| Document and Entity Information Document | Jul. 28, 2021 |
| Document And Entity Information [Abstract] | |
| Entity Emerging Growth Company | false |
| Title of 12(b) Security | Common Stock, $0.10 Par Value(voting) |
| Pre-commencement Issuer Tender Offer | false |
| Pre-commencement Tender Offer | false |
| Soliciting Material | false |
| Written Communications | false |
| Entity Incorporation, State or Country Code | DE |
| Entity Registrant Name | Automatic Data Processing, Inc. |
| Entity Central Index Key | 0000008670 |
| Document Type | 8-K |
| Document Period End Date | Jul. 28, 2021 |
| Entity Address, Address Line One | One ADP Boulevard, |
| Entity Address, City or Town | Roseland, |
| Entity Address, State or Province | NJ |
| Entity Address, Postal Zip Code | 07068 |
| City Area Code | 973 |
| Local Phone Number | 974-5000 |
| Amendment Flag | false |
| Entity File Number | 1-5397 |
| Entity Tax Identification Number | 22-1467904 |
| Trading Symbol | ADP |
| Security Exchange Name | NASDAQ |
