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Asset Retirement Obligations - Summary of Asset Retirement Obligation (Details) - USD ($)
$ in Thousands
3 Months Ended 9 Months Ended 12 Months Ended
Sep. 30, 2017
Sep. 30, 2016
Sep. 30, 2017
Sep. 30, 2016
Dec. 31, 2016
Asset Retirement Obligation Disclosure [Abstract]          
Balance, beginning of period     $ 4,894 $ 4,468 $ 4,468
Liabilities settled     (37)   (54)
Liabilities disposed     (106)  
Accretion expense $ 132 $ 120 395 $ 360 480
Balance, end of period 5,146   5,146   4,894
Less: Current portion (121)   (121)   (121)
Less: Liabilities held for sale     (105)
Non-current Portion $ 5,025   $ 5,025   $ 4,668