Property and Equipment (Details) - USD ($) $ in Thousands	9 Months Ended		12 Months Ended
	Apr. 25, 2015	Apr. 26, 2014	Jul. 25, 2015	Jul. 26, 2014	Jul. 27, 2013
Property, Plant and Equipment [Line Items]
Total			$ 624,106	$ 558,710
Less: accumulated depreciation			(392,542)	(353,297)
Property and equipment, net			231,564	205,413
Depreciation expense	$ 79,331	$ 74,517			$ 64,756
Repairs and maintenance expense			$ 22,054	$ 21,829	$ 19,408
Land
Property, Plant and Equipment [Line Items]
Estimated Useful Lives
Total			$ 3,475	$ 3,408
Buildings
Property, Plant and Equipment [Line Items]
Total			11,944	11,589
Leasehold improvements
Property, Plant and Equipment [Line Items]
Total			8,491	5,335
Vehicles
Property, Plant and Equipment [Line Items]
Total			316,979	279,631
Computer hardware and software
Property, Plant and Equipment [Line Items]
Total			80,091	73,349
Office furniture and equipment
Property, Plant and Equipment [Line Items]
Total			8,183	7,790
Equipment and machinery
Property, Plant and Equipment [Line Items]
Total			$ 194,943	$ 177,608
Minimum | Buildings
Property, Plant and Equipment [Line Items]
Estimated Useful Lives			10 years	10 years
Minimum | Leasehold improvements
Property, Plant and Equipment [Line Items]
Estimated Useful Lives			1 year	1 year
Minimum | Vehicles
Property, Plant and Equipment [Line Items]
Estimated Useful Lives			1 year	1 year
Minimum | Computer hardware and software
Property, Plant and Equipment [Line Items]
Estimated Useful Lives			1 year	3 years
Minimum | Office furniture and equipment
Property, Plant and Equipment [Line Items]
Estimated Useful Lives			1 year	2 years
Minimum | Equipment and machinery
Property, Plant and Equipment [Line Items]
Estimated Useful Lives			1 year	1 year
Maximum | Buildings
Property, Plant and Equipment [Line Items]
Estimated Useful Lives			35 years	35 years
Maximum | Leasehold improvements
Property, Plant and Equipment [Line Items]
Estimated Useful Lives			10 years	10 years
Maximum | Vehicles
Property, Plant and Equipment [Line Items]
Estimated Useful Lives			5 years	5 years
Maximum | Computer hardware and software
Property, Plant and Equipment [Line Items]
Estimated Useful Lives			7 years	10 years
Maximum | Office furniture and equipment
Property, Plant and Equipment [Line Items]
Estimated Useful Lives			7 years	7 years
Maximum | Equipment and machinery
Property, Plant and Equipment [Line Items]
Estimated Useful Lives			10 years	10 years