Cover Page - shares	3 Months Ended
	Mar. 31, 2020	May 01, 2020
Document Information [Line Items]
Entity Central Index Key	0000891103
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	Q1
Amendment Flag	false
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Mar. 31, 2020
Document Transition Report	false
Entity File Number	0-20570
Entity Registrant Name	IAC/INTERACTIVECORP
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	59-2712887
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
Title of 12(b) Security	Common Stock, par value $0.001
Trading Symbol	IAC
Security Exchange Name	NASDAQ
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Common Stock
Document Information [Line Items]
Entity Common Stock, Shares Outstanding		79,175,691
Class B Common Stock
Document Information [Line Items]
Entity Common Stock, Shares Outstanding		5,789,499