SEGMENT INFORMATION - Schedule of Reconciliation of Operating Income (Loss) to Adjusted EBITDA (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Segment Reporting, Other Significant Reconciling Item [Line Items]
Operating income (loss)	$ 75,635	$ (252,446)	$ 112,695	$ (231,029)
Stock-based compensation expense	38,915	27,764	72,890	58,949
Depreciation	18,339	17,575	38,227	33,370
Amortization of intangibles	8,624	36,975	17,785	50,795
Acquisition-related Contingent Consideration Fair Value Adjustments	2,994	6,801	4,886	10,470
Goodwill impairment	0	275,367	0	275,367
Adjusted EBITDA	144,507	112,036	246,483	197,922
Interest expense	(24,728)	(27,644)	(49,520)	(55,504)
Other income (expense), net	10,230	(7,192)	2,516	8,705
Earnings (loss) before income taxes	61,137	(287,282)	65,691	(277,828)
Income tax benefit (provision)	19,420	96,740	43,329	95,220
Net earnings (loss)	80,557	(190,542)	109,020	(182,608)
Net earnings attributable to noncontrolling interests	(14,289)	(4,233)	(16,543)	(3,885)
Net earnings (loss) attributable to IAC shareholders	66,268	(194,775)	92,477	(186,493)
Operating segments \| Match Group
Segment Reporting, Other Significant Reconciling Item [Line Items]
Operating income (loss)	82,975	77,500	141,846	111,686
Stock-based compensation expense	15,654	12,644	33,678	30,092
Depreciation	7,883	7,176	15,472	12,927
Amortization of intangibles	404	4,894	807	11,622
Acquisition-related Contingent Consideration Fair Value Adjustments	2,994	(755)	4,338	2,406
Goodwill impairment		0		0
Adjusted EBITDA	109,910	101,459	196,141	168,733
Operating segments \| HomeAdvisor
Segment Reporting, Other Significant Reconciling Item [Line Items]
Operating income (loss)	8,264	11,910	14,284	13,824
Stock-based compensation expense	443	408	1,133	815
Depreciation	3,218	1,925	6,214	3,798
Amortization of intangibles	2,750	773	4,117	1,545
Acquisition-related Contingent Consideration Fair Value Adjustments	0	0	0	0
Goodwill impairment		0		0
Adjusted EBITDA	14,675	15,016	25,748	19,982
Operating segments \| Video
Segment Reporting, Other Significant Reconciling Item [Line Items]
Operating income (loss)	(7,829)	(5,039)	(23,418)	(22,524)
Stock-based compensation expense	133	0	133	0
Depreciation	552	477	1,096	875
Amortization of intangibles	312	587	625	965
Acquisition-related Contingent Consideration Fair Value Adjustments	0	0	0	(192)
Goodwill impairment		0		0
Adjusted EBITDA	(6,832)	(3,975)	(21,564)	(20,876)
Operating segments \| Applications
Segment Reporting, Other Significant Reconciling Item [Line Items]
Operating income (loss)	39,134	18,921	71,902	46,599
Stock-based compensation expense	0	0	0	0
Depreciation	921	1,082	1,932	2,231
Amortization of intangibles	491	1,523	1,097	3,054
Acquisition-related Contingent Consideration Fair Value Adjustments	0	7,556	548	8,256
Goodwill impairment		0		0
Adjusted EBITDA	40,546	29,082	75,479	60,140
Operating segments \| Publishing
Segment Reporting, Other Significant Reconciling Item [Line Items]
Operating income (loss)	(2,857)	(316,934)	(8,645)	(310,158)
Stock-based compensation expense	0	0	0	0
Depreciation	930	2,148	2,949	4,337
Amortization of intangibles	4,667	27,574	9,615	30,023
Acquisition-related Contingent Consideration Fair Value Adjustments	0	0	0	0
Goodwill impairment		275,367		275,367
Adjusted EBITDA	2,740	(11,845)	3,919	(431)
Operating segments \| Other
Segment Reporting, Other Significant Reconciling Item [Line Items]
Operating income (loss)	0	(5,518)	(5,621)	(10,618)
Stock-based compensation expense	0	54	1,729	104
Depreciation		1,557	836	3,016
Amortization of intangibles	0	1,624	1,524	3,586
Acquisition-related Contingent Consideration Fair Value Adjustments	0	0	0	0
Goodwill impairment		0		0
Adjusted EBITDA	0	(2,283)	(1,532)	(3,912)
Corporate
Segment Reporting, Other Significant Reconciling Item [Line Items]
Operating income (loss)	(44,052)	(33,286)	(77,653)	(59,838)
Stock-based compensation expense	22,685	14,658	36,217	27,938
Depreciation	4,835	3,210	9,728	6,186
Amortization of intangibles	0	0	0	0
Acquisition-related Contingent Consideration Fair Value Adjustments	0	0	0	0
Goodwill impairment		0		0
Adjusted EBITDA	$ (16,532)	$ (15,418)	$ (31,708)	$ (25,714)

The Company's primary financial measure is Adjusted EBITDA, which is defined as operating income excluding: (1) stock-based compensation expense; (2) depreciation; and (3) acquisition-related items consisting of (i) amortization of intangible assets and impairments of goodwill and intangible assets, if applicable, and (ii) gains and losses recognized on changes in the fair value of contingent consideration arrangements. The Company believes this measure is useful for analysts and investors as this measure allows a more meaningful comparison between our performance and that of our competitors. Moreover, our management uses this measure internally to evaluate the performance of our business as a whole and our individual business segments, and this measure is one of the primary metrics by which our internal budgets are based and by which management is compensated. The above items are excluded from our Adjusted EBITDA measure because these items are non-cash in nature, and we believe that by excluding these items, Adjusted EBITDA corresponds more closely to the cash operating income generated from our business, from which capital investments are made and debt is serviced. Adjusted EBITDA has certain limitations in that it does not take into account the impact to IAC's statement of operations of certain expenses.

No definition available.