Stock-Based Compensation (Tables)

9 Months Ended

Sep. 30, 2015

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

Schedule of stock-based compensation expense

Stock-based compensation expense is included in the consolidated statements of operations as follows (in thousands):

	Three Months Ended September 30,				Nine Months Ended September 30,
	2015		2014		2015		2014
Research and development (1)	$	181	$	227	$	710	$	734
Selling, general and administrative	1,042		828		3,049		2,896
Total	$	1,223	$	1,055	$	3,759	$	3,630

(1) Stock-based compensation expense associated with cost of biocatalyst product sales is included in research and development. Amounts were immaterial for all periods presented.

Schedule of Share-based Compensation, Restricted Stock and Restricted Stock Units Activity

The following table presents total stock-based compensation expense by security types included in the condensed consolidated statements of operations for the three and nine months ended September 30, 2015 and 2014 (in thousands):

	Three Months Ended September 30,				Nine Months Ended September 30,
	2015		2014		2015		2014
Stock options	$	281	$	247	$	798	$	843
RSUs and RSAs	566		722		2,020		2,383
PSUs	376		86		941		404
Total	$	1,223	$	1,055	$	3,759	$	3,630

Schedule of Share-based Payment Award, Stock Options, Valuation Assumptions

The weighted-average assumptions used to estimate the fair value of employee stock options granted were as follows:

	Three Months Ended September 30,						Nine Months Ended September 30,
	2015			2014			2015			2014
Expected term (in years) (1)	5.2			6.0			6.0			6.0
Volatility	67		%	68		%	66		%	65		%
Risk-free interest rate	1.64		%	1.91		%	1.70		%	1.915		%
Dividend yield	—		%	—		%	—		%	—		%
Weighted-average estimated fair value of stock options granted	$	2.31		$	1.43		$	2.09		$	1.20