Stockholders' Equity and Stock-Based Compensation (Tables)

3 Months Ended

Mar. 30, 2019

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Employee stock purchase plan assumptions

	Three Months Ended
	March 30, 2019	March 31, 2018
Employee Stock Purchase Plan:
Expected life	0.5 years	0.5 years
Volatility	41.3%	27.2%
Risk free interest rate	2.51%	1.61%
Dividends	—	—

Stock option plans activity

A summary of activity of stock options during the three months ended March 30, 2019 is as follows:

	Number of Shares Outstanding (Options)		Weighted Average Exercise Price		Weighted Average Remaining Contractual Term (Years)		Aggregate Intrinsic Value (inThousands)
Options
Outstanding at December 29, 2018		83,394	$	15.80		1.19	$	988
Exercised		—		—
Cancelled		—		—
Outstanding at March 30, 2019		83,394	$	15.80		0.94	$	1,258
Exercisable at March 30, 2019		83,394	$	15.80		0.94	$	1,258

Summary of activity for RSUs

A summary of activity for RSUs during the three months ended March 30, 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		99,644			28.95
Released		(107,063	)		23.06
Cancelled		(22,876	)		30.83
Outstanding RSUs as of March 30, 2019		738,708		$	32.28

Summary of activity for PSUs

A summary of activity for PSUs for the three months ended March 30, 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 March 30, 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 for all share-based payment awards

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
	March 30, 2019		March 31, 2018
Cost of products	$	260	$	99
Cost of service		185		155
Research and development		772		476
Selling		805		533
General and administrative		1,092		1,075
Total stock-based compensation expense related to employee stock options and employee stock purchases	$	3,114	$	2,338