Note 9 - Income Taxes (Details Textual)	12 Months Ended
Mar. 31, 2021
Domestic Tax Authority [Member] \| Internal Revenue Service (IRS) [Member]
Open Tax Year	2018 2019 2020
State and Local Jurisdiction [Member]
Open Tax Year	2017 2018 2019 2020

Tax year that remains open to examination under enacted tax laws, in YYYY format.

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=121826272&loc=d3e32718-109319

Name:	us-gaap_OpenTaxYear
Namespace Prefix:	us-gaap_
Data Type:	dtr-types:gYearListItemType
Balance Type:	na
Period Type:	duration