| Cover | Mar. 31, 2023 |
| Document Information [Line Items] | |
| Document Type | 8-K |
| Document Period End Date | Mar. 31, 2023 |
| Entity Registrant Name | OMNIAB, INC. |
| Entity Incorporation, State or Country Code | DE |
| Entity File Number | 001-40720 |
| Entity Tax Identification Number | 98-1584818 |
| Entity Address, Address Line One | 5980 Horton Street, Suite 600 |
| Entity Address, City or Town | Emeryville |
| Entity Address, State or Province | CA |
| Entity Address, Postal Zip Code | 94608 |
| City Area Code | 510 |
| Local Phone Number | 250-7800 |
| Written Communications | true |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Entity Emerging Growth Company | true |
| Entity Ex Transition Period | false |
| Amendment Flag | false |
| Entity Central Index Key | 0001846253 |
| Common Stock | |
| Document Information [Line Items] | |
| Title of 12(b) Security | Common Stock, par value $0.0001 per share |
| Trading Symbol | OABI |
| Security Exchange Name | NASDAQ |
| Warrant | |
| Document Information [Line Items] | |
| Title of 12(b) Security | Warrants to purchase common stock |
| Trading Symbol | OABIW |
| Security Exchange Name | NASDAQ |
