Disclosures About Fair Value of Financial Instruments (Details) Gain (Loss) Recognized in Income on Derivative (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013 Futures Cost of Sales, Canola Oil and Meal		Mar. 31, 2012 Futures Operating and Other Costs		Mar. 31, 2013 Forwards Cost of Sales, Canola Oil and Meal		Mar. 31, 2012 Forwards Operating and Other Costs		Mar. 31, 2013 Swaps Cost of Sales, Canola Oil and Meal		Mar. 31, 2012 Swaps Operating and Other Costs
Derivative Instruments, Gain (Loss) [Line Items]
Gain (loss) on derivatives	$ (2,171)	[1]	$ (708)	[2]	$ (814)	[1]	$ 707	[2]	$ 367	[1]	$ 1,884	[2]

[1] Represents the activity post-completion of the Company’s canola processing plant.

[2] Represents the activity pre-completion of the Company’s canola processing plant.