Property and Equipment (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Oct. 26, 2013	Oct. 27, 2012	Jul. 27, 2013
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	$ 535,746		$ 522,141
Less: accumulated depreciation	(331,830)		(319,438)
Property and equipment, net	203,916		202,703
Depreciation and repairs and maintenance expenses [Abstract]
Depreciation expense	18,401	13,720
Repairs and maintenance expense	5,994	3,811
Land
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	0 years
Property, Plant and Equipment, Gross	3,479		3,479
Buildings
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	11,511		11,449
Leasehold Improvements
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	5,273		5,154
Vehicles
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	264,023		258,211
Computer hardware and software
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	66,961		64,191
Office furniture and equipment
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	8,155		7,915
Equipment and machinery
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	$ 176,344		$ 171,742
Maximum | Buildings
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	35 years
Maximum | Leasehold Improvements
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	15 years
Maximum | Vehicles
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	5 years
Maximum | Computer hardware and software
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	10 years
Maximum | Office furniture and equipment
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	7 years
Maximum | Equipment and machinery
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	10 years
Minimum | Buildings
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	10 years
Minimum | Leasehold Improvements
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	1 year
Minimum | Vehicles
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	1 year
Minimum | Computer hardware and software
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	3 years
Minimum | Office furniture and equipment
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	2 years
Minimum | Equipment and machinery
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	1 year