SEGMENT INFORMATION - Revenue Disaggregated by Service (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Segment Reporting Information [Line Items]
Revenue	$ 1,104,592	$ 828,434	$ 3,158,789	$ 2,356,654
Operating segments | Match Group
Segment Reporting Information [Line Items]
Revenue	443,943	343,418	1,272,506	951,754
Operating segments | ANGI Homeservices
Segment Reporting Information [Line Items]
Revenue	303,116	181,717	853,249	513,173
Operating segments | Video
Segment Reporting Information [Line Items]
Revenue	64,193	78,338	193,112	184,097
Operating segments | Applications
Segment Reporting Information [Line Items]
Revenue	153,973	136,333	429,034	439,199
Operating segments | Publishing
Segment Reporting Information [Line Items]
Revenue	139,439	88,755	411,116	244,959
North America | Operating segments | ANGI Homeservices
Segment Reporting Information [Line Items]
Revenue	286,594	167,104	800,125	470,667
International
Segment Reporting Information [Line Items]
Revenue	365,993	251,072	1,054,039	685,674
Europe | Operating segments | ANGI Homeservices
Segment Reporting Information [Line Items]
Revenue	16,522	14,613	53,124	42,506
Direct revenue | Operating segments | Match Group
Segment Reporting Information [Line Items]
Revenue	431,545	330,098	1,232,009	917,273
Direct revenue | North America | Operating segments | Match Group
Segment Reporting Information [Line Items]
Revenue	233,643	186,868	667,163	540,701
Direct revenue | International | Operating segments | Match Group
Segment Reporting Information [Line Items]
Revenue	197,902	143,230	564,846	376,572
Indirect revenue | Operating segments | Match Group
Segment Reporting Information [Line Items]
Revenue	12,398	13,320	40,497	34,481
Marketplace revenue | North America | Operating segments | ANGI Homeservices
Segment Reporting Information [Line Items]
Revenue	213,049	156,601	583,392	442,000
Consumer connection revenue | North America | Operating segments | ANGI Homeservices
Segment Reporting Information [Line Items]
Revenue	195,065	141,055	531,297	398,218
Membership subscription revenue | North America | Operating segments | ANGI Homeservices
Segment Reporting Information [Line Items]
Revenue	17,034	14,486	49,226	40,942
Other revenue | North America | Operating segments | ANGI Homeservices
Segment Reporting Information [Line Items]
Revenue	950	1,060	2,869	2,840
Other revenue | Operating segments | Video
Segment Reporting Information [Line Items]
Revenue	14,263	4,064	39,800	13,547
Other revenue | North America | Operating segments | ANGI Homeservices
Segment Reporting Information [Line Items]
Revenue	73,545	10,503	216,733	28,667
Consumer connection revenue | Europe | Operating segments | ANGI Homeservices
Segment Reporting Information [Line Items]
Revenue	12,022	10,001	38,885	29,636
Membership subscription revenue | Europe | Operating segments | ANGI Homeservices
Segment Reporting Information [Line Items]
Revenue	4,217	4,320	13,405	12,198
Other revenue | Europe | Operating segments | ANGI Homeservices
Segment Reporting Information [Line Items]
Revenue	283	292	834	672
Subscription revenue | Operating segments | Video
Segment Reporting Information [Line Items]
Revenue	33,964	28,348	101,031	79,947
Media production and distribution revenue | Operating segments | Video
Segment Reporting Information [Line Items]
Revenue	15,966	45,926	52,281	90,603
Desktop | Operating segments | Applications
Segment Reporting Information [Line Items]
Revenue	118,542	122,622	350,560	395,306
Advertising revenue | Operating segments | Applications
Segment Reporting Information [Line Items]
Revenue	114,265	113,930	334,205	369,417
Google advertising revenue | Operating segments | Applications
Segment Reporting Information [Line Items]
Revenue	110,855	112,356	326,982	364,622
Other | Operating segments | Applications
Segment Reporting Information [Line Items]
Revenue	3,410	1,574	7,223	4,795
Subscription and other revenue | Operating segments | Applications
Segment Reporting Information [Line Items]
Revenue	4,277	8,692	16,355	25,889
Mobile | Operating segments | Applications
Segment Reporting Information [Line Items]
Revenue	35,431	13,711	78,474	43,893
Subscription and other revenue | Operating segments | Applications
Segment Reporting Information [Line Items]
Revenue	31,157	6,216	63,687	23,150
Advertising revenue | Operating segments | Applications
Segment Reporting Information [Line Items]
Revenue	4,274	7,495	14,787	20,743
Premium Brands | Operating segments | Publishing
Segment Reporting Information [Line Items]
Revenue	39,097	30,621	117,664	84,967
Advertising revenue | Operating segments | Publishing
Segment Reporting Information [Line Items]
Revenue	37,757	29,865	113,918	83,562
Google advertising revenue | Operating segments | Publishing
Segment Reporting Information [Line Items]
Revenue	11,526	11,956	37,517	32,553
Other | Operating segments | Publishing
Segment Reporting Information [Line Items]
Revenue	26,231	17,909	76,401	51,009
Other revenue | Operating segments | Publishing
Segment Reporting Information [Line Items]
Revenue	1,340	756	3,746	1,405
Ask & Other | Operating segments | Publishing
Segment Reporting Information [Line Items]
Revenue	100,342	58,134	293,452	159,992
Advertising revenue | Operating segments | Publishing
Segment Reporting Information [Line Items]
Revenue	93,914	57,923	283,444	159,395
Google advertising revenue | Operating segments | Publishing
Segment Reporting Information [Line Items]
Revenue	81,507	51,995	254,762	140,476
Other | Operating segments | Publishing
Segment Reporting Information [Line Items]
Revenue	12,407	5,928	28,682	18,919
Other revenue | Operating segments | Publishing
Segment Reporting Information [Line Items]
Revenue	$ 6,428	$ 211	$ 10,008	$ 597