| 
           Basis of Presentation (Details) (USD $) 
        In Millions, unless otherwise specified  | 
        3 Months Ended | 6 Months Ended | 3 Months Ended | 6 Months Ended | ||||||
|---|---|---|---|---|---|---|---|---|---|---|
| 
           Jun. 30, 2012 
         | 
        
           Jul. 02, 2011 
         | 
        
           Jun. 30, 2012 
         | 
        
           Jul. 02, 2011 
         | 
        
           Jun. 30, 2012
 
          Test Systems Segment [Member] 
         | 
        
           Jul. 02, 2011
 
          Test Systems Segment [Member] 
         | 
        
           Jun. 30, 2012
 
          Test Systems Segment [Member] 
         | 
        
           Jul. 02, 2011
 
          Test Systems Segment [Member] 
         | 
        
           Nov. 30, 2011
 
          Ballard [Member] 
         | 
        
           Jul. 30, 2012
 
          Max-viz, Inc [Member] 
         | 
      |
| Basis of Presentation (Textual) [Abstract] | ||||||||||
| Percentage of acquired stock | 100.00% | 100.00% | ||||||||
| Percentage of Revenue Recognized from Long Term Fixed Price Contracts | 39.00% | 68.00% | 39.00% | 83.00% | ||||||
| Basis of Presentation (Additional Textual) [Abstract] | ||||||||||
| Research and development, design and related engineering | $ 11.1 | $ 8.8 | $ 21.1 | $ 17.1 | ||||||
| X | ||||||||||
| 
             
- Details 
          
  | 
        
| X | ||||||||||
| 
             
- Details 
          
  | 
        
| X | ||||||||||
| 
             
- Definition 
          Percentage of revenue recognized from long term fixed price contracts. No definition available. 
  | 
        
| X | ||||||||||
| 
             
- Definition 
          Percentage of voting equity interests acquired in the business combination. Reference 1: http://www.xbrl.org/2003/role/presentationRef 
  | 
        
| X | ||||||||||
| 
             
- Definition 
          The aggregate costs incurred (1) in a planned search or critical investigation aimed at discovery of new knowledge with the hope that such knowledge will be useful in developing a new product or service, a new process or technique, or in bringing about a significant improvement to an existing product or process; or (2) to translate research findings or other knowledge into a plan or design for a new product or process or for a significant improvement to an existing product or process whether intended for sale or the entity's use, during the reporting period charged to research and development projects, including the costs of developing computer software up to the point in time of achieving technological feasibility, and costs allocated in accounting for a business combination to in-process projects deemed to have no alternative future use. Reference 1: http://www.xbrl.org/2003/role/presentationRef 
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