Information Related to Effect of Derivative Instruments on Our Consolidated Condensed Statements of Income (Detail) - USD ($) $ in Thousands		3 Months Ended
	Mar. 31, 2018	Mar. 31, 2019
Derivative Instruments Gain Loss [Line Items]
Gain (loss) on derivatives	$ 2,121	$ 969
Commodity Derivatives
Derivative Instruments Gain Loss [Line Items]
Gain (loss) on derivatives	(73)
Other comprehensive income | Foreign Currency Derivatives
Derivative Instruments Gain Loss [Line Items]
Gain (loss) on derivatives	2,112	766
Other comprehensive income | Commodity Derivatives
Derivative Instruments Gain Loss [Line Items]
Gain (loss) on derivatives	(218)
Cost of sales | Foreign Currency Derivatives
Derivative Instruments Gain Loss [Line Items]
Gain (loss) on derivatives	(81)	240
Cost of sales | Commodity Derivatives
Derivative Instruments Gain Loss [Line Items]
Gain (loss) on derivatives	145
Selling, general and administrative expense | Foreign Currency Derivatives
Derivative Instruments Gain Loss [Line Items]
Gain (loss) on derivatives	53
Foreign currency (loss) gain | Foreign Currency Derivatives
Derivative Instruments Gain Loss [Line Items]
Gain (loss) on derivatives	$ 37	$ (37)