Note 6 - Income Taxes - Reconciliation of Income Taxes Rates (Details)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent	21.00%	21.00%	35.00%
State and local taxes, net of federal benefit	3.70%
Equity compensation	(5.70%)
Other	(0.20%)	(21.00%)
Effective rate	18.80%