Basis of Presentation and Accounting Policies (Policies)	6 Months Ended
	Jan. 23, 2016
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation Dycom Industries, Inc. ("Dycom" or the "Company") is a leading provider of specialty contracting services throughout the United States and in Canada. The Company provides program management, 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. The accompanying unaudited condensed consolidated financial statements include the results of Dycom and its subsidiaries, all of which are wholly-owned. All intercompany accounts and transactions have been eliminated and the financial statements reflect all adjustments, consisting of only normal recurring accruals that are, in the opinion of management, necessary for a fair presentation of such statements. These financial statements 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. 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 25, 2015 included in the Company's Annual Report on Form 10-K for the year ended July 25, 2015, filed with the SEC on September 4, 2015.
Segment Information	Segment Information – The Company operates in one reportable segment. Its services are provided by its operating segments on a decentralized basis. Each operating segment consists of a subsidiary (or in certain instances, the combination of two or more subsidiaries). Management of the operating segments report to the Company's Chief Operating Officer who reports to the Chief Executive Officer, the chief operating decision maker. All of the Company's operating segments have been aggregated into one reportable segment based on their similar economic characteristics, nature of services and production processes, type of customers, and service distribution methods. The Company's operating segments provide services throughout the United States and in Canada. Revenues from services provided in Canada were approximately $1.8 million and $4.6 million during the three and six months ended January 23, 2016, respectively, and $3.1 million and $7.8 million during the three and six months ended January 24, 2015, respectively. The Company had no material long-lived assets in Canada as of January 23, 2016 or July 25, 2015.
Accounting Period	Accounting Period – The Company's fiscal year ends on the last Saturday in July. As a result, each fiscal year consists of either fifty-two weeks or fifty-three weeks of operations (with an additional week of operations occurring in the fourth quarter). Fiscal 2015 contained fifty-two weeks and fiscal 2016 will contain fifty-three weeks of operations.
Use of Estimates	Use of Estimates – The preparation of financial statements in conformity with GAAP requires management to make certain estimates and assumptions that affect the amounts reported in these condensed consolidated financial statements and accompanying notes. These estimates are based on the Company's historical experience and management's understanding of current facts and circumstances. 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 23, 2016 and July 25, 2015, the Company had approximately $5.0 million and $4.5 million, respectively, in restricted cash, which is held as collateral in support of the Company's insurance obligations. Restricted cash is included in 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.
Business Combinations	Business Combinations – The Company accounts for business combinations under the acquisition method of accounting. The purchase price of each business acquired is allocated to the tangible and intangible assets acquired and the liabilities assumed based on information regarding their respective fair values on the date of acquisition. Any excess of the purchase price over the fair value of the separately identifiable assets acquired and the liabilities assumed is allocated to goodwill. Management determines the fair values used in purchase price allocations for intangible assets based on historical data, estimated discounted future cash flows, contract backlog amounts, if applicable, and expected royalty rates for trademarks and trade names, as well as certain other information. The valuation of assets acquired and liabilities assumed requires a number of judgments and is subject to revision as additional information about the fair value of assets and liabilities becomes available. Additional information, which existed as of the acquisition date but unknown to the Company at that time, may become known during the remainder of the measurement period, a period not to exceed twelve months from the acquisition date. Adjustments to the preliminary purchase price allocation, if necessary, are recorded to the value of the assets acquired and liabilities assumed, with a corresponding adjustment to goodwill. Acquisition costs are expensed as incurred. The results of operations of businesses acquired are included in the accompanying condensed consolidated financial statements from their dates of acquisition.
Fair Value of Financial Instruments	Fair Value of Financial Instruments – The Company's financial instruments primarily consist of cash and equivalents, restricted cash, accounts receivable, income taxes receivable and payable, accounts payable, certain accrued expenses, and long-term debt. The carrying amounts of these items approximate fair value due to their short maturity, except for certain of the Company's outstanding long-term debt, which is based on observable market-based inputs (Level 2). See Note 10, Debt, for further information regarding the fair value of such financial instruments. The Company's cash and equivalents are based on quoted market prices in active markets for identical assets (Level 1) as of January 23, 2016 and July 25, 2015. During the three and six months ended January 23, 2016 and January 24, 2015, the Company had no material nonrecurring fair value measurements of assets or liabilities subsequent to their initial recognition.
