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Note 6 - Discontinued Operations (Details Textual) - Dillco Fluid Service, Inc [Member] - USD ($)
3 Months Ended
Oct. 29, 2018
Mar. 31, 2019
Mar. 31, 2018
Discontinued Operation, Gain (Loss) from Disposal of Discontinued Operation, before Income Tax, Total  
Discontinued Operation, Provision for Loss (Gain) on Disposal, before Income Tax, Total  
Discontinued Operations, Disposed of by Sale [Member]      
Discontinued Operation, Gain (Loss) from Disposal of Discontinued Operation, before Income Tax, Total $ 129,000    
Discontinued Operation, Provision for Loss (Gain) on Disposal, before Income Tax, Total $ 130,000