ACCUMULATED OTHER COMPREHENSIVE LOSS - Summary (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Accumulated Other Comprehensive Loss
Balance at beginning of period			$ (1,414,417,000)
Other comprehensive income (loss)	$ (99,308,000)	$ 16,205,000	(121,943,000)	$ 13,997,000
Amounts reclassified into earnings		(4,000)		(168,000)
Net period other comprehensive income (loss)		16,201,000		13,829,000
Allocation of accumulated other comprehensive loss related to the noncontrolling interests				628,000
Separation of IAC				13,781,000
Balance at end of period	(68,352,000)		(68,352,000)
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	(104,089,000)	(124,312,000)	(81,454,000)	(136,349,000)
Balance at end of period	(203,397,000)	(108,111,000)	(203,397,000)	(108,111,000)
Foreign Currency Translation Adjustment
Accumulated Other Comprehensive Loss
Balance at beginning of period	(104,089,000)	(124,312,000)	(81,454,000)	(136,349,000)
Other comprehensive income (loss)	(99,308,000)	16,205,000	(121,943,000)	13,998,000
Amounts reclassified into earnings		(4,000)		(168,000)
Net period other comprehensive income (loss)		16,201,000		13,830,000
Allocation of accumulated other comprehensive loss related to the noncontrolling interests				628,000
Separation of IAC				13,780,000
Balance at end of period	$ (203,397,000)	(108,111,000)	$ (203,397,000)	(108,111,000)
Unrealized Loss on Available-For-Sale Security
Accumulated Other Comprehensive Loss
Balance at beginning of period				0
Other comprehensive income (loss)				(1,000)
Amounts reclassified into earnings				0
Net period other comprehensive income (loss)				(1,000)
Allocation of accumulated other comprehensive loss related to the noncontrolling interests				0
Separation of IAC				1,000
Balance at end of period		$ 0		$ 0