Note 4 - Property & Equipment - Property & Equipment (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Property and equipment, gross	$ 52,414	$ 52,274
Less accumulated depreciation	36,387	36,215
Property and equipment, net	16,027	16,059
Land [Member]
Property and equipment, gross	5,052	5,052
Land Improvements [Member]
Property and equipment, gross	13,862	13,853
Building [Member]
Property and equipment, gross	22,869	22,869
Machinery and Equipment [Member]
Property and equipment, gross	10,500	10,500
Construction in Progress [Member]
Property and equipment, gross	$ 131	$ 0