Note 1 - Organization and Significant Accounting Policies (Details Textual) - USD ($)					1 Months Ended	3 Months Ended						4 Months Ended	6 Months Ended			9 Months Ended	12 Months Ended		16 Months Ended
		Feb. 24, 2025	Jun. 11, 2024	Mar. 07, 2023	Jul. 24, 2025	Jun. 30, 2025	Mar. 31, 2025	Dec. 31, 2024		Jun. 30, 2024	Mar. 31, 2024	Jun. 30, 2025	Jun. 30, 2025		Jun. 30, 2024	Feb. 28, 2025	Dec. 31, 2024		Jun. 30, 2024
Stock Issued During Period, Shares, New Issues (in shares)	[1]							4,533,067					45,026,250				31,327,547
Stock Issued During Period, Value, New Issues						$ 139,416,000	$ 205,424,000	$ 35,630	[1],[2]	$ 100,698,000	$ 13,109,000		$ 344,840,000	[1],[2]			$ 259,328,000	[1],[2]
Proceeds from Issuance of Common Stock													$ 344,840,000		$ 113,807,000
March 2023 Equity Distribution Agreement [Member]
Equity Agreement, Maximum Number of Shares Issuable				$ 250,000,000
Stock Issued During Period, Shares, New Issues (in shares)																			24,675,497
Stock Issued During Period, Value, New Issues																			$ 228,800,000
Proceeds from Issuance of Common Stock																			$ 225,000,000
June 2024 Equity Distribution Agreement [Member]
Equity Agreement, Maximum Number of Shares Issuable			$ 250,000,000
Stock Issued During Period, Shares, New Issues (in shares)																30,513,253
Stock Issued During Period, Value, New Issues																$ 250,000,000
Proceeds from Issuance of Common Stock																$ 245,800,000
February 2025 Equity Distribution Agreement [Member]
Equity Agreement, Maximum Number of Shares Issuable		$ 350,000,000
Stock Issued During Period, Shares, New Issues (in shares)												34,355,086
Stock Issued During Period, Value, New Issues												$ 265,400,000
Proceeds from Issuance of Common Stock												$ 261,200,000
February 2025 Equity Distribution Agreement [Member] | Subsequent Event [Member]
Stock Issued During Period, Shares, New Issues (in shares)					162,498
Stock Issued During Period, Value, New Issues					$ 1,200,000
Proceeds from Issuance of Common Stock					$ 1,200,000

[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.