Restructuring and Excess Facilities - Additional Information (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]
Restructuring and Related Cost, Incurred Cost	$ 3,076	$ 2,244	$ 0
Restructuring and asset impairment charges	2,761	1,421	0
Harmonic 2015 Restructuring [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring reserve	322
Restructuring charges in continued operations	2,169
Harmonic 2015 Restructuring [Member] | Fixed Asset Impairment [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring reserve	0
Restructuring charges in continued operations	1,138
Harmonic 2015 Restructuring [Member] | Severance [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and Related Cost, Number of Positions Eliminated	19
Restructuring reserve	305
Restructuring charges in continued operations	599
Harmonic 2015 Restructuring [Member] | Contract Termination [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring reserve	0
Restructuring charges in continued operations	307
Harmonic 2015 Restructuring [Member] | Other Restructuring [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring reserve	17
Restructuring charges in continued operations	125
Harmonic 2013 Restructuring [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and Related Cost, Incurred Cost	900	2,200
Restructuring reserve	0	179
Restructuring charges in continued operations	924	2,168
Harmonic 2013 Restructuring [Member] | Inventory Valuation and Obsolescence [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and Related Cost, Incurred Cost		400
Restructuring reserve	0	0
Restructuring charges in continued operations	0	404
Harmonic 2013 Restructuring [Member] | Excess Facilities [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring reserve	0	0
Restructuring charges in continued operations	32	0
Harmonic 2013 Restructuring [Member] | Severance [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and Related Cost, Incurred Cost	800	1,700
Restructuring and Related Cost, Number of Positions Eliminated	25	85
Restructuring reserve	0	179
Restructuring charges in continued operations	829	1,663
Harmonic 2013 Restructuring [Member] | Contract Termination [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring reserve	0	0
Restructuring charges in continued operations	63	0
Harmonic 2013 Restructuring [Member] | Leasehold Improvements [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and Related Cost, Incurred Cost		100
Restructuring reserve	0	0
Restructuring charges in continued operations	0	101
HFC Restructuring [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring charges. Discontinued Operations		600
Number of employees terminated required to be hired		10
Restructuring reserve	0	13
HFC Restructuring [Member] | Severance [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring charges. Discontinued Operations		505
Restructuring and Related Cost, Number of Positions Eliminated		9
Restructuring reserve	0	13
HFC Restructuring [Member] | Contract Termination [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring charges. Discontinued Operations		95
Restructuring reserve	0	0
Omneon Restructuring [Member] | Excess Facilities [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and asset impairment charges		28		3,000
Restructuring reserve		$ 0	$ 869
Lease Expiration Date	Jun. 01, 2013