Note 6 - Business Segments, Risks and Major Customers - Table of Natural Gas Sales to Significant Purchasers as a Percentage of Consolidated Crude Oil and Natural Gas Sale (Details) - Customer Concentration Risk [Member] - Natural Gas Sales [Member]	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Concentration Risk, Percentage	46.00%	56.00%
Dominion Field Services, Inc. [Member]
Concentration Risk, Percentage	43.00%	44.00%
Interstate Gas Supply, Inc. [Member]
Concentration Risk, Percentage	3.00%	12.00%