Quarterly report pursuant to Section 13 or 15(d)

Stock-Based Compensation (Details Textual)

v3.7.0.1
Stock-Based Compensation (Details Textual)
6 Months Ended
Jun. 01, 2015
shares
Jul. 01, 2017
USD ($)
$ / shares
shares
Jul. 01, 2017
GBP (£)
shares
Jul. 02, 2016
USD ($)
$ / shares
shares
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]        
Aggregate shares of restricted stock grant   74,000 74,000  
Ratio for additional common stock shares issued, under ESPP   16.67% 16.67%  
2012 Director Equity Plan [Member]        
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]        
Aggregate shares of restricted stock grant   270,000    
Common stock shares for each nonemployee director 250      
Fee for the chairs of each Board committee 150.00%      
Annual retainer of common stock received by non employee directors   2,000 2,000  
Stock option granted, shares   12,750 12,750 12,750
Share-based compensation expenses under Director's plan | $   $ 501,000   $ 407,000
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% 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   563,202    
Aggregate shares of restricted stock grant   1,096,875    
Number of shares purchased by employees   15,090 15,090 25,896
Weighted average price | $ / shares   $ 30.90   $ 25.89
Share-based compensation expenses | $   $ 131,000   $ 137,000
Maximum [Member] | 2012 Director Equity Plan [Member]        
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]        
Maximum number of share issuable to non employee directors per year   35,000    
Minimum [Member] | Employee Stock Purchase Plan and U.K. Plan [Member] | United States [Member]        
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]        
Shares allowed to be purchased by employees | $   $ 25,000    
Minimum [Member] | Employee Stock Purchase Plan and U.K. Plan [Member] | United Kingdom [Member]        
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]        
Shares allowed to be purchased by employees | £     £ 1,500  
Allowable employees purchase rate of common stock based on annual salary   10.00% 10.00%  
Equity Incentive Plan (2011 Plan) [Member]        
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]        
Shares available for issuance   453,737    
Restricted stock expense | $   $ 1,397,000   $ 2,316,000
Total unrecognized compensation | $   $ 3,102,000    
Recognized weighted average period (in years)   1 year 1 month 24 days 1 year 1 month 24 days  
Equity Incentive Plan (2011 Plan) [Member] | Maximum [Member]        
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]        
Aggregate shares of restricted stock grant   1,000,000 1,000,000  
Nonemployee Director Equity and Deferred Compensation Plan [Member]        
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]        
Shares available for issuance   162,124