Derivatives (Details Textual) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Derivatives (Textual) [Abstract]
Maximum period in which contracts for the sale of grain to processors or other consumers extend	1 year
Estimated fair value of inventory	$ 7.7	$ 1.0
Amount reclassified from accumulated and other comprehensive income	0.3	0.1	0.1
Amount to be reclassified from accumulated and other comprehensive income in next twelve months	$ 0.5