Stock-Based Compensation (Tables)

9 Months Ended

Sep. 30, 2017

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Stock-Based Compensation Expense

Total stock-based compensation expense recognized during the three and nine months ended September 30, 2017 and 2016 was comprised of the following (in thousands):

	Three Months Ended September 30,					Nine Months Ended September 30,
	2017			2016		2017		2016
Cost of goods sold	$	(155	)	$	10	$	294	$	61
Selling, general and administrative		2,226			2,195		6,719		5,669
Research and development		617			586		1,512		2,164
	$	2,688		$	2,791	$	8,525	$	7,894

Fair Value of Each Option Award

The fair value of each option award is estimated on the date of grant using the Black-Scholes option valuation model. The following weighted-average assumptions were utilized for the calculations during each period:

	Three Months Ended September 30,						Nine Months Ended September 30,
	2017			2016			2017			2016
Expected life (in years)		5.9			5.5			5.9			5.5
Expected volatility		79.9	%		95.5	%		79.9	%		95.4	%
Risk-free interest rate		2.0	%		1.2	%		2.1	%		1.3	%
Expected dividend yield		—			—			—			—