STOCK-BASED COMPENSATION (Details) - USD ($) $ / shares in Units, $ in Thousands			3 Months Ended
	Mar. 31, 2015	Dec. 31, 2014	Mar. 31, 2016	Mar. 31, 2015	Dec. 31, 2015
Aggregate Intrinsic Value
Outstanding at beginning of period					$ 5,000
Exercised			$ 76,687
Outstanding at the end of the period			8,116,912
Exercisable at end of period			$ 1,430,199
Additional disclosures
Stock Issued During Period, Shares, Employee Stock Purchase Plans			42,481
Service-based stock options
Stock-Based Compensation
Vesting period			4 years
Expiration period			10 years
Grant date fair value			$ 2.19	$ 2.22
Net compensation expense related to employees and directors (in dollars)			$ 500	$ 900
Weighted average assumptions used to estimate fair value of each service-based stock option grant
Expected dividend rate (as a percent)			0.00%
Options
Outstanding at the beginning of the period (in shares)			2,523,400
Granted (in shares)			835,480
Exercised (in shares)			38,919
Expired (in shares)			(34,187)
Forfeited (in shares)			(72,340)
Outstanding at the end of the period (in shares)			3,213,434
Exercisable at the end of the period (in shares)			739,346
Weighted Average Exercise Price
Outstanding at the beginning of the period (in dollars per share)			$ 6.36
Granted (in dollars per share)			3.09
Exercised (in dollars per share)			3.06
Expired (in dollars per share)			49.45
Forfeited (in dollars per share)			3.94
Outstanding at the end of the period (in dollars per share)			5.14
Exercisable at the end of the period (in dollars per share)			$ 11.20
Weighted Average Remaining Contractual Term
Outstanding at the beginning of the period	8 years 9 months 5 days	8 years 8 months 25 days
Outstanding at the end of the period	8 years 9 months 5 days	8 years 8 months 25 days
Exercisable at the end of the period	7 years 5 months 5 days
Additional disclosures
Total unrecognized compensation cost (in dollars)			$ 3,900
Weighted average period over which unrecognized compensation is expected to be recognized (in years)			3 years 3 months 18 days
Total fair value of options vested (in dollars)			$ 500	$ 300
Service-based stock options | Minimum
Weighted average assumptions used to estimate fair value of each service-based stock option grant
Expected stock price volatility (as a percent)			80.30%	82.40%
Risk-free interest rate (as a percent)			1.50%	2.10%
Expected life (in years)			5 years 6 months	6 years 1 month 5 days
Service-based stock options | Maximum
Weighted average assumptions used to estimate fair value of each service-based stock option grant
Expected stock price volatility (as a percent)			88.10%	83.30%
Risk-free interest rate (as a percent)			1.90%	2.20%
Expected life (in years)			6 years 3 months 18 days	6 years 3 months 18 days
Employee Stock [Member]
Stock-Based Compensation
Net compensation expense related to employees and directors (in dollars)			$ 100
Additional disclosures
Stock Issued During Period, Value, Employee Stock Purchase Plan			$ 100