| Document and Entity Information | Nov. 01, 2019 |
| Cover [Abstract] | |
| Entity Address, State or Province | CA |
| Amendment Flag | false |
| Entity Central Index Key | 0001271214 |
| Document Type | 8-K |
| Document Period End Date | Nov. 1, 2019 |
| Entity Registrant Name | Intersect ENT, Inc. |
| Entity Incorporation State Country Code | DE |
| Entity File Number | 001-36545 |
| Entity Tax Identification Number | 20-0280837 |
| Entity Address, Address Line One | Intersect ENT, Inc. |
| Entity Address, Address Line Two | 1555 Adams Drive |
| Entity Address, City or Town | Menlo Park |
| Entity Address, Postal Zip Code | 94025 |
| City Area Code | (650) |
| Local Phone Number | 641-2100 |
| Written Communications | false |
| Soliciting Material | false |
| Pre Commencement Tender Offer | false |
| Pre Commencement Issuer Tender Offer | false |
| Security 12b Title | Common Stock, 0.001 par value |
| Trading Symbol | XENT |
| Security Exchange Name | NASDAQ |
| Entity Emerging Growth Company | false |
