Annual report pursuant to Section 13 and 15(d)

Document And Entity Information

Document And Entity Information - USD ($)
12 Months Ended
Mar. 31, 2020
Jun. 26, 2020
Sep. 30, 2019
Document Information [Line Items]      
Entity Registrant Name Acasti Pharma Inc.    
Entity Central Index Key 0001444192    
Trading Symbol acst    
Current Fiscal Year End Date --03-31    
Entity Filer Category Non-accelerated Filer    
Entity Current Reporting Status Yes    
Entity Voluntary Filers No    
Entity Well-known Seasoned Issuer No    
Entity Emerging Growth Company false    
Entity Small Business true    
Entity Interactive Data Current Yes    
Entity Common Stock, Shares Outstanding (in shares)   92,488,385  
Entity Public Float     $ 161,005,499
Entity Shell Company false    
Document Type 10-K    
Document Period End Date Mar. 31, 2020    
Document Fiscal Year Focus 2020    
Document Fiscal Period Focus FY    
Amendment Flag false    
Title of 12(b) Security Common Shares, no par value per share