Quarterly report pursuant to Section 13 or 15(d)

Stock-Based Compensation (Details Textual)

v3.21.1
Stock-Based Compensation (Details Textual) - USD ($)
$ / shares in Units, $ in Thousands
3 Months Ended
Apr. 03, 2021
Mar. 28, 2020
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]    
Recognized weighted average period (in years) 2 years 7 months 6 days  
Contractual term of stock options 10 years  
Unrecognized compensation cost related to the stock options $ 476  
Award of shares granted (in shares) 99,000  
Stock-based compensation expense $ 2,107 $ 1,533
2012 Nonemployee Director Fees Plan [Member]    
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]    
Award of shares granted (in shares) 7,375 5,500
Stock-based compensation expense $ 538 $ 235
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 7,408 10,927
Weighted average price $ 44.90 $ 32.46
Share-based compensation expenses $ 195 $ 60
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%  
Restricted Stock and Restricted Stock Units [Member]    
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]    
Compensation expense $ 1,360 $ 1,253
Total unrecognized compensation $ 10,396  
Recognized weighted average period (in years) 2 years 1 month 6 days