Accrued Insurance Claims (Details) (USD $)	Oct. 27, 2012	Jul. 28, 2012
Accrued Insurance Claims [Line Items]
Aggregate stop loss coverage for automobile liability, general liability and workers' compensation claims	$ 41,800,000
Insurance Liability, Retained Risk of Loss, Annual basis	250,000
Retained risk of loss per participant for employee health plan for claim amounts that aggregate across all participants in excess of $250,000	550,000
Insurance Liability, Retained Risk of Loss, Employee Health Plan Threshold	250,000
Amounts expected to be paid within one year:
Accrued auto, general liability and workers' compensation	15,829,000	16,514,000
Accrued employee group health	2,624,000	2,867,000
Accrued damage claims	5,791,000	5,837,000
Accrued insurance claims	24,244,000	25,218,000
Amounts expected to be paid beyond one year:
Accrued auto, general liability and workers' compensation	20,747,000	21,423,000
Accrued damage claims	2,100,000	2,168,000
Accrued insurance claims, Noncurrent	22,847,000	23,591,000
Total accrued insurance claims	47,091,000	48,809,000
Maximum
Accrued Insurance Claims [Line Items]
Retained risk of loss, general liability and workers' compensation, maximum automobile liability	$ 1,000,000