Property and Equipment (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Apr. 29, 2017	Apr. 23, 2016	Apr. 29, 2017	Apr. 23, 2016	Jul. 30, 2016
Property, Plant and Equipment [Line Items]
Total	$ 881,835		$ 881,835		$ 781,493
Less: accumulated depreciation	(503,427)		(503,427)		(454,823)
Property and equipment, net	378,408		378,408		326,670
Depreciation expense	31,200	$ 27,000	89,200	$ 74,900
Land
Property, Plant and Equipment [Line Items]
Total	3,475		3,475		3,475
Buildings
Property, Plant and Equipment [Line Items]
Total	$ 12,006		12,006		11,969
Buildings | Minimum
Property, Plant and Equipment [Line Items]
Estimated Useful Lives (Years)	10 years
Buildings | Maximum
Property, Plant and Equipment [Line Items]
Estimated Useful Lives (Years)	35 years
Leasehold improvements
Property, Plant and Equipment [Line Items]
Total	$ 13,959		13,959		13,753
Leasehold improvements | Minimum
Property, Plant and Equipment [Line Items]
Estimated Useful Lives (Years)	1 year
Leasehold improvements | Maximum
Property, Plant and Equipment [Line Items]
Estimated Useful Lives (Years)	10 years
Vehicles
Property, Plant and Equipment [Line Items]
Total	$ 461,059		461,059		404,273
Vehicles | Minimum
Property, Plant and Equipment [Line Items]
Estimated Useful Lives (Years)	1 year
Vehicles | Maximum
Property, Plant and Equipment [Line Items]
Estimated Useful Lives (Years)	5 years
Computer hardware and software
Property, Plant and Equipment [Line Items]
Total	$ 104,659		104,659		95,570
Computer hardware and software | Minimum
Property, Plant and Equipment [Line Items]
Estimated Useful Lives (Years)	1 year
Computer hardware and software | Maximum
Property, Plant and Equipment [Line Items]
Estimated Useful Lives (Years)	7 years
Office furniture and equipment
Property, Plant and Equipment [Line Items]
Total	$ 11,949		11,949		10,374
Office furniture and equipment | Minimum
Property, Plant and Equipment [Line Items]
Estimated Useful Lives (Years)	1 year
Office furniture and equipment | Maximum
Property, Plant and Equipment [Line Items]
Estimated Useful Lives (Years)	10 years
Equipment and machinery
Property, Plant and Equipment [Line Items]
Total	$ 274,728		$ 274,728		$ 242,079
Equipment and machinery | Minimum
Property, Plant and Equipment [Line Items]
Estimated Useful Lives (Years)	1 year
Equipment and machinery | Maximum
Property, Plant and Equipment [Line Items]
Estimated Useful Lives (Years)	10 years