| Cover | Jul. 25, 2022 |
| Cover [Abstract] | |
| Document Type | 8-K |
| Amendment Flag | false |
| Document Period End Date | Jul. 25, 2022 |
| Entity File Number | 001-35798 |
| Entity Registrant Name | Humanigen, Inc. |
| Entity Central Index Key | 0001293310 |
| Entity Tax Identification Number | 77-0557236 |
| Entity Incorporation, State or Country Code | DE |
| Entity Address, Address Line One | 830 Morris Turnpike |
| Entity Address, Address Line Two | 4th Floor |
| Entity Address, City or Town | Short Hills |
| Entity Address, State or Province | NJ |
| Entity Address, Postal Zip Code | 07078 |
| City Area Code | (973) |
| Local Phone Number | 200-3010 |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Title of 12(b) Security | Common Stock |
| Trading Symbol | HGEN |
| Security Exchange Name | NASDAQ |
| Entity Emerging Growth Company | false |
