v3.10.0.1
Document And Entity Information - shares
9 Months Ended
Sep. 30, 2018
Nov. 02, 2018
Document Information [Line Items]    
Document Type 10-Q  
Amendment Flag false  
Document Period End Date Sep. 30, 2018  
Document Fiscal Year Focus 2018  
Document Fiscal Period Focus Q3  
Entity Registrant Name ENZON PHARMACEUTICALS, INC.  
Entity Central Index Key 0000727510  
Current Fiscal Year End Date --12-31  
Entity Filer Category Non-accelerated Filer  
Trading Symbol ENZN  
Entity Common Stock, Shares Outstanding   44,214,603
Entity Emerging Growth Company false  
Entity Small Business true