Property and Equipment (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jan. 23, 2016	Jan. 24, 2015	Jan. 23, 2016	Jan. 24, 2015	Jul. 25, 2015
Property, Plant and Equipment [Line Items]
Total	$ 721,951		$ 721,951		$ 624,106
Less: accumulated depreciation	(431,415)		(431,415)		(392,542)
Property and equipment, net	290,536		290,536		231,564
Depreciation expense	$ 25,200	$ 19,100	47,900	$ 38,000
Land
Property, Plant and Equipment [Line Items]
Estimated Useful Lives	0 years	0 years
Total	$ 3,475		3,475		3,475
Buildings
Property, Plant and Equipment [Line Items]
Total	11,969		11,969		11,944
Leasehold improvements
Property, Plant and Equipment [Line Items]
Total	12,859		12,859		8,491
Vehicles
Property, Plant and Equipment [Line Items]
Total	366,242		366,242		316,979
Computer hardware and software
Property, Plant and Equipment [Line Items]
Total	92,411		92,411		80,091
Office furniture and equipment
Property, Plant and Equipment [Line Items]
Total	9,907		9,907		8,183
Equipment and machinery
Property, Plant and Equipment [Line Items]
Total	$ 225,088		$ 225,088		$ 194,943
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