| Document and Entity Information | Feb. 03, 2021 |
| Cover [Abstract] | |
| Entity Registrant Name | EQUIFAX INC |
| Amendment Flag | false |
| Entity Central Index Key | 0000033185 |
| Current Fiscal Year End Date | --12-31 |
| Document Type | 8-K |
| Document Period End Date | Feb. 3, 2021 |
| Entity Incorporation State Country Code | GA |
| Entity File Number | 001-06605 |
| Entity Tax Identification Number | 58-0401110 |
| Entity Address, Address Line One | 1550 Peachtree Street |
| Entity Address, Address Line Two | N.W. |
| Entity Address, City or Town | Atlanta |
| Entity Address, State or Province | GA |
| Entity Address, Postal Zip Code | 30309 |
| City Area Code | (404) |
| Local Phone Number | 885-8000 |
| Written Communications | false |
| Soliciting Material | false |
| Pre Commencement Tender Offer | false |
| Pre Commencement Issuer Tender Offer | false |
| Security 12b Title | Common stock, $1.25 par value per share |
| Trading Symbol | EFX |
| Security Exchange Name | NYSE |
| Entity Emerging Growth Company | false |
