| 
           Derivative and Other Comprehensive Income (Details) (USD $) 
         | 
        3 Months Ended | 6 Months Ended | |||||||
|---|---|---|---|---|---|---|---|---|---|
| 
           Jul. 13, 2014
 
          Interest Rate Swap
 
          Rabobank
 
          interest_rate_swap 
         | 
        
           Dec. 29, 2013
 
          Interest Rate Swap
 
          Rabobank
 
          interest_rate_swap 
         | 
        
           Jul. 13, 2014
 
          Cash Flow Hedging 
         | 
        
           Jul. 14, 2013
 
          Cash Flow Hedging 
         | 
        
           Jul. 13, 2014
 
          Cash Flow Hedging 
         | 
        
           Jul. 14, 2013
 
          Cash Flow Hedging 
         | 
        
           Jul. 13, 2014
 
          Cash Flow Hedging
 
          Interest Rate Swap
 
          Rabobank 
         | 
        
           Dec. 29, 2013
 
          Cash Flow Hedging
 
          Interest Rate Swap
 
          Rabobank 
         | 
        
           Aug. 05, 2011
 
          Cash Flow Hedging
 
          Interest Rate Swap
 
          Rabobank 
         | 
      |
| Derivative and other comprehensive income | |||||||||
| Number of derivative instruments held | 1 | 1 | |||||||
| Notional amount of derivatives | $ 56,300,000 | $ 61,900,000 | $ 74,100,000 | ||||||
| Estimated notional hedge amount on expiration date which is June 30, 2015 | 50,600,000 | ||||||||
| Fixed rate of interest on derivative (as a percent) | 1.135% | ||||||||
| Gains (Losses) recognized in OCI on derivative (effective portion) | (7,000) | 130,000 | (78,000) | 50,000 | |||||
| Losses reclassified from AOCI into income (effective portion) | (22,000) | (18,000) | (51,000) | (38,000) | |||||
| Gains (Losses) recognized in income on derivative (ineffective portion and amount excluded from effectiveness testing) | $ 2,000 | $ (3,000) | $ 2,000 | $ 1,000 | |||||