Derivative Financial Instruments (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Derivative not designated as hedging instrument:
Net amount recognized in earnings	$ 0	$ (737)	$ 0	$ (1,427)
Commodity Contract [Member] | Sales [Member]
Derivative not designated as hedging instrument:
Net amount recognized in earnings	0	(26)	0	(906)
Commodity Contract [Member] | Cost of Sales [Member]
Derivative not designated as hedging instrument:
Net amount recognized in earnings	$ 0	$ (711)	$ 0	$ (521)