Note 1 - Organization and Significant Accounting Policies (Details Textual) - USD ($) $ in Thousands					1 Months Ended	3 Months Ended		4 Months Ended	9 Months Ended			12 Months Ended		16 Months Ended	17 Months Ended
		Jun. 11, 2024	Mar. 07, 2023	Oct. 29, 2021	Oct. 30, 2024	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2024		Sep. 30, 2023	Dec. 31, 2023		Jun. 30, 2024	Mar. 30, 2023
Stock Issued During Period, Shares, New Issues (in shares)	[1]								26,794,480			15,880,039
Stock Issued During Period, Value, New Issues						$ 109,891	$ 80,426		$ 223,698	[1],[2]	$ 159,438	$ 159,438	[1],[2]
Proceeds from Issuance of Common Stock									$ 223,698		$ 159,438
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)								15,309,022
Stock Issued During Period, Value, New Issues								$ 128,600
Proceeds from Issuance of Common Stock								$ 126,500
June 2024 Equity Distribution Agreement [Member] | Subsequent Event [Member]
Stock Issued During Period, Shares, New Issues (in shares)					332,000
Stock Issued During Period, Value, New Issues					$ 2,700
Proceeds from Issuance of Common Stock					$ 2,700

[1] The Company has entered into eleven equity distribution agreements, ten 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.