SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Details 3) (USD $)	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Stock-Based Compensation Expense
Stock-based compensation expense included in operating expenses	$ 2,102,000	$ 886,000	$ 3,743,000	$ 2,234,000
April 2013 Restructuring
Stock-Based Compensation Expense
Stock-based compensation expense related to extension of the post-termination exercise period		28,000		28,000
Research and development
Stock-Based Compensation Expense
Stock-based compensation expense included in operating expenses	690,000	231,000	1,279,000	911,000
Restructuring charges
Stock-Based Compensation Expense
Stock-based compensation expense included in operating expenses		28,000		28,000
General and administrative
Stock-Based Compensation Expense
Stock-based compensation expense included in operating expenses	$ 1,412,000	$ 627,000	$ 2,464,000	$ 1,295,000