Interim Condensed Consolidated Statements of Comprehensive Income (Unaudited) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Statement of Comprehensive Income [Abstract]
Net Income	$ 18,771	$ 12,316	$ 33,354	$ 24,483
Other comprehensive income:
Foreign currency translation adjustments	(11,850)	7,098	(8,733)	10,144
Net gain on pension and other postretirement benefits	228	217	423	434
Other comprehensive income before income tax expense	(11,622)	7,315	(8,310)	10,578
Income tax expense related to items of other comprehensive loss	(20)	(80)	(89)	(159)
Other comprehensive income	(11,642)	7,235	(8,399)	10,419
Comprehensive Income	$ 7,129	$ 19,551	$ 24,955	$ 34,902