Stock-Based Compensation (Tables)

9 Months Ended

Sep. 28, 2018

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

Schedule Of Compensation Cost [Table Text Block]

The cost that has been charged against income for stock-based compensation is set forth below (in thousands):

	Three Months Ended				Nine Months Ended
	September 28, 2018		September 29, 2017		September 28, 2018		September 29, 2017
Employee stock options	$	1,197	$	443	$	2,713	$	1,204
Restricted stock		82		50		192		136
Restricted stock units		501		314		1,593		845
Nonemployee stock options		247		—		428		—
Total	$	2,027	$	807	$	4,926	$	2,185

Schedule of Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Table Text Block]

The Company recorded stock-based compensation costs in the following categories on the accompanying Condensed Consolidated Statements of Operations (in thousands):

	Three Months Ended				Nine Months Ended
	September 28, 2018		September 29, 2017		September 28, 2018		September 29, 2017
Cost of sales	$	4	$	2	$	11	$	6
General and administrative		701		377		1,875		1,035
Marketing and selling		471		214		1,297		558
Research and development		851		214		1,743		586
Total stock-based compensation expense		2,027		807		4,926		2,185
Amounts capitalized as part of inventory		182		107		449		269
Total stock-based compensation	$	2,209	$	914	$	5,375	$	2,454

Schedule of Share-based Payment Award, Stock Options, Valuation Assumptions [Table Text Block]

The risk-free rate is based on the U.S. Treasury yield curve corresponding to the expected term at the time of the grant.

	Three Months Ended						Nine Months Ended
	September 28, 2018			September 29, 2017			September 28, 2018			September 29, 2017
Expected dividend yield		0	%		0	%		0	%		0	%
Expected volatility		53	%		57	%		53	%		57	%
Risk-free interest rate		2.84	%		1.83	%		2.71	%		1.95	%
Expected term (in years)		5.72			5.67			5.72			5.67

Share-based Compensation, Stock Options, Activity [Table Text Block]

A summary of option activity under the Plan for the quarter ended September 28, 2018 is presented below:

	Option ‎ Shares ‎ (000’s)
Outstanding at December 29, 2017		3,725
Granted		805
Exercised		(524	)
Forfeited or expired		(27	)
Outstanding at September 28, 2018		3,979
Exercisable at September 28, 2018		2,584

Schedule of Share-based Compensation, Restricted Stock and Restricted Stock Units Activity [Table Text Block]

A summary of restricted stock and RSU activity under the Plan for the quarter ended September 28, 2018 is presented below:

	Restricted Shares (000’s)			Restricted ‎ Units ‎ (000’s)
Outstanding at December 29, 2017		21			488
Granted		11			49
Vested		(21	)		(185	)
Forfeited or expired		—			(8	)
Outstanding at September 28, 2018		11			344