Cash Equivalents and Investments - Available-For-Sale (Details) - USD ($) $ in Millions	Sep. 30, 2023	Dec. 31, 2022
Available-for-sale debt securities:
Amortized Cost	$ 562.9	$ 437.8
Gross Unrealized Gains	37.4	37.4
Gross Unrealized Losses	(3.5)	(9.5)
Estimated Fair Value	596.8	465.7
Cash equivalents
Available-for-sale debt securities:
Amortized Cost	371.6	70.6
Gross Unrealized Gains	0.0	0.0
Gross Unrealized Losses	0.0	0.0
Estimated Fair Value	371.6	70.6
Short-term investments
Available-for-sale debt securities:
Amortized Cost	128.8	205.9
Gross Unrealized Gains	0.0	0.0
Gross Unrealized Losses	(2.6)	(3.3)
Estimated Fair Value	126.2	202.6
Long-term investments
Available-for-sale debt securities:
Amortized Cost	41.8	145.8
Gross Unrealized Gains	0.0	0.0
Gross Unrealized Losses	(0.9)	(6.2)
Estimated Fair Value	40.9	139.6
Other long-term assets
Available-for-sale debt securities:
Amortized Cost	20.7	15.5
Gross Unrealized Gains	37.4	37.4
Gross Unrealized Losses	0.0	0.0
Estimated Fair Value	58.1	52.9
Total fixed income securities
Available-for-sale debt securities:
Amortized Cost	542.2	422.3
Gross Unrealized Gains	0.0	0.0
Gross Unrealized Losses	(3.5)	(9.5)
Estimated Fair Value	538.7	412.8
Asset-backed and mortgage-backed securities
Available-for-sale debt securities:
Amortized Cost	24.7	37.8
Gross Unrealized Gains	0.0	0.0
Gross Unrealized Losses	(0.6)	(1.2)
Estimated Fair Value	24.1	36.6
Corporate debt securities
Available-for-sale debt securities:
Amortized Cost	123.9	277.5
Gross Unrealized Gains	0.0	0.0
Gross Unrealized Losses	(2.5)	(7.1)
Estimated Fair Value	121.4	270.4
Commercial paper
Available-for-sale debt securities:
Amortized Cost	20.9	0.0
Gross Unrealized Gains	0.0	0.0
Gross Unrealized Losses	0.0	0.0
Estimated Fair Value	20.9	0.0
Foreign government debt securities
Available-for-sale debt securities:
Amortized Cost	5.2	8.8
Gross Unrealized Gains	0.0	0.0
Gross Unrealized Losses	(0.2)	(0.4)
Estimated Fair Value	5.0	8.4
Time deposits
Available-for-sale debt securities:
Amortized Cost	342.1	70.6
Gross Unrealized Gains	0.0	0.0
Gross Unrealized Losses	0.0	0.0
Estimated Fair Value	342.1	70.6
U.S. government agency securities
Available-for-sale debt securities:
Amortized Cost	8.0	18.6
Gross Unrealized Gains	0.0	0.0
Gross Unrealized Losses	(0.1)	(0.6)
Estimated Fair Value	7.9	18.0
U.S. government securities
Available-for-sale debt securities:
Amortized Cost	17.4	9.0
Gross Unrealized Gains	0.0	0.0
Gross Unrealized Losses	(0.1)	(0.2)
Estimated Fair Value	17.3	8.8
Privately-held debt and redeemable preferred stock securities
Available-for-sale debt securities:
Amortized Cost	20.7	15.5
Gross Unrealized Gains	37.4	37.4
Gross Unrealized Losses	0.0	0.0
Estimated Fair Value	$ 58.1	$ 52.9

Amount, before tax, of unrealized gain in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481800/320-10-50-2

+ Details

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

- Definition

Amount, before tax, of unrealized loss in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481800/320-10-50-2

+ Details

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

- References

No definition available.

+ Details

Name:	us-gaap_AvailableForSaleSecuritiesAbstract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Amortized cost excluding accrued interest, after allowance for credit loss, of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 326
-SubTopic 30
-Name Accounting Standards Codification
-Section 45
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479130/326-30-45-1

+ Details

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

- Definition

Amount excluding accrued interest, of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

+ References

+ Details

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

- Details

Name:	us-gaap_BalanceSheetLocationAxis=us-gaap_CashEquivalentsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_BalanceSheetLocationAxis=us-gaap_ShortTermInvestmentsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_BalanceSheetLocationAxis=us-gaap_OtherLongTermInvestmentsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_BalanceSheetLocationAxis=jnpr_OtherLongTermAssetsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancialInstrumentAxis=us-gaap_FixedIncomeSecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancialInstrumentAxis=jnpr_AssetBackedSecuritiesAndMortgageBackedSecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancialInstrumentAxis=us-gaap_CorporateDebtSecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancialInstrumentAxis=us-gaap_CommercialPaperMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancialInstrumentAxis=us-gaap_ForeignGovernmentDebtSecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancialInstrumentAxis=us-gaap_BankTimeDepositsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancialInstrumentAxis=us-gaap_USGovernmentSponsoredEnterprisesDebtSecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancialInstrumentAxis=us-gaap_USGovernmentDebtSecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancialInstrumentAxis=jnpr_PrivatelyHeldDebtAndRedeemablePreferredStockSecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: