Note 13 - Income Taxes - Reconciliation of Federal Income Tax Attributable to Operations to Income Tax Expense (Benefit) (Details) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Statutory federal income tax benefit	$ (3,530,000)	$ (2,118,000)
Intangible assets	69,000	673,000
Change in valuation allowance	197,000	(681,000)
Expiration of net operating losses	1,558,000	1,187,000
Disallowed financing costs	1,619,000	1,119,000
State and local taxes	(18,000)	(205,000)
Other	105,000	25,000
Total income tax expense