Note 6 - Property, Equipment and Improvements - Major Classes of Property, Equipment and Improvements (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2018	Oct. 01, 2017	Sep. 30, 2018	Oct. 01, 2017	Dec. 31, 2017
Property, equipment and improvements	$ 69,234		$ 69,234		$ 66,711
Less: Accumulated Depreciation	(60,442)		(60,442)		(59,141)
Property, Equipment and Improvements, Net	8,792		8,792		7,570
Depreciation expense	496	$ 497	1,476	$ 1,507
Land [Member]
Property, equipment and improvements	123		123		123
Building and Building Improvements [Member]
Property, equipment and improvements	7,924		7,924		7,858
Machinery and Equipment [Member]
Property, equipment and improvements	51,054		51,054		50,852
Furniture and Fixtures [Member]
Property, equipment and improvements	1,983		1,983		2,005
Computer Equipment [Member]
Property, equipment and improvements	5,549		5,549		5,338
Construction in Progress [Member]
Property, equipment and improvements	$ 2,601		$ 2,601		$ 535

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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The amount of expense recognized in the current period that reflects the allocation of the cost of tangible assets over the assets' useful lives. Includes production and non-production related depreciation.

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Amount after accumulated depreciation, depletion and amortization of physical assets used in the normal conduct of business to produce goods and services 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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