Note 4 - Repurchase Agreements and Reverse Purchase Agreements - Schedule of Repurchase Agreements (Details) - USD ($) $ in Thousands	Dec. 31, 2025	Dec. 31, 2024
Fair market value of securities pledged, including accrued interest receivable	$ 10,551,280	$ 5,231,921
Repurchase agreement liabilities associated with these securities	$ 10,115,466	$ 5,025,543
Net weighted average borrowing rate	3.98%	4.66%
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	$ 6,821,306	$ 4,850,491
Repurchase agreement liabilities associated with these securities	$ 6,544,072	$ 4,656,303
Net weighted average borrowing rate	4.00%	4.66%
Maturity 30 to 90 Days [Member]
Fair market value of securities pledged, including accrued interest receivable	$ 3,445,678	$ 199,993
Repurchase agreement liabilities associated with these securities	$ 3,297,567	$ 192,338
Net weighted average borrowing rate	3.96%	4.56%
Maturity Greater than 90 Days [Member]
Fair market value of securities pledged, including accrued interest receivable	$ 284,296	$ 181,437
Repurchase agreement liabilities associated with these securities	$ 273,827	$ 176,902
Net weighted average borrowing rate	3.92%	4.76%