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Note 7 - Business Segments, Risks and Major Customers (Tables)
12 Months Ended
Dec. 31, 2016
Notes Tables  
Schedule of Revenue by Major Customers by Reporting Segments [Table Text Block]
Natural Gas Purchaser    
2016
     
2015
 
Dominion Field Services, Inc. ("Dominion")
   
25
%
   
27
%
Interstate Gas Supply, Inc. ("IGS")
   
13
     
14
 
                 
     
38
%
   
41
%