Document and Entity Information - shares	6 Months Ended
	Jul. 03, 2015	Jul. 30, 2015
Document And Entity Information [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Jul. 03, 2015
Document Fiscal Year Focus	2015
Document Fiscal Period Focus	Q2
Trading Symbol	HLIT
Entity Registrant Name	HARMONIC INC
Entity Central Index Key	0000851310
Current Fiscal Year End Date	--12-31
Entity Filer Category	Accelerated Filer
Entity Common Stock, Shares Outstanding		88,128,032