STOCKHOLDERS' EQUITY AND SHARE-BASED COMPENSATION EXPENSE (Tables)

3 Months Ended

Mar. 31, 2013

Stockholders Equity And Share Based Compensation Expense [Abstract]

Share-based compensation expense

The Company recognized share-based compensation expense as follows (in thousands):

	Three Months Ended
	March 31,
	2013		2012
Costs of product sales	$	167	$	372
Research and development		329		367
Selling, general and administrative		1,339		1,653
Total share-based compensation expense	$	1,835	$	2,392

Fair value of options estimated at the date of grant with weighted-average assumptions

The fair value of options was estimated at the date of grant using the Black Scholes Merton option pricing model with the following weighted‑average assumptions:

	Three Months Ended
	March 31,
	2013			2012
Risk free interest rate		0.8	%		1.0	%
Expected dividend yield		0.0	%		0.0	%
Expected volatility		68	%		67	%
Expected option term (in years)		4.6			4.6

Assumptions Used to Value Employees Stock Purchase Rights

During the three months ended March 31, 2013 and 2012, the fair value of shares under the ESPP was estimated using the following assumptions:

	Three Months Ended
	March 31,
	2013			2012
Risk free interest rate		0.1	%		0.1	%
Expected dividend yield		0.0	%		0.0	%
Expected volatility		52	%		67	%
Expected term (in years)		0.6			0.8