Derivatives (Volume of Contracts Outstanding) (Details) lb in Thousands, gal in Thousands, bu in Thousands, T in Thousands	Jun. 30, 2021 bu	Jun. 30, 2021 gal	Jun. 30, 2021 lb	Jun. 30, 2021 T	Dec. 31, 2020 bu	Dec. 31, 2020 gal	Dec. 31, 2020 lb	Dec. 31, 2020 T	Jun. 30, 2020 bu	Jun. 30, 2020 gal	Jun. 30, 2020 lb	Jun. 30, 2020 T
Amounts of quantities outstanding included in commodity derivative contracts
Nonmonetary notional amount	1,329,057	333,570	99,697	2,122	1,303,744	220,429	63,279	2,008	1,049,013	216,101	8,853	2,578
Non-exchange Traded
Amounts of quantities outstanding included in commodity derivative contracts
Nonmonetary notional amount	955,058	202,273	97,346	1,925	899,689	126,853	63,265	1,859	656,478	146,549	8,513	2,370
Non-exchange Traded | Corn
Amounts of quantities outstanding included in commodity derivative contracts
Nonmonetary notional amount	696,674	0	0	0	684,654	0	0	0	437,275	0	0	0
Non-exchange Traded | Soybeans
Amounts of quantities outstanding included in commodity derivative contracts
Nonmonetary notional amount	75,507	0	0	0	73,521	0	0	0	50,012	0	0	0
Non-exchange Traded | Wheat
Amounts of quantities outstanding included in commodity derivative contracts
Nonmonetary notional amount	129,264	0	0	0	109,661	0	0	0	95,133	0	0	0
Non-exchange Traded | Oats
Amounts of quantities outstanding included in commodity derivative contracts
Nonmonetary notional amount	45,810	0	0	0	27,482	0	0	0	49,053	0	0	0
Non-exchange Traded | Ethanol
Amounts of quantities outstanding included in commodity derivative contracts
Nonmonetary notional amount	0	198,316	0	0	0	124,795	0	0	0	141,549	0	0
Non-exchange Traded | Corn oil
Amounts of quantities outstanding included in commodity derivative contracts
Nonmonetary notional amount	0	0	70,637	0	0	0	36,015	0	0	0	8,098	0
Non-exchange Traded | Soybean oil
Amounts of quantities outstanding included in commodity derivative contracts
Nonmonetary notional amount	0	0	23,952	0	0	0	26,510	0
Non-exchange Traded | Other
Amounts of quantities outstanding included in commodity derivative contracts
Nonmonetary notional amount	7,803	3,957	2,757	1,925	4,371	2,058	740	1,859	25,005	5,000	415	2,370
Exchange Traded
Amounts of quantities outstanding included in commodity derivative contracts
Nonmonetary notional amount	373,999	131,297	2,351	197	404,055	93,576	14	149	392,535	69,552	340	208
Exchange Traded | Corn
Amounts of quantities outstanding included in commodity derivative contracts
Nonmonetary notional amount	243,190	0	0	0	267,792	0	0	0	287,840	0	0	0
Exchange Traded | Soybeans
Amounts of quantities outstanding included in commodity derivative contracts
Nonmonetary notional amount	49,375	0	0	0	53,730	0	0	0	36,970	0	0	0
Exchange Traded | Wheat
Amounts of quantities outstanding included in commodity derivative contracts
Nonmonetary notional amount	80,004	0	0	0	80,733	0	0	0	67,040	0	0	0
Exchange Traded | Oats
Amounts of quantities outstanding included in commodity derivative contracts
Nonmonetary notional amount	1,430	0	0	0	1,800	0	0	0	685	0	0	0
Exchange Traded | Ethanol
Amounts of quantities outstanding included in commodity derivative contracts
Nonmonetary notional amount	0	112,812	0	0	0	73,584	0	0	0	27,300	0	0
Exchange Traded | Propane
Amounts of quantities outstanding included in commodity derivative contracts
Nonmonetary notional amount	0	18,480	0	0	0	17,094	0	0	0	28,602	0	0
Exchange Traded | Other
Amounts of quantities outstanding included in commodity derivative contracts
Nonmonetary notional amount	0	5	2,351	197	0	2,898	14	149	0	13,650	340	208