Consolidated Condensed Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Statement Of Income And Comprehensive Income [Abstract]
Net income	$ 19,494	$ 16,423	$ 39,314	$ 33,002
Other comprehensive income (loss), gross of tax:
Foreign currency translation adjustments gain (loss)	4,722	(730)	(14,883)	(3,355)
Unrealized (loss) gain on foreign currency derivative securities	(430)	99	(777)	160
Unrealized loss on commodity derivative securities	(124)		(48)
Unrealized gain on interest rate derivative securities				39
Other comprehensive income (loss), gross of tax	4,168	(631)	(15,708)	(3,156)
Other comprehensive income, related tax effect:
Foreign currency translation adjustments	246	280	713	854
Unrealized gain on foreign currency derivative securities	121		210
Other comprehensive income, related tax effect	367	280	923	854
Other comprehensive income (loss), net of tax	4,535	(351)	(14,785)	(2,302)
Comprehensive income	$ 24,029	$ 16,072	$ 24,529	$ 30,700