Note 11 - Equity Incentive Plan (Details Textual) - The 2017 Plan [Member] - shares shares in Millions	Jun. 18, 2019	Jun. 17, 2019
Share-based Compensation Arrangement by Share-based Payment Award, Number of Additional Shares Authorized (in shares)	1.1
Common Stock, Capital Shares Reserved for Future Issuance (in shares)	4.6	3.5

Aggregate number of common shares reserved for future issuance.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.29)
-URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

Name:	us-gaap_CommonStockCapitalSharesReservedForFutureIssuance
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant