SEGMENT INFORMATION - Revenue Disaggregated by Service (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Segment Reporting Information [Line Items]
Revenue	$ 1,228,765	$ 1,105,843
Operating segments | Match Group
Segment Reporting Information [Line Items]
Revenue	544,642	464,625
Operating segments | ANGI Homeservices
Segment Reporting Information [Line Items]
Revenue	343,650	303,443
Operating segments | Vimeo
Segment Reporting Information [Line Items]
Revenue	56,968	43,581
Operating segments | Dotdash
Segment Reporting Information [Line Items]
Revenue	44,120	33,961
Operating segments | Applications
Segment Reporting Information [Line Items]
Revenue	104,148	143,549
Operating segments | Applications | Mosaic Group
Segment Reporting Information [Line Items]
Revenue	50,677	47,563
Operating segments | Emerging & Other
Segment Reporting Information [Line Items]
Revenue	135,305	116,748
North America | Operating segments | ANGI Homeservices
Segment Reporting Information [Line Items]
Revenue	324,132	281,994
International
Segment Reporting Information [Line Items]
Revenue	441,425	393,462
Europe | Operating segments | ANGI Homeservices
Segment Reporting Information [Line Items]
Revenue	19,518	21,449
Direct revenue | Operating segments | Match Group
Segment Reporting Information [Line Items]
Revenue	534,824	453,962
Direct revenue | North America | Operating segments | Match Group
Segment Reporting Information [Line Items]
Revenue	263,347	237,773
Direct revenue | International | Operating segments | Match Group
Segment Reporting Information [Line Items]
Revenue	271,477	216,189
Indirect revenue (principally advertising revenue) | Operating segments | Match Group
Segment Reporting Information [Line Items]
Revenue	9,818	10,663
Total Marketplace revenue | North America | Operating segments | ANGI Homeservices
Segment Reporting Information [Line Items]
Revenue	258,776	220,500
Consumer connection revenue | North America | Operating segments | ANGI Homeservices
Segment Reporting Information [Line Items]
Revenue	239,830	201,582
Service professional membership subscription revenue | North America | Operating segments | ANGI Homeservices
Segment Reporting Information [Line Items]
Revenue	14,115	16,517
Other revenue | North America | Operating segments | ANGI Homeservices
Segment Reporting Information [Line Items]
Revenue	4,831	2,401
Advertising and other revenue | North America | Operating segments | ANGI Homeservices
Segment Reporting Information [Line Items]
Revenue	65,356	61,494
Advertising and other revenue | Europe | Operating segments | ANGI Homeservices
Segment Reporting Information [Line Items]
Revenue	530	584
Consumer connection revenue | Europe | Operating segments | ANGI Homeservices
Segment Reporting Information [Line Items]
Revenue	15,689	17,123
Service professional membership subscription revenue | Europe | Operating segments | ANGI Homeservices
Segment Reporting Information [Line Items]
Revenue	3,299	3,742
Platform revenue | Operating segments | Vimeo
Segment Reporting Information [Line Items]
Revenue	56,968	41,302
Hardware revenue | Operating segments | Vimeo
Segment Reporting Information [Line Items]
Revenue	0	2,279
Display advertising revenue | Operating segments | Dotdash
Segment Reporting Information [Line Items]
Revenue	29,889	26,008
Display advertising revenue | Operating segments | Applications | Mosaic Group
Segment Reporting Information [Line Items]
Revenue	1,606	2,415
Display advertising revenue | Operating segments | Emerging & Other
Segment Reporting Information [Line Items]
Revenue	104,229	103,449
Google advertising revenue | Operating segments | Emerging & Other
Segment Reporting Information [Line Items]
Revenue	81,968	96,273
Non-Google advertising revenue | Operating segments | Emerging & Other
Segment Reporting Information [Line Items]
Revenue	22,261	7,176
Performance marketing revenue | Operating segments | Dotdash
Segment Reporting Information [Line Items]
Revenue	14,231	7,953
Total Desktop revenue | Operating segments | Applications
Segment Reporting Information [Line Items]
Revenue	53,471	95,986
Total advertising revenue | Operating segments | Applications
Segment Reporting Information [Line Items]
Revenue	49,314	91,398
Google advertising revenue | Operating segments | Applications
Segment Reporting Information [Line Items]
Revenue	46,091	88,050
Non-Google advertising revenue | Operating segments | Applications
Segment Reporting Information [Line Items]
Revenue	3,223	3,348
Subscription and other revenue | Operating segments | Applications
Segment Reporting Information [Line Items]
Revenue	4,157	4,588
Subscription and other revenue | Operating segments | Applications | Mosaic Group
Segment Reporting Information [Line Items]
Revenue	49,071	45,148
Other revenue | Operating segments | Emerging & Other
Segment Reporting Information [Line Items]
Revenue	$ 31,076	$ 13,299