CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Statement of Comprehensive Income [Abstract]
Net income	$ 6,256	$ 10,675	$ 27,760	$ 35,469
Other comprehensive income (loss):
Foreign currency translation adjustments	(658)	9,438	(9,262)	23,951
Pension liability adjustment, net of tax	198	172	595	516
Unrealized gain (loss) on hedging activities, net of tax	14	37	89	(7)
Comprehensive income	$ 5,810	$ 20,322	$ 19,182	$ 59,929