Other Assets	Other Assets – As of January 23, 2016 and July 25, 2015, other non-current assets consist of deferred financing costs of $7.6 million and $11.6 million, respectively, insurance recoveries/receivables related to accrued claims of $5.9 million and $8.9 million, respectively, as well as long-term deposits, prepaid discounts, and other non-current assets totaling $18.0 million and $13.6 million, respectively. As of January 23, 2016 and July 25, 2015, other non-current assets also included $4.0 million for an investment in nonvoting senior units of a customer, which
Recently Issued Accounting Pronouncements	Recently Issued Accounting Pronouncements There have been no changes in the expected dates of adoption or estimated effects on the Company's consolidated financial statements of recently issued accounting pronouncements from those disclosed in the Company's Annual Report on Form 10-K. Accounting standards adopted during the period covered in this Quarterly Report on Form 10-Q and recently issued accounting pronouncements are discussed below. Recently Adopted Accounting Standards In April 2014, the Financial Accounting Standards Board ("FASB") issued Accounting Standards Update No. 2014-08, Presentation of Financial Statements (Topic 205) and Property, Plant, and Equipment (Topic 360): Reporting Discontinued Operations and Disclosures of Disposals of Components of an Entity ("ASU 2014-08"). ASU 2014-08 changes the criteria for reporting discontinued operations. In accordance with ASU 2014-08, a disposal of a component of an entity or a group of components of an entity is required to be reported in discontinued operations only if the disposal represents a strategic shift that has (or will have) a major effect on an entity's operations and financial results. ASU 2014-08 also requires expanded disclosures about the assets, liabilities, income, and expenses of discontinued operations as well as disclosure of the pre-tax income arising from a disposal of a significant part of an organization that does not qualify for discontinued operations reporting. The Company adopted ASU 2014-08 in fiscal 2016 and it did not have a material effect on the Company's consolidated financial statements. Accounting Standards Not Yet Adopted In September 2015, the FASB issued Accounting Standards Update No. 2015-16, Simplifying the Accounting for Measurement-Period Adjustments ("ASU 2015-16"). ASU 2015-16 replaces the requirement for an acquirer in a business combination to retrospectively adjust provisional amounts recognized at the acquisition date with a corresponding adjustment to goodwill when measurement period adjustments are identified. The new guidance requires an acquirer to recognize adjustments in the reporting period in which the adjustment amounts are determined. The acquirer must record, in the same period's financial statements, the effect on earnings of changes in depreciation, amortization, or other income effects, if any, as a result of the change to the provisional amounts, calculated as if the accounting had been completed at the acquisition date. Additionally, the acquirer must present separately on the face of the income statement, or disclose in the notes, the portion of the amount recorded in current period earnings by line item that would have been recorded in previous reporting periods if the adjustments had been recognized as of the acquisition date. ASU 2015-16 will be effective for the Company in fiscal 2017 and interim reporting periods within that year. The adoption of this guidance is not expected to have a material effect on the Company's consolidated financial statements. In November 2015, the FASB issued Accounting Standards Update No. 2015-17, Income Taxes (Topic 740): Balance Sheet Classification of Deferred Taxes ("ASU 2015-17"). ASU 2015-17 eliminates the current requirement for an entity to separate deferred income tax liabilities and assets into current and non-current amounts in a classified statement of financial position. To simplify the presentation of deferred income taxes, the amendments in ASU 2015-17 require that deferred tax liabilities and assets be classified as non-current in a classified statement of financial position. ASU 2015-17 will be effective for the Company in fiscal 2018 and interim reporting periods within that year. Early adoption is permitted as of the beginning of an interim or annual reporting period. The Company is currently evaluating the effect of the adoption of this guidance on the Company's consolidated financial statements.