v3.25.4
Document And Entity Information - USD ($)
 12 Months Ended
Dec. 31, 2025
Mar. 13, 2026
Jun. 30, 2025
Document Information [Line Items]      
Document Type 10-K    
Document Annual Report true    
Document Period End Date Dec. 31, 2025    
Document Transition Report false    
Entity File Number 001-37437    
Entity Registrant Name XBIOTECH INC.    
Entity Incorporation, State or Country Code A1    
Entity Address, Address Line One 5217 Winnebago Ln    
Entity Address, City or Town Austin    
Entity Address, State or Province TX    
Entity Address, Postal Zip Code 78744    
City Area Code 512    
Local Phone Number 386-2900    
Title of 12(b) Security Common Stock, no par value    
Trading Symbol XBIT    
Security Exchange Name NASDAQ    
Entity Well-known Seasoned Issuer No    
Entity Voluntary Filers No    
Entity Current Reporting Status Yes    
Entity Interactive Data Current Yes    
Entity Filer Category Non-accelerated Filer    
Entity Small Business true    
Entity Emerging Growth Company false    
ICFR Auditor Attestation Flag false    
Document Financial Statement Error Correction [Flag] false    
Entity Shell Company false    
Entity Public Float     $ 77,050,226
Entity Common Stock, Shares Outstanding (in shares)   30,487,731  
Auditor Firm ID 726    
Auditor Name Whitley Penn LLP    
Auditor Location Austin, Texas    
Entity Central Index Key 0001626878    
Current Fiscal Year End Date --12-31    
Document Fiscal Year Focus 2025    
Document Fiscal Period Focus FY    
Amendment Flag false