Derivative Instruments - Summary of Amount Recognized as and Reclassified from Accumulated Other Comprehensive Income (Loss) (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Derivative [Line Items]
Accumulated Other Comprehensive Income (Loss) Beginning of the Period	$ 117	$ 468	$ 739	$ 551
Plus Recognized as Comprehensive Income (Loss)	(198)	217	(519)	456
Less Gain (Loss) Reclassified from Accumulated Other Comprehensive Loss	(46)	150	255	472
Accumulated Other Comprehensive Income (Loss) End of the Period	(35)	535	(35)	535
Foreign Currency Purchase Contracts [Member]
Derivative [Line Items]
Accumulated Other Comprehensive Income (Loss) Beginning of the Period	230	203	239	216
Plus Recognized as Comprehensive Income (Loss)	0	0	0	0
Less Gain (Loss) Reclassified from Accumulated Other Comprehensive Loss	7	11	16	24
Accumulated Other Comprehensive Income (Loss) End of the Period	223	192	223	192
Futures Contracts - Copper and Aluminum [Member]
Derivative [Line Items]
Accumulated Other Comprehensive Income (Loss) Beginning of the Period	(113)	265	500	335
Plus Recognized as Comprehensive Income (Loss)	(198)	217	(519)	456
Less Gain (Loss) Reclassified from Accumulated Other Comprehensive Loss	(53)	139	239	448
Accumulated Other Comprehensive Income (Loss) End of the Period	$ (258)	$ 343	$ (258)	$ 343