DERIVATIVE INSTRUMENTS - CHANGES IN DERIVATIVE WARRANT LIABILITY (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015	Mar. 31, 2016	Feb. 29, 2016
Changes in Derivative Warrant Liability
Balance at beginning of year			$ 1,907
Reduction in derivative liability due to exercise and modification of warrants				$ (16,122)
Balance at end of period	$ 2,695		2,695
Warrants
Changes in Derivative Warrant Liability
Balance at beginning of year	2,359	$ 7,722	1,907	7,224
Reduction in derivative liability due to exercise and modification of warrants		(1,680)		(16,122)
Increase (decrease) in the fair value of warrants	336	(3,591)	788	11,349
Balance at end of period	$ 2,695	$ 2,451	$ 2,695	$ 2,451
Warrant Exercise Price					$ 3.87	$ 5.75
Warrants for purchase of common stock (in shares)					587,950	395,716