Joint Venture - Operating Results (Details) (USD $)
In Thousands, unless otherwise specified
3 Months Ended
Mar. 31, 2015
Mar. 31, 2014
Schedule of Equity Method Investments [Line Items]    
Net sales $ 222,228 $ 253,410
Cost of materials 168,111 188,531
Income (loss) before taxes (21,531) (16,049)
Net (Loss) Income (20,706) (15,998)
Joint venture    
Schedule of Equity Method Investments [Line Items]    
Net sales 52,606 65,251
Cost of materials 44,350 54,303
Income (loss) before taxes 1,990 4,804
Net (Loss) Income $ 1,750 $ 3,814