Property and Equipment (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jan. 25, 2014	Jan. 26, 2013	Jan. 25, 2014	Jan. 26, 2013	Jul. 27, 2013
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	$ 551,316		$ 551,316		$ 522,141
Less: accumulated depreciation	(347,677)		(347,677)		(319,438)
Property and equipment, net	203,639		203,639		202,703
Depreciation and repairs and maintenance expenses [Abstract]
Depreciation expense	18,657	15,868	37,058	29,588
Repairs and maintenance expense	5,245	4,376	11,239	8,188
Land
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life			0 years
Property, Plant and Equipment, Gross	3,479		3,479		3,479
Buildings
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	11,567		11,567		11,449
Leasehold Improvements
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	5,355		5,355		5,154
Vehicles
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	272,828		272,828		258,211
Computer hardware and software
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	71,223		71,223		64,191
Office furniture and equipment
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	8,240		8,240		7,915
Equipment and machinery
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	$ 178,624		$ 178,624		$ 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