Balance Sheet Components - Property and Equipment, Net (Details) - USD ($) $ in Thousands		Mar. 27, 2020	Dec. 31, 2019
Property, Plant and Equipment [Line Items]
Property and Equipment, Gross		$ 152,166	$ 136,131
Less: accumulated depreciation and amortization		(115,075)	(113,203)
Property and Equipment, Net		37,091	22,928
Machinery and Equipment [Member]
Property, Plant and Equipment [Line Items]
Property and Equipment, Gross		77,213	75,229
Capitalized Software [Member]
Property, Plant and Equipment [Line Items]
Property and Equipment, Gross		34,395	34,190
Construction in Progress [Member]
Property, Plant and Equipment [Line Items]
Property and Equipment, Gross	[1]	19,482	5,506
Leasehold Improvements [Member]
Property, Plant and Equipment [Line Items]
Property and Equipment, Gross		15,072	15,170
Furniture and Fixtures [Member]
Property, Plant and Equipment [Line Items]
Property and Equipment, Gross		6,004	$ 6,036
Harmonic Headquarter Lease Commencing May 2019 [Member] | Construction in Progress [Member]
Property, Plant and Equipment [Line Items]
Property and Equipment, Gross		$ 18,200

[1] During fiscal 2019, the Company entered into a lease for a new facility which will become the Company’s new headquarters in 2020. The new lease commenced in May 2019, as the facility was made available to the Company for constructing leasehold improvements. Construction in progress includes $18.2 million for constructing leasehold improvements in the new headquarters facility.