Derivatives (Details 4)	Dec. 31, 2013 lb	Dec. 31, 2012 bu
Amounts of quantities outstanding included in commodity derivative contracts
Nonmonetary notional amount	25,911,000	426,616,000
Non-exchange traded:
Amounts of quantities outstanding included in commodity derivative contracts
Nonmonetary notional amount	179,212,000	76,099,000
Non-exchange traded: | Corn
Amounts of quantities outstanding included in commodity derivative contracts
Nonmonetary notional amount	185,978,000	0
Non-exchange traded: | Soybeans
Amounts of quantities outstanding included in commodity derivative contracts
Nonmonetary notional amount	0	0
Non-exchange traded: | Wheat
Amounts of quantities outstanding included in commodity derivative contracts
Nonmonetary notional amount	11,485,000	19,407,000
Non-exchange traded: | Oats
Amounts of quantities outstanding included in commodity derivative contracts
Nonmonetary notional amount	0	0
Non-exchange traded: | Ethanol
Amounts of quantities outstanding included in commodity derivative contracts
Nonmonetary notional amount	0	76,099,000
Non-exchange traded: | Corn oil
Amounts of quantities outstanding included in commodity derivative contracts
Nonmonetary notional amount	0	0
Non-exchange traded: | Other
Amounts of quantities outstanding included in commodity derivative contracts
Nonmonetary notional amount	89,000	0
Exchange traded:
Amounts of quantities outstanding included in commodity derivative contracts
Nonmonetary notional amount	0	3,795,000
Exchange traded: | Corn
Amounts of quantities outstanding included in commodity derivative contracts
Nonmonetary notional amount	0	106,305,000
Exchange traded: | Soybeans
Amounts of quantities outstanding included in commodity derivative contracts
Nonmonetary notional amount	0	0
Exchange traded: | Wheat
Amounts of quantities outstanding included in commodity derivative contracts
Nonmonetary notional amount	23,980,000	0
Exchange traded: | Oats
Amounts of quantities outstanding included in commodity derivative contracts
Nonmonetary notional amount	6,820,000	4,345,000
Exchange traded: | Bean Oil
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	0	0
Exchange traded: | Other
Amounts of quantities outstanding included in commodity derivative contracts
Nonmonetary notional amount		0