SEGMENT INFORMATION - Financial Data by Segment (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 income (loss)	172,832	(18,589)	431,219	94,106
Operating segments | Match Group
Segment Reporting Information [Line Items]
Revenue	443,943	343,418	1,272,506	951,754
Operating income (loss)	139,895	91,008	402,293	232,854
Adjusted EBITDA	165,039	119,564	478,341	315,705
Operating segments | ANGI Homeservices
Segment Reporting Information [Line Items]
Revenue	303,116	181,717	853,249	513,173
Operating income (loss)	33,515	(112,505)	46,021	(115,258)
Adjusted EBITDA	77,700	(2,266)	181,319	21,612
Operating segments | Video
Segment Reporting Information [Line Items]
Revenue	64,193	78,338	193,112	184,097
Operating income (loss)	(10,250)	(1,809)	(41,107)	(25,227)
Adjusted EBITDA	(7,390)	(822)	(31,432)	(22,386)
Operating segments | Applications
Segment Reporting Information [Line Items]
Revenue	153,973	136,333	429,034	439,199
Operating income (loss)	33,041	29,386	91,579	101,288
Adjusted EBITDA	34,989	31,077	97,145	106,556
Operating segments | Publishing
Segment Reporting Information [Line Items]
Revenue	139,439	88,755	411,116	244,959
Operating income (loss)	17,398	5,677	46,016	(2,968)
Adjusted EBITDA	18,467	7,088	49,435	11,007
Operating segments | Other
Segment Reporting Information [Line Items]
Revenue				23,980
Operating income (loss)				(5,621)
Adjusted EBITDA	0	0	0	(1,532)
Inter-segment eliminations
Segment Reporting Information [Line Items]
Revenue	(72)	(127)	(228)	(508)
Corporate
Segment Reporting Information [Line Items]
Operating income (loss)	(40,767)	(30,346)	(113,583)	(90,962)
Adjusted EBITDA	$ (21,478)	$ (17,070)	$ (54,038)	$ (46,908)