Note 7 - Income Taxes - Deferred Tax Assets (Liabilities) (Details) - USD ($)	Dec. 31, 2019	Dec. 31, 2018
Operating loss carryforwards	$ 36,577,000	$ 35,706,000
Accrued expenses	5,940,000	5,953,000
Tax credit carryforwards	4,017,000	3,951,000
Intellectual property	4,049,000	3,996,000
Equipment	71,000	110,000
Total deferred tax assets	50,654,000	49,716,000
Deferred tax liabilities:
Net deferred tax asset	50,654,000	49,716,000
Valuation allowance	$ (50,654,000)	$ (49,716,000)