ACCUMULATED OTHER COMPREHENSIVE LOSS - Components of Accumulated Other Comprehensive Loss (Details) - USD ($)	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Balance at beginning of period	$ 2,430,028,000
Other comprehensive income before reclassifications	28,479,000	$ 18,064,000
Amounts reclassified to earnings	139,000	714,000
Net current period other comprehensive income	28,618,000	18,778,000
Balance at end of period	2,494,527,000
Tax provision (benefit) on accumulated other comprehensive income	0	0
Accumulated Other Comprehensive (Loss) Income
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Balance at beginning of period	(103,568,000)	(166,123,000)
Balance at end of period	$ (74,950,000)	(147,345,000)
Foreign Currency Translation Adjustment
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Balance at beginning of period		(170,149,000)
Other comprehensive income before reclassifications		18,062,000
Amounts reclassified to earnings		714,000
Net current period other comprehensive income		18,776,000
Balance at end of period		(151,373,000)
Unrealized Gains On Available-For-Sale Securities
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Balance at beginning of period		4,026,000
Other comprehensive income before reclassifications		2,000
Amounts reclassified to earnings		0
Net current period other comprehensive income		2,000
Balance at end of period		$ 4,028,000