance sheet at September 30, 2018.