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Note 14 - Income Tax Expense (Details Textual) - USD ($) | Nov. 01, 2020 | Sep. 30, 2020
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Decrease in Unrecognized Tax Benefits is Reasonably Possible |  | $ 139,000
State and Local Jurisdiction [Member] | North Dakota Department of Revenue [Member] | Subsequent Event [Member] |  |
Open Tax Year | 2017 2018 2019 |
State and Local Jurisdiction [Member] | Minnesota Department of Revenue [Member] | Subsequent Event [Member] |  |
Open Tax Year | 2016 2017 2018 2019 |
Domestic Tax Authority [Member] | Subsequent Event [Member] |  |
Open Tax Year | 2017 2018 2019 |

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- Definition Amount of decrease reasonably possible in the next twelve months for the unrecognized tax benefit. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 15 -Subparagraph (d)(3) -URI http://asc.fasb.org/extlink&oid=84230637&loc=d3e32718-109319 + Details
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- Definition Tax year that remains open to examination under enacted tax laws, in CCYY format. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 15 -Subparagraph (e) -URI http://asc.fasb.org/extlink&oid=84230637&loc=d3e32718-109319 + Details
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