Note 7 - Offsetting Assets and Liabilities - Offsetting Liabilities (Details) - Liability [Member] - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Gross amount, recognized	$ 3,718,343	$ 3,385,606
Gross Amount, offset	0	0
Net Amount	3,718,343	3,385,606
Gross Amount, not recognized	(3,705,649)	(3,365,104)
Gross amount, not offset	(12,694)	(14,520)
Net amount, after deduction	0	5,982
Repurchase Agreements [Member]
Gross amount, recognized	3,705,649	3,378,445
Gross Amount, offset	0	0
Net Amount	3,705,649	3,378,445
Gross Amount, not recognized	(3,705,649)	(3,365,104)
Gross amount, not offset	0	(13,341)
Net amount, after deduction	0	0
TBA Contracts [Member]
Gross amount, recognized	12,694	1,179
Gross Amount, offset	0	0
Net Amount	12,694	1,179
Gross Amount, not recognized	0	0
Gross amount, not offset	(12,694)	(1,179)
Net amount, after deduction	$ 0	0
Payer Swaptions [Member]
Gross amount, recognized		5,982
Gross Amount, offset		0
Net Amount		5,982
Gross Amount, not recognized		0
Gross amount, not offset		0
Net amount, after deduction		$ 5,982