| Document and Entity Information Document | Dec. 04, 2019 |
| Document and Entity Information [Abstract] | |
| Title of 12(b) Security | Common stock, par value $0.33 1/3 per share |
| Entity Central Index Key | 0000067215 |
| Entity Incorporation, State or Country Code | FL |
| Entity Registrant Name | DYCOM INDUSTRIES, INC. |
| Document Type | 8-K |
| Document Period End Date | Dec. 4, 2019 |
| City Area Code | 561 |
| Local Phone Number | 627-7171 |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Entity Emerging Growth Company | false |
| Entity File Number | 001-10613 |
| Entity Tax Identification Number | 59-1277135 |
| Entity Address, Address Line One | 11780 U.S. Highway One, Suite 600 |
| Entity Address, City or Town | Palm Beach Gardens, |
| Entity Address, State or Province | FL |
| Entity Address, Postal Zip Code | 33408 |
| Amendment Flag | false |
| Trading Symbol | DY |
| Security Exchange Name | NYSE |
