Restructuring and Related Charges - Additional Information (Detail) - USD ($) $ in Thousands		3 Months Ended	9 Months Ended
		Sep. 27, 2019	Sep. 27, 2019	Sep. 28, 2018	Dec. 31, 2018
Restructuring Cost and Reserve [Line Items]
Restructuring charges			$ 1,893
Payments for Restructuring			3,367
Restructuring Reserve		$ 3,441	3,441		$ 5,335
Restructuring Reserve, Current		3,000	3,000		3,300
Restructuring Reserve, Noncurrent		400	400		2,000
Excess facilities
Restructuring Cost and Reserve [Line Items]
Payments for Restructuring			1,409
Restructuring Reserve		1,182	1,182		2,926
Excess facilities | Prior Restructuring Plans
Restructuring Cost and Reserve [Line Items]
Restructuring Reserve		2,200	2,200
Severance and benefits
Restructuring Cost and Reserve [Line Items]
Restructuring charges			1,476
Payments for Restructuring			382
Restructuring Reserve		1,094	1,094		0
Severance and benefits | Harmonic 2019 Restructuring Plan [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring charges		1,100	1,500
Payments for Restructuring			400
Restructuring Reserve		1,100	1,100
TVN Voluntary Departure Plan
Restructuring Cost and Reserve [Line Items]
Restructuring charges	[1]		50
Payments for Restructuring	[1]		1,324
Restructuring Reserve	[1]	1,050	1,050		$ 2,409
TVN [Member]
Restructuring Cost and Reserve [Line Items]
TVN VDP liability balance payable through 2020		$ 1,100	$ 1,100
TVN [Member] | TVN Voluntary Departure Plan
Restructuring Cost and Reserve [Line Items]
Restructuring charges				$ 1,800

[1] “TVN VDP” consists of restructuring-related costs in connection with the TVN acquisition that included global workforce reductions, exiting certain operating facilities and disposing of excess assets and an employee voluntary departure plan in France.