Quarterly report pursuant to Section 13 or 15(d)

Note 3 - Income Taxes (Details Textual)

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Note 3 - Income Taxes (Details Textual)
3 Months Ended 6 Months Ended 12 Months Ended
Dec. 31, 2018
Dec. 31, 2017
Dec. 31, 2018
Dec. 31, 2017
Jun. 30, 2019
Jun. 30, 2018
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent           28.00%
Effective Income Tax Rate Reconciliation, Percent, Total 25.10% 16.00% 25.00% 23.50%    
Scenario, Forecast [Member]            
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent         21.00%  
Domestic Tax Authority [Member] | Internal Revenue Service (IRS) [Member]            
Income Tax Examination, Year under Examination     2015 2016