SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Details 3) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Stock-Based Compensation Expense
Stock-based compensation expense included in operating expenses	$ 1,641	$ 1,348
Research and development
Stock-Based Compensation Expense
Stock-based compensation expense included in operating expenses	589	680
General and administrative
Stock-Based Compensation Expense
Stock-based compensation expense included in operating expenses	$ 1,052	$ 668