Note 4 - Property - Property, Plant and Equipment (Details) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Property, plant and equipment, gross	$ 51,414	$ 51,956
Less accumulated depreciation	33,789	33,445
Property, net	17,625	18,511
Land [Member]
Property, plant and equipment, gross	5,072	5,072
Land Improvements [Member]
Property, plant and equipment, gross	12,943	12,943
Building [Member]
Property, plant and equipment, gross	22,892	23,465
Machinery and Equipment [Member]
Property, plant and equipment, gross	10,485	10,476
Construction in Progress [Member]
Property, plant and equipment, gross	$ 22	$ 0

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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