Disclosures About Fair Value of Financial Instruments (Details) Gain (Loss) Recognized in Income on Derivative (Cost of Sales, Canola Oil and Meal, USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Derivative Instruments, Gain (Loss) [Line Items]
Gain (loss) on derivatives	$ 4,095	$ (2,618)
Futures
Derivative Instruments, Gain (Loss) [Line Items]
Gain (loss) on derivatives	(1,054)	(2,171)
Forwards
Derivative Instruments, Gain (Loss) [Line Items]
Gain (loss) on derivatives	1,474	(814)
Swaps
Derivative Instruments, Gain (Loss) [Line Items]
Gain (loss) on derivatives	$ 3,675	$ 367