Accrued Insurance Claims (Details)	Oct. 28, 2017 USD ($) state	Jul. 29, 2017 USD ($)
Accrued Insurance Claims [Line Items]
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	$ 67,100,000
Insurance liability, annual retained risk loss	400,000
Accrued insurance	109,200,000	$ 101,900,000
Accrued insurance claims, Noncurrent	60,782,000	62,007,000
Insurance recoveries for accrued insurance claims	14,135,000	9,243,000
Other Noncurrent assets
Accrued Insurance Claims [Line Items]
Insurance recoveries for accrued insurance claims	14,100,000	$ 9,200,000
Maximum
Accrued Insurance Claims [Line Items]
Retained risk of loss, general liability and workers' compensation, maximum automobile liability	$ 1,000,000