Document and Entity Information - shares	6 Months Ended
	Jun. 30, 2023	Jul. 27, 2023
Document and Entity Information
Document Type	10-Q
Document Quarterly Report	true
Document Transition Report	false
Document Period End Date	Jun. 30, 2023
Amendment Flag	false
Document Fiscal Year Focus	2023
Document Fiscal Period Focus	Q2
Entity Registrant Name	Enzon Pharmaceuticals, Inc.
Entity Central Index Key	0000727510
Current Fiscal Year End Date	--12-31
Entity File Number	001-36435
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	22-2372868
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
Title of 12(b) Security	None
No Trading Symbol Flag	true
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		74,214,603