Note 1 - Organization and Significant Accounting Policies - Property and Equipment (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019
Total cost	$ 32,109	$ 31,836
Less accumulated depreciation	(26,889)	(26,174)
Total net book value	5,220	5,662
Land [Member]
Total cost	1,050	1,050
Building [Member]
Total cost	$ 3,950	3,950
Depreciable Life (Year)	39 years
Building and Leasehold Improvements [Member]
Total cost	$ 2,886	2,886
Building and Leasehold Improvements [Member] \| Minimum [Member]
Depreciable Life (Year)	3 years
Building and Leasehold Improvements [Member] \| Maximum [Member]
Depreciable Life (Year)	39 years
Field Equipment [Member]
Total cost	$ 19,748	19,507
Field Equipment [Member] \| Minimum [Member]
Depreciable Life (Year)	3 years
Field Equipment [Member] \| Maximum [Member]
Depreciable Life (Year)	4 years
Computer Equipment and Software [Member]
Total cost	$ 2,954	2,936
Computer Equipment and Software [Member] \| Minimum [Member]
Depreciable Life (Year)	2 years
Computer Equipment and Software [Member] \| Maximum [Member]
Depreciable Life (Year)	3 years
Furniture and Fixtures [Member]
Total cost	$ 1,477	1,475
Furniture and Fixtures [Member] \| Minimum [Member]
Depreciable Life (Year)	3 years
Furniture and Fixtures [Member] \| Maximum [Member]
Depreciable Life (Year)	10 years
Vehicles [Member]
Total cost	$ 32	32
Depreciable Life (Year)	5 years
Construction in Progress [Member]
Total cost	$ 12

Amount of accumulated depreciation, depletion and amortization for physical assets used in the normal conduct of business to produce goods and services.

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Amount before accumulated depreciation, depletion and amortization of physical assets used in the normal conduct of business and not intended for resale. Examples include, but are not limited to, land, buildings, machinery and equipment, office equipment, and furniture and fixtures.

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Useful life of long lived, physical assets used in the normal conduct of business and not intended for resale, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. Examples include, but not limited to, land, buildings, machinery and equipment, office equipment, furniture and fixtures, and computer equipment.

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