Condensed Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Statement Of Income And Comprehensive Income [Abstract]
Net Income	$ 13,277	$ 5,313	$ 38,987	$ 23,472
Other Comprehensive income (loss):
Foreign currency translation adjustment	6,673	90	21,157	(1,000)
Change in defined benefit pension plans	65	14	(232)	134
Change in fair value of derivative financial instruments, net of tax	(331)	0	326	0
Other comprehensive income (loss):	6,407	104	21,251	(866)
Comprehensive income	$ 19,684	$ 5,417	$ 60,238	$ 22,606