Information Related to Effect of Derivative Instrument's on Our Consolidated Statements of Income (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Derivative Instruments Gain Loss [Line Items]
Gain (loss) on derivatives	$ 777	$ 2,180
Commodity Derivatives
Derivative Instruments Gain Loss [Line Items]
Gain (loss) on derivatives	(73)	256
Other comprehensive (loss) income | Foreign Currency Derivatives
Derivative Instruments Gain Loss [Line Items]
Gain (loss) on derivatives	1,096	302
Other comprehensive (loss) income | Commodity Derivatives
Derivative Instruments Gain Loss [Line Items]
Gain (loss) on derivatives	(218)	54
Product revenues | Foreign Currency Derivatives
Derivative Instruments Gain Loss [Line Items]
Gain (loss) on derivatives		(3)
Cost of sales | Foreign Currency Derivatives
Derivative Instruments Gain Loss [Line Items]
Gain (loss) on derivatives	(444)	2,209
Cost of sales | Commodity Derivatives
Derivative Instruments Gain Loss [Line Items]
Gain (loss) on derivatives	145	202
Selling, general and administrative expense | Foreign Currency Derivatives
Derivative Instruments Gain Loss [Line Items]
Gain (loss) on derivatives	75	(216)
Foreign currency gain | Foreign Currency Derivatives
Derivative Instruments Gain Loss [Line Items]
Gain (loss) on derivatives	$ 50	$ (112)