v3.25.4
Cover - USD ($)
 12 Months Ended
Dec. 31, 2025
Feb. 05, 2026
Jun. 30, 2025
Cover [Abstract]      
Document type 10-K    
Document Annual Report true    
Document period end date Dec. 31, 2025    
Current Fiscal Year End Date --12-31    
Document Transition Report false    
Entity File Number 001-38912    
Entity registrant name Avantor, Inc.    
Entity Incorporation, State or Country Code DE    
Entity Tax Identification Number 82-2758923    
Entity Address, Address Line One Radnor Corporate Center, Building One, Suite 200    
Entity Address, Address Line Two 100 Matsonford Road    
Entity Address, City or Town Radnor    
Entity Address, State or Province PA    
Entity Address, Postal Zip Code 19087    
City Area Code 610    
Local Phone Number 386-1700    
Title of 12(b) Security Common stock, $0.01 par value    
Trading Symbol AVTR    
Security Exchange Name NYSE    
Entity well-known seasoned issuer Yes    
Entity voluntary filers No    
Entity current reporting status Yes    
Entity interactive data current Yes    
Entity filer category Large Accelerated Filer    
Entity Small Business false    
Entity Emerging Growth Company false    
ICFR Auditor Attestation Flag true    
Document Financial Statement Error Correction [Flag] false    
Entity Shell Company false    
Entity public float     $ 9,173,395,483
Entity common stock, shares outstanding   682,055,932  
Documents Incorporated by Reference
DOCUMENTS INCORPORATED BY REFERENCE
Portions of our definitive proxy statement for our 2026 annual meeting of stockholders will be filed with the SEC on or before 120 days after our 2025 fiscal year-end and are incorporated by reference into Part III of this report.
    
Amendment flag false    
Entity central index key 0001722482    
Document fiscal year focus 2025    
Document fiscal period focus FY