STOCK-BASED COMPENSATION (Details 2) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Valuation and Expenses Information
Total stock-based compensation expense (in dollars)	$ 2,298	$ 2,342	$ 2,802
Stock options
Assumptions used for fair values of employee stock options granted
Expected stock price volatility, minimum (as a percent)	70.00%	68.00%	65.00%
Expected stock price volatility, maximum (as a percent)	72.00%	70.00%	67.00%
Expected option term	6 years	6 years	6 years 2 months 12 days
Risk-free interest rate, minimum (as a percent)	0.90%	1.40%	1.80%
Risk-free interest rate, maximum (as a percent)	1.40%	2.90%	3.20%
Research and development
Valuation and Expenses Information
Total stock-based compensation expense (in dollars)	1,415	1,412	1,625
General and administrative
Valuation and Expenses Information
Total stock-based compensation expense (in dollars)	$ 883	$ 930	$ 1,177