Disclosures About Fair Value - Gain (Loss) Recognized in Income on Derivative (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2015		Mar. 31, 2014
Cost of canola oil and meal sold
Derivative Instruments, Gain (Loss) [Line Items]
Gain (loss) on derivatives	$ (674)		$ 4,095
Futures | Cost of canola oil and meal sold
Derivative Instruments, Gain (Loss) [Line Items]
Gain (loss) on derivatives	136		(1,054)
Futures | Other income
Derivative Instruments, Gain (Loss) [Line Items]
Gain (loss) on derivatives	(159)	[1]
Forwards | Cost of canola oil and meal sold
Derivative Instruments, Gain (Loss) [Line Items]
Gain (loss) on derivatives	(180)		1,474
Swaps | Cost of canola oil and meal sold
Derivative Instruments, Gain (Loss) [Line Items]
Gain (loss) on derivatives	$ (630)		$ 3,675

[1] Represents derivative transactions classified as trading.