Note 6 - Income Taxes (Details Textual) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Unrecognized Tax Benefits, Ending Balance	$ 44	$ 33
Unrecognized Tax Benefits that Would Impact Effective Tax Rate	25
Domestic Tax Authority [Member]
Tax Credit Carryforward, Amount	284
State and Local Jurisdiction [Member] \| Minnesota Department of Revenue [Member]
Tax Credit Carryforward, Amount	190
State and Local Jurisdiction [Member] \| Iowa Department of Revenue [Member]
Operating Loss Carryforwards, Total	$ 1

Amount of operating loss carryforward, before tax effects, available to reduce future taxable income under enacted tax laws.

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The amount of the tax credit carryforward, before tax effects, available to reduce future taxable income under enacted tax laws.

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Amount of unrecognized tax benefits.

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The total amount of unrecognized tax benefits that, if recognized, would affect the effective tax rate.

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