ACCUMULATED OTHER COMPREHENSIVE LOSS - Summary (Details) - USD ($)	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Accumulated Other Comprehensive Loss
Balance at beginning of period	$ (1,415,084,000)
Other comprehensive loss	(20,576,000)	$ (21,319,000)
Net period other comprehensive loss		(21,339,000)
Allocation of accumulated other comprehensive loss related to the noncontrolling interests		403,000
Balance at end of period	(1,214,591,000)
Tax benefit / provision in accumulated other comprehensive loss	0	0
Accumulated Other Comprehensive Loss
Accumulated Other Comprehensive Loss
Balance at beginning of period	(81,454,000)	(136,349,000)
Amounts reclassified into earnings		(20,000)
Balance at end of period	(102,030,000)	(157,285,000)
Foreign Currency Translation Adjustment
Accumulated Other Comprehensive Loss
Balance at beginning of period	(81,454,000)	(136,349,000)
Other comprehensive loss	(20,576,000)	(21,307,000)
Amounts reclassified into earnings		(20,000)
Net period other comprehensive loss		(21,327,000)
Allocation of accumulated other comprehensive loss related to the noncontrolling interests		403,000
Balance at end of period	$ (102,030,000)	(157,273,000)
Unrealized Gain on Available-For-Sale Security
Accumulated Other Comprehensive Loss
Balance at beginning of period		0
Other comprehensive loss		(12,000)
Amounts reclassified into earnings		0
Net period other comprehensive loss		(12,000)
Allocation of accumulated other comprehensive loss related to the noncontrolling interests		0
Balance at end of period		$ (12,000)