Goodwill and Intangible Assets (Details) (USD $)	3 Months Ended		9 Months Ended
	Apr. 26, 2014	Apr. 27, 2013	Apr. 26, 2014	Apr. 27, 2013	Jul. 27, 2013	Dec. 03, 2012
Finite-Lived and Indefinite-Lived Intangible Assets [Line Items]
Goodwill	$ 267,810,000		$ 267,810,000		$ 267,810,000	$ 87,900,000
Amortization expense for finite-lived intangible assets	4,100,000	7,100,000	14,100,000	13,600,000
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		$ 4,700,000
Margin of excess					20.00%
Goodwill [Member]
Finite-Lived and Indefinite-Lived Intangible Assets [Line Items]
Fair Value Inputs, Discount Rate			11.50%
Maximum | Goodwill [Member]
Finite-Lived and Indefinite-Lived Intangible Assets [Line Items]
Fair Value Assumptions, Terminal Growth Rate			2.00%