Note 4 - Property - Property, Plant and Equipment (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Property, plant and equipment, gross	$ 66,151	$ 65,962
Less accumulated depreciation	37,907	36,741
Property, net	28,244	29,221
Land [Member]
Property, plant and equipment, gross	5,086	5,059
Land Improvements [Member]
Property, plant and equipment, gross	24,727	24,727
Building [Member]
Property, plant and equipment, gross	24,763	24,884
Machinery and Equipment [Member]
Property, plant and equipment, gross	11,295	11,143
Construction in Progress [Member]
Property, plant and equipment, gross	$ 280	$ 149

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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