Derivative Instruments (Details 3) (Commodity [Member], Not Designated as Hedging Instrument [Member], USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Commodity [Member] | Not Designated as Hedging Instrument [Member]
Effect of Non-designated Derivative Instruments on the Consolidated Statement of Operations
Amount of Unrealized Gain (Loss) Recognized in Other Income Expense	$ 0	$ (437)