Restructuring and Related Charges - Additional Information (Detail) $ in Thousands		1 Months Ended	3 Months Ended			6 Months Ended	9 Months Ended		12 Months Ended	21 Months Ended
		Jan. 31, 2016 USD ($)	Sep. 29, 2017 USD ($)	Dec. 31, 2016 USD ($) Employees	Sep. 30, 2016 USD ($)	Jun. 30, 2017 Employee	Sep. 29, 2017 USD ($)	Sep. 30, 2016 USD ($)	Dec. 31, 2016 USD ($) Employees	Sep. 29, 2017 USD ($)	Jan. 04, 2016 USD ($)
Restructuring Cost and Reserve [Line Items]
Adjustments to restructuring provisions			$ 2,028		$ (27)		$ 4,084	$ 4,488
Harmonic 2017 Restructuring Plan [Member]
Restructuring Cost and Reserve [Line Items]
Charges for 2016 Harmonic Restructuring Plan			2,435
Harmonic 2016 Restructuring Plan [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and Related Cost, Incurred Cost			100				2,900		$ 20,000
Charges for 2016 Harmonic Restructuring Plan							2,991
Adjustments to restructuring provisions							(7)
Facility Closing [Member] | Harmonic 2017 Restructuring Plan [Member]
Restructuring Cost and Reserve [Line Items]
Charges for 2016 Harmonic Restructuring Plan			318
Facility Closing [Member] | Harmonic 2016 Restructuring Plan [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and Related Cost, Incurred Cost									2,200
Charges for 2016 Harmonic Restructuring Plan							73
Adjustments to restructuring provisions							0
Employee Severance And Benefit Arrangements [Member] | Harmonic 2016 Restructuring Plan [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and Related Cost, Incurred Cost									$ 17,800
Number of positions eliminated | Employees									118
Employee Severance [Member] | Harmonic 2017 Restructuring Plan [Member]
Restructuring Cost and Reserve [Line Items]
Charges for 2016 Harmonic Restructuring Plan			2,117
Employee Severance [Member] | Harmonic 2016 Restructuring Plan [Member]
Restructuring Cost and Reserve [Line Items]
Charges for 2016 Harmonic Restructuring Plan	[1]						1,137
Adjustments to restructuring provisions	[1]						(7)
TVN Voluntary Departure Plan [Member] | Harmonic 2016 Restructuring Plan [Member]
Restructuring Cost and Reserve [Line Items]
Charges for 2016 Harmonic Restructuring Plan	[2]						1,781
Adjustments to restructuring provisions	[2]						0
TVN [Member]
Restructuring Cost and Reserve [Line Items]
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Gain (Loss) Due to Curtailment									$ 2,000
Business Combination, Acquisition and Integration Related Expenses									16,900
Business Combination, Integration Related Costs			117		$ 4,734		2,734	$ 7,912
Number of employees applied for VDP | Employees				83
Voluntary Departure Plan Anticipated Cost									$ 15,300
Voluntary Departure Plan Benefit Obligation Term									4 years
Number of employees required to work beyond minimum statutory notice period under VDP | Employees				11
Accrued Voluntary Departure Plan, Current				$ 14,800					$ 14,800
TVN [Member] | Employee Severance And Benefit Arrangements [Member] | Harmonic 2016 Restructuring Plan [Member]
Restructuring Cost and Reserve [Line Items]
Number of positions eliminated						21			83
TVN [Member] | Employee Severance [Member] | Harmonic 2016 Restructuring Plan [Member]
Restructuring Cost and Reserve [Line Items]
Postemployment Benefits, Period Expense							1,800
Charges for 2016 Harmonic Restructuring Plan							1,100
TVN [Member] | TVN Voluntary Departure Plan [Member]
Restructuring Cost and Reserve [Line Items]
Charges for 2016 Harmonic Restructuring Plan							1,800		$ 13,100
Defined Benefit Plan, Benefit Obligation, Benefits Paid							6,200		$ 3,500	$ 9,700
Postemployment Benefits Liability			$ 6,000				$ 6,000			$ 6,000
San Jose CA Excess Facility [Member] | Facility Closing [Member] | Harmonic 2016 Restructuring Plan [Member]
Restructuring Cost and Reserve [Line Items]
Charges for 2016 Harmonic Restructuring Plan		$ 1,400
Fair Value of Excess Facility Restructuring											$ 2,500
Deferred Rent Credit											$ 1,100
Adjustments to restructuring provisions				$ 600

[1] The Company anticipates that the remaining severance and benefits accrual at September 29, 2017 will be fully paid in 2017.

[2] See discussion of the TVN VDP above for future estimated payments through 2020.