Comprehensive Income (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Equity [Abstract]
Net income	$ 5,825	$ 7,197	$ 25,201	$ 8,791
Pension liability, net of income tax	510	500	1,529	1,501
Cash flow hedging gain (loss), net of income tax	1,185	(1,348)	6,598	(3,946)
Foreign currency translation adjustment	(384)	4,097	(5,483)	13,320
Comprehensive income	7,136	10,446	27,845	19,666
Pension liability, tax	162	294	488	880
Cash flow hedging gain (loss), tax	$ 378	$ (790)	$ 2,102	$ (2,312)