SEGMENT INFORMATION - Revenue Disaggregated by Service (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Segment Reporting Information [Line Items]
Revenue	$ 1,105,843	$ 995,075
Operating segments | Match Group
Segment Reporting Information [Line Items]
Revenue	464,625	407,367
Operating segments | ANGI Homeservices
Segment Reporting Information [Line Items]
Revenue	303,443	255,311
Operating segments | Vimeo
Segment Reporting Information [Line Items]
Revenue	43,581	35,568
Operating segments | Dotdash
Segment Reporting Information [Line Items]
Revenue	33,961	30,031
Operating segments | Applications
Segment Reporting Information [Line Items]
Revenue	143,549	131,987
Operating segments | Emerging & Other
Segment Reporting Information [Line Items]
Revenue	116,748	134,885
North America | Operating segments | ANGI Homeservices
Segment Reporting Information [Line Items]
Revenue	281,994	236,026
International
Segment Reporting Information [Line Items]
Revenue	393,462	337,495
Europe | Operating segments | ANGI Homeservices
Segment Reporting Information [Line Items]
Revenue	21,449	19,285
Direct revenue | Operating segments | Match Group
Segment Reporting Information [Line Items]
Revenue	453,962	392,737
Direct revenue | North America | Operating segments | Match Group
Segment Reporting Information [Line Items]
Revenue	237,773	211,357
Direct revenue | International | Operating segments | Match Group
Segment Reporting Information [Line Items]
Revenue	216,189	181,380
Indirect revenue | Operating segments | Match Group
Segment Reporting Information [Line Items]
Revenue	10,663	14,630
Marketplace revenue | North America | Operating segments | ANGI Homeservices
Segment Reporting Information [Line Items]
Revenue	219,925	165,608
Consumer connection revenue | North America | Operating segments | ANGI Homeservices
Segment Reporting Information [Line Items]
Revenue	201,582	149,060
Membership subscription revenue | North America | Operating segments | ANGI Homeservices
Segment Reporting Information [Line Items]
Revenue	16,517	15,627
Other revenue | North America | Operating segments | ANGI Homeservices
Segment Reporting Information [Line Items]
Revenue	1,826	921
Consumer connection revenue | Europe | Operating segments | ANGI Homeservices
Segment Reporting Information [Line Items]
Revenue	17,123	14,367
Membership subscription revenue | Europe | Operating segments | ANGI Homeservices
Segment Reporting Information [Line Items]
Revenue	3,742	4,671
Advertising and other revenue | North America | Operating segments | ANGI Homeservices
Segment Reporting Information [Line Items]
Revenue	62,069	70,418
Advertising and other revenue | Europe | Operating segments | ANGI Homeservices
Segment Reporting Information [Line Items]
Revenue	584	247
Platform revenue | Operating segments | Vimeo
Segment Reporting Information [Line Items]
Revenue	41,302	32,932
Hardware revenue | Operating segments | Vimeo
Segment Reporting Information [Line Items]
Revenue	2,279	2,636
Advertising revenue | Operating segments | Dotdash
Segment Reporting Information [Line Items]
Revenue	28,919	25,744
Advertising revenue | Operating segments | Emerging & Other
Segment Reporting Information [Line Items]
Revenue	103,250	106,020
Google advertising revenue | Operating segments | Emerging & Other
Segment Reporting Information [Line Items]
Revenue	96,273	92,751
Other | Operating segments | Emerging & Other
Segment Reporting Information [Line Items]
Revenue	6,977	13,269
Affiliate commerce commission and other revenue | Operating segments | Dotdash
Segment Reporting Information [Line Items]
Revenue	5,042	4,287
Other revenue | Operating segments | Emerging & Other
Segment Reporting Information [Line Items]
Revenue	13,498	28,865
Desktop | Operating segments | Applications
Segment Reporting Information [Line Items]
Revenue	95,986	117,588
Advertising revenue | Operating segments | Applications
Segment Reporting Information [Line Items]
Revenue	91,398	110,272
Google advertising revenue | Operating segments | Applications
Segment Reporting Information [Line Items]
Revenue	88,050	108,577
Other | Operating segments | Applications
Segment Reporting Information [Line Items]
Revenue	3,348	1,695
Subscription and other revenue | Operating segments | Applications
Segment Reporting Information [Line Items]
Revenue	4,588	7,316
Mosaic Group | Operating segments | Applications
Segment Reporting Information [Line Items]
Revenue	47,563	14,399
Mosaic Group | Advertising revenue | Operating segments | Applications
Segment Reporting Information [Line Items]
Revenue	2,415	5,390
Mosaic Group | Subscription and other revenue | Operating segments | Applications
Segment Reporting Information [Line Items]
Revenue	$ 45,148	$ 9,009