| Cover | Dec. 19, 2019 |
| Cover [Abstract] | |
| Document Type | 8-K |
| Amendment Flag | false |
| Document Period End Date | Dec. 19, 2019 |
| Entity File Number | 0-20570 |
| Entity Registrant Name | IAC/INTERACTIVECORP |
| Entity Central Index Key | 0000891103 |
| Entity Tax Identification Number | 59-2712887 |
| Entity Incorporation, State or Country Code | DE |
| Entity Address, Address Line One | 555 West 18th Street |
| Entity Address, City or Town | New York |
| Entity Address, State or Province | NY |
| Entity Address, Postal Zip Code | 10011 |
| City Area Code | 212 |
| Local Phone Number | 314-7300 |
| Written Communications | true |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Title of 12(b) Security | Common Stock, par value $0.001 |
| Trading Symbol | IAC |
| Security Exchange Name | NASDAQ |
| Entity Emerging Growth Company | false |
