Restructuring and Excess Facilities - Activities in Restructuring Accrual (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended			3 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2010
Restructuring Cost and Reserve [Line Items]
Product cost of revenue	$ 315	$ 823	$ 0
Restructuring and asset impairment charges	2,761	1,421	0
Restructuring and Related Cost, Incurred Cost	3,076	2,244	0
Harmonic 2015 Restructuring [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring charges in continued operations	2,169
Cash payments	(601)
Non-cash write-offs	(1,246)
Ending Balance	322
Harmonic 2015 Restructuring [Member] | Fixed Asset Impairment [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring charges in continued operations	1,138
Cash payments	0
Non-cash write-offs	(1,138)
Ending Balance	0
Harmonic 2015 Restructuring [Member] | Severance [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring charges in continued operations	599
Cash payments	(294)
Non-cash write-offs	0
Ending Balance	305
Harmonic 2015 Restructuring [Member] | Contract Termination [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring charges in continued operations	307
Cash payments	(307)
Non-cash write-offs	0
Ending Balance	0
Harmonic 2015 Restructuring [Member] | Other Restructuring [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring charges in continued operations	125
Cash payments	0
Non-cash write-offs	(108)
Ending Balance	17
Harmonic 2013 Restructuring [Member]
Restructuring Cost and Reserve [Line Items]
Beginning Balance	179
Restructuring and Related Cost, Incurred Cost	900	2,200
Restructuring charges in continued operations	924	2,168
Adjustments to restructuring provisions	(17)	77
Cash payments	(1,086)	(1,513)
Non-cash write-offs		(553)
Ending Balance	0	179
Harmonic 2013 Restructuring [Member] | Excess Facilities [Member]
Restructuring Cost and Reserve [Line Items]
Beginning Balance	0
Restructuring charges in continued operations	32	0
Adjustments to restructuring provisions	0	0
Cash payments	(32)	0
Non-cash write-offs		0
Ending Balance	0	0
Harmonic 2013 Restructuring [Member] | Severance [Member]
Restructuring Cost and Reserve [Line Items]
Beginning Balance	179
Restructuring and Related Cost, Incurred Cost	800	1,700
Restructuring charges in continued operations	829	1,663
Adjustments to restructuring provisions	(17)	29
Cash payments	(991)	(1,513)
Non-cash write-offs		0
Ending Balance	0	179
Harmonic 2013 Restructuring [Member] | Contract Termination [Member]
Restructuring Cost and Reserve [Line Items]
Beginning Balance	0
Restructuring charges in continued operations	63	0
Adjustments to restructuring provisions	0	0
Cash payments	(63)	0
Non-cash write-offs		0
Ending Balance	0	0
Harmonic 2013 Restructuring [Member] | Impairment of Leasehold Improvements [Member]
Restructuring Cost and Reserve [Line Items]
Beginning Balance	0
Restructuring and Related Cost, Incurred Cost		100
Restructuring charges in continued operations	0	101
Adjustments to restructuring provisions	0	48
Cash payments	0	0
Non-cash write-offs		(149)
Ending Balance	0	0
Harmonic 2013 Restructuring [Member] | Obsolete Inventories [Member]
Restructuring Cost and Reserve [Line Items]
Beginning Balance	0
Restructuring and Related Cost, Incurred Cost		400
Restructuring charges in continued operations	0	404
Adjustments to restructuring provisions	0	0
Cash payments	0	0
Non-cash write-offs		(404)
Ending Balance	0	0
HFC Restructuring [Member]
Restructuring Cost and Reserve [Line Items]
Beginning Balance	13
Charges for HFC Restructuring Plan recorded in discontinued operations		527
Adjustments to restructuring provisions		73
Cash payments	(13)	(587)
Ending Balance	0	13
HFC Restructuring [Member] | Severance [Member]
Restructuring Cost and Reserve [Line Items]
Beginning Balance	13
Charges for HFC Restructuring Plan recorded in discontinued operations		403
Adjustments to restructuring provisions		102
Cash payments	(13)	(492)
Ending Balance	0	13
HFC Restructuring [Member] | Contract Termination [Member]
Restructuring Cost and Reserve [Line Items]
Beginning Balance	0
Charges for HFC Restructuring Plan recorded in discontinued operations		124
Adjustments to restructuring provisions		(29)
Cash payments	0	(95)
Ending Balance	0	0
Omneon Restructuring [Member] | Excess Facilities [Member]
Restructuring Cost and Reserve [Line Items]
Beginning Balance		869
Restructuring and asset impairment charges		28		3,000
Cash payments, net of sublease income		(897)
Ending Balance		$ 0