| Document and Entity Information | Feb. 09, 2021 |
| Cover [Abstract] | |
| Document Type | 8-K |
| Amendment Flag | false |
| Document Period End Date | Feb. 9, 2021 |
| Entity Registrant Name | Surmodics, Inc. |
| Entity Incorporation, State or Country Code | MN |
| Entity File Number | 0-23837 |
| Entity Tax Identification Number | 41-1356149 |
| Entity Address, Address Line One | 9924 West 74th Street |
| Entity Address, City or Town | Eden Prairie |
| Entity Address, State or Province | MN |
| Entity Address, Postal Zip Code | 55344 |
| City Area Code | 952 |
| Local Phone Number | 500-7000 |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Entity Emerging Growth Company | false |
| Entity Central Index Key | 0000924717 |
| Title of 12(b) Security | Common Stock, $0.05 par value |
| Trading Symbol | SRDX |
| Security Exchange Name | NASDAQ |
