| Document And Entity Information | Nov. 10, 2021 |
| Document Information [Line Items] | |
| Entity, Registrant Name | AMERICAN SHARED HOSPITAL SERVICES |
| Document, Type | 8-K |
| Document, Period End Date | Nov. 10, 2021 |
| Entity, Incorporation, State or Country Code | CA |
| Entity, File Number | 1-08789 |
| Entity, Tax Identification Number | 94-2918118 |
| Entity, Address, Address Line One | Two Embarcadero Center, Suite 410 |
| Entity, Address, City or Town | San Francisco |
| Entity, Address, State or Province | CA |
| Entity, Address, Postal Zip Code | 94111 |
| City Area Code | 415 |
| Local Phone Number | 788-5300 |
| Title of 12(b) Security | Common Stock |
| Trading Symbol | AMS |
| Security Exchange Name | NYSE |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Entity, Emerging Growth Company | false |
| Amendment Flag | false |
| Entity, Central Index Key | 0000744825 |
