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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, 2017
Sep. 30, 2016
Sep. 30, 2017
Sep. 30, 2016
Dec. 31, 2016
Sep. 30, 2017
Dec. 31, 2016
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]              
Asset retirement obligation, beginning of period     $ 17,033 $ 8,573 $ 8,573    
Revision of estimate     0   4,186    
Acquired in asset acquisitions or business combinations     0   5,454    
Accretion of liabilities $ 345 $ 175 1,036 526 906    
Settlements     (732)   (2,086)    
Asset retirement obligation, end of period 17,337   17,337   17,033    
Asset Retirement Obligation [Abstract]              
Current           $ 32 $ 32
Non-current           17,305 17,001
Asset retirement obligation, end of period $ 17,337   $ 17,033 $ 8,573 $ 8,573 $ 17,337 $ 17,033