Note 4 - Property - Property, Plant and Equipment (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Property, plant and equipment, gross	$ 65,664	$ 65,650
Less accumulated depreciation	35,856	34,971
Net property	29,808	30,679
Land [Member]
Property, plant and equipment, gross	5,059	5,059
Land Improvements [Member]
Property, plant and equipment, gross	24,727	24,727
Building [Member]
Property, plant and equipment, gross	24,884	24,884
Machinery and Equipment [Member]
Property, plant and equipment, gross	$ 10,994	$ 10,980

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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