ACCUMULATED OTHER COMPREHENSIVE LOSS - Summary (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Balance at beginning of period			$ 2,430,028
Other comprehensive income before reclassifications	$ (37,576)	$ 14,669	(9,097)	$ 32,733
Amounts reclassified to earnings	(191)	(4,062)	(52)	(3,348)
Net current period other comprehensive income (loss)	(37,767)	10,607	(9,149)	29,385
Balance at end of period	2,576,079		2,576,079
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	(74,950)	(147,345)	(103,568)	(166,123)
Balance at end of period	(112,717)	(136,738)	(112,717)	(136,738)
Foreign Currency Translation Adjustment
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Balance at beginning of period	(74,950)	(151,373)	(103,568)	(170,149)
Other comprehensive income before reclassifications	(37,589)	14,664	(9,110)	32,726
Amounts reclassified to earnings	(191)	(29)	(52)	685
Net current period other comprehensive income (loss)	(37,780)	14,635	(9,162)	33,411
Balance at end of period	(112,730)	(136,738)	(112,730)	(136,738)
Unrealized Gains On Available-For-Sale Securities
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Balance at beginning of period	0	4,028	0	4,026
Other comprehensive income before reclassifications	13	5	13	7
Amounts reclassified to earnings	0	(4,033)	0	(4,033)
Net current period other comprehensive income (loss)	13	(4,028)	13	(4,026)
Balance at end of period	$ 13	$ 0	$ 13	$ 0