ACCUMULATED OTHER COMPREHENSIVE LOSS - Summary (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Accumulated Other Comprehensive Loss
Balance at beginning of period			$ (1,414,417,000)
Other comprehensive loss	$ (2,059,000)	$ 19,111,000	(22,635,000)	$ (2,208,000)
Amounts reclassified into earnings		(144,000)		(164,000)
Net period other comprehensive income (loss)		18,967,000		(2,372,000)
Allocation of accumulated other comprehensive loss related to the noncontrolling interests		225,000		628,000
Separation of IAC		13,781,000		13,781,000
Balance at end of period	(142,245,000)		(142,245,000)
Tax benefit / provision in accumulated other comprehensive loss	0	0	0	0
Accumulated Other Comprehensive Loss
Accumulated Other Comprehensive Loss
Balance at beginning of period	(102,030,000)	(157,285,000)	(81,454,000)	(136,349,000)
Balance at end of period	(104,089,000)	(124,312,000)	(104,089,000)	(124,312,000)
Foreign Currency Translation Adjustment
Accumulated Other Comprehensive Loss
Balance at beginning of period	(102,030,000)	(157,273,000)	(81,454,000)	(136,349,000)
Other comprehensive loss	(2,059,000)	19,100,000	(22,635,000)	(2,207,000)
Amounts reclassified into earnings		(144,000)		(164,000)
Net period other comprehensive income (loss)		18,956,000		(2,371,000)
Allocation of accumulated other comprehensive loss related to the noncontrolling interests		225,000		628,000
Separation of IAC		13,780,000		13,780,000
Balance at end of period	$ (104,089,000)	(124,312,000)	$ (104,089,000)	(124,312,000)
Unrealized Gain on Available-For-Sale Security
Accumulated Other Comprehensive Loss
Balance at beginning of period		(12,000)		0
Other comprehensive loss		11,000		(1,000)
Amounts reclassified into earnings		0		0
Net period other comprehensive income (loss)		11,000		(1,000)
Allocation of accumulated other comprehensive loss related to the noncontrolling interests		0		0
Separation of IAC		1,000		1,000
Balance at end of period		$ 0		$ 0