ACCUMULATED OTHER COMPREHENSIVE LOSS - Summary (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Accumulated Other Comprehensive Loss
Balance at beginning of period			$ 1,314,288
Other comprehensive income (loss)	$ 3,053	$ (3,071)	971	$ (2,883)
Balance at end of period	1,273,912		1,273,912
Foreign Currency Translation Adjustment
Accumulated Other Comprehensive Loss
Balance at beginning of period	(2,740)	(1,482)	(1,379)	(1,864)
Other comprehensive income (loss)	1,755	(2,681)	394	(2,299)
Balance at end of period	(985)	(4,163)	(985)	(4,163)
Accumulated Other Comprehensive (Loss) Income
Accumulated Other Comprehensive Loss
Balance at beginning of period	(2,740)	(1,482)	(1,379)	(1,861)
Other comprehensive income (loss)	1,755	(2,681)	394	(2,302)
Balance at end of period	$ (985)	(4,163)	$ (985)	(4,163)
Unrealized Gains (Losses) On Available-For-Sale Debt Securities
Accumulated Other Comprehensive Loss
Balance at beginning of period				3
Other comprehensive income (loss)				(3)
Balance at end of period		$ 0		$ 0