Stock-Based Compensation (Tables)

3 Months Ended

Mar. 31, 2014

Disclosure of Compensation Related Costs, Share-based Payments [Abstract]

Assumptions used in the Black-Scholes Option-Pricing Model

The assumptions used in the Black-Scholes option-pricing model for the three months ended March 31, 2014 and 2013 are as follows:

	Three Months Ended March 31,
	2014		2013
Risk free interest rate	2.0%		0.8% to 1.1%
Expected term	6.0 to 6.1 years		5.0 to 6.1 years
Expected volatility	84.9%		86.8% to 87.9%
Expected dividend yield	—	%	—	%

Stock-Based Compensation Expense

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

	Three Months Ended March 31,
	2014		2013
Cost of sales	$	127	$	45
Research and development	357		216
Selling, general and administrative	2,023		1,325
Total	$	2,507	$	1,586