Derivative Instruments - Additional Information (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013 Customer	Jun. 30, 2012	Jun. 30, 2013 Customer	Jun. 30, 2012
Derivative [Line Items]
Anticipated foreign-denominated sales hedge	$ 15,785		$ 15,785
Foreign-denominated sales cash flow contracts	0		0
Fair value of assets held as collateral related to futures	500		500
Percentage of purchase commitments covering anticipated natural gas usage	46.00%		46.00%
Purchase commitment amount of anticipated natural gas usage	5,617		5,617
Number of subsidiaries purchased commitments for natural gas usage	1		1
Purchase commitments covering period anticipated usage, Description			Through 2015 at one of its subsidiaries
Gains (losses) on foreign exchange transactions included in other income (expense)	(93)	52	(393)	78
Foreign Currency Sales Contract - Fair Value Hedges [Member]
Derivative [Line Items]
Fair value of assets held as collateral related to forward exchange contracts	760		760
Copper Purchases [Member]
Derivative [Line Items]
Percentage of anticipated purchases hedged	57.00%		57.00%
Time period for hedged purchases	9 months		9 months
Copper Purchases [Member] | Cash Flow Hedges [Member]
Derivative [Line Items]
Anticipated purchases, hedged	3,195		3,195
Aluminum Purchases [Member]
Derivative [Line Items]
Percentage of anticipated purchases hedged	56.00%		56.00%
Time period for hedged purchases	6 months		6 months
Aluminum Purchases [Member] | Cash Flow Hedges [Member]
Derivative [Line Items]
Anticipated purchases, hedged	$ 479		$ 479