v2.4.0.8
Goodwill and intangible assets (Details) (USD $)
In Thousands, unless otherwise specified
 12 Months Ended
Dec. 28, 2013
Dec. 29, 2012
Dec. 31, 2011
Goodwill And Intangible Assets Disclosure [Abstract]      
Goodwill Opening $ 57,414 $ 49,387  
Goodwill, Acquired During Period   7,892  
Goodwill impairment 3,552 0 0
Goodwill, Translation Adjustments (189) 135  
Goodwill Ending 53,673 57,414 49,387
Finite Lived Intangible Assets Accumulated Amortization 29,033 24,300  
Finite-Lived Intangible Assets, Amortization Expense, Next Twelve Months 4,718    
Finite-Lived Intangible Assets, Amortization Expense, Year Two 4,551    
Finite-Lived Intangible Assets, Amortization Expense, Year Three 4,359    
Finite-Lived Intangible Assets, Amortization Expense, Year Four 4,359    
Finite-Lived Intangible Assets, Amortization Expense, Year Five 4,324    
Finite-Lived Intangible Assets, Amortization Expense, after Year Five 25,680    
Finite-Lived Intangible Assets, Amortization Expense, Remainder of Fiscal Year 47,991    
Finite-Lived Intangible Assets [Line Items]      
Finite-Lived Intangible Assets, Net, Opening 52,885 48,035  
Acquisitions   9,347  
Additions 182 128  
Impairments (310)    
Amortization 4,733 4,933 4,061
Impact of foreign exchange (33) 308  
Finite-Lived Intangible Assets, Net, Ending 47,991 52,885 48,035
Customer Relationships [Member]
      
Finite-Lived Intangible Assets [Line Items]      
Finite-Lived Intangible Assets, Net, Opening 50,848 45,369  
Acquisitions   9,347  
Additions 0 0  
Impairments (310)    
Amortization (4,206) (4,163)  
Impact of foreign exchange 246 295  
Finite-Lived Intangible Assets, Net, Ending 46,578 50,848  
Patents And Trademark [Member]
      
Finite-Lived Intangible Assets [Line Items]      
Finite-Lived Intangible Assets, Net, Opening 445 546  
Acquisitions   0  
Additions 12 0  
Impairments 0    
Amortization (91) (101)  
Impact of foreign exchange 0 0  
Finite-Lived Intangible Assets, Net, Ending 366 445  
Other Intangible Assets [Member]
      
Finite-Lived Intangible Assets [Line Items]      
Finite-Lived Intangible Assets, Net, Opening 1,592 2,120  
Acquisitions   0  
Additions 170 128  
Impairments 0    
Amortization (436) (669)  
Impact of foreign exchange (279) 13  
Finite-Lived Intangible Assets, Net, Ending $ 1,047 $ 1,592