| 
           Product Warranties (Details) (USD $) 
        In Thousands, unless otherwise specified  | 
        3 Months Ended | 6 Months Ended | ||
|---|---|---|---|---|
| 
           Jun. 30, 2012 
         | 
        
           Jul. 02, 2011 
         | 
        
           Jun. 30, 2012 
         | 
        
           Jul. 02, 2011 
         | 
      |
| Summary of activity in the warranty accrual | ||||
| Beginning balance | $ 1,448 | $ 1,657 | $ 1,092 | $ 1,699 | 
| Warranties issued | 246 | 448 | 772 | 987 | 
| Warranties settled | (303) | (408) | (473) | (953) | 
| Reassessed warranty exposure | (307) | (343) | ||
| Ending balance | $ 1,391 | $ 1,390 | $ 1,391 | $ 1,390 | 
| X | ||||||||||
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- Details 
          
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- Definition 
          Carrying value as of the balance sheet date of obligations incurred through that date and payable for estimated claims under standard and extended warranty protection rights granted to customers. Reference 1: http://www.xbrl.org/2003/role/presentationRef 
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| X | ||||||||||
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- Definition 
          Represents the aggregate decrease in the liability related to payments to satisfy claims for standard and extended product warranties. Reference 1: http://www.xbrl.org/2003/role/presentationRef 
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| X | ||||||||||
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- Definition 
          Total increases or decreases in the standard and extended product warranty liability during the period. Reference 1: http://www.xbrl.org/2003/role/presentationRef 
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| X | ||||||||||
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- Definition 
          Represents the aggregate increase in the liability for accruals related to standard and extended product warranties issued during the reporting period. Reference 1: http://www.xbrl.org/2003/role/presentationRef 
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