| Document and Entity Information | Dec. 15, 2021 |
| Cover [Abstract] | |
| Amendment Flag | false |
| Entity Central Index Key | 0001383701 |
| Document Type | 8-K |
| Document Period End Date | Dec. 15, 2021 |
| Entity Registrant Name | HISTOGEN INC. |
| Entity Incorporation State Country Code | DE |
| Entity File Number | 001-36003 |
| Entity Tax Identification Number | 20-3183915 |
| Entity Address, Address Line One | 10655 Sorrento Valley Road |
| Entity Address, Address Line Two | Suite 200 |
| Entity Address, City or Town | San Diego |
| Entity Address, State or Province | CA |
| Entity Address, Postal Zip Code | 92121 |
| City Area Code | (858) |
| Local Phone Number | 526-3100 |
| Written Communications | false |
| Soliciting Material | false |
| Pre Commencement Tender Offer | false |
| Pre Commencement Issuer Tender Offer | false |
| Security 12b Title | Common Stock, par value $0.0001 per share |
| Trading Symbol | HSTO |
| Security Exchange Name | NASDAQ |
| Entity Emerging Growth Company | false |
