Note 7 - Income Taxes (Details Textual) - State and Local Jurisdiction [Member] $ in Thousands	Dec. 31, 2020 USD ($)
Operating Loss Carryforwards, Total	$ 302
Iowa Department of Revenue [Member]
Operating Loss Carryforwards, Total	190
Tax Credit Carryforward, Amount	212
Minnesota Department of Revenue [Member]
Tax Credit Carryforward, Amount	326
Wisconsin Department of Revenue [Member]
Tax Credit Carryforward, Amount	$ 586

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

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 3
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=84230637&loc=d3e32559-109319

Name:	us-gaap_TaxCreditCarryforwardAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant