Note 4 - Income Taxes - Effective Income Tax Rate Reconciliation (Details)	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Tax at federal statutory rate	21.00%	21.00%	21.00%
State taxes, net of federal	7.40%	39.20%	36.60%
Permanent items	30.60%	284.40%	312.20%
Other	(0.20%)	5.60%	5.60%
State rate change	(0.50%)	0.20%	(24.30%)
Valuation allowance	(58.80%)	(352.50%)	(362.70%)
Effective tax rate	(0.50%)	(2.10%)	(11.60%)