| Document And Entity Information | Aug. 11, 2021 |
| Cover [Abstract] | |
| Document Type | 8-K |
| Amendment Flag | false |
| Document Period End Date | Aug. 11, 2021 |
| Entity Registrant Name | ACV Auctions Inc. |
| Entity Central Index Key | 0001637873 |
| Entity Emerging Growth Company | true |
| Entity File Number | 001-40256 |
| Entity Incorporation, State or Country Code | DE |
| Entity Tax Identification Number | 47-2415221 |
| Entity Address, Address Line One | 640 ELLICOTT STREET #321 |
| Entity Address, City or Town | Buffalo |
| Entity Address, State or Province | NY |
| Entity Address, Postal Zip Code | 14203 |
| City Area Code | (800) |
| Local Phone Number | 553-4070 |
| Entity Information, Former Legal or Registered Name | Not Applicable |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Entity Ex Transition Period | false |
| Title of 12(b) Security | Class A common stock, par value $0.001 per share |
| Trading Symbol | ACVA |
| Security Exchange Name | NASDAQ |
