Note 7 - Offsetting Assets and Liabilities - Offsetting Liabilities (Details) - Liability [Member] - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Gross amount, recognized	$ 3,711,578	$ 3,718,343
Gross Amount, offset	0	0
Net Amount	3,711,578	3,718,343
Gross Amount, not recognized	(3,704,080)	(3,705,649)
Gross amount, not offset	(7,483)	(12,694)
Net amount, after deduction	15	0
Repurchase Agreements [Member]
Gross amount, recognized	3,711,498	3,705,649
Gross Amount, offset	0	0
Net Amount	3,711,498	3,705,649
Gross Amount, not recognized	(3,704,080)	(3,705,649)
Gross amount, not offset	(7,418)	0
Net amount, after deduction	0	0
TBA Contracts [Member]
Gross amount, recognized	80	12,694
Gross Amount, offset	0	0
Net Amount	80	12,694
Gross Amount, not recognized	0	0
Gross amount, not offset	(65)	(12,694)
Net amount, after deduction	$ 15	$ 0