Note 6 - Convertible Promissory Notes (Details Textual) - USD ($)		3 Months Ended
Jul. 23, 2019	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020
Amortization of Debt Discount (Premium)		$ 908,000	$ 522,000
Convertible Debt [Member] \| The July 2019 Note [Member]
Debt Instrument, Face Amount	$ 1,000,000	$ 1,000,000		$ 1,000,000
Debt Instrument, Convertible, Conversion Price (in dollars per share)		$ 1.80		$ 1.80
Debt Instrument, Convertible, Threshold Percentage of Stock Price Trigger	90.00%
Debt Instrument, Interest Rate, Stated Percentage	24.00%	24.00%		24.00%
Amortization of Debt Discount (Premium)		$ 80,000
Interest Expense, Debt, Total		$ 60,000	$ 60,000
Convertible Debt [Member] \| The July 2019 Note [Member] \| Maximum [Member]
Debt Instrument, Convertible, Conversion Price (in dollars per share)	$ 1.80
Convertible Debt [Member] \| The July 2019 Note [Member] \| Minimum [Member]
Debt Instrument, Convertible, Conversion Price (in dollars per share)	$ 0.50

Amount of noncash expense included in interest expense to amortize debt discount and premium associated with the related debt instruments. Excludes amortization of financing costs. Alternate captions include noncash interest expense.

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The price per share of the conversion feature embedded in the debt instrument.

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Minimum percentage of common stock price to conversion price of convertible debt instruments to determine eligibility of conversion.

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Face (par) amount of debt instrument at time of issuance.

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Contractual interest rate for funds borrowed, under the debt agreement.

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Amount of the cost of borrowed funds accounted for as interest expense for debt.

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