Note 7 - Stockholders' Equity and Stock-based Compensation Expense - Stock Option and Performance Award Activity (Details) - shares	3 Months Ended	6 Months Ended
Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Outstanding, options (in shares)			3,039,029
Options granted (in shares)			193,000
Options exercised (in shares)	0	(262,158)	0	(281,175)
Options forfeited/canceled (in shares)			(154,700)
Outstanding, options (in shares)	3,077,329		3,077,329
Performance Shares [Member]
Outstanding, performance awards (in shares)			7,142
Performance awards granted (in shares)			0
Performance awards exercised (in shares)			0
Performance awards forfeited/canceled (in shares)			0
Outstanding, performance awards (in shares)	7,142		7,142

Number of non-option equity instruments exercised by participants.

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Number of shares under non-option equity instrument agreements that were cancelled as a result of occurrence of a terminating event.

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Net number of non-option equity instruments granted to participants.

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Number of equity instruments other than options outstanding, including both vested and non-vested instruments.

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