Basis of Presentation and Accounting Policies (Policies)	6 Months Ended
	Jan. 25, 2014
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation - Dycom Industries, Inc. and its wholly-owned subsidiaries (collectively, "Dycom" or the "Company") is a leading provider of specialty contracting services throughout the United States and in Canada. These services include engineering, construction, maintenance and installation services to telecommunications providers, underground facility locating services to various utilities, including telecommunications providers, and other construction and maintenance services to electric and gas utilities and others. The accompanying unaudited condensed consolidated financial statements of Dycom have been prepared in accordance with accounting principles generally accepted in the United States of America ("GAAP") for interim financial information and with the instructions to Form 10-Q and Rule 10-01 of Regulation S-X of the Securities and Exchange Commission ("SEC"). Accordingly, they do not include all of the information and notes required by GAAP for complete financial statements. The condensed consolidated financial statements and accompanying notes reflect all adjustments, consisting of only normal recurring accruals that are, in the opinion of management, necessary for a fair presentation of such statements. Operating results for the interim period are not necessarily indicative of the results expected for any other interim period or for the full fiscal year. These condensed consolidated financial statements and accompanying notes should be read in conjunction with Management's Discussion and Analysis of Financial Condition and Results of Operations contained in this report and the Company's audited financial statements for the year ended July 27, 2013 included in the Company's 2013 Annual Report on Form 10-K, filed with the SEC on September 13, 2013. The condensed consolidated financial statements include the accounts of the Company. All significant transactions and balances between Dycom Industries, Inc. and its subsidiaries have been eliminated. All of the Company's operating segments have been aggregated into one reporting segment due to their similar economic characteristics, customers, service distribution methods, and the nature of their services and production processes. The Company's services are provided by its subsidiaries throughout the United States and Canada. Revenues from services provided in Canada were approximately $2.1 million and $5.4 million during the three and six months ended January 25, 2014, respectively, and $2.5 million and $6.4 million during the three and six months ended January 26, 2013, respectively. The Company had no material long-lived assets in Canada at January 25, 2014 or July 27, 2013.
Business Combinations	Acquisitions - On December 3, 2012, the Company acquired substantially all of the telecommunications infrastructure services subsidiaries of Quanta Services, Inc. Additionally, during the fourth quarter of fiscal 2013, the Company acquired Sage Telecommunications Corp of Colorado, LLC and certain assets of a tower construction and maintenance company. The results of operations of these businesses are included in the accompanying condensed consolidated financial statements from their dates of acquisition.
Accounting Period	Accounting Period - The Company uses a fiscal year ending on the last Saturday in July.
Use of Estimates	Use of Estimates - The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the amounts reported in these condensed consolidated financial statements and accompanying notes. Significant estimates made by management include revenue recognition of long-term contracts, including estimates of costs to complete, accruals for self-insurance claims, provision for income taxes, accruals for legal matters and other contingencies, the fair value of reporting units for goodwill impairment analysis, the assessment of impairment of intangibles and other long-lived assets, preliminary purchase price allocations of businesses acquired, stock-based compensation expense for performance-based stock awards, asset lives used in computing depreciation and amortization, and allowance for doubtful accounts. At the time they are made, the Company believes that such estimates are fair when considered in conjunction with the consolidated financial position and results of operations taken as a whole. However, actual results could differ materially from those estimates.
Restricted Cash	Restricted Cash - As of January 25, 2014 and July 27, 2013, the Company had approximately $4.0 million and $3.7 million, respectively, in restricted cash which is held as collateral in support of the Company's insurance obligations. Restricted cash is included in other current assets and other assets in the condensed consolidated balance sheets and changes in restricted cash are reported in cash flows used in investing activities in the condensed consolidated statements of cash flows.
Fair Value of Financial Instruments	Fair Value of Financial Instruments - ASC Topic 820, Fair Value Measurements and Disclosures ("ASC Topic 820") requires that assets and liabilities carried at fair value are classified and disclosed in one of the following three categories: (1) Level 1 - Quoted market prices in active markets for identical assets or liabilities; (2) Level 2 - Observable market-based inputs or unobservable inputs that are corroborated by market data; and (3) Level 3 - Unobservable inputs not corroborated by market data which require the reporting entity's own assumptions. The Company's financial instruments consist primarily of cash and equivalents, restricted cash, accounts receivables, income taxes receivable and payable, accounts payable and certain accrued expenses, and long-term debt. The carrying amounts of these items approximate fair value due to their short maturity, except for the Company's outstanding 7.125% senior subordinated notes due 2021 (the "2021 Notes") which are categorized as Level 2 as of January 25, 2014 and July 27, 2013, based on observable market-based inputs. See Note 10, Debt, for further information regarding the fair value of the 2021 Notes. The Company's cash and equivalents are categorized as Level 1 as of January 25, 2014 and July 27, 2013, based on quoted market prices in active markets for identical assets. During the three and six months ended January 25, 2014 and January 26, 2013, the Company had no non-recurring fair value measurements of assets or liabilities subsequent to their initial recognition.

Disclosure of accounting policy for completed business combinations (purchase method, acquisition method or combination of entities under common control). This accounting policy may include a general discussion of the purchase method or acquisition method of accounting (including for example, the treatment accorded contingent consideration, the identification of assets and liabilities, the purchase price allocation process, how the fair values of acquired assets and liabilities are determined) and the entity's specific application thereof. An entity that acquires another entity in a leveraged buyout transaction generally discloses the accounting policy followed by the acquiring entity in determining the basis used to value its interest in the acquired entity, and the rationale for that accounting policy.

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- Definition

Entity's cash and cash equivalents accounting policy with respect to restricted balances. Restrictions may include legally restricted deposits held as compensating balances against short-term borrowing arrangements, contracts entered into with others, or company statements of intention with regard to particular deposits; however, time deposits and short-term certificates of deposit are not generally included in legally restricted deposits.

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- Definition

Disclosure of accounting policy for determining an entity's fiscal year or other fiscal period. This disclosure may include identification of the fiscal period end-date, the length of the fiscal period, any reporting period lag between the entity and its subsidiaries, or equity investees. If a reporting lag exists, the closing date of the entity having a different period end is generally noted, along with an explanation of the necessity for using different closing dates. Any intervening events that materially affect the entity's financial position or results of operations are generally also disclosed.

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