Note 4 - Fair Value Measurement and Fair Value of Financial Instruments - Warrant Liabilities Inputs and Assumptions (Details)	Mar. 31, 2021	Sep. 30, 2020
Montage Warrant [Member] | Measurement Input, Price Volatility [Member]
Volatility	0.863	0.84
Montage Warrant [Member] | Measurement Input, Risk Free Interest Rate [Member]
Volatility	0.0078	0.0028
Montage Warrant [Member] | Measurement Input, Share Price [Member]
Volatility	2.89	1.86
Series C Warrants [Member] | Measurement Input, Price Volatility [Member]
Volatility	0.893	0.841
Series C Warrants [Member] | Measurement Input, Risk Free Interest Rate [Member]
Volatility	0.005	0.002
Series C Warrants [Member] | Measurement Input, Share Price [Member]
Volatility	2.89	1.86