Note 1 - Nature of Business, Financial Condition and Basis of Presentation (Details Textual) $ / shares in Units, $ in Thousands					1 Months Ended			3 Months Ended			9 Months Ended			12 Months Ended
		Aug. 25, 2020 USD ($) $ / shares shares	Jul. 10, 2020 USD ($) shares	Jul. 06, 2020 USD ($) $ / shares shares	Jul. 31, 2020 shares	Apr. 30, 2020	Aug. 31, 2019 USD ($)	Sep. 30, 2020 USD ($) $ / shares shares		Sep. 30, 2019 USD ($)	Sep. 30, 2020 USD ($) $ / shares shares		Sep. 30, 2019 USD ($)	Dec. 31, 2019 USD ($) shares		Jul. 06, 2025 $ / shares	Aug. 31, 2020 shares
Percentage of Salaries Reductions in Reponse to COVID-19					20.00%	20.00%
Restructuring Charges, Total								$ (50)			$ 254
Cash and Cash Equivalents, at Carrying Value, Ending Balance								$ 80,621		80,600	$ 80,621		80,600	$ 16,302
Class of Warrant or Right, Number of Securities Called by Warrants or Rights (in shares) | shares								2,734,198			2,734,198			56,033,028
Proceeds from Issuance or Sale of Equity, Total				$ 16,100
Stock Issued During Period, Shares Upon Exercise of Warrants (in shares) | shares											52,953,400
Proceeds from Warrant Exercises											$ 16,647
Gain (Loss) on Conversion of Notes to Common Stock								$ (543)			(543)
Proceeds from Issuance of Common Stock											69,985		$ 9,647
Income Tax Expense (Benefit), Total											0
Blocksize Capital GmbH [Member]
Payments for Software, Total											$ 100
Customer Concentration Risk [Member] | Accounts Receivable [Member]
Number of Customer								4			4			3
Customer Concentration Risk [Member] | Accounts Receivable [Member] | Coryton Advanced Fuels Ltd [Member]
Concentration Risk, Percentage											27.00%
Customer Concentration Risk [Member] | Accounts Receivable [Member] | Total Petrochemicals & Refining USA, Inc. [Member]
Concentration Risk, Percentage											20.00%
Customer Concentration Risk [Member] | Accounts Receivable [Member] | Eco-Energy, LLC [Member]
Concentration Risk, Percentage											14.00%			57.00%
Customer Concentration Risk [Member] | Accounts Receivable [Member] | World Kinect Energy Services [Member]
Concentration Risk, Percentage											12.00%
Customer Concentration Risk [Member] | Accounts Receivable [Member] | Purina Animal Nutrition, LLC [Member]
Concentration Risk, Percentage														13.00%
Customer Concentration Risk [Member] | Accounts Receivable [Member] | HCS Group GmbH [Member]
Concentration Risk, Percentage														15.00%
Customer Concentration Risk [Member] | Revenue Benchmark [Member] | Coryton Advanced Fuels Ltd [Member]
Concentration Risk, Percentage								52.00%
Customer Concentration Risk [Member] | Revenue Benchmark [Member] | Total Petrochemicals & Refining USA, Inc. [Member]
Concentration Risk, Percentage								39.00%
Customer Concentration Risk [Member] | Revenue Benchmark [Member] | Eco-Energy, LLC [Member]
Concentration Risk, Percentage										73.00%	57.00%		73.00%
Customer Concentration Risk [Member] | Revenue Benchmark [Member] | Purina Animal Nutrition, LLC [Member]
Concentration Risk, Percentage										16.00%	17.00%		16.00%
Customer Concentration Risk [Member] | Revenue Benchmark [Member] | HCS Group GmbH [Member]
Concentration Risk, Percentage											15.00%
Convertible 2020 Notes [Member]
Debt Conversion, Original Debt, Amount			$ 2,000
Debt Conversion, Converted Instrument, Shares Issued (in shares) | shares			4,169,426
Gain (Loss) on Conversion of Notes to Common Stock			$ (500)
Measurement Input, Price Volatility [Member] | Minimum [Member]
Warrants and Rights Outstanding, Measurement Input								1.3			1.3
Measurement Input, Price Volatility [Member] | Maximum [Member]
Warrants and Rights Outstanding, Measurement Input								1.41			1.41
Measurement Input, Risk Free Interest Rate [Member] | Minimum [Member]
Warrants and Rights Outstanding, Measurement Input								0.003			0.003
Measurement Input, Risk Free Interest Rate [Member] | Maximum [Member]
Warrants and Rights Outstanding, Measurement Input								0.0031			0.0031
Measurement Input, Expected Term [Member]
Warrants and Rights Outstanding, Measurement Input								5			5
August 2020 Offering [Member]
Proceeds from Issuance or Sale of Equity, Total		$ 45,800
