Balance Sheet Components Additional Information (Details) - USD ($) $ in Thousands	9 Months Ended
Sep. 25, 2020	Dec. 31, 2019
Property and Equipment, Gross	$ 150,304	$ 136,131
TVN [Member]
French R&D tax credits receivable, noncurrent	$ 19,500
TVN [Member] \| Research Tax Credit Carryforward [Member]
The number of years R&D tax credits can be used to offset against income tax payable after incurred	4 years
Other Noncurrent Assets [Member] \| TVN [Member] \| Research Tax Credit Carryforward [Member]
French R&D tax credits receivable, noncurrent	$ 19,500
Leasehold Improvements [Member]
Property and Equipment, Gross	37,436	$ 15,170
Leasehold Improvements [Member] \| Harmonic Headquarter Lease Commencing May 2019 [Member]
Property and Equipment, Gross	$ 22,900

The number of years R&D tax credits can be used to offset against income tax payable after incurred

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- Definition

Carrying amount as of the balance sheet date of income taxes previously overpaid to tax authorities (such as U.S. Federal, state and local tax authorities) representing refunds of overpayments or recoveries based on agreed-upon resolutions of disputes. Also called income tax refund receivable.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(8))
-URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03(10))
-URI http://asc.fasb.org/extlink&oid=120400017&loc=d3e572229-122910

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- Definition

Amount before accumulated depreciation, depletion and amortization of physical assets used in the normal conduct of business and not intended for resale. Examples include, but are not limited to, land, buildings, machinery and equipment, office equipment, and furniture and fixtures.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 360
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=6391035&loc=d3e2868-110229

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.13)
-URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

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