Acquisitions Acquisitions (Details) (USD $)	3 Months Ended	12 Months Ended				3 Months Ended	12 Months Ended		3 Months Ended		12 Months Ended			0 Months Ended					0 Months Ended
	Jul. 27, 2013	Jul. 27, 2013	Jul. 28, 2012	Jul. 30, 2011	Dec. 03, 2012	Jul. 27, 2013 Quanta Services, Inc.	Jul. 27, 2013 Quanta Services, Inc.	Dec. 03, 2012 Quanta Services, Inc.	Jul. 27, 2013 Sage Telecommunications Corp of Colorado, LLC	Jan. 26, 2013 Sage Telecommunications Corp of Colorado, LLC	Jul. 27, 2013 Sage Telecommunications Corp of Colorado, LLC	Jul. 27, 2013 Senior Loan and Revolving Credit Credit Agreement, December 3, 2012, Maturing December 2017	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	Jul. 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	Jul. 30, 2011 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								$ 275,000,000
Estimated adjustment for working capital received in excess of target amount								40,400,000
Amount paid for other specified items								3,700,000										3,800,000
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%	7.125%
Repayments of credit facility												90,000,000
Acquisition related costs									200,000	6,500,000	200,000
Integration related costs		3,400,000
Number of states in which entity operates					49
Number of Customers Served					300
Acquisition payments									11,300,000
Goodwill	267,810,000	267,810,000	174,849,000	174,849,000	87,900,000				5,000,000		5,000,000
Carrying amount					90,600,000
Goodwill purchase adjustment	600,000
Working capital adjustment	3,800,000
Asset fair value adjustments	3,200,000
Revenues generated by acquired subsidiaries						335,400,000
Amortization expense for finite-lived intangible assets		$ 20,700,000	$ 6,500,000	$ 6,800,000			$ 14,300,000