Derivatives (Details Textual) (USD $) In Millions, unless otherwise specified	6 Months Ended		3 Months Ended
	Jun. 30, 2013	Dec. 31, 2012	Jun. 30, 2013 Commodity Futures Contracts [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivatives scheduled to mature			December 2014
Cash flow hedge derivative gains (losses) expected to be reclassified into earnings within the next 12 months			$ 5.8
Derivatives (Textual) [Abstract]
Hedged value of revolving credit facility		$ 100
Variable Interest Rate Swap Expiration Date	Oct. 12, 2012
Variable portion of the interest rate swap tied	1-Month LIBOR