Stock Issued During Period, Shares, New Issues (in shares) | shares		21,929,313
Shares Issued, Price Per Share (in dollars per share) | $ / shares		$ 1.30
At-the-market Offering [Member]
Stock Issued During Period, Shares, New Issues (in shares) | shares								0			1,343,121
Increase (Decrease) in At-the-Market Offering of Stock							$ 10,700
Proceeds from Issuance of Common Stock											$ 2,200
Offering of Stock, Remaining Capacity, Shares (in shares) | shares								6,500,000			6,500,000
Series 2020 B Warrants [Member]
Units Issued Warrant Per Unit (in shares) | shares				1
Class of Warrant or Right, Number of Securities Called by Each Warrant or Right (in shares) | shares				1
Class of Warrant or Right, Exercise Price of Warrants or Rights (in dollars per share) | $ / shares	[1]							$ 0.01			$ 0.01
Class of Warrant or Right, Number of Securities Called by Warrants or Rights (in shares) | shares				30,000,000	9,103,334				[1]			[1]		9,103,334	[1]
Stock Issued During Period, Shares Upon Exercise of Warrants (in shares) | shares											9,103,334
Proceeds from Warrant Exercises											$ 91
Warrants and Rights Outstanding								$ 2,900			$ 2,900
Series 2020 B Warrants [Member] | Forecast [Member]
Class of Warrant or Right, Exercise Price of Warrants or Rights (in dollars per share) | $ / shares																$ 0.01
The Series 2020 A Warrants [Member]
Warrants and Rights Outstanding, Term (Year)				5 years
Class of Warrant or Right, Exercise Price of Warrants or Rights (in dollars per share) | $ / shares	[1]							$ 0.60			$ 0.60
Class of Warrant or Right, Number of Securities Called by Warrants or Rights (in shares) | shares					30,000,000			2,682,166	[1]		2,682,166	[1]		30,000,000	[1]
Stock Issued During Period, Shares Upon Exercise of Warrants (in shares) | shares								27,317,834			27,317,834
Proceeds from Warrant Exercises								$ 16,400			$ 16,391
Warrants and Rights Outstanding								$ 8,300			$ 8,300
Series 2020C Warrants [Member]
Class of Warrant or Right, Number of Securities Called by Each Warrant or Right (in shares) | shares		1
Class of Warrant or Right, Exercise Price of Warrants or Rights (in dollars per share) | $ / shares		$ 0.01						$ 0.01	[1]		$ 0.01	[1]
Class of Warrant or Right, Number of Securities Called by Warrants or Rights (in shares) | shares		16,532,232							[1]			[1]		16,532,232	[1]		16,532,232
Stock Issued During Period, Shares Upon Exercise of Warrants (in shares) | shares											16,532,232
Proceeds from Warrant Exercises											$ 165
Class of Warrant or Right, Issuance Price (in dollars per share) | $ / shares		$ 1.29
Warrants and Rights Outstanding								$ 21,400			21,400
Series 1 Unit [Member]
Units Issued During Period (in shares) | shares				20,896,666
Units Issued Price Per Unit (in dollars per share) | $ / shares				$ 0.60
Units Issued Common Share Per Unit (in shares) | shares				1
Units Issued Warrant Per Unit (in shares) | shares				1
Series 1 Unit [Member] | Forecast [Member]
Class of Warrant or Right, Exercise Price of Warrants or Rights (in dollars per share) | $ / shares																$ 0.60
Series 2 Unit [Member]
Units Issued During Period (in shares) | shares				9,103,334
Units Issued Price Per Unit (in dollars per share) | $ / shares				$ 0.59
Coupon Make Whole Payments [Member] | Convertible 2020 Notes [Member]
Debt Conversion, Original Debt, Amount			$ 300
Gevo [Member]
Restructuring Charges, Total											20
Gevo Development / Agri-Energy [Member]
Restructuring Charges, Total											$ 300
Workforce Reduced at Luverne Facility [Member]
Restructuring and Related Cost, Number of Positions Eliminated											26
Workforce Reduced at Corporate Headquarters [Member]
Restructuring and Related Cost, Number of Positions Eliminated											4
Employee Severance [Member]
Restructuring Charges, Total											$ 96
Lease Agreement [Member]
Restructuring Charges, Total											$ 158
Officers [Member]
Percentage of Salaries Reductions in Reponse to COVID-19						20.00%
Certain Remaining Employees [Member]
Percentage of Salaries Reductions in Reponse to COVID-19						20.00%
COVID-19 [Member]
Percentage of Revenue Reduction								97.00%

[1] The Series 2020-A, Series 2020-B and Series 2020-C Warrants are equity-classified warrants.