Note 4 - Income Taxes (Details Textual) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Mar. 31, 2020	Dec. 31, 2019
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent	21.00%	21.00%
Deferred Tax Assets, Valuation Allowance, Total	$ 0.1
Deferred Tax Liabilities, Net, Total	78.7
Deferred Tax Assets Related to State Net Operating Loss Carry Forwards [Member]
Deferred Tax Assets, Valuation Allowance, Total	$ 0.4