| Document and Entity Information | Jul. 13, 2023 |
| Cover [Abstract] | |
| Amendment Flag | false |
| Entity Central Index Key | 0001722482 |
| Document Type | 8-K |
| Document Period End Date | Jul. 13, 2023 |
| Entity Registrant Name | Avantor, Inc. |
| Entity Incorporation State Country Code | DE |
| Entity File Number | 001-38912 |
| Entity Tax Identification Number | 82-2758923 |
| Entity Address, Address Line One | Radnor Corporate Center, Building One, Suite 200 |
| Entity Address, Address Line Three | 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 |
| Written Communications | false |
| Soliciting Material | false |
| Pre Commencement Tender Offer | false |
| Pre Commencement Issuer Tender Offer | false |
| Security 12b Title | Common Stock, $0.01 par value |
| Trading Symbol | AVTR |
| Security Exchange Name | NYSE |
| Entity Emerging Growth Company | false |
