Derivative Instruments - Additional Information (Detail)	3 Months Ended
	Mar. 31, 2018 USD ($) Customer Derivative	Mar. 31, 2017 USD ($)
Derivative [Line Items]
Anticipated foreign-denominated sales hedge	$ 22,782,000
Percentage of purchase commitments covering anticipated natural gas usage	58.00%
Purchase commitment amount of anticipated natural gas usage	$ 864,000
Number of subsidiaries purchased commitments for natural gas usage | Customer	1
Purchase commitments covering period anticipated usage, Description	for one of its subsidiaries.
Purchase of natural gas	$ 422,000	$ 0
Number of derivative instruments holds for trading purposes | Derivative	0
Losses on foreign exchange transactions included in other income (expense)	$ (821,000)	$ (1,064,000)
Copper Purchases [Member]
Derivative [Line Items]
Percentage of anticipated purchases hedged	46.00%
Copper Purchases [Member] | Cash Flow Hedges [Member]
Derivative [Line Items]
Anticipated purchases, hedged	$ 2,464,000
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	$ 535,000