Fair Value Measurements - Various Instruments That Require Fair Value Measurement (Detail) (Fair Value, Measurements, Recurring [Member], USD $) In Thousands, unless otherwise specified	Jun. 30, 2013	Dec. 31, 2012
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Pension assets	$ 156,741	$ 143,540
Foreign currency option contracts	(9)	15
Copper derivative contracts	56	267
Interest Rate Swap Instrument designated as hedging instruments, other assets (liabilities)	(249)	(361)
Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Pension assets	106,619	98,269
Foreign currency option contracts	0	0
Copper derivative contracts	0	0
Interest Rate Swap Instrument designated as hedging instruments, other assets (liabilities)	0	0
Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Pension assets	33,530	29,869
Foreign currency option contracts	(9)	15
Copper derivative contracts	56	267
Interest Rate Swap Instrument designated as hedging instruments, other assets (liabilities)	(249)	(361)
Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Pension assets	16,592	15,402
Foreign currency option contracts	0	0
Copper derivative contracts	0	0
Interest Rate Swap Instrument designated as hedging instruments, other assets (liabilities)	$ 0	$ 0