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+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Article 12
-Section 13
-Sentence Column B

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+ References

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COMMITMENTS AND CONTINGENCIES (Details)	3 Months Ended		9 Months Ended		12 Months Ended
COMMITMENTS AND CONTINGENCIES (Details)	Jul. 31, 2018 USD ($)	Jul. 31, 2017 USD ($)	Jul. 31, 2018 USD ($) bu	Jul. 31, 2017 USD ($)	Oct. 31, 2017 USD ($) bu gal
Commitments and contingencies
Accrual for leased railcar damages	$ 0		$ 0
Granite Falls Energy, LLC Excluding Heron Lake BioEnergy, LLC \| Corn Forward Cash and Basis Contracts Purchase Commitments [Member]
Commitments and contingencies
Quantity of commitment \| bu			6,384,000
Granite Falls Energy, LLC Excluding Heron Lake BioEnergy, LLC \| Corn Contracts
Commitments and contingencies
Quantity of commitment \| bu			5,725,000		1,495,000
Granite Falls Energy, LLC Excluding Heron Lake BioEnergy, LLC \| Ethanol Contracts
Commitments and contingencies
Quantity of commitment \| gal					420,000
Granite Falls Energy, LLC Excluding Heron Lake BioEnergy, LLC \| Board Members \| Corn Contracts
Commitments and contingencies
Amount of corn purchased	1,754,000	$ 0	$ 3,839,000	$ 0
Granite Falls Energy, LLC Excluding Heron Lake BioEnergy, LLC \| Short/Sale position \| Corn Contracts
Commitments and contingencies
Quantity of commitment \| bu			5,535,000		1,295,000
Granite Falls Energy, LLC Excluding Heron Lake BioEnergy, LLC \| Short/Sale position \| Ethanol Contracts
Commitments and contingencies
Value of commitment	11,832,000		$ 11,832,000
Granite Falls Energy, LLC Excluding Heron Lake BioEnergy, LLC \| Short/Sale position \| Distillers' Grains
Commitments and contingencies
Value of commitment	848,000		848,000
Granite Falls Energy, LLC Excluding Heron Lake BioEnergy, LLC \| Short/Sale position \| Corn Oil
Commitments and contingencies
Value of commitment	829,000		$ 829,000
Granite Falls Energy, LLC Excluding Heron Lake BioEnergy, LLC \| Long/Purchase position \| Corn Contracts
Commitments and contingencies
Quantity of commitment \| bu			190,000		200,000
Heron Lake BioEnergy, LLC \| Corn Forward Cash and Basis Contracts Purchase Commitments [Member]
Commitments and contingencies
Quantity of commitment \| bu			4,189,000
Heron Lake BioEnergy, LLC \| Corn Contracts
Commitments and contingencies
Quantity of commitment \| bu			4,125,000		1,120,000
Heron Lake BioEnergy, LLC \| Ethanol Contracts
Commitments and contingencies
Quantity of commitment \| gal					420,000
Heron Lake BioEnergy, LLC \| Board Members \| Corn Contracts
Commitments and contingencies
Amount of corn purchased	3,382,000	$ 143,000	$ 10,479,000	$ 5,737,000
Heron Lake BioEnergy, LLC \| Short/Sale position \| Corn Contracts
Commitments and contingencies
Quantity of commitment \| bu					905,000
Heron Lake BioEnergy, LLC \| Short/Sale position \| Ethanol Contracts
Commitments and contingencies
Value of commitment	11,716,000		11,716,000
Heron Lake BioEnergy, LLC \| Short/Sale position \| Distillers' Grains
Commitments and contingencies
Value of commitment	2,517,000		2,517,000
Heron Lake BioEnergy, LLC \| Short/Sale position \| Corn Oil
Commitments and contingencies
Value of commitment	$ 775,000		775,000
Heron Lake BioEnergy, LLC \| Long/Purchase position \| Corn Contracts
Commitments and contingencies
Quantity of commitment \| bu					215,000
Heron Lake BioEnergy, LLC \| Accounts Payable \| Board Members \| Corn Contracts
Commitments and contingencies
Amount of corn purchased			$ 0		$ 607,000