Stock-Based Compensation (Tables)

6 Months Ended

Jun. 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 June 30,				Six Months Ended June 30,
	2015		2014		2015		2014
Research and development (1)	$	238	$	268	$	529	$	507
Selling, general and administrative	1,013		1,078		2,007		2,068
Total	$	1,251	$	1,346	$	2,536	$	2,575

(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 six months ended June 30, 2015 and 2014 (in thousands):

	Three Months Ended June 30,				Six Months Ended June 30,
	2015		2014		2015		2014
Stock options	$	269	$	320	$	517	$	596
RSUs and RSAs	662		792		1,454		1,661
PSUs	320		234		565		318
Total	$	1,251	$	1,346	$	2,536	$	2,575

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

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

	Three Months Ended June 30,						Six Months Ended June 30,
	2015			2014			2015			2014
Expected term (in years)	6.0			—			6.0			6.0
Volatility	66		%	—		%	66		%	64		%
Risk-free interest rate	1.78		%	—		%	1.70		%	0.19		%
Dividend yield	—		%	—		%	—		%	—		%
Weighted-average estimated fair value of stock options granted	$	2.58		$	—		$	2.09		$	1.15