Note 10 - Stock-based Compensation and Incentive Plans - Common Stock Shares Reserved for Issuance and Shares Available for Grant (Details) - shares	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Shares of common stock reserved for issuance under the plans (in shares)	6,473,228	6,473,228	3,973,228
Shares of common stock available for future grants (in shares)	2,466,167	3,037,187	1,591,577

The difference between the maximum number of shares (or other type of equity) authorized for issuance under the plan (including the effects of amendments and adjustments), and the sum of: 1) the number of shares (or other type of equity) already issued upon exercise of options or other equity-based awards under the plan; and 2) shares (or other type of equity) reserved for issuance on granting of outstanding awards, net of cancellations and forfeitures, if applicable.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-URI https://asc.fasb.org/extlink&oid=128089324&loc=d3e5070-113901

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