Acquisitions (Details) (USD $)	3 Months Ended		6 Months Ended					3 Months Ended			6 Months Ended						0 Months Ended
	Jan. 25, 2014	Jan. 26, 2013	Jan. 25, 2014	Jan. 26, 2013	Jul. 27, 2013	Dec. 03, 2012	Dec. 03, 2012 Quanta Services, Inc.	Jan. 25, 2014 Sage Telecommunications Corp of Colorado, LLC	Jan. 25, 2014 Businesses Acquired in Fiscal 2013	Jan. 26, 2013 Businesses Acquired in Fiscal 2013	Jan. 25, 2014 Businesses Acquired in Fiscal 2013	Jan. 26, 2013 Businesses Acquired in Fiscal 2013	Jan. 25, 2014 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	Jan. 25, 2014 Senior Subordinated Notes 7.125% Senior Subordinated Notes Due 2021	Jul. 27, 2013 Senior Subordinated Notes 7.125% Senior Subordinated Notes Due 2021	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
Credit facility amount														400,000,000
Proceeds from issuance of long-term debt			0	125,000,000													90,000,000
Debt, interest rate (in percent)															0.00%	7.125%
Repayments of credit facility													90,000,000
Acquisition payments								11,300,000
Goodwill	267,810,000		267,810,000		267,810,000	87,900,000		5,000,000
Carrying amount						90,600,000
Revenues									106,300,000	75,900,000	256,500,000	75,900,000
Amortization expense for finite-lived intangible assets	4,800,000	5,000,000	9,900,000	6,500,000					3,100,000	3,400,000	6,600,000	3,400,000
Operating Income (Loss)										$ 0	$ 4,000,000	$ 0