ACCUMULATED OTHER COMPREHENSIVE LOSS - Summary (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Balance at beginning of period			$ 2,430,028
Other comprehensive income (loss) before reclassifications	$ (138)	$ 37,225	(9,235)	$ 69,958
Amounts reclassified to earnings			(52)	(3,348)
Net current period other comprehensive income (loss)			(9,287)	66,610
Balance at end of period	2,600,482		2,600,482
Tax provision (benefit) on accumulated other comprehensive income		3,800		3,800
Accumulated Other Comprehensive (Loss) Income
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Balance at beginning of period	(112,717)	(136,738)	(103,568)	(166,123)
Balance at end of period	(112,855)	(99,513)	(112,855)	(99,513)
Foreign Currency Translation Adjustment
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Balance at beginning of period	(112,730)	(136,738)	(103,568)	(170,149)
Other comprehensive income (loss) before reclassifications	(111)	37,225	(9,221)	69,951
Amounts reclassified to earnings			(52)	685
Net current period other comprehensive income (loss)			(9,273)	70,636
Balance at end of period	(112,841)	(99,513)	(112,841)	(99,513)
Unrealized Gains (Losses) On Available-For-Sale Securities
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Balance at beginning of period	13	0	0	4,026
Other comprehensive income (loss) before reclassifications	(27)	0	(14)	7
Amounts reclassified to earnings			0	(4,033)
Net current period other comprehensive income (loss)			(14)	(4,026)
Balance at end of period	$ (14)	$ 0	$ (14)	$ 0