Investments in Securities - Schedule of Investments Classified by Contractual Maturity Date (Details) - USD ($) $ in Thousands |
Sep. 30, 2026 |
Dec. 31, 2025 |
|---|---|---|
| Fair Value | ||
| Less than 1 year | $ 0 | $ 0 |
| Greater than or equal to 1 year and less than 3 years | 0 | 1,934,537 |
| Greater than or equal to 3 years and less than 5 years | 648,954 | 8,305,993 |
| Greater than or equal to 5 years | 19,816,938 | 9,775,219 |
| Totals | 20,465,892 | 20,015,749 |
| Amortized Cost | ||
| Less than 1 year | 0 | 0 |
| Greater than or equal to 1 year and less than 3 years | 0 | 1,910,316 |
| Greater than or equal to 3 years and less than 5 years | 679,929 | 8,201,320 |
| Greater than or equal to 5 years | 21,008,850 | 9,744,210 |
| Totals | $ 21,688,779 | $ 19,855,846 |