Note 1 - Organization and Significant Accounting Policies - Property and Equipment (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Total cost	$ 23,242	$ 22,992
Less accumulated depreciation	(18,703)	(18,557)
Total net book value	4,539	4,435
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	$ 2,655	2,626
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	$ 12,100	11,882
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	$ 2,049	2,117
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	$ 1,307	1,306
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	$ 99	$ 29