Note 8 - Commitments and Contingencies (Details Textual) $ in Thousands	12 Months Ended
	Dec. 31, 2016 USD ($) $ / a	Dec. 31, 2012 a
Acreage Sold with Production Requirements | a		28,800
Refund price per acre | $ / a	1,250
Lease Renewal Period	90 days
Reserve for Potential Refunded Acreage | $	$ 0
Minimum [Member]
Contingency Period for Producing Leases	5 years