Quarterly report pursuant to Section 13 or 15(d)

Stock-Based Compensation (Details Textual)

v3.22.1
Stock-Based Compensation (Details Textual) - USD ($)
$ / shares in Units, $ in Thousands
3 Months Ended
Apr. 02, 2022
Apr. 03, 2021
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]    
Stock option granted, shares 84,000  
Stock-based compensation expense $ 2,494 $ 2,107
2012 Nonemployee Director Fees Plan [Member]    
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]    
Stock option granted, shares   7,375
Stock-based compensation expense   $ 538
2019 Equity Incentive Plan [Member]    
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]    
Stock option granted, shares 3,799  
Stock-based compensation expense $ 23  
Employee Stock Purchase Plan [Member]    
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]    
Rate of common stock at market value 85.00%  
Employee Stock Purchase Plan and U.K. Plan [Member]    
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]    
Number of shares purchased by employees 7,734 7,408
Weighted average price $ 68.48 $ 44.90
Share-based compensation expenses $ 91 $ 195
Ratio for additional common stock shares issued, under ESPP 6  
Time Based [Member]    
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]    
Vesting period 3 years  
Performance Based [Member]    
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]    
Vesting period 3 years  
RSUs [Member] | Minimum [Member]    
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]    
Target amount percentage 0.00%  
RSUs [Member] | Maximum [Member]    
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]    
Target amount percentage 200.00%  
Stock Options [Member]    
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]    
Recognized weighted average period (in years) 1 year 8 months 12 days  
Contractual term of stock options 10 years  
Unrecognized compensation cost related to the stock options $ 234  
Unvested options 14,931  
Vested unexercised options 10,034  
Exercise prices per share, lower range limit $ 35.04  
Exercise prices per share, upper range limit $ 55.30  
Restricted Stock and Restricted Stock Units [Member]    
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]    
Compensation expense $ 2,259 $ 1,360
Total unrecognized compensation $ 12,419  
Recognized weighted average period (in years) 2 years 2 months 12 days