Quarterly report pursuant to Section 13 or 15(d)

Fair Value of Financial Instruments (Details Textual)

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Fair Value of Financial Instruments (Details Textual) (USD $)
3 Months Ended 9 Months Ended
Sep. 27, 2014
Sep. 27, 2014
Sep. 28, 2013
Fair Value of Financial Instruments (Textual) [Abstract]      
Securities held with stated maturities   12 months  
Securities classifies as current assets under caption marketable securities maturities   12 months  
Realized loss on available for sale securities   $ 180,000 $ 7,000
Other than Temporary Impairment Losses, Investments 0    
Nonrecurring [Member]
     
Fair Value of Financial Instruments (Textual) [Abstract]      
Fair value adjustments for assets measured at fair value   0  
Fair value adjustments for liabilities measured at fair value   0  
Phantom stock units [Member]
     
Fair Value of Financial Instruments (Textual) [Abstract]      
Phantom stock units, Vesting Period   3 years  
Deferred director stock units and phantom stock units liability [Member]
     
Fair Value of Financial Instruments (Textual) [Abstract]      
Recognized expense related to deferred director stock units and phantom stock units liability   $ 26,000 $ 50,000