COMPREHENSIVE INCOME - Schedule of Comprehensive Income (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Equity [Abstract]
Net income	$ 10,992	$ 6,394
Foreign currency translation adjustment	13,780	4,064
Change in unrealized gain on derivatives, net of tax	7,838	347
Unrealized gain on short-term investments	0	1,292
Pension liability adjustment, net of tax	(6)	(2)
Comprehensive income, net	$ 32,604	$ 12,095