Fair Value (Details) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
Fair Value, Inputs, Level 1 [Member] | Inventories [Member]
Assets:
Assets, Fair Value Disclosure	$ 150,530	$ 165,586
Fair Value, Inputs, Level 1 [Member] | Aluminum futures contracts [Member]
Assets:
Assets, Fair Value Disclosure	7,346	9,769
Fair Value, Inputs, Level 1 [Member] | Foreign Currency Future Contracts [Member]
Assets:
Assets, Fair Value Disclosure	$ 159	$ 1,337
Fair Value, Inputs, Level 2 [Member]
Assets:
Assets, Fair Value Disclosure
Fair Value, Inputs, Level 2 [Member] | Inventories [Member]
Assets:
Assets, Fair Value Disclosure
Fair Value, Inputs, Level 2 [Member] | Aluminum futures contracts [Member]
Assets:
Assets, Fair Value Disclosure
Fair Value, Inputs, Level 2 [Member] | Foreign Currency Future Contracts [Member]
Assets:
Assets, Fair Value Disclosure
Fair Value, Inputs, Level 2 [Member] | Embedded Derivative Financial Instruments [Member]
Liabilities:
Liabilities, Fair Value Disclosure
Fair Value, Inputs, Level 3 [Member] | Embedded conversion option [Member]
Liabilities:
Liabilities, Fair Value Disclosure	$ 1,325	$ 2,734