Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Statement Of Income And Comprehensive Income [Abstract]
Net Income	$ 76,598	$ 95,393	$ 70,119
Other comprehensive loss, gross of tax:
Net gain (loss) on pension benefit obligations	(675)	847	(2,295)
Foreign currency translation adjustments	(16,678)	(25,904)	(25,044)
Unrealized gain (loss) on foreign currency derivative securities	(1,395)	10	(10)
Unrealized gain on interest rate derivative securities			81
Unrealized loss (gain) on commodity derivative securities	743	(725)
Other comprehensive loss, gross of tax	(18,005)	(25,772)	(27,268)
Other comprehensive loss, related tax effects:
Net gain (loss) on pension benefit obligations	185	(234)	680
Foreign currency translation adjustments	297	(417)	6,048
Unrealized gain on foreign currency derivative securities	375
Unrealized (gain) loss on commodity derivative securities	(273)	496
Other comprehensive loss, related tax effect	584	(155)	6,728
Other comprehensive loss, net of tax:	(17,421)	(25,927)	(20,540)
Comprehensive income:	$ 59,177	$ 69,466	$ 49,579