Annual report pursuant to Section 13 and 15(d)

Note 5 - Employee Benefit Plans (Details Textual)

v3.6.0.2
Note 5 - Employee Benefit Plans (Details Textual) - USD ($)
 12 Months Ended
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Dec. 31, 2014
Defined Contribution Plan, Employer Discretionary Contribution Amount   $ 51,438 $ 46,519 $ 41,172
Other Comprehensive (Income) Loss, Reclassification Adjustment from AOCI, Pension and Other Postretirement Benefit Plans, Net of Tax   91,422 95,899 33,632
Other Comprehensive (Income) Loss, Reclassification Adjustment from AOCI, Pension and Other Postretirement Benefit Plans, Tax   49,227 51,638 18,109
Other Comprehensive (Income) Loss, Amortization Adjustment from AOCI, Pension and Other Postretirement Benefit Plans, for Net Prior Service Cost (Credit), Net of Tax   $ 91,422 $ 95,899 $ 33,632
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Expected Long-term Return on Assets   7.00% 7.00% 7.00%
Defined Benefit Plan Benefit Payment Term   10 years    
Inflation Rate [Member]        
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Expected Long-term Return on Assets   2.50%    
Minimum [Member]        
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Expected Long-term Return on Assets   2.50%    
Minimum [Member] | Fixed Income Securities [Member]        
Defined Benefit Plan, Target Plan Asset Allocations   30.00%    
Minimum [Member] | Equity Securities [Member]        
Defined Benefit Plan, Target Plan Asset Allocations   20.00%    
Maximum [Member]        
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Expected Long-term Return on Assets   8.50%    
Maximum [Member] | Fixed Income Securities [Member]        
Defined Benefit Plan, Target Plan Asset Allocations   80.00%    
Maximum [Member] | Equity Securities [Member]        
Defined Benefit Plan, Target Plan Asset Allocations   60.00%    
Scenario, Forecast [Member]        
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI, Pension and Other Postretirement Benefit Plans, for Net Gain (Loss), Net of Tax $ 107,510      
Other Comprehensive (Income) Loss, Amortization Adjustment from AOCI, Pension and Other Postretirement Benefit Plans, for Net Prior Service Cost (Credit), Net of Tax $ 0