Note 5 - Business Segments, Risks and Major Customers (Details Textual)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Gas Purchasers [Member]
Gas, Productive Well, Number of Wells, Gross	590
Product Concentration Risk [Member] | Revenue, Product and Service Benchmark [Member] | Product, Natural Gas [Member]
Concentration Risk, Percentage	69.00%	66.00%
Number of Major Customers	1
Product Concentration Risk [Member] | Revenue, Product and Service Benchmark [Member] | Crude Oil and Natural Gas from Operated Wells [Member]
Concentration Risk, Percentage	79.00%	71.00%
Product Concentration Risk [Member] | Revenue, Product and Service Benchmark [Member] | Product, Oil Purchaser [Member]
Number of Major Customers	1	1
Product Concentration Risk [Member] | Natural Gas Sales [Member] | Gas Purchasers [Member]
Concentration Risk, Percentage	50.00%	43.00%
Customer Concentration Risk [Member] | Natural Gas Sales from Operated Wells [Member] | Gas Purchasers [Member]
Concentration Risk, Percentage	71.00%	65.00%