Goodwill and Intangible Assets - Schedule of 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 Intangible Assets [Line Items]
Amortization of Intangible Assets	$ 4,100,000	$ 7,100,000	$ 14,100,000	$ 13,600,000
Carrying amount						90,600,000
Gross Intangible Assets	193,679,000		193,679,000		193,082,000
Net Intangible Assets	111,819,000		111,819,000		125,275,000
Customer Relationships
Finite-Lived Intangible Assets [Line Items]
Carrying amount	165,094,000		165,094,000		164,497,000
Accumulated Amortization	65,795,000		65,795,000		56,219,000
Contract Backlog
Finite-Lived Intangible Assets [Line Items]
Carrying amount	15,285,000		15,285,000		15,285,000
Accumulated Amortization	12,883,000		12,883,000		9,433,000
Trade Names
Finite-Lived Intangible Assets [Line Items]
Carrying amount	8,200,000		8,200,000		8,200,000
Accumulated Amortization	3,038,000		3,038,000		2,071,000
UtiliQuest trade name
Finite-Lived Intangible Assets [Line Items]
Indefinite-Lived Intangible Assets	4,700,000		4,700,000		4,700,000
Noncompete Agreements
Finite-Lived Intangible Assets [Line Items]
Carrying amount	400,000		400,000		400,000
Accumulated Amortization	$ 144,000		$ 144,000		$ 84,000