Note 3 - Stock-based Compensation - Stock Options Outstanding Weighted Average Fair Value (Details) - Employee Stock Purchase Plan ESPP [Member] - $ / shares	12 Months Ended
Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2018
Weighted average remaining life (years) (Year)	1 year 109 days
Weighted average fair value on grant date of options granted (in dollars per share)	$ 1.63	$ 2.28	$ 2.23

Weighted average remaining contractual term for fully vested and expected to vest options outstanding, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days. Includes, but is not limited to, unvested options for which requisite service period has not been rendered but that are expected to vest based on achievement of performance condition, if forfeitures are recognized when they occur.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (e)(1)
-URI http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901

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