v3.25.2
Document and Entity Information - shares
 6 Months Ended
Jun. 30, 2025
Aug. 07, 2025
Document and Entity Information    
Document Type 10-Q  
Document Quarterly Report true  
Document Period End Date Jun. 30, 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 Current Reporting Status Yes  
Entity Interactive Data Current Yes  
Entity Filer Category Non-accelerated Filer  
Entity Small Business true  
Entity Emerging Growth Company true  
Entity Ex Transition Period false  
Entity Shell Company false  
Entity Common Stock, Shares Outstanding   3,178,710
Entity Central Index Key 0001787297  
Current Fiscal Year End Date --12-31  
Document Fiscal Year Focus 2025  
Document Fiscal Period Focus Q2  
Amendment Flag false