Consolidated Condensed Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Statement Of Income And Comprehensive Income [Abstract]
Net income	$ 8,414	$ 12,966
Other comprehensive (loss) income, gross of tax:
Foreign currency translation adjustments (loss) gain	(4,074)	11,741
Unrealized gain on foreign currency derivative securities	766	2,112
Unrealized loss on commodity derivative securities		(218)
Other comprehensive (loss) income, gross of tax	(3,308)	13,635
Other comprehensive (loss) income, related tax effect:
Cumulative effect of accounting change due to ASU 2018-02		(40)
Foreign currency translation adjustments (loss) gain	(177)	(76)
Unrealized gain on foreign currency derivative securities	(167)	(567)
Unrealized loss on commodity derivative securities		(59)
Other comprehensive (loss) income, related tax effect	(344)	(742)
Other comprehensive (loss) income, net of tax	(3,652)	12,893
Comprehensive income	$ 4,762	$ 25,859