Note 1 - Organization and Significant Accounting Policies (Details Textual) - USD ($) $ in Thousands					1 Months Ended	12 Months Ended					16 Months Ended	17 Months Ended
		Jun. 11, 2024	Mar. 07, 2023	Oct. 29, 2021	Jan. 31, 2025	Dec. 31, 2024		Dec. 31, 2023		Dec. 31, 2022	Jun. 30, 2024	Mar. 30, 2023
Stock Issued During Period, Shares, New Issues (in shares)	[1]					31,327,547		15,880,039
Stock Issued During Period, Value, New Issues						$ 259,328	[1],[2]	$ 159,438	[1],[2]	$ 40,580
Proceeds from Issuance of Common Stock						$ 259,328		$ 159,438		$ 40,580
October 2021 Equity Distribution Agreement [Member]
Equity Agreement, Maximum Number of Shares Issuable (in shares)				250,000,000
Stock Issued During Period, Shares, New Issues (in shares)												9,742,188
Stock Issued During Period, Value, New Issues												$ 151,800
Proceeds from Issuance of Common Stock												$ 149,300
March 2023 Equity Distribution Agreement [Member]
Equity Agreement, Maximum Number of Shares Issuable (in shares)			250,000,000
Stock Issued During Period, Shares, New Issues (in shares)											24,675,497
Stock Issued During Period, Value, New Issues											$ 228,800
Proceeds from Issuance of Common Stock											$ 225,000
June 2024 Equity Distribution Agreement [Member]
Equity Agreement, Maximum Number of Shares Issuable (in shares)		250,000,000
Stock Issued During Period, Shares, New Issues (in shares)						19,842,089
Stock Issued During Period, Value, New Issues						$ 164,900
Proceeds from Issuance of Common Stock						$ 162,100
June 2024 Equity Distribution Agreement [Member] | Subsequent Event [Member]
Stock Issued During Period, Shares, New Issues (in shares)					10,671,164
Stock Issued During Period, Value, New Issues					$ 85,100
Proceeds from Issuance of Common Stock					$ 83,800

[1] As of December 31, 2024, the Company had entered into twelve equity distribution agreements, eleven of which have either been terminated because all shares were sold or were replaced with a subsequent agreement.

[2] Net proceeds are net of the underwriters’ discount, if applicable, and other offering costs.