Derivative Instruments (Fair Value of Derivative Instruments in the Balance Sheet) (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Derivative [Line Items]
Total derivatives	$ 626	$ 1,406
Total derivatives designated as hedging instruments
Derivative [Line Items]
Total derivatives	667	1,778
Total derivatives designated as hedging instruments | Prepaid and other current assets | Commodity contracts
Derivative [Line Items]
Total derivatives	667	1,778
Total derivatives not designated as hedging instruments
Derivative [Line Items]
Total derivatives	(41)	(372)
Total derivatives not designated as hedging instruments | Prepaid and other current assets/(Accrued liabilities) | Commodity contracts
Derivative [Line Items]
Total derivatives	97	(158)
Total derivatives not designated as hedging instruments | Other liabilities | Interest rate swap agreements
Derivative [Line Items]
Total derivatives	$ (138)	$ (214)