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Note 14 - Income Tax Expense (Details Textual) - USD ($)	May 01, 2020	Mar. 31, 2020
Decrease in Unrecognized Tax Benefits is Reasonably Possible		$ 725,000
Domestic Tax Authority [Member] | Subsequent Event [Member]
Open Tax Year	2016 2017 2018 2019
State and Local Jurisdiction [Member] | Subsequent Event [Member] | North Dakota Department of Revenue [Member]
Open Tax Year	2016 2017 2018 2019
State and Local Jurisdiction [Member] | Subsequent Event [Member] | Minnesota Department of Revenue [Member]
Open Tax Year	2016 2017 2018 2019

X

- 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

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X

- 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
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