Derivatives (Details 2)	Sep. 30, 2012 lb
Amounts of quantities outstanding included in commodity derivative contracts
Nonmonetary notional amount	36,579,000
Non-exchange Traded
Amounts of quantities outstanding included in commodity derivative contracts
Nonmonetary notional amount	76,641,000
Non-exchange Traded | Corn
Amounts of quantities outstanding included in commodity derivative contracts
Nonmonetary notional amount	0
Non-exchange Traded | Soybeans
Amounts of quantities outstanding included in commodity derivative contracts
Nonmonetary notional amount	40,473,000
Non-exchange Traded | Wheat
Amounts of quantities outstanding included in commodity derivative contracts
Nonmonetary notional amount	0
Non-exchange Traded | Oats
Amounts of quantities outstanding included in commodity derivative contracts
Nonmonetary notional amount	0
Non-exchange Traded | Ethanol
Amounts of quantities outstanding included in commodity derivative contracts
Nonmonetary notional amount	0
Non-exchange Traded | Corn Oil
Amounts of quantities outstanding included in commodity derivative contracts
Nonmonetary notional amount	0
Non-exchange Traded | Other
Amounts of quantities outstanding included in commodity derivative contracts
Nonmonetary notional amount	0
Exchange Traded
Amounts of quantities outstanding included in commodity derivative contracts
Nonmonetary notional amount	3,000
Exchange Traded | Corn
Amounts of quantities outstanding included in commodity derivative contracts
Nonmonetary notional amount	0
Exchange Traded | Soybeans
Amounts of quantities outstanding included in commodity derivative contracts
Nonmonetary notional amount	30,825,000
Exchange Traded | Wheat
Amounts of quantities outstanding included in commodity derivative contracts
Nonmonetary notional amount	0
Exchange Traded | Oats
Amounts of quantities outstanding included in commodity derivative contracts
Nonmonetary notional amount	0
Exchange Traded | Ethanol
Amounts of quantities outstanding included in commodity derivative contracts
Nonmonetary notional amount	924,000
Exchange Traded | Other
Amounts of quantities outstanding included in commodity derivative contracts
Nonmonetary notional amount	0