Note 8 - Capital Stock - Issuance of Common Stock (Details) - USD ($)		3 Months Ended													9 Months Ended				12 Months Ended
		Sep. 30, 2024		Jun. 30, 2024	[1]	Mar. 31, 2024	[1]	Dec. 31, 2023	Sep. 30, 2023		Jun. 30, 2023	[1]	Mar. 31, 2023	[1]	Sep. 30, 2024		Sep. 30, 2023		Dec. 31, 2023
Price per share (in dollars per share)	[1],[2]
Issuance of common stock pursuant to public offerings, net (in shares)	[1]														26,794,480				15,880,039
Issuance of common stock pursuant to public offerings, net		$ 109,891,000							$ 80,426,000						$ 223,698,000	[1],[3]	$ 159,438,000		$ 159,438,000	[1],[3]
At the Market Offering Program [Member]
Price per share (in dollars per share)		$ 8.25	[1],[2]	$ 8.4	[2]	$ 8.8	[2]	$ 0	$ 9.54	[1],[2]	$ 9.95	[2]	$ 11.77	[2]	$ 8.25	[1],[2]	$ 9.54	[1],[2]	$ 0
Issuance of common stock pursuant to public offerings, net (in shares)		13,314,022	[1]	11,990,383		1,490,075		0	8,432,086	[1]	4,757,953		2,690,000
Issuance of common stock pursuant to public offerings, net		$ 109,891,000	[1],[3]	$ 100,698,000	[3]	$ 13,109,000	[3]	$ 0	$ 80,426,000	[1],[3]	$ 47,355,000	[3]	$ 31,657,000	[3]

[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] Weighted average price received per share is after deducting the underwriters’ discount, if applicable, and other offering costs.

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