Other Financial Information, Other Long Term Assets (Details) (USD $) In Millions, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014	Oct. 01, 2014
Other Financial Information [Line Items]
Privately-held investments	$ 93.1jnpr_PrivatelyheldInvestments	$ 89.9jnpr_PrivatelyheldInvestments
Licensed software	8.3us-gaap_CapitalizedComputerSoftwareNet	8.6us-gaap_CapitalizedComputerSoftwareNet
Federal income tax receivable	28.9us-gaap_IncomeTaxesReceivableNoncurrent	20.0us-gaap_IncomeTaxesReceivableNoncurrent
Customer financing receivable	4.5jnpr_FinancedCustomerReceivable	16.9jnpr_FinancedCustomerReceivable
Inventory	9.8us-gaap_InventoryNoncurrent	8.0us-gaap_InventoryNoncurrent
Prepaid costs, deposits, and other	63.7	35.5
Promissory note in connection with the sale of Junos Pulse	125.0	125.0
Other long-term assets	333.3us-gaap_OtherAssetsNoncurrent	303.9us-gaap_OtherAssetsNoncurrent
Junos Pulse [Member]
Other Financial Information [Line Items]
Promissory note in connection with the sale of Junos Pulse			125.0
Consideration			230.7
Cash Consideration			105.7
Working capital adjustment			$ 19.3

Disposal Group, Including Discontinued Operation, Cash Consideration

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- Definition

Disposal Group, Including Discontinued Operation, Promissory Note

+ References

No definition available.

+ Details

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- Definition

Disposal Group, Including Discontinued Operation, Working Capital Adjustment

+ References

No definition available.

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- Definition

Financed Customer Receivable

+ References

No definition available.

+ Details

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- Details

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- Definition

Privately-held Investments

+ References

No definition available.

+ Details

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- Definition

The carrying amount of capitalized computer software costs net of accumulated amortization as of the balance sheet date.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 985

-SubTopic 20

-Section 50

-Paragraph 2

-URI http://asc.fasb.org/extlink&oid=6501960&loc=d3e128487-111756

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-Publisher FASB

-Name Accounting Standards Codification

-Topic 985

-SubTopic 20

-Section 50

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=6501960&loc=d3e128462-111756

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- Definition

Amount of consideration received or receivable for the disposal of assets and liabilities, including discontinued operation.

+ References

No definition available.

+ Details

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- Definition

Carrying amount due after one year of the balance sheet date (or one operating cycle, if longer) from tax authorities as of the balance sheet date representing refunds of overpayments or recoveries based on agreed-upon resolutions of disputes.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.17)

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-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 8

-Article 5

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-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 03

-Paragraph 5

-Subparagraph c

-Article 7

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- Definition

Inventories not expected to be converted to cash, sold or exchanged within the normal operating cycle.

+ References

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-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.6(d))

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-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 6

-Subparagraph d

-Article 5

+ Details

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- Definition

Aggregate carrying amount, as of the balance sheet date, of noncurrent assets not separately disclosed in the balance sheet. Noncurrent assets are expected to be realized or consumed after one year (or the normal operating cycle, if longer).

+ References

+ Details

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- Definition

Amount of asset related to consideration paid in advance for costs that provide economic benefits in future periods, and amount of other assets that are expected to be realized or consumed after one year or the normal operating cycle, if longer.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 942

-SubTopic 210

-Section S99

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

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-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 17

-Article 5

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