Note 7 - Income Taxes (Details Textual) - USD ($)	3 Months Ended		12 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018	Dec. 31, 2017
Effective Income Tax Rate Reconciliation, Percent, Total	18.40%	13.50%	21.00%	35.00%
Income Tax Expense (Benefit), Total	$ (102,738)	$ (20,416)
Unrecognized Tax Benefits, Ending Balance	$ 0