Acquisitions Acquisitions (Details) (USD $)	3 Months Ended	9 Months Ended					0 Months Ended				0 Months Ended
	Apr. 27, 2013	Apr. 27, 2013	Dec. 03, 2012	Apr. 27, 2013 Quanta Services, Inc.	Dec. 03, 2012 Quanta Services, Inc.	Dec. 03, 2012 Senior Loan and Revolving Credit Credit Agreement, December 3, 2012, Maturing December 2017	Dec. 12, 2012 Senior Subordinated Notes 7.125% Senior Subordinated Notes Due 2021	Apr. 27, 2013 Senior Subordinated Notes 7.125% Senior Subordinated Notes Due 2021	Jul. 28, 2012 Senior Subordinated Notes 7.125% Senior Subordinated Notes Due 2021	Dec. 12, 2012 Senior Subordinated Notes 7.125% Senior Subordinated Notes Due 2021 Quanta Services, Inc.	Dec. 12, 2012 Senior Subordinated Notes 7.125% Senior Subordinated Notes Due 2021 Dycom Investments, Inc.
Business Acquisition [Line Items]
Cash paid to acquire Quanta Services					$ 275,000,000
Estimated adjustment for working capital received in excess of target amount					40,400,000
Amount paid for other specified items					0					3,800,000
Accrued remaining purchase price of acquisition				318,984,000
Business Acquisition, Cost of Acquired Entity, Final Payment				(4,154,000)
Credit facility amount						400,000,000
Proceeds from issuance of long-term debt							90,000,000				90,000,000
Debt, interest rate (in percent)								7.125%	7.125%
Acquisition related costs		6,500,000
Integration related costs	1,400,000	2,300,000
Revenues generated by acquired subsidiaries	122,900,000	198,800,000
Amortization of Intangible Assets	$ 5,500,000	$ 8,800,000
Number of States in which Entity Operates			49
Number of Customers Served			300