Significant Accounting Policies and Estimates (Policies)	3 Months Ended
	Apr. 27, 2019
Accounting Policies [Abstract]
Lessee, Leases [Policy Text Block]	Leases. The Company’s leases are accounted for as operating leases, with lease expense recognized on a straight-line basis over the lease term. The lease term may include options to extend or terminate the lease when it is reasonably certain that the Company will exercise that option. For leases with initial terms greater than 12 months, the Company records operating lease right-of-use assets and corresponding operating lease liabilities. Operating lease right-of-use assets represent the Company’s right to use the underlying asset for the lease term and operating lease liabilities represent the Company’s obligation to make the related lease payments. These assets and liabilities are recognized at commencement date based on the present value of lease payments over the lease term. As the Company’s leases do not provide an implicit rate, the Company uses its incremental borrowing rate based on the information available at commencement date in determining the present value of lease payments. Leases with an initial term of 12 months or less are not recorded on the Company’s consolidated balance sheet.
Basis of Presentation	Dycom Industries, Inc. (“Dycom” or the “Company”) is a leading provider of specialty contracting services throughout the United States. The Company provides program management, engineering, construction, maintenance and installation services for telecommunications providers, underground facility locating services for various utilities, including telecommunications providers, and other construction and maintenance services for electric and gas utilities. The accompanying unaudited condensed consolidated financial statements of the Company and its subsidiaries, all of which are wholly-owned, 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 U.S. Securities and Exchange Commission (“SEC”). Accordingly, they do not include all of the information and notes required by GAAP for annual financial statements and 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 included in the Company’s Annual Report on Form 10-K for fiscal 2019, filed with the SEC on March 4, 2019. In the opinion of management, all adjustments considered necessary for a fair statement of the results for the interim periods presented have been included. This includes all normal and recurring adjustments and elimination of intercompany accounts and transactions. Operating results for the interim period are not necessarily indicative of the results expected for any subsequent interim or annual period.
Accounting Period	Accounting Period. The Company’s fiscal year ends on the last Saturday in January and consists of either 52 or 53 weeks of operations (with the additional week of operations occurring in the fourth fiscal quarter). Fiscal 2019 and fiscal 2020 each consist of 52 weeks of operations. The next 53 week fiscal period will occur in the fiscal year ending January 30, 2021.
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 Company’s consolidated financial position and results of operations taken as a whole. However, actual results could differ materially from those estimates.
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 the fair value of the Company’s long-term debt, which is based on observable market-based inputs (Level 2). See Note 14, 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 April 27, 2019 and January 26, 2019. During the three months ended April 27, 2019 and April 28, 2018, the Company had no material nonrecurring fair value measurements of assets or liabilities subsequent to their initial recognition.
Recently Issued Accounting Pronouncements	Recently Adopted Accounting Standards Leases. In February 2016, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) No. 2016-02, Leases (Topic 842) (“ASU 2016-02”) which is intended to increase transparency and comparability of accounting for lease transactions. For all leases with terms greater than 12 months, the new guidance requires lessees to recognize right-of-use assets and corresponding lease liabilities on the balance sheet and to disclose qualitative and quantitative information about lease transactions. The new standard maintains a distinction between finance leases and operating leases. As a result, the effect of leases in the statement of operations and statement of cash flows is largely unchanged. Effective January 27, 2019, the first day of fiscal 2020, the Company adopted the requirements of ASU 2016-02 using the transition provisions at the date of adoption instead of at the earliest comparative period presented in the financial statements. Accordingly, comparative financial statements for periods prior to the date of adoption were not adjusted. The Company elected the group of practical expedients that allowed it not to reassess the following: whether any expired or existing contracts represent leases, the classification of any expired or existing leases, and the initial direct costs for any expired or existing leases. The Company did not elect the practical expedient to use hindsight to determine the lease term. On adoption, the Company recognized approximately $71.0 million of operating lease right-of-use assets and corresponding lease liabilities on its condensed consolidated balance sheet for its operating leases with terms greater than 12 months. The adoption of ASU 2016-02 did not have a material impact on the Company’s consolidated statements of operations, comprehensive income, or cash flows.