| Document And Entity Information | Oct. 02, 2023 |
| Document Information [Line Items] | |
| Entity, Registrant Name | ATHERSYS, INC / NEW |
| Document, Type | 8-K |
| Document, Period End Date | Oct. 02, 2023 |
| Entity, Incorporation, State or Country Code | DE |
| Entity, File Number | 001-33876 |
| Entity, Tax Identification Number | 20-4864095 |
| Entity, Address, Address Line One | 3201 Carnegie Avenue |
| Entity, Address, City or Town | Cleveland |
| Entity, Address, State or Province | OH |
| Entity, Address, Postal Zip Code | 44115-2634 |
| City Area Code | 216 |
| Local Phone Number | 431-9900 |
| 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 | ATHX |
| Security Exchange Name | NASDAQ |
| Entity, Emerging Growth Company | false |
| Amendment Flag | false |
| Entity, Central Index Key | 0001368148 |
