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Note 7 - Stockholders' Equity and Stock-based Compensation Expense (Details Textual) - USD ($)		1 Months Ended	3 Months Ended		9 Months Ended
	May 05, 2022	Oct. 30, 2024	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023	Dec. 31, 2023	May 01, 2023
Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Outstanding, Weighted Average Exercise Price (in dollars per share)			$ 17.79		$ 17.79
Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Outstanding, Weighted Average Remaining Contractual Term (Year)			2 years 1 month 6 days
Share-Based Payment Arrangement, Nonvested Award, Option, Cost Not yet Recognized, Amount			$ 45,200,000		$ 45,200,000
Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Exercises in Period (in shares)			0	214,124	(0)	495,299
Proceeds from Stock Options Exercised				$ 464,000	$ 0	$ 1,417,000
Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Grants in Period, Gross (in shares)					1,273,000
Share-Based Payment Arrangement, Expense			$ 5,609,000	949,000	$ 10,547,000	2,457,000
Common Stock, Par or Stated Value Per Share (in dollars per share)			$ 0.001		$ 0.001		$ 0.001
The 2018 Equity Incentive Plan [Member]
Share-Based Compensation Arrangement by Share-Based Payment Award, Expiration Period (Year)	10 years
Share-Based Compensation Arrangement by Share-Based Payment Award, Number of Shares Authorized (in shares)	5,000,000
Common Stock, Par or Stated Value Per Share (in dollars per share)	$ 0.001
Employee Severance [Member]
Share-Based Payment Arrangement, Expense			$ 1,800,000	$ 0	$ 1,800,000	$ 0
President and Chief Executive Officer [Member] \| Subsequent Event [Member]
Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Grants in Period, Gross (in shares)		600,000
Share-Based Compensation Arrangements by Share-Based Payment Award, Options, Exercises in Period, Weighted Average Exercise Price (in dollars per share)		$ 27.42
President and Chief Executive Officer [Member] \| Subsequent Event [Member] \| Share-Based Payment Arrangement, Tranche One [Member]
Share-Based Compensation Arrangement by Share-Based Payment Award, Award Vesting Rights, Percentage		25.00%
Performance Shares [Member]
Share-Based Payment Arrangement, Nonvested Award, Excluding Option, Cost Not yet Recognized, Amount			$ 100,000		$ 100,000
Stock Options Net Settled in Satisfaction of the Exercise Price [Member]
Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Exercises in Period (in shares)				3,853		101,058
Proceeds from Stock Options Exercised				$ 0		$ 0
At-the-market Common Stock Offering [Member]
Equity Offering, Maximum Amount								$ 200,000,000
Equity Offering, Percentage of Commission								3.00%
Stock Issued During Period, Shares, New Issues (in shares)			0		0