Information Related to Effect of Derivative Instruments on Our Consolidated Condensed Statements of Income (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Derivative Instruments Gain Loss [Line Items]
Gain (loss) on derivatives	$ 700	$ (2,053)	$ 1,669	$ 68
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	297	(1,561)	1,063	551
Other comprehensive income \| Commodity Derivatives
Derivative Instruments Gain Loss [Line Items]
Gain (loss) on derivatives				(218)
Product revenues \| Foreign Currency Derivatives
Derivative Instruments Gain Loss [Line Items]
Gain (loss) on derivatives	435	(524)	675	(605)
Selling, general and administrative expense \| Foreign Currency Derivatives
Derivative Instruments Gain Loss [Line Items]
Gain (loss) on derivatives		22		75
Foreign currency (loss) gain \| Foreign Currency Derivatives
Derivative Instruments Gain Loss [Line Items]
Gain (loss) on derivatives	$ (32)	$ 10	$ (69)	47
Cost of sales \| Commodity Derivatives
Derivative Instruments Gain Loss [Line Items]
Gain (loss) on derivatives				$ 145