Stock-Based Compensation Expense (Tables)

3 Months Ended

Mar. 31, 2018

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

Schedule of Employee Service Share-based Compensation, Allocation of Recognized Period Costs

The stock-based compensation expense before income tax expense for the three months ended March 31, 2018 and 2017, consisted of the following (in thousands):



	Three Months Ended March 31,
	2018		2017
Cost of sales	$	184	$	96
Research and development	124		52
Selling, general and administrative	948		429
Stock-based compensation expense before taxes	$	1,256	$	577

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

In applying the Black-Scholes methodology to the option grants, the fair value of our stock-based awards granted was estimated using the following assumptions for the periods indicated below:



	Three Months Ended
	March 31, 2018
Risk-free interest rate	2.63%
Expected option life	5.0 years
Expected dividend yield	—
Expected price volatility	34.32%