v3.26.3
Cover page - USD ($)
 6 Months Ended
Jun. 30, 2026
Sep. 16, 2026
Dec. 31, 2025
Cover [Abstract]      
Document Type 10-KT    
Document Annual Report false    
Document Period Start Date Jan. 01, 2026    
Document Period End Date Jun. 30, 2026    
Current Fiscal Year End Date --06-30    
Document Transition Report true    
Entity File Number 001-37985    
Entity Registrant Name ANAPTYSBIO, INC.    
Entity Incorporation, State or Country Code DE    
Entity Tax Identification Number 20-3828755    
Entity Address, Address Line One 10770 Wateridge Circle    
Entity Address, Address Line Two Suite 210    
Entity Address, City or Town San Diego    
Entity Address, State or Province CA    
Entity Address, Postal Zip Code 92121    
City Area Code 858    
Local Phone Number 362-6295    
Title of 12(b) Security Common Stock, $0.001 par value    
Trading Symbol ANAB    
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 false    
Entity Shell Company false    
Entity Public Float     $ 632,722,403
Entity Common Stock, Shares Outstanding   29,895,244  
Entity Central Index Key 0001370053    
Document Fiscal Year Focus 2026    
Document Fiscal Period Focus FY    
Amendment Flag false