Property and Equipment (Details) - USD ($) $ in Thousands	3 Months Ended
	Oct. 29, 2016	Oct. 24, 2015	Jul. 30, 2016
Property, Plant and Equipment [Line Items]
Total	$ 813,298		$ 781,493
Less: accumulated depreciation	(475,645)		(454,823)
Property and equipment, net	337,653		326,670
Depreciation expense	28,400	$ 22,700
Land
Property, Plant and Equipment [Line Items]
Total	3,475		3,475
Buildings
Property, Plant and Equipment [Line Items]
Total	12,011		11,969
Leasehold improvements
Property, Plant and Equipment [Line Items]
Total	14,757		13,753
Vehicles
Property, Plant and Equipment [Line Items]
Total	423,195		404,273
Computer hardware and software
Property, Plant and Equipment [Line Items]
Total	98,972		95,570
Office furniture and equipment
Property, Plant and Equipment [Line Items]
Total	10,852		10,374
Equipment and machinery
Property, Plant and Equipment [Line Items]
Total	$ 250,036		$ 242,079
Minimum | Buildings
Property, Plant and Equipment [Line Items]
Estimated Useful Lives (Years)	10 years
Minimum | Leasehold improvements
Property, Plant and Equipment [Line Items]
Estimated Useful Lives (Years)	1 year
Minimum | Vehicles
Property, Plant and Equipment [Line Items]
Estimated Useful Lives (Years)	1 year
Minimum | Computer hardware and software
Property, Plant and Equipment [Line Items]
Estimated Useful Lives (Years)	1 year
Minimum | Office furniture and equipment
Property, Plant and Equipment [Line Items]
Estimated Useful Lives (Years)	1 year
Minimum | Equipment and machinery
Property, Plant and Equipment [Line Items]
Estimated Useful Lives (Years)	1 year
Maximum | Buildings
Property, Plant and Equipment [Line Items]
Estimated Useful Lives (Years)	35 years
Maximum | Leasehold improvements
Property, Plant and Equipment [Line Items]
Estimated Useful Lives (Years)	10 years
Maximum | Vehicles
Property, Plant and Equipment [Line Items]
Estimated Useful Lives (Years)	5 years
Maximum | Computer hardware and software
Property, Plant and Equipment [Line Items]
Estimated Useful Lives (Years)	7 years
Maximum | Office furniture and equipment
Property, Plant and Equipment [Line Items]
Estimated Useful Lives (Years)	10 years
Maximum | Equipment and machinery
Property, Plant and Equipment [Line Items]
Estimated Useful Lives (Years)	10 years