Financial Instruments, Derivatives and Hedging Activities - Outstanding contracts (Details) lb in Millions, gal in Millions, bu in Millions, MMBTU in Millions	Sep. 30, 2019 MMBTU lb gal bu
Corn Commodity
Financial instruments, derivatives and hedging activities
Futures contract (in bushels for corn and gallons for ethanol) | bu	47
Soy Bean Oil
Financial instruments, derivatives and hedging activities
Soybean oil futures contract (in pounds) | lb	0
Natural Gas Commodity
Financial instruments, derivatives and hedging activities
Natural gas futures contract (in mmbtu) | MMBTU	30
Ethanol Commodity
Financial instruments, derivatives and hedging activities
Futures contract (in bushels for corn and gallons for ethanol) | gal	8