Note 7 - Investment and Note Receivable (Details Textual) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2018	Mar. 31, 2017	Mar. 31, 2016
Investment Income, Interest	$ 4	$ 4
Proceeds from Collection of Notes Receivable	0	$ 19
Test Products International Inc. [Member]
Equity Method Investment, Ownership Percentage			8.50%
Notes Receivable, Related Parties	300		$ 400
Interest Rate on Note Receivable			5.00%
Allowance for Notes, Loans and Financing Receivable, Current	$ 0

The interest rate on a note receivable

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- Definition

A valuation allowance relating to a written agreement to receive money (at a specified future date(s) within one year from the reporting date (or the normal operating cycle, whichever is longer), consisting of principal as well as any accrued interest) for the portion that is expected to be uncollectible.

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- Definition

The percentage of ownership of common stock or equity participation in the investee accounted for under the equity method of accounting.

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- Definition

Amount before accretion (amortization) of purchase discount (premium) of interest income on nonoperating securities.

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- Definition

For an unclassified balance sheet, amounts due from parties associated with the reporting entity as evidenced by a written promise to pay.

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The cash inflow associated with principal collections from a borrowing supported by a written promise to pay an obligation.

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