DOCUMENT AND ENTITY INFORMATION - shares	9 Months Ended
	Sep. 30, 2018	Nov. 02, 2018
Entity Registrant Name	IAC/INTERACTIVECORP
Entity Central Index Key	0000891103
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Emerging Growth Company	false
Small Business	false
Document Type	10-Q
Document Period End Date	Sep. 30, 2018
Document Fiscal Year Focus	2018
Document Fiscal Period Focus	Q3
Amendment Flag	false
Common Class A
Entity Common Stock, Shares Outstanding		77,724,487
Class B Convertible Common Stock
Entity Common Stock, Shares Outstanding		5,789,499