Annual report pursuant to Section 13 and 15(d)

Stock-Based Compensation (Details Textual)

v3.22.4
Stock-Based Compensation (Details Textual) - USD ($)
$ / shares in Units, $ in Millions
1 Months Ended 12 Months Ended
Feb. 28, 2015
Dec. 31, 2022
Jan. 01, 2022
Jan. 02, 2021
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]        
Stock option granted, shares   108,000    
Stock-based compensation expense   $ 8.6 $ 8.9 $ 5.8
Monte Carlo Valuation Model [Member] | Minimum [Member]        
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]        
Vesting period   1 year    
Monte Carlo Valuation Model [Member] | Maximum [Member]        
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]        
Vesting period   2 years    
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]        
Shares available for issuance   343,818    
Number of shares purchased by employees   38,392 29,420  
Weighted average price   $ 51.54 $ 60.71  
Share-based compensation expenses   $ 0.4 $ 0.7 0.4
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   $ 7.0 6.0 4.2
Fair value of RSUs/restricted stock granted   9.7 $ 6.2 6.8
Total unrecognized compensation   $ 8.0    
Recognized weighted average period (in years)   1 year 8 months 12 days    
Stock Options [Member]        
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]        
Unrecognized compensation cost related to the stock options   $ 1.9    
Recognized weighted average period (in years)   10 months 24 days    
Stock Options [Member] | Monte Carlo Valuation Model [Member]        
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]        
Contractual term of stock options   10 years    
Options grant date fair value   $ 2.3    
Unvested stock options   82,500    
Vested unexercised stock options   0    
Exercise price per share   $ 50.60    
Stock Options [Member] | Black Scholes Valuation Model [Member]        
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]        
Vesting period   3 years    
Contractual term of stock options   10 years    
Exercise prices per share, lower range limit   $ 35.04    
Exercise prices per share, upper range limit   $ 55.03    
Unvested stock options   13,222    
Vested unexercised stock options   11,011    
2019 Plan [Member]        
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]        
Shares available for issuance   790,190    
Stock option granted, shares   18,260    
Stock-based compensation expense   $ 0.5    
2012 Non-Employee Director Fees Plan [Member]        
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]        
Common stock shares for each nonemployee director 2,000      
Fee for the chairs of each Board committee 150.00%      
Annual retainer of common stock received by non employee directors 250      
Stock option granted, shares     26,500  
Stock-based compensation expense     $ 2.2 $ 1.2