| Document and Entity Information | Aug. 19, 2019 |
| Cover [Abstract] | |
| Entity Registrant Name | JUNIPER NETWORKS INC |
| Amendment Flag | false |
| Entity Central Index Key | 0001043604 |
| Document Type | 8-K |
| Document Period End Date | Aug. 19, 2019 |
| Entity Incorporation State Country Code | DE |
| Entity File Number | 001-34501 |
| Entity Tax Identification Number | 77-0422528 |
| Entity Address, Address Line One | 1133 Innovation Way |
| Entity Address, City or Town | Sunnyvale |
| Entity Address, State or Province | CA |
| Entity Address, Postal Zip Code | 94089 |
| City Area Code | (408) |
| Local Phone Number | 745-2000 |
| Written Communications | false |
| Soliciting Material | false |
| Pre Commencement Tender Offer | false |
| Pre Commencement Issuer Tender Offer | false |
| Security 12b Title | Common Stock, par value $0.00001 per share |
| Trading Symbol | JNPR |
| Security Exchange Name | NYSE |
| Entity Emerging Growth Company | false |
