SEGMENT INFORMATION - Reconciliation of Operating Income (Loss) to Adjusted EBITDA (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019
Segment Reporting, Other Significant Reconciling Item [Line Items]
Operating (loss) income	$ (177,780)	$ 79,873
Stock-Based Compensation Expense	58,464	67,444
Depreciation	24,738	18,971
Amortization of Intangibles	52,162	22,752
Goodwill Impairment	211,973	0	$ 3,318
Interest expense	(44,866)	(31,143)
Other income (expense), net	(49,893)	651
(Loss) earnings before income taxes	(272,539)	49,381
Income tax benefit	89,896	63,604
Net (loss) earnings	(182,643)	112,985
Net earnings attributable to noncontrolling interests	(28,397)	(24,290)
Net (loss) earnings attributable to IAC shareholders	(211,040)	88,695
ANGI Homeservices
Segment Reporting, Other Significant Reconciling Item [Line Items]
Goodwill Impairment	0		0
Applications
Segment Reporting, Other Significant Reconciling Item [Line Items]
Goodwill Impairment	211,973		0
Emerging & Other
Segment Reporting, Other Significant Reconciling Item [Line Items]
Goodwill Impairment			$ 3,318
Operating segments \| Match Group
Segment Reporting, Other Significant Reconciling Item [Line Items]
Operating (loss) income	134,681	118,828
Stock-Based Compensation Expense	21,172	27,997
Depreciation	9,246	7,831
Amortization of Intangibles	6,403	411
Acquisition-related Contingent Consideration Fair Value Adjustments	0	0
Goodwill Impairment	0
Adjusted EBITDA	171,502	155,067
Operating segments \| ANGI Homeservices
Segment Reporting, Other Significant Reconciling Item [Line Items]
Operating (loss) income	(16,296)	(3,641)
Stock-Based Compensation Expense	25,575	19,282
Depreciation	12,138	6,999
Amortization of Intangibles	12,980	14,539
Acquisition-related Contingent Consideration Fair Value Adjustments	0	0
Goodwill Impairment	0
Adjusted EBITDA	34,397	37,179
Operating segments \| Vimeo
Segment Reporting, Other Significant Reconciling Item [Line Items]
Operating (loss) income	(14,589)	(17,784)
Stock-Based Compensation Expense	0	0
Depreciation	58	193
Amortization of Intangibles	3,123	1,391
Acquisition-related Contingent Consideration Fair Value Adjustments	0	0
Goodwill Impairment	0
Adjusted EBITDA	(11,408)	(16,200)
Operating segments \| Dotdash
Segment Reporting, Other Significant Reconciling Item [Line Items]
Operating (loss) income	2,411	3,047
Stock-Based Compensation Expense	0	0
Depreciation	210	226
Amortization of Intangibles	4,390	3,877
Acquisition-related Contingent Consideration Fair Value Adjustments	0	0
Goodwill Impairment	0
Adjusted EBITDA	7,011	7,150
Operating segments \| Applications
Segment Reporting, Other Significant Reconciling Item [Line Items]
Operating (loss) income	(218,588)	25,356
Stock-Based Compensation Expense	0	0
Depreciation	237	419
Amortization of Intangibles	22,811	2,384
Acquisition-related Contingent Consideration Fair Value Adjustments	(6,282)	1,529
Goodwill Impairment	211,973
Adjusted EBITDA	10,151	29,688
Operating segments \| Emerging & Other
Segment Reporting, Other Significant Reconciling Item [Line Items]
Operating (loss) income	(19,845)	(2,520)
Stock-Based Compensation Expense	25	0
Depreciation	385	275
Amortization of Intangibles	2,455	150
Acquisition-related Contingent Consideration Fair Value Adjustments	0	0
Goodwill Impairment	0
Adjusted EBITDA	(16,980)	(2,095)
Corporate
Segment Reporting, Other Significant Reconciling Item [Line Items]
Operating (loss) income	(45,554)	(43,413)
Stock-Based Compensation Expense	11,692	20,165
Depreciation	2,464	3,028
Amortization of Intangibles	0	0
Acquisition-related Contingent Consideration Fair Value Adjustments	0	0
Goodwill Impairment	0
Adjusted EBITDA	$ (31,398)	$ (20,220)

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.