v3.25.1
Cover
 12 Months Ended
Mar. 31, 2025
shares
Entity Addresses [Line Items]  
Document Type 40-F
Document Registration Statement false
Document Annual Report true
Current Fiscal Year End Date --03-31
Document Period End Date Mar. 31, 2025
Entity File Number 001-38705
Entity Registrant Name ALITHYA GROUP INC.
Entity Incorporation, State or Country Code A8
Entity Address, Address Line One 1100, Robert-Bourassa Boulevard, Suite 400
Entity Address, City or Town Montréal, Québec
Entity Address, Country CA
Entity Address, Postal Zip Code H3B 3A5
City Area Code +1 (514)
Local Phone Number 285-5552
Annual Information Form true
Audited Annual Financial Statements true
Entity Current Reporting Status Yes
Entity Interactive Data Current Yes
Entity Emerging Growth Company false
ICFR Auditor Attestation Flag true
Document Financial Statement Error Correction [Flag] false
Amendment Flag false
Document Fiscal Year Focus 2025
Document Fiscal Period Focus FY
Entity Central Index Key 0001734520
Business Contact  
Entity Addresses [Line Items]  
Entity Address, Address Line One 28 Liberty Street
Entity Address, City or Town New York
Entity Address, State or Province NY
Entity Address, Country US
Entity Address, Postal Zip Code 10005
City Area Code +1 (212)
Local Phone Number 894-8940
Contact Personnel Name C T Corporation System
Class A Shares  
Entity Addresses [Line Items]  
Entity Common Stock, Shares Outstanding 92,030,852
Class B Shares  
Entity Addresses [Line Items]  
Entity Common Stock, Shares Outstanding 7,274,248