v3.25.4
Document and Entity Information - USD ($)
$ in Millions
 12 Months Ended
Dec. 31, 2025
Feb. 26, 2026
Jun. 30, 2025
Document and Entity Information      
Document Type 10-K    
Document Annual Report true    
Document Period End Date Dec. 31, 2025    
Document Transition Report false    
Securities Act File Number 001-39231    
Entity Registrant Name PASSAGE BIO, INC.    
Entity Incorporation, State or Country Code DE    
Entity Tax Identification Number 82-2729751    
Entity Address, Address Line One One Commerce Square    
Entity Address, Address Line Two 2005 Market Street, 39th Floor    
Entity Address, City or Town Philadelphia    
Entity Address, State or Province PA    
Entity Address, Postal Zip Code 19103    
City Area Code 267    
Local Phone Number 866-0311    
Title of 12(b) Security Common stock    
Trading Symbol PASG    
Security Exchange Name NASDAQ    
Entity Well-known Seasoned Issuer No    
Entity Voluntary Filers No    
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    
ICFR Auditor Attestation Flag false    
Document Financial Statement Error Correction [Flag] false    
Entity Shell Company false    
Entity Public Float     $ 25.4
Entity Common Stock, Shares Outstanding   3,207,810  
Documents Incorporated by Reference [Text Block]

Portions of the Registrant’s Definitive Proxy Statement (“Proxy Statement”) relating to the 2026 Annual Meeting of Stockholders will be filed with the Commission within 120 days after the end of the Registrant’s 2025 fiscal year and is incorporated by reference into Part III of this Report.

    
Entity Central Index Key 0001787297    
Current Fiscal Year End Date --12-31    
Document Fiscal Year Focus 2025    
Document Fiscal Period Focus FY    
Amendment Flag false    
Auditor Name KPMG LLP    
Auditor Firm ID 185    
Auditor Location Philadelphia, PA