LOSS PER COMMON SHARE - Computation of Earnings per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
LOSS PER COMMON SHARE
Net loss	$ (13,263)	$ (26,444)	$ (57,462)	$ (66,617)
Loss attributable to common shareholders — basic and diluted	$ (13,263)	$ (26,444)	$ (57,462)	$ (66,617)
Weighted-average number of common shares used in net loss per share - basic and diluted	29,753,043	23,460,340	29,517,396	23,334,558
Loss per share - basic and diluted	$ (0.45)	$ (1.13)	$ (1.95)	$ (2.85)