Note 4 - Repurchase Agreements - Schedule of Repurchase Agreements (Details) - USD ($) $ in Thousands	Dec. 31, 2024	Dec. 31, 2023
Fair market value of securities pledged, including accrued interest receivable	$ 5,231,921	$ 3,900,476
Repurchase agreement liabilities associated with these securities	$ 5,025,543	$ 3,705,649
Net weighted average borrowing rate	4.66%	5.55%
Maturity Overnight [Member]
Fair market value of securities pledged, including accrued interest receivable	$ 0	$ 0
Repurchase agreement liabilities associated with these securities	$ 0	$ 0
Net weighted average borrowing rate	0.00%	0.00%
Maturity 2 to 30 Days [Member]
Fair market value of securities pledged, including accrued interest receivable	$ 4,850,491	$ 3,125,315
Repurchase agreement liabilities associated with these securities	$ 4,656,303	$ 2,966,650
Net weighted average borrowing rate	4.66%	5.55%
Maturity 30 to 90 Days [Member]
Fair market value of securities pledged, including accrued interest receivable	$ 199,993	$ 710,055
Repurchase agreement liabilities associated with these securities	$ 192,338	$ 674,696
Net weighted average borrowing rate	4.56%	5.54%
Maturity Greater than 90 Days [Member]
Fair market value of securities pledged, including accrued interest receivable	$ 181,437	$ 65,106
Repurchase agreement liabilities associated with these securities	$ 176,902	$ 64,303
Net weighted average borrowing rate	4.76%	5.46%