Note 2 - Basis of Presentation and Summary of Significant Accounting Policies - Other Property and Equipment, Net (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Other property and equipment, net	$ 1,044	$ 1,092
Land [Member]
Other property and equipment, net	725	725
Technology Equipment [Member]
Other property and equipment, net	250	292
Transportation Equipment [Member]
Other property and equipment, net	39	41
Leasehold Improvements [Member]
Other property and equipment, net	20	24
Field Equipment [Member]
Other property and equipment, net	$ 10	$ 10