Note 2 - Mortgage-backed Securities, At Fair Value (Details Textual) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023	Dec. 31, 2023
Notional Balance, Interest Only Securities Portfolio, Amount	$ 92,000		$ 92,000		$ 98,600
Notional Balance, Inverse Interest Only Securities Portfolio, Amount	25,000		25,000		$ 26,800
Collateralized Mortgage-Backed Securities [Member]
Investment Sold at Carrying Value	$ (0)	$ (0)	$ (221,700)	$ (0)