ACCUMULATED OTHER COMPREHENSIVE LOSS - Accumulated Other Comprehensive (Loss) Income (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Accumulated Other Comprehensive Loss
Balance at beginning of period	$ 1,314,288
Other comprehensive income (loss)	(6,568)	$ 1,862
Balance at end of period	1,281,750
Accumulated Other Comprehensive Loss
Accumulated Other Comprehensive Loss
Balance at beginning of period	(1,379)	(1,861)
Other comprehensive income (loss)	(6,614)	1,670
Balance at end of period	(7,993)	(191)
Foreign Currency Translation Adjustment
Accumulated Other Comprehensive Loss
Balance at beginning of period	(1,379)	(1,864)
Other comprehensive income (loss)	(6,614)	1,673
Balance at end of period	$ (7,993)	(191)
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