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Associate Retirement Plans - Summary of Reconciliation of Beginning and Ending Balances for Level 3 Assets (Detail) - USD ($)
$ in Thousands
 12 Months Ended
Dec. 30, 2017
Dec. 31, 2016
Defined Benefit Plan Disclosure [Line Items]    
Balance at beginning of year $ 81,982  
Balance at end of year 81,255 $ 81,982
Guaranteed annuity contract [Member]    
Defined Benefit Plan Disclosure [Line Items]    
Balance at beginning of year 15,426  
Balance at end of year 13,891 15,426
Significant unobservable inputs (Level 3) [Member]    
Defined Benefit Plan Disclosure [Line Items]    
Balance at beginning of year 15,426  
Balance at end of year 13,891 15,426
Significant unobservable inputs (Level 3) [Member] | Guaranteed annuity contract [Member]    
Defined Benefit Plan Disclosure [Line Items]    
Balance at beginning of year 15,426 16,198
Purchases, sales, issuances and settlements, net (2,222) (1,733)
Interest income 552 631
Unrealized gains 135 330
Balance at end of year $ 13,891 $ 15,426