Document and Entity Information - shares	6 Months Ended
	Jul. 27, 2019	Aug. 26, 2019
Document and Entity Information [Abstract]
Title of 12(b) Security	Common stock, par value $0.33 1/3 per share
Trading Symbol	DY
Entity Incorporation, State or Country Code	FL
Entity Tax Identification Number	59-1277135
Entity Address, Address Line One	11780 US Highway 1, Suite 600
Entity Address, Postal Zip Code	33408
Entity Address, City or Town	Palm Beach Gardens,
Entity Address, State or Province	FL
Security Exchange Name	NYSE
Entity Registrant Name	DYCOM INDUSTRIES, INC.
City Area Code	561
Local Phone Number	627-7171
Entity Central Index Key	0000067215
Current Fiscal Year End Date	--01-25
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Shell Company	false
Entity Filer Category	Large Accelerated Filer
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	Q2
Document Type	10-Q
Document Quarterly Report	true
Entity File Number	001-10613
Entity Emerging Growth Company	false
Entity Small Business	false
Amendment Flag	false
Document Period End Date	Jul. 27, 2019
Document Transition Report	false
Entity Common Stock, Shares Outstanding		31,492,682