WARRANTS TO PURCHASE CONVERTIBLE PREFERRED SHARES - Fair value assumptions (Details) - Convertible Preferred Stock Warrant	12 Months Ended
	Dec. 31, 2014 $ / shares
Investors and finder fee warrants
Fair Value Assumptions and Methodology for Assets and Liabilities [Abstract]
Expected dividend yield(4)	0.00%
Investors and finder fee warrants | Minimum
Fair Value Assumptions and Methodology for Assets and Liabilities [Abstract]
Risk-free interest rate(1)	0.28%
Expected volatility(2)	44.90%
Expected life (in years)(3)	1 year 29 days
Warrants	$ 7.32
Investors and finder fee warrants | Maximum
Fair Value Assumptions and Methodology for Assets and Liabilities [Abstract]
Risk-free interest rate(1)	1.83%
Expected volatility(2)	116.80%
Expected life (in years)(3)	6 years 1 month 17 days
Warrants	$ 10.10
Bank
Fair Value Assumptions and Methodology for Assets and Liabilities [Abstract]
Risk-free interest rate(1)	2.05%
Expected volatility(2)	107.50%
Expected life (in years)(3)	8 years 1 month 24 days
Expected dividend yield(4)	0.00%
Warrants	$ 7.69