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GOODWILL IMPAIRMENT (Details) - USD ($)
$ in Thousands
9 Months Ended
Sep. 30, 2020
Dec. 31, 2019
GOODWILL IMPAIRMENT    
Goodwill $ 4,373 $ 136,399
Impairments of goodwill 132,026  
Hamilton mining complex    
GOODWILL IMPAIRMENT    
Goodwill   $ 132,000
Impairments of goodwill $ 132,000