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Accrued Insurance Claims - Narratives (Details)
 12 Months Ended
Jan. 26, 2019
USD ($)
state
Jan. 27, 2018
USD ($)
Jul. 29, 2017
USD ($)
Jul. 30, 2016
USD ($)
Accrued Insurance Claims [Line Items]        
Increase (Decrease) in Insurance Liabilities $ (6,700,000)      
Number of states with state-sponsored insurance fund | state 2      
Aggregate stop loss coverage for automobile liability, general liability, and workers' compensation claims before adjustment $ 78,900,000 $ 67,100,000 $ 103,700,000 $ 84,600,000
Insurance liability, annual retained risk loss 400,000      
Insurance Liability, Annual Retained Risk of Loss, Under Employee Health Plan Per Participant, Maximum Threshold 425,000      
Maximum        
Accrued Insurance Claims [Line Items]        
Retained risk of loss, general liability and workers' compensation, maximum automobile liability $ 1,000,000