Goodwill and Intangible Assets (Details) (USD $)	3 Months Ended
	Oct. 26, 2013	Oct. 27, 2012	Jul. 27, 2013	Dec. 03, 2012
Finite-Lived and Indefinite-Lived Intangible Assets [Line Items]
Goodwill	$ 267,810,000		$ 267,810,000	$ 87,900,000
Amortization expense for finite-lived intangible assets	5,200,000	1,600,000
UtiliQuest trade name
Finite-Lived and Indefinite-Lived Intangible Assets [Line Items]
Goodwill			35,600,000
Indefinite-Lived Intangible Assets	$ 4,700,000		$ 4,700,000
Margin of excess			20.00%