Property and Equipment (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Oct. 25, 2014	Oct. 26, 2013	Jul. 26, 2014
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 573,039		$ 558,710
Less: accumulated depreciation	(366,900)		(353,297)
Property and equipment, net	206,139		205,413
Depreciation and repairs and maintenance expenses [Abstract]
Depreciation expense	18,841	18,401
Repairs and maintenance expense	5,484	5,994
Land
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	3,408		3,408
Buildings
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	11,598		11,589
Leasehold Improvements
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	5,602		5,335
Vehicles
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	286,831		279,631
Computer hardware and software
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	77,004		73,349
Office furniture and equipment
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	7,873		7,790
Equipment and machinery
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 180,723		$ 177,608
Maximum | Buildings
Property, Plant and Equipment [Line Items]
General useful life	35 years
Maximum | Leasehold Improvements
Property, Plant and Equipment [Line Items]
General useful life	10 years
Maximum | Vehicles
Property, Plant and Equipment [Line Items]
General useful life	5 years
Maximum | Computer hardware and software
Property, Plant and Equipment [Line Items]
General useful life	10 years
Maximum | Office furniture and equipment
Property, Plant and Equipment [Line Items]
General useful life	7 years
Maximum | Equipment and machinery
Property, Plant and Equipment [Line Items]
General useful life	10 years
Minimum | Buildings
Property, Plant and Equipment [Line Items]
General useful life	10 years
Minimum | Leasehold Improvements
Property, Plant and Equipment [Line Items]
General useful life	1 year
Minimum | Vehicles
Property, Plant and Equipment [Line Items]
General useful life	1 year
Minimum | Computer hardware and software
Property, Plant and Equipment [Line Items]
General useful life	3 years
Minimum | Office furniture and equipment
Property, Plant and Equipment [Line Items]
General useful life	2 years
Minimum | Equipment and machinery
Property, Plant and Equipment [Line Items]
General useful life	1 year