v2.4.0.8
Document and Entity Information
9 Months Ended
Sep. 30, 2013
Oct. 31, 2013
Document Document And Entity Information [Abstract]    
Document Type 10-Q  
Amendment Flag false  
Document Period End Date Sep. 30, 2013  
Document Fiscal Year Focus 2013  
Document Fiscal Period Focus Q3  
Trading Symbol PRTA  
Entity Registrant Name Prothena Corp plc  
Entity Central Index Key 0001559053  
Current Fiscal Year End Date --12-31  
Entity Filer Category Smaller Reporting Company  
Entity Ordinary Shares Outstanding   21,856,261