Derivatives and Hedging (Details Textual) (USD $)	6 Months Ended	3 Months Ended				6 Months Ended		6 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011 2010 Swap [Member]	Jun. 30, 2012 2010 Swap [Member]	Dec. 31, 2011 2010 Swap [Member]	Jun. 24, 2010 2010 Swap [Member]	Jun. 30, 2012 2012 Metal Swap No.1 [Member]	Apr. 20, 2012 2012 Metal Swap No.1 [Member] Mg	Jun. 30, 2012 2012 Metal Swap No. 2 [Member]	May 30, 2012 2012 Metal Swap No. 2 [Member] Mg	Jun. 30, 2012 2012 Metal Swap No.3 [Member]	May 30, 2012 2012 Metal Swap No.3 [Member] Mg
Derivatives and Hedging (Textual) [Abstract]
Term of derivative instrument					2 years		8 months		7 months		10 months
Quantity of derivative instrument							35		10		35
Notional amount of derivative instrument					$ 115,000,000		$ 294,700		$ 77,900		$ 272,500
Start date of forward derivatives	May 31, 2011
Termination date of derivative	May 31, 2013					Dec. 31, 2012		Dec. 31, 2012		Mar. 31, 2013
Price of copper							8.42		7.79		7.785
Interest rate of derivative instrument					2.47%
Unrealized gain (loss) on derivatives		643,000
Fair value of derivative liability			(833,000)	(1,205,000)
Fair value of derivative liability							$ (30,000)		$ (30,000)		$ (30,000)