Disclosures About Fair Value (Details) Notional Amounts of Derivatives	Dec. 31, 2014 T		Dec. 31, 2013 T
Agricultural Commodities | Exchange Traded | Short
Derivatives, Fair Value [Line Items]
Notional amount of nonmonetary derivative	99,268,000	[1]	23,038,000	[1]
Agricultural Commodities | Exchange Traded | Long
Derivatives, Fair Value [Line Items]
Notional amount of nonmonetary derivative	85,602,000	[1]	34,380,000	[1]
Natural Gas (in million metric British Thermal Units) | Exchange Traded | Long
Derivatives, Fair Value [Line Items]
Notional amount of nonmonetary derivative	690,000,000	[1],[2]	460,000,000	[1],[2]
Forwards | Non-exchange Traded | Short
Derivatives, Fair Value [Line Items]
Notional amount of nonmonetary derivative	126,615,000	[1]	132,428,000	[1]
Forwards | Non-exchange Traded | Long
Derivatives, Fair Value [Line Items]
Notional amount of nonmonetary derivative	29,666,000	[1]	30,367,000	[1]
Swaps | Non-exchange Traded | Long
Derivatives, Fair Value [Line Items]
Notional amount of nonmonetary derivative			75,000,000	[1]

[1] Exchange and non-exchange traded futures, forwards, and swaps are presented on a gross (short) and long position basis.

[2] Million Metric British Thermal Units.