Lease - Narratives (Details) - USD ($) $ in Thousands	9 Months Ended
Sep. 27, 2019	Jun. 28, 2019
Operating Leased Assets [Line Items]
Operating lease right-of-use assets	$ 27,694
Operating Lease, Liability, Current	9,453
Operating Lease, Liability, Noncurrent	$ 25,395
Minimum [Member] \| Leaseholds and Leasehold Improvements [Member]
Operating Leased Assets [Line Items]
Lessee, Operating Lease, Term of Contract	1 year
Maximum [Member] \| Leaseholds and Leasehold Improvements [Member]
Operating Leased Assets [Line Items]
Lessee, Operating Lease, Term of Contract	11 years
Lessee, Operating Lease, Initial Term Not Capitalized	12 months
Harmonic Headquarter Lease Commencing May 2019 [Member] \| Leaseholds and Leasehold Improvements [Member]
Operating Leased Assets [Line Items]
Lessee, Operating Lease, Term of Contract		11 years
Operating lease right-of-use assets		$ 10,300
Harmonic Headquarter Lease Commencing May 2019 [Member] \| Prepaid Expenses and Other Current Assets [Member] \| Leaseholds and Leasehold Improvements [Member]
Operating Leased Assets [Line Items]
Lease Incentive Receivable, Current		4,000
Harmonic Headquarter Lease Commencing May 2019 [Member] \| Other Noncurrent Liabilities [Member] \| Leaseholds and Leasehold Improvements [Member]
Operating Leased Assets [Line Items]
Operating Lease, Liability, Current		14,000
Harmonic Headquarter Lease Commencing May 2019 [Member] \| Accrued Liabilities [Member] \| Leaseholds and Leasehold Improvements [Member]
Operating Leased Assets [Line Items]
Operating Lease, Liability, Noncurrent		$ 300

Initial Lease Term Threshold Not Capitalized as Operating Lease

No definition available.

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- Definition

This item represents the current receivable for an incentive or inducement contractually stipulated between parties to a lease whereby the lessor has committed to provide the entity (lessee) with a cash payment as inducement to enter the lease. The receivable is due within one year. For classified balance sheets, this element represents the current amount receivable, that is amounts expected to be collected within one year or the normal operating cycle, if longer.

+ 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=6877327&loc=d3e13212-122682

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Term of lessee's operating lease, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
-SubTopic 20
-Section 50
-Paragraph 3
-Subparagraph (a)(3)
-URI http://asc.fasb.org/extlink&oid=77888426&loc=SL77918673-209980

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	instant

- Definition

Present value of lessee's discounted obligation for lease payments from operating lease, classified as current.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
-SubTopic 20
-Section 45
-Paragraph 1
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=77888419&loc=SL77918627-209977

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Present value of lessee's discounted obligation for lease payments from operating lease, classified as noncurrent.

+ References

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of lessee's right to use underlying asset under operating lease.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
-SubTopic 20
-Section 45
-Paragraph 1
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=77888419&loc=SL77918627-209977

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

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- Details

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- Details

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- Details

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- Details

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- Details

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- Details

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