Document and Entity Information - USD ($)	12 Months Ended
	Jul. 30, 2016	Aug. 29, 2016	Jan. 23, 2016
Document and Entity Information [Abstract]
Entity Registrant Name	DYCOM INDUSTRIES INC
Entity Central Index Key	0000067215
Current Fiscal Year End Date	--07-30
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Filer Category	Large Accelerated Filer
Entity Public Float			$ 2,045,494,004
Entity Common Stock, Shares Outstanding		31,425,887
Document Fiscal Year Focus	2016
Document Fiscal Period Focus	Q4
Document Type	10-K
Amendment Flag	false
Document Period End Date	Jul. 30, 2016