Note 6 - Stockholders' Equity (Details Textual) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023	Feb. 18, 2021
Subsidiary or Equity Method Investee [Line Items]
Share-Based Payment Arrangement, Expense	$ 3,000	$ 1,500	$ 4,100	$ 2,700
Share-Based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Amount, Total	$ 12,100		$ 12,100
Share-Based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Period for Recognition (Year)			2 years 3 months 18 days
Share-Based Payment Arrangement, Shares Withheld for Tax Withholding Obligation (in shares)			277,966
Share-Based Payment Arrangement, Decrease for Tax Withholding Obligation			$ 1,200
Shares Withheld for Tax Withholding Obligation, Price Per Share (in dollars per share)	$ 4.31		$ 4.31
Equity Distribution Agreement, Maximum Number of Shares to be Sold (in shares)	14,753,958		14,753,958
Proceeds from Issuance or Sale of Equity			$ 1,100
Payments of Stock Issuance Costs			$ 40
Common stock issued under ATM program, net shares		2,080,060	248,561	4,253,334
At the market Offering [Member]
Subsidiary or Equity Method Investee [Line Items]
Equity Distribution Agreement, Maximum Number of Shares to be Sold (in shares)					60,000,000
At the market Offering [Member] | At The Market Equity Distribution Agreement [Member]
Subsidiary or Equity Method Investee [Line Items]
Proceeds from Issuance or Sale of Equity			$ 76,700
Payments of Stock Issuance Costs			$ 1,200