MEMBERS’ EQUITY (Details)				1 Months Ended				12 Months Ended
	Dec. 21, 2017 USD ($) $ / shares	Dec. 17, 2015 USD ($) $ / shares shares	Dec. 18, 2014 USD ($) $ / shares shares	Dec. 31, 2017 USD ($) $ / shares	Dec. 31, 2016 USD ($) $ / shares	Dec. 31, 2015 USD ($) $ / shares	Dec. 31, 2014 USD ($) $ / shares	Oct. 31, 2017 USD ($) item $ / shares shares	Oct. 31, 2016 USD ($) $ / shares shares	Oct. 31, 2015 USD ($) $ / shares shares
Common Units Authorized								30,606	30,606
Common Units Issued								30,606	30,606
Common Units Outstanding								30,606	30,606
Distribution per unit declared (in dollars per unit) | $ / shares								$ 365.00	$ 315.00	$ 1,050.00
Amount of distribution declared | $								$ 11,171,190	$ 11,647,445	$ 36,757,640
Amount of distribution paid | $								$ 11,171,190	9,640,886	32,136,300
Non-controlling Interest
Amount of distribution declared | $									$ 2,006,559	$ 4,621,340
Granite Falls Energy, LLC Excluding Heron Lake BioEnergy, LLC
Number of classes of membership units | item								1
Membership Units, Par value | $ / shares								$ 0
Common Units Authorized								30,606	30,606	30,606
Common Units Issued								30,606	30,606	30,606
Common Units Outstanding								30,606	30,606	30,606
Distribution per unit declared (in dollars per unit) | $ / shares				$ 385	$ 365	$ 315	$ 1,050
Amount of distribution declared | $				$ 11,783,000	$ 11,171,000	$ 9,641,000	$ 32,136,000
Granite Falls Energy, LLC Excluding Heron Lake BioEnergy, LLC | Heron Lake BioEnergy, LLC
Distributions received | $		$ 1,971,000	$ 4,731,000
Heron Lake BioEnergy, LLC
Distribution per unit declared (in dollars per unit) | $ / shares	$ 0.11	$ 0.05	$ 0.12
Amount of distribution declared | $	$ 8,573,000	$ 3,897,000	$ 9,352,000
Heron Lake BioEnergy, LLC | Non-controlling Interest
Amount of distribution paid | $		$ 1,926,000	$ 4,621,000
Heron Lake BioEnergy, LLC | Capital Unit, Class A
Common Units Outstanding		39,420,949	39,420,949
Heron Lake BioEnergy, LLC | Capital Unit, Class B
Common Units Outstanding		15,000,000	15,000,000