Note 17 - Income Taxes - Reconciling Items from Income Tax Computed at the Statutory Federal Rate (Details)	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Federal income tax at statutory rate	21.00%	21.00%	21.00%
State income taxes, net of federal benefits	3.80%	4.10%	7.00%
Impact of change in statutory tax rates	0.00%	(0.80%)	(0.20%)
Impact of NOL write-offs	0.00%	(250.40%)	0.00%
Impact of Research and Development credit write-off	0.00%	(8.70%)	0.00%
Permanent deductions	0.30%	(5.30%)	(0.10%)
Valuation allowance	(25.20%)	240.10%	(27.70%)
Effective tax rate	0.00%	0.00%	0.00%