Document and Entity Information
12 Months Ended
Dec. 31, 2018
Document and Entity Information [Abstract]  
Entity Registrant Name AC Immune SA
Entity Central Index Key 0001651625
Current Fiscal Year End Date --12-31
Entity Well-known Seasoned Issuer No
Entity Current Reporting Status Yes
Entity Shell Company false
Entity Filer Category Accelerated Filer
Entity Emerging Growth Company true
Entity Ex Transition Period false
Entity Common Stock, Shares Outstanding 67,562,333
Document Type 20-F
Amendment Flag false
Document Period End Date Dec. 31, 2018
Document Fiscal Year Focus 2018
Document Fiscal Period Focus FY