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ASSET RETIREMENT OBLIGATIONS AND RESTRICTED CASH - Schedule of Change in Asset Retirement Obligation (Details) - USD ($)
$ in Thousands
3 Months Ended 9 Months Ended 12 Months Ended
Sep. 30, 2016
Sep. 30, 2015
Sep. 30, 2016
Sep. 30, 2015
Dec. 31, 2015
Sep. 30, 2016
Dec. 31, 2015
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]              
Asset retirement obligation, beginning of period     $ 8,573 $ 5,683 $ 5,683    
Revision of estimate     71   877    
Acquired in asset acquisitions or business combinations     5,454   2,145    
Accretion of liabilities $ 175 $ 143 526 350 494    
Settlements     (1,375)   (626)    
Asset retirement obligation, end of period 13,249   13,249   8,573    
Asset Retirement Obligation [Abstract]              
Current           $ 360 $ 1,000
Non-current           12,889 7,573
Asset retirement obligation, end of period $ 13,249   $ 8,573 $ 5,683 $ 5,683 $ 13,249 $ 8,573