Derivative Instruments (Fair Value of Derivative Instruments in the Balance Sheet) (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Derivative [Line Items]
Total derivatives	$ (108)	$ 185
Total derivatives designated as hedging instruments
Derivative [Line Items]
Total derivatives	(111)	197
Total derivatives designated as hedging instruments | (Accrued liabilities)/Prepaid and other current assets | Commodity contracts
Derivative [Line Items]
Total derivatives	(111)	197
Total derivatives not designated as hedging instruments
Derivative [Line Items]
Total derivatives	3	(12)
Total derivatives not designated as hedging instruments | Prepaid and other current assets | Commodity contracts
Derivative [Line Items]
Total derivatives	3	18
Total derivatives not designated as hedging instruments | Other non-current liabilities | Interest rate swap agreements
Derivative [Line Items]
Total derivatives	$ 0	$ (30)