Employee Benefit Plans - Amounts Recognized in Other Comprehensive (Gain) Loss (Detail) - USD ($)
$ in Thousands
3 Months Ended 12 Months Ended
Mar. 29, 2014
Dec. 27, 2014
Dec. 28, 2013
Dec. 29, 2012
Amounts recognized in other comprehensive loss (income):        
Total amount recognized $ (2,164) $ 3,919 $ (4,407) $ 3,648
Pension Benefits [Member]        
Amounts recognized in other comprehensive loss (income):        
Net actuarial gain (loss)   4,650 (2,838) 2,444
Amortization of gain   (117) (387) (261)
Total amount recognized   4,533 (3,225) 2,183
Healthcare & Life Ins [Member]        
Amounts recognized in other comprehensive loss (income):        
Net actuarial gain (loss)   1,992 (1,048) 1,597
Prior service cost   (2,553)    
Amortization of prior year service cost   174 180 180
Curtailment benefit   1,346    
Amortization of gain   (227) (314) (312)
Total amount recognized   $ 732 $ (1,182) $ 1,465