Note 4 - Repurchase Agreements - Schedule of Repurchase Agreements (Details) - USD ($) $ in Thousands	Sep. 30, 2025	Dec. 31, 2024
Fair value of securities pledged, including accrued interest receivable	$ 8,357,969	$ 5,231,921
Repurchase agreement liabilities associated with these securities	$ 8,006,978	$ 5,025,543
Net weighted average borrowing rate	4.33%	4.66%
Maturity Overnight [Member]
Fair 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 value of securities pledged, including accrued interest receivable	$ 6,396,320	$ 4,850,491
Repurchase agreement liabilities associated with these securities	$ 6,128,953	$ 4,656,303
Net weighted average borrowing rate	4.37%	4.66%
Maturity 30 to 90 Days [Member]
Fair value of securities pledged, including accrued interest receivable	$ 1,416,980	$ 199,993
Repurchase agreement liabilities associated with these securities	$ 1,355,453	$ 192,338
Net weighted average borrowing rate	4.26%	4.56%
Maturity Greater than 90 Days [Member]
Fair value of securities pledged, including accrued interest receivable	$ 544,669	$ 181,437
Repurchase agreement liabilities associated with these securities	$ 522,572	$ 176,902
Net weighted average borrowing rate	4.13%	4.76%