ACCUMULATED OTHER COMPREHENSIVE LOSS (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2018 USD ($)
Components of accumulated other comprehensive loss:
Balance at the beginning of the period	$ 16,659
Other comprehensive loss (gain) before reclassifications	(2,938)
Net current-period other comprehensive loss (gain)	(2,938)
Balance at the end of the period	13,721
Currency Translation Losses
Components of accumulated other comprehensive loss:
Balance at the beginning of the period	15,818
Other comprehensive loss (gain) before reclassifications	(2,723)
Net current-period other comprehensive loss (gain)	(2,723)
Balance at the end of the period	13,095
Unrealized (Gains) Losses on Available-for-Sale Securities
Components of accumulated other comprehensive loss:
Balance at the beginning of the period	841
Other comprehensive loss (gain) before reclassifications	(215)
Net current-period other comprehensive loss (gain)	(215)
Balance at the end of the period	$ 626