NOTES PAYABLE - Schedule of Carrying Amount of Debt (Details) - Convertible Debt - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Debt Instrument [Line Items]
Aggregate principle amount of Notes	$ 46,000	$ 46,000
Unamortized debt discount	(2,098)	(2,712)
Net carrying amount	$ 43,902	$ 43,288