Document and Entity Information - USD ($)
 12 Months Ended
Dec. 31, 2021
Mar. 04, 2022
Jun. 30, 2021
Document Information [Line Items]      
Document Type 10-K    
Amendment Flag false    
Document Period End Date Dec. 31, 2021    
Document Fiscal Year Focus 2021    
Document Fiscal Period Focus FY    
Entity Registrant Name Aligos Therapeutics, Inc.    
Entity Central Index Key 0001799448    
Entity Current Reporting Status Yes    
Entity Voluntary Filers No    
Entity Interactive Data Current Yes    
Current Fiscal Year End Date --12-31    
Entity Filer Category Non-accelerated Filer    
Entity Well-known Seasoned Issuer No    
Entity Public Float     $ 25,583,489
ICFR Auditor Attestation Flag false    
Entity Shell Company false    
Entity Small Business true    
Entity Emerging Growth Company true    
Entity Ex Transition Period false    
Title of 12(b) Security Common Stock, par value, $0.0001 per share    
Trading Symbol ALGS    
Security Exchange Name NASDAQ    
Entity File Number 001-39617    
Entity Incorporation, State or Country Code DE    
Entity Tax Identification Number 82-4724808    
Entity Address, Address Line One One Corporate Drive    
Entity Address, Address Line Two 2nd Floor    
Entity Address, City or Town South San Francisco    
Entity Address, State or Province CA    
Entity Address, Postal Zip Code 94080    
City Area Code 800    
Local Phone Number 466-6059    
Document Annual Report true    
Document Transition Report false    
Auditor Firm ID 42    
Auditor Name Ernst & Young LLP    
Auditor Location Redwood City, California    
Documents Incorporated by Reference

DOCUMENTS INCORPORATED BY REFERENCE

Portions of the Registrant’s Definitive Proxy Statement relating to the 2022 Annual Meeting of Stockholders, which will be filed with the Securities and Exchange Commission within 120 days after the end of the Registrant’s fiscal year ended December 31, 2021, are incorporated by reference into Part III of this Report.

    
Voting Common Stock [Member]      
Document Information [Line Items]      
Entity Common Stock, Shares Outstanding   39,601,796  
Non-voting Common Stock [Member]      
Document Information [Line Items]      
Entity Common Stock, Shares Outstanding   3,092,338