Restructuring and Related Charges - Activities in Restructuring Accrual (Detail) (USD $)	3 Months Ended		9 Months Ended				12 Months Ended	9 Months Ended			3 Months Ended		9 Months Ended		3 Months Ended		9 Months Ended
	Sep. 26, 2014	Sep. 27, 2013	Sep. 26, 2014	Sep. 27, 2013	Sep. 26, 2014 Harmonic Two Thousand And Thirteen Restructuring [Member]	Sep. 27, 2013 Harmonic Two Thousand And Thirteen Restructuring [Member]	Dec. 31, 2013 Harmonic Two Thousand And Thirteen Restructuring [Member]	Sep. 26, 2014 Harmonic Two Thousand And Thirteen Restructuring [Member] Severance [Member]	Sep. 26, 2014 Harmonic Two Thousand And Thirteen Restructuring [Member] Termination of a research and development project [Member]	Sep. 26, 2014 Harmonic Two Thousand And Thirteen Restructuring [Member] Excess Facilities [Member]	Sep. 26, 2014 Product cost of revenue [Member]	Sep. 27, 2013 Product cost of revenue [Member]	Sep. 26, 2014 Product cost of revenue [Member]	Sep. 27, 2013 Product cost of revenue [Member]	Sep. 26, 2014 Operating Expense [Member]	Sep. 27, 2013 Operating Expense [Member]	Sep. 26, 2014 Operating Expense [Member]	Sep. 27, 2013 Operating Expense [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and Related Cost, Incurred Cost	$ 403,000	$ 583,000	$ 915,000	$ 1,455,000							$ 15,000	$ 324,000	$ 94,000	$ 530,000	$ 388,000	$ 259,000	$ 821,000	$ 925,000
Restructuring Reserve [Roll Forward]
Beginning Balance					179,000			179,000	0	0
Restructuring and related charges	388,000	259,000	821,000	925,000	924,000	1,455,000	2,200,000	829,000	63,000	32,000
Adjustments to restructuring provisions					(9,000)			(9,000)	0	0
Cash payments					(747,000)			(715,000)	0	(32,000)
Ending Balance					$ 347,000		$ 179,000	$ 284,000	$ 63,000	$ 0