Derivative Financial Instruments (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Derivative not designated as hedging instrument:
Net amount recognized in earnings	$ 0	$ (1,957)	$ 0	$ (3,384)
Commodity Contract [Member] | Sales [Member]
Derivative not designated as hedging instrument:
Net amount recognized in earnings	0	(592)	0	(1,498)
Commodity Contract [Member] | Cost of Sales [Member]
Derivative not designated as hedging instrument:
Net amount recognized in earnings	$ 0	$ (1,365)	$ 0	$ (1,886)