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Postretirement Benefits Other Than Pensions - Additional Information (Detail) (Other Postretirement Benefit Plans, Defined Benefit, USD $)
 12 Months Ended
Dec. 29, 2013
Dec. 30, 2012
Dec. 25, 2011
Other Postretirement Benefit Plans, Defined Benefit
      
Defined Benefit Plan Disclosure [Line Items]      
Pension and Other Postretirement Benefit Plans, Accumulated Other Comprehensive Income (Loss), before Tax $ 10,117,000 $ 1,407,000  
Net actuarial losses recognized in accumulated other comprehensive loss (6,087,000) (23,467,000)  
Prior service credits recognized in accumulated other comprehensive loss 16,204,000 24,874,000  
Actuarial loss estimated to be amortized from accumulated other comprehensive loss into net periodic benefit cost 600,000    
Prior service credit estimated to be amortized from accumulated other comprehensive loss into net periodic benefit cost (8,400,000)    
Annual rate of increase in the per capita cost of covered health care benefits assumed 7.17% 6.50% 6.50%
Percentage of change in the health care cost trend rate 1.00%    
Effect on postretirement benefit obligation of a 1% change in the health care cost trend rate 5,400,000    
Effect on the aggregate service and interest components of expense of a 1% change in the health care cost trend rate $ 200,000