Stockholders' Equity and Stock-Based Compensation (Tables)

9 Months Ended

Sep. 28, 2019

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Employee Stock Purchase Plan Assumptions

	Three Months Ended		Nine Months Ended
	September 28, 2019	September 29, 2018	September 28, 2019	September 29, 2018
Employee Stock Purchase Plan:
Expected life	0.5 years	0.5 years	0.5	0.5 years
Volatility	44.4%	52.5%	41.3% - 44.4%	39.1%
Risk free interest rate	2.10%	2.14%	2.10% - 2.51%	1.86%
Dividends	—	—	—	—

Summary of Activity of Stock Options

A summary of activity of stock options during the nine months ended September 28, 2019 is as follows:

	Number of Shares Outstanding (Options)			Weighted Average Exercise Price		Weighted Average Remaining Contractual Term (Years)		Aggregate Intrinsic Value (in Thousands)
Options
Outstanding at December 29, 2018		83,394		$	15.80		1.19	$	988
Exercised		(71,365	)		15.72
Cancelled		(25	)		14.95
Outstanding at September 28, 2019		12,004			16.27		0.80		198
Exercisable at September 28, 2019		12,004		$	16.27		0.80	$	198

Summary of Activity for RSUs

A summary of activity for RSUs during the nine months ended September 28, 2019 is as follows:

Summary of activity for RSUs	Number of RSUs			Weighted Average Fair Value
Outstanding RSUs as of December 29, 2018		769,003		$	31.39
Granted		352,337			28.63
Released		(322,915	)		28.86
Cancelled		(57,907	)		32.37
Outstanding RSUs as of September 28, 2019		740,518		$	31.10

Summary of Activity for PSUs

A summary of activity for PSUs for the nine months ended September 28, 2019 is as follows:

Summary of activity for PSUs	Number of PSUs			Weighted Average Fair Value
Outstanding PSUs as of December 29, 2018		112,163		$	22.37
Granted		43,429			19.09
Released		(16,066	)		25.09
Cancelled		(1,138	)		26.75
Outstanding PSUs as of September 28, 2019		138,388		$	20.99

PSUs Valuation Assumptions

The assumptions for the valuation of PSUs are summarized as follows:

	2019 Award		2018 Award
Grant Date Fair Value Per Share	$13.12-$23.75		$20.73-$25.18
Weighted-average assumptions/inputs:
Expected Dividend		—		—
Range of risk-free interest rates	2.45%		2.39%-2.63%
Range of expected volatilities for peer group	22%-63%		22%-66%

Stock-based Compensation Expense

Stock-based compensation expense for all share-based payment awards made to the Company’s employees and directors pursuant to the employee stock option and employee stock purchase plans by function were as follows (in thousands):

	Three Months Ended				Nine Months Ended
	September 28, 2019		September 29, 2018		September 28, 2019		September 29, 2018
Cost of products	$	326	$	224	$	858	$	455
Cost of service		235		223		629		564
Research and development		813		744		2,324		1,727
Selling		834		779		2,378		2,049
General and administrative		1,191		1,242		3,524		3,434
Total stock-based compensation expense related to employee stock options and employee stock purchases	$	3,399	$	3,212	$	9,713	$	8,229