ACCUMULATED OTHER COMPREHENSIVE LOSS - Summary (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Accumulated Other Comprehensive Loss
Balance at beginning of period	$ 2,946,823	$ 2,010,670	$ 2,215,825
Other comprehensive income (loss) before reclassifications, net of tax (provision) benefit related to unrealized gains (losses) on available-for-sale securities	(25,102)	65,915	(42,088)
Amounts reclassified to earnings	(52)	(3,360)	6,937
Net current period other comprehensive (loss) income	(25,154)	62,555	(35,151)
Reallocation of accumulated other comprehensive loss (income) related to the noncontrolling interests created in the Match Group IPO			21,131
Balance at end of period	3,551,801	2,946,823	2,010,670
Tax benefit related to unrealized losses on available-for-sale securities			700
Foreign Currency Translation Adjustment
Accumulated Other Comprehensive Loss
Balance at beginning of period	(103,568)	(170,149)	(154,645)
Other comprehensive income (loss) before reclassifications, net of tax (provision) benefit related to unrealized gains (losses) on available-for-sale securities	(25,106)	65,908	(46,943)
Amounts reclassified to earnings	(52)	673	9,850
Net current period other comprehensive (loss) income	(25,158)	66,581	(37,093)
Reallocation of accumulated other comprehensive loss (income) related to the noncontrolling interests created in the Match Group IPO			21,589
Balance at end of period	(128,726)	(103,568)	(170,149)
Unrealized Gains On Available-For-Sale Securities
Accumulated Other Comprehensive Loss
Balance at beginning of period	0	4,026	2,542
Other comprehensive income (loss) before reclassifications, net of tax (provision) benefit related to unrealized gains (losses) on available-for-sale securities	4	7	4,855
Amounts reclassified to earnings	0	(4,033)	(2,913)
Net current period other comprehensive (loss) income	4	(4,026)	1,942
Reallocation of accumulated other comprehensive loss (income) related to the noncontrolling interests created in the Match Group IPO			(458)
Balance at end of period	4	0	4,026
Accumulated Other Comprehensive Loss
Accumulated Other Comprehensive Loss
Balance at beginning of period	(103,568)	(166,123)	(152,103)
Balance at end of period	$ (128,722)	$ (103,568)	$ (166,123)

Accumulated Other Comprehensive Income (Loss) [Roll Forward]

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Noncontrolling Interest, Reallocation of Interests, Attributable to Parent

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Amount after tax, before reclassification adjustments of other comprehensive income (loss).

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Amount after tax of other comprehensive income (loss) attributable to parent entity.

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Amount of stockholders' equity (deficit), net of receivables from officers, directors, owners, and affiliates of the entity, attributable to both the parent and noncontrolling interests. Amount excludes temporary equity. Alternate caption for the concept is permanent equity.

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