Document and Entity Information - shares	3 Months Ended
	Mar. 31, 2017	May 02, 2017
Document And Entity Information [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Mar. 31, 2017
Document Fiscal Year Focus	2017
Document Fiscal Period Focus	Q1
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		80,531,096