| Cover | Nov. 09, 2020 |
| Cover [Abstract] | |
| Document Type | 8-K |
| Amendment Flag | false |
| Document Period End Date | Nov. 9, 2020 |
| Entity File Number | 001-38586 |
| Entity Registrant Name | RUBIUS THERAPEUTICS, INC. |
| Entity Central Index Key | 0001709401 |
| Entity Tax Identification Number | 46-2688109 |
| Entity Incorporation, State or Country Code | DE |
| Entity Address, Address Line One | 399 Binney Street |
| Entity Address, Address Line Two | Suite 300 |
| Entity Address, City or Town | Cambridge |
| Entity Address, State or Province | MA |
| Entity Address, Postal Zip Code | 02139 |
| City Area Code | 617 |
| Local Phone Number | 679-9600 |
| 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 $0.001 per share |
| Trading Symbol | RUBY |
| Security Exchange Name | NASDAQ |
| Entity Emerging Growth Company | true |
| Elected Not To Use the Extended Transition Period | false |
