Property and Equipment (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jan. 28, 2017	Jan. 23, 2016	Jan. 28, 2017	Jan. 23, 2016	Jul. 30, 2016
Property, Plant and Equipment [Line Items]
Total	$ 838,605		$ 838,605		$ 781,493
Less: accumulated depreciation	(494,485)		(494,485)		(454,823)
Property and equipment, net	344,120		344,120		326,670
Depreciation expense	29,600	$ 25,200	58,000	$ 47,900
Land
Property, Plant and Equipment [Line Items]
Total	3,475		3,475		3,475
Buildings
Property, Plant and Equipment [Line Items]
Total	12,021		12,021		11,969
Leasehold improvements
Property, Plant and Equipment [Line Items]
Total	15,118		15,118		13,753
Vehicles
Property, Plant and Equipment [Line Items]
Total	439,263		439,263		404,273
Computer hardware and software
Property, Plant and Equipment [Line Items]
Total	99,129		99,129		95,570
Office furniture and equipment
Property, Plant and Equipment [Line Items]
Total	11,699		11,699		10,374
Equipment and machinery
Property, Plant and Equipment [Line Items]
Total	$ 257,900		$ 257,900		$ 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