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LONG-TERM DEBT - Summary (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Feb. 11, 2020	Dec. 31, 2019	Feb. 15, 2019	Dec. 04, 2017	Jun. 01, 2016
Debt Instrument [Line Items]
Less: unamortized original issue discount	$ 347,306
Less: current portion of ANGI Term Loan	13,750		$ 13,750
Less: unamortized debt issuance costs	50,499
Long-term debt, net	3,625,008		3,121,572
Match Group
Debt Instrument [Line Items]
Aggregate principal amount	2,125,000		1,625,000
Less: unamortized original issue discount	6,618		6,282
Less: unamortized debt issuance costs	20,428		15,235
Long-term debt, net	2,097,954		1,603,483
Match Group \| Term Loan \| MTCH Term Loan due February 13, 2027
Debt Instrument [Line Items]
Aggregate principal amount	425,000		425,000
Match Group \| Senior Notes \| 6.375% MTCH Senior Notes
Debt Instrument [Line Items]
Aggregate principal amount	$ 400,000		400,000
Stated interest rate (as a percent)	6.375%					6.375%
Match Group \| Senior Notes \| 5.00% MTCH Senior Notes
Debt Instrument [Line Items]
Aggregate principal amount	$ 450,000		450,000
Stated interest rate (as a percent)	5.00%				5.00%
Match Group \| Senior Notes \| 5.625% MTCH Senior Notes
Debt Instrument [Line Items]
Aggregate principal amount	$ 350,000		350,000
Stated interest rate (as a percent)	5.625%			5.625%
Match Group \| Senior Notes \| 4.125% MTCH Senior Notes
Debt Instrument [Line Items]
Aggregate principal amount	$ 500,000		0
Stated interest rate (as a percent)	4.125%	4.125%
ANGI Homeservices
Debt Instrument [Line Items]
Less: current portion of ANGI Term Loan	$ 13,750		13,750
Less: unamortized debt issuance costs	1,670		1,804
Long-term debt, net	228,643		231,946
ANGI Homeservices \| Term Loan \| ANGI Term Loan due November 5, 2023
Debt Instrument [Line Items]
Aggregate principal amount	244,063		247,500
IAC
Debt Instrument [Line Items]
Aggregate principal amount	1,667,500		1,667,500
Less: unamortized original issue discount	340,688		351,605
Less: unamortized debt issuance costs	28,401		29,752
Long-term debt, net	1,298,411		1,286,143
IAC \| Senior Notes \| 2022 Exchangeable Notes
Debt Instrument [Line Items]
Aggregate principal amount	517,500		517,500
Less: unamortized original issue discount	$ 37,314		40,768
Stated interest rate (as a percent)	0.875%
IAC \| Senior Notes \| 2026 Exchangeable Notes
Debt Instrument [Line Items]
Aggregate principal amount	$ 575,000		575,000
Less: unamortized original issue discount	$ 124,820		129,037
Stated interest rate (as a percent)	0.875%
IAC \| Senior Notes \| 2030 Exchangeable Notes
Debt Instrument [Line Items]
Aggregate principal amount	$ 575,000		575,000
Less: unamortized original issue discount	$ 178,554		$ 181,800
Stated interest rate (as a percent)	2.00%