Note 4 - Property - Property, Plant and Equipment (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Property, plant and equipment, gross	$ 52,215	$ 52,164
Less accumulated depreciation	33,091	32,445
Property, net	19,124	19,719
Land [Member]
Property, plant and equipment, gross	5,073	5,073
Land Improvements [Member]
Property, plant and equipment, gross	13,153	13,153
Building [Member]
Property, plant and equipment, gross	23,439	23,439
Machinery and Equipment [Member]
Property, plant and equipment, gross	10,529	10,495
Construction in Progress [Member]
Property, plant and equipment, gross	$ 21	$ 4

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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