Document and Entity Information	3 Months Ended
	Oct. 27, 2012	Nov. 19, 2012
Document and Entity Information [Abstract]
Entity Registrant Name	DYCOM INDUSTRIES INC
Entity Central Index Key	0000067215
Current Fiscal Year End Date	--07-27
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		32,597,712
Document Fiscal Year Focus	2013
Document Fiscal Period Focus	Q1
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Oct. 27, 2012