Restructuring and Related Charges - Activities in Restructuring Accrual (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2016	Oct. 02, 2015	Sep. 30, 2016	Oct. 02, 2015	Dec. 31, 2015	Dec. 31, 2014
Restructuring Cost and Reserve [Line Items]
Product cost of revenue		$ 113		$ 113
Production Related Impairment Cost Recovery	$ (1)		$ (24)
Adjustments to restructuring provisions	(27)	397	4,488	626
Restructuring and Related Cost, Incurred Cost	(28)	510	4,464	739
Restructuring Reserve [Roll Forward]
Adjustments to restructuring provisions	(27)	$ 397	4,488	$ 626
Harmonic 2016 Restructuring Plan [Member]
Restructuring Cost and Reserve [Line Items]
Adjustments to restructuring provisions			(87)
Restructuring Reserve [Roll Forward]
Restructuring charges			4,862
Adjustments to restructuring provisions			(87)
Reclassification of deferred rent			1,087
Cash payments			(3,766)
Non-cash write-offs			(246)
Foreign exchange gain (loss)			(12)
Ending Balance	1,838		1,838
Harmonic 2016 Restructuring Plan [Member] | Other Restructuring [Member]
Restructuring Reserve [Roll Forward]
Restructuring charges			246
Reclassification of deferred rent			0
Cash payments			0
Non-cash write-offs			(246)
Ending Balance	0		0
Increase (Decrease) in Restructuring Reserve			0
Harmonic 2016 Restructuring Plan [Member] | Facility Closing [Member]
Restructuring Reserve [Roll Forward]
Restructuring charges	1,400		1,445
Reclassification of deferred rent			1,087
Cash payments			(705)
Non-cash write-offs			0
Ending Balance	1,827		1,827
Increase (Decrease) in Restructuring Reserve			0
Harmonic 2016 Restructuring Plan [Member] | Employee Severance [Member]
Restructuring Cost and Reserve [Line Items]
Adjustments to restructuring provisions			(87)
Restructuring Reserve [Roll Forward]
Restructuring charges			3,171
Adjustments to restructuring provisions			(87)
Reclassification of deferred rent			0
Cash payments			(3,061)
Non-cash write-offs			0
Foreign exchange gain (loss)			(12)
Ending Balance	11		11
Harmonic Two Thousand And Fifteen Restructuring [Member]
Restructuring Reserve [Roll Forward]
Restructuring charges					$ 1,500	$ 2,200
Harmonic Two Thousand And Fifteen Restructuring [Member] | Employee Severance [Member]
Restructuring Cost and Reserve [Line Items]
Adjustments to restructuring provisions			(65)
Restructuring Reserve [Roll Forward]
Beginning Balance			264
Adjustments to restructuring provisions			(65)
Cash payments			(194)
Ending Balance	$ 5		$ 5		$ 264