Document and Entity Information (USD $)	12 Months Ended
	Jul. 28, 2012	Aug. 29, 2012	Jan. 28, 2012
Document and Entity Information [Abstract]
Entity Registrant Name	DYCOM INDUSTRIES INC
Entity Central Index Key	0000067215
Current Fiscal Year End Date	--07-28
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Filer Category	Large Accelerated Filer
Entity Public Float			$ 733,294,688
Entity Common Stock, Shares Outstanding		33,609,200
Document Fiscal Year Focus	2012
Document Fiscal Period Focus	FY
Document Type	10-K
Amendment Flag	false
Document Period End Date	Jul. 28, 2012