| Document And Entity Information | Sep. 24, 2021 |
| Cover [Abstract] | |
| Document Type | 8-K |
| Amendment Flag | false |
| Document Period End Date | Sep. 24, 2021 |
| Entity Registrant Name | Caribou Biosciences, Inc. |
| Entity Central Index Key | 0001619856 |
| Entity Emerging Growth Company | true |
| Entity File Number | 001-40631 |
| Entity Incorporation, State or Country Code | DE |
| Entity Tax Identification Number | 45-3728228 |
| Entity Address, Address Line One | 2929 7th Street, Suite 105 |
| Entity Address, City or Town | Berkeley |
| Entity Address, State or Province | CA |
| Entity Address, Postal Zip Code | 94710 |
| City Area Code | (510) |
| Local Phone Number | 982-6030 |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Entity Ex Transition Period | false |
| Title of 12(b) Security | Common Stock, $0.0001 par value per share |
| Trading Symbol | CRBU |
| Security Exchange Name | NASDAQ |
