SEGMENT INFORMATION - Reconciliation of Segment Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Segment Reporting, Asset Reconciling Item
Segment Assets	$ 3,132,718	$ 2,263,516
Long-lived assets (excluding goodwill and intangible assets)	318,800	315,170
Goodwill	2,726,859	2,559,066	$ 1,924,052
Indefinite-Lived Intangible Assets	458,104	459,143
Definite-Lived Intangible Assets, Net	173,318	204,594
Assets before deferred tax assets	6,809,799	5,801,489
Add: Deferred tax assets	64,786	66,321
TOTAL ASSETS	6,874,585	5,867,810
Match Group
Segment Reporting, Asset Reconciling Item
Goodwill	1,245,013	1,247,899	1,206,538
ANGI Homeservices
Segment Reporting, Asset Reconciling Item
Goodwill	892,800	768,317	170,611
Applications
Segment Reporting, Asset Reconciling Item
Goodwill	504,892	447,242	447,242
Emerging & Other
Segment Reporting, Asset Reconciling Item
Goodwill	7,002	18,305	$ 90,012
Operating Segments \| Match Group
Segment Reporting, Asset Reconciling Item
Segment Assets	377,965	467,338
Long-lived assets (excluding goodwill and intangible assets)	58,351	61,620
Goodwill	1,245,013	1,247,899
Indefinite-Lived Intangible Assets	230,684	228,296
Definite-Lived Intangible Assets, Net	6,956	2,049
Assets before deferred tax assets	1,918,969	2,007,202
Operating Segments \| ANGI Homeservices
Segment Reporting, Asset Reconciling Item
Segment Assets	497,327	264,450
Long-lived assets (excluding goodwill and intangible assets)	70,859	53,292
Goodwill	892,800	768,317
Indefinite-Lived Intangible Assets	171,486	153,447
Definite-Lived Intangible Assets, Net	132,809	175,124
Assets before deferred tax assets	1,765,281	1,414,630
Operating Segments \| Vimeo
Segment Reporting, Asset Reconciling Item
Segment Assets	33,568	30,507
Long-lived assets (excluding goodwill and intangible assets)	1,014	1,972
Goodwill	77,152	77,303
Indefinite-Lived Intangible Assets	0	0
Definite-Lived Intangible Assets, Net	9,442	15,655
Assets before deferred tax assets	121,176	125,437
Operating Segments \| Dotdash
Segment Reporting, Asset Reconciling Item
Segment Assets	39,276	27,190
Long-lived assets (excluding goodwill and intangible assets)	3,229	4,077
Goodwill	0	0
Indefinite-Lived Intangible Assets	13,500	6,000
Definite-Lived Intangible Assets, Net	1,514	3,152
Assets before deferred tax assets	57,519	40,419
Operating Segments \| Applications
Segment Reporting, Asset Reconciling Item
Segment Assets	153,781	345,532
Long-lived assets (excluding goodwill and intangible assets)	4,867	7,004
Goodwill	504,892	447,242
Indefinite-Lived Intangible Assets	39,463	60,600
Definite-Lived Intangible Assets, Net	22,447	847
Assets before deferred tax assets	725,450	861,225
Operating Segments \| Emerging & Other
Segment Reporting, Asset Reconciling Item
Segment Assets	95,858	255,107
Long-lived assets (excluding goodwill and intangible assets)	1,638	2,377
Goodwill	7,002	18,305
Indefinite-Lived Intangible Assets	2,971	10,800
Definite-Lived Intangible Assets, Net	150	7,767
Assets before deferred tax assets	107,619	294,356
Corporate
Segment Reporting, Asset Reconciling Item
Segment Assets	1,934,943	873,392
Long-lived assets (excluding goodwill and intangible assets)	178,842	184,828
Goodwill	0	0
Indefinite-Lived Intangible Assets	0	0
Definite-Lived Intangible Assets, Net	0	0
Assets before deferred tax assets	$ 2,113,785	$ 1,058,220

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