XML 50 R37.htm IDEA: XBRL DOCUMENT v3.7.0.1
Asset Retirement Obligations - Summary of Asset Retirement Obligation (Details) - USD ($)
$ in Thousands
3 Months Ended 6 Months Ended 12 Months Ended
Jun. 30, 2017
Jun. 30, 2016
Jun. 30, 2017
Jun. 30, 2016
Dec. 31, 2016
Asset Retirement Obligation Disclosure [Abstract]          
Balance, beginning of period     $ 4,894 $ 4,468 $ 4,468
Liabilities settled     (30)   (54)
Liabilities disposed     (105)  
Accretion expense $ 131 $ 120 263 $ 240 480
Balance, end of period 5,022   5,022   4,894
Less: Current portion (121)   (121)   (121)
Less: Liabilities held for sale     (105)
Non-current Portion $ 4,901   $ 4,901   $ 4,668