Derivatives (Comodity Derivative Contracts Outstanding) (Details) lb in Thousands, gal in Thousands, bu in Thousands, T in Thousands	Dec. 31, 2020 bu	Dec. 31, 2020 gal	Dec. 31, 2020 lb	Dec. 31, 2020 T	Dec. 31, 2019 bu	Dec. 31, 2019 gal	Dec. 31, 2019 lb	Dec. 31, 2019 T
Amounts of quantities outstanding included in commodity derivative contracts
Derivative, Nonmonetary Notional Amount	1,303,744	220,429	63,279	2,008	1,055,476	300,982	14,873	2,495
Non-exchange traded
Amounts of quantities outstanding included in commodity derivative contracts
Derivative, Nonmonetary Notional Amount	899,689	126,853	63,265	1,859	724,330	120,448	14,873	2,263
Non-exchange traded | Corn
Amounts of quantities outstanding included in commodity derivative contracts
Derivative, Nonmonetary Notional Amount	684,654	0	0	0	552,359	0	0	0
Non-exchange traded | Soybeans
Amounts of quantities outstanding included in commodity derivative contracts
Derivative, Nonmonetary Notional Amount	73,521	0	0	0	34,912	0	0	0
Non-exchange traded | Wheat
Amounts of quantities outstanding included in commodity derivative contracts
Derivative, Nonmonetary Notional Amount	109,661	0	0	0	100,996	0	0	0
Non-exchange traded | Oats
Amounts of quantities outstanding included in commodity derivative contracts
Derivative, Nonmonetary Notional Amount	27,482	0	0	0	24,700	0	0	0
Non-exchange traded | Ethanol
Amounts of quantities outstanding included in commodity derivative contracts
Derivative, Nonmonetary Notional Amount	0	124,795	0	0	0	116,448	0	0
Non-exchange traded | Corn oil
Amounts of quantities outstanding included in commodity derivative contracts
Derivative, Nonmonetary Notional Amount	0	0	36,015	0	0	0	14,568	0
Non-exchange traded | Other
Amounts of quantities outstanding included in commodity derivative contracts
Derivative, Nonmonetary Notional Amount	4,371	2,058	740	1,859	11,363	4,000	305	2,263
Non-exchange traded | Soybean Oil [Member]
Amounts of quantities outstanding included in commodity derivative contracts
Derivative, Nonmonetary Notional Amount	0	0	26,510	0
Exchange traded
Amounts of quantities outstanding included in commodity derivative contracts
Derivative, Nonmonetary Notional Amount	404,055	93,576	14	149	331,146	180,534	0	232
Exchange traded | Corn
Amounts of quantities outstanding included in commodity derivative contracts
Derivative, Nonmonetary Notional Amount	267,792	0	0	0	221,740	0	0	0
Exchange traded | Soybeans
Amounts of quantities outstanding included in commodity derivative contracts
Derivative, Nonmonetary Notional Amount	53,730	0	0	0	39,145	0	0	0
Exchange traded | Wheat
Amounts of quantities outstanding included in commodity derivative contracts
Derivative, Nonmonetary Notional Amount	80,733	0	0	0	68,171	0	0	0
Exchange traded | Oats
Amounts of quantities outstanding included in commodity derivative contracts
Derivative, Nonmonetary Notional Amount	1,800	0	0	0	2,090	0	0	0
Exchange traded | Ethanol
Amounts of quantities outstanding included in commodity derivative contracts
Derivative, Nonmonetary Notional Amount	0	73,584	0	0	0	175,353	0	0
Exchange traded | Propane [Member]
Amounts of quantities outstanding included in commodity derivative contracts
Derivative, Nonmonetary Notional Amount	0	17,094	0	0	0	5,166	0	0
Exchange traded | Other
Amounts of quantities outstanding included in commodity derivative contracts
Derivative, Nonmonetary Notional Amount	0	2,898	14	149	0	15	0	232