Note 2 - Mortgage-backed Securities, At Fair Value (Details Textual) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Dec. 31, 2023
Notional Balance, Interest Only Securities Portfolio, Amount	$ 88,800		$ 98,600
Notional Balance, Inverse Interest Only Securities Portfolio, Amount	23,400		$ 26,800
Investment Sold at Carrying Value	(287,732)	$ 0
Collateralized Mortgage-Backed Securities [Member]
Investment Sold at Carrying Value	$ (221,700)