| Cover | May 12, 2022 |
| Cover [Abstract] | |
| Document Type | 8-K |
| Document Period End Date | Aug. 15, 2022 |
| Entity Registrant Name | NEXIMMUNE, INC. |
| Entity Incorporation, State or Country Code | DE |
| Entity File Number | 001-40045 |
| Entity Tax Identification Number | 45-2518457 |
| Entity Address, Address Line One | 9119 Gaither Road |
| Entity Address, City or Town | Gaithersburg, |
| Entity Address, State or Province | MD |
| Entity Address, Postal Zip Code | 20877 |
| City Area Code | (301) |
| Local Phone Number | 825-9810 |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Title of 12(b) Security | Common Stock, $0.0001 par value per share |
| Trading Symbol | NEXI |
| Security Exchange Name | NASDAQ |
| Entity Emerging Growth Company | true |
| Entity Central Index Key | 0001538210 |
| Amendment Flag | false |
| Entity Ex Transition Period | false |
