Disclosures About Fair Value - Fair Value of Assets and Liabilities on a Recurring Basis (Details) (USD $)	Mar. 31, 2015		Dec. 31, 2014
Assets
Available-for-sale securities	$ 26,816,000		$ 31,032,000
Fair Value, Measurements, Recurring
Assets
Available-for-sale securities	18,404,000	[1]	21,990,000	[1]
Available-for-sale debt maturities	5,751,000	[1]	6,380,000	[1]
Readily marketable inventory	4,363,000	[2]	11,472,000	[2]
Derivative instruments	1,353,000	[3]	1,701,000	[3]
Liabilities
Derivative instruments	1,886,000	[3]	1,546,000	[3]
Contingent consideration	3,745,000	[4]	3,902,000	[4]
Fair Value, Measurements, Recurring | Quoted Prices In Active Markets for Identical Assets (Level 1)
Assets
Available-for-sale securities	10,858,000	[1]	10,892,000	[1]
Available-for-sale debt maturities	5,751,000	[1]	6,380,000	[1]
Readily marketable inventory	1,546,000	[2]	7,992,000	[2]
Derivative instruments	723,000	[3]	121,000	[3]
Liabilities
Derivative instruments	1,385,000	[3]	1,181,000	[3]
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2)
Assets
Available-for-sale securities	7,546,000	[1]	11,098,000	[1]
Available-for-sale debt maturities		[1]		[1]
Readily marketable inventory	2,817,000	[2]	3,480,000	[2]
Derivative instruments	630,000	[3]	1,580,000	[3]
Liabilities
Derivative instruments	501,000	[3]	365,000	[3]
Fair Value, Measurements, Recurring | Significant Unobservable Inputs (Level 3)
Liabilities
Contingent consideration	3,745,000	[4]	3,902,000	[4]
Equity Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Level 1 to Level 2 transfers	$ 1,600,000		$ 5,600,000

[1] Where there are quoted market prices that are readily available in an active market, securities are classified as Level 1 of the valuation hierarchy. Level 1 available-for-sale investments are valued using quoted market prices multiplied by the number of shares owned and debt securities are valued using a market quote in an active market. All Level 2 available-for-sale securities are one class because they all contain similar risks and are valued using market prices and include securities where the markets are not active, that is where there are few transactions, or the prices are not current or the prices vary considerably over time. Inputs include directly or indirectly observable inputs such as quoted prices. Level 3 available-for-sale securities would include securities where valuation is based on unobservable inputs that are supported by little or no market activity and that are significant to the fair value of the assets. This includes certain pricing models, discounted cash flow methodologies and similar techniques that use significant unobservable inputs.

[2] Readily marketable inventory comprises commodity inventories that are reported at fair value based on commodity exchange quotations. Canola seed inventories are valued based on the quoted market price multiplied by the quantity of inventory and are classified as Level 1. Canola oil and meal inventories are classified as Level 2 because the inputs are directly observable, such as the quoted market price of the corresponding soybean commodity.

[3] Included in this caption are exchange traded futures and forward commodity purchase and sale contracts. The exchange traded futures contracts are valued based on quoted prices in active markets multiplied by the number of contracts and are classified as Level 1. Forward commodity purchase and sale contracts classified as derivatives are valued using quantitative models that require the use of multiple inputs including quoted market prices and various other assumptions including time value. These contracts are categorized as Level 2 and are valued based on the difference between the quoted market price and the price in the contract multiplied by the undelivered notional quantity deliverable under the contract.

[4] Included in this caption is the contingent consideration that the Company entered into as part of the acquisition of Citizens Homes, Inc. (“Citizens”). The estimated fair value of the contingent consideration was estimated based on applying the income approach and a weighted probability of achievement of the performance milestones. The estimated fair value of the contingent consideration was calculated by using a Monte Carlo simulation model. The fair value of the contingent consideration was then estimated as the arithmetic average of all simulation paths. The model was based on forecast adjusted net income over the contingent consideration period. The measurement is based on significant inputs that are not observable in the market, which are defined as Level 3 inputs.