Hedging Transactions and Derivative Financial Instruments (Additional Information) (Detail) (USD $) In Millions, unless otherwise specified	Dec. 31, 2012	Jul. 31, 2012
Derivative Instruments and Hedging Activities Disclosure [Line Items]
Total outstanding debt	98.0
Interest rate spread over variable rate	2.25%
Bank Term Loan [Member]
Derivative Instruments and Hedging Activities Disclosure [Line Items]
Number of derivative contracts related to minimizing risk associated with potential rise in copper prices	2
Term loan debt	90.0
Variable interest rate	0.25%
Interest rate spread over variable rate	2.25%
Bank Term Loan [Member] | Cash Flow Hedging [Member] | Subsequent Event [Member]
Derivative Instruments and Hedging Activities Disclosure [Line Items]
Interest rate swap derivative, percentage of debt hedged	65.00%	65.00%