| Document and Entity Information | Sep. 19, 2023 |
| Document And Entity Information [Line Items] | |
| Document Type | 8-K |
| Document Period End Date | Sep. 19, 2023 |
| Entity Registrant Name | HilleVax, Inc. |
| Entity Incorporation, State or Country Code | DE |
| Entity File Number | 001-41365 |
| Entity Tax Identification Number | 85-0545060 |
| Entity Address, Address Line One | 321 Harrison Avenue |
| Entity Address, City or Town | Boston |
| Entity Address, State or Province | MA |
| Entity Address, Postal Zip Code | 02118 |
| City Area Code | 617 |
| Local Phone Number | 213-5054 |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Title of 12(b) Security | Common Stock, par value $0.0001 per share |
| Trading Symbol | HLVX |
| Security Exchange Name | NASDAQ |
| Entity Emerging Growth Company | true |
| Entity Ex Transition Period | false |
| Amendment Flag | false |
| Entity Central Index Key | 0001888012 |
| Former Address [Member] | |
| Document And Entity Information [Line Items] | |
| Entity Address, Address Line One | 75 State Street |
| Entity Address, Address Line Two | Suite 100 - #9995 |
| Entity Address, City or Town | Boston |
| Entity Address, State or Province | MA |
| Entity Address, Postal Zip Code | 02109 |
