Derivative Instruments - Additional Information (Detail)	3 Months Ended
	Mar. 31, 2016 USD ($) Customer	Mar. 31, 2015 USD ($)
Derivative [Line Items]
Anticipated foreign-denominated sales hedge	$ 14,458,000
Percentage of purchase commitments covering anticipated natural gas usage	44.00%
Purchase commitment amount of anticipated natural gas usage	$ 1,976,000
Number of subsidiaries purchased commitments for natural gas usage | Customer	1
Purchase commitments covering period anticipated usage, Description	Through 2017 at one of its subsidiaries
Purchase of natural gas	$ 823,000	$ 781,000
Gains (losses) on foreign exchange transactions included in other income (expense)	1,173,000	$ (380,000)
Foreign Currency Sales Contract - Fair Value Hedges [Member]
Derivative [Line Items]
Fair value of assets held as collateral related to forward exchange contracts	$ 718,000
Copper Purchases [Member]
Derivative [Line Items]
Percentage of anticipated purchases hedged	43.00%
Time period for hedged purchases	9 months
Copper Purchases [Member] | Cash Flow Hedges [Member]
Derivative [Line Items]
Anticipated purchases, hedged	$ 2,486,000
Aluminum Purchases [Member]
Derivative [Line Items]
Percentage of anticipated purchases hedged	56.00%
Time period for hedged purchases	6 months
Aluminum Purchases [Member] | Cash Flow Hedges [Member]
Derivative [Line Items]
Anticipated purchases, hedged	$ 386,000