| Cover | Dec. 18, 2024 |
| Cover [Abstract] | |
| Document Type | 8-K |
| Amendment Flag | false |
| Document Period End Date | Dec. 18, 2024 |
| Entity File Number | 001-36435 |
| Entity Registrant Name | ENZON PHARMACEUTICALS, INC. |
| Entity Central Index Key | 0000727510 |
| Entity Tax Identification Number | 22-2372868 |
| Entity Incorporation, State or Country Code | DE |
| Entity Address, Address Line One | 20 Commerce Drive (Suite 135) |
| Entity Address, City or Town | Cranford |
| Entity Address, State or Province | NJ |
| Entity Address, Postal Zip Code | 07016 |
| City Area Code | 732 |
| Local Phone Number | 980-4500 |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Entity Emerging Growth Company | false |
