Derivative Instruments and Hedging Activities - Futures (Details) - Futures, net - USD ($) |
6 Months Ended | 12 Months Ended |
|---|---|---|
Jun. 30, 2026 |
Dec. 31, 2025 |
|
| Derivative [Line Items] | ||
| Notional | $ (5,637,700,000) | $ (4,357,800,000) |
| Carrying Value | $ 0 | $ 0 |
| Weighted Average Months to Expiration | 2 years 6 months 1 day | 2 years 11 months 30 days |
| U.S. Treasury Futures | 2 Years | ||
| Derivative [Line Items] | ||
| Notional | $ (2,052,400,000) | $ (1,448,000,000) |
| Carrying Value | $ 0 | $ 0 |
| Weighted Average Months to Expiration | 3 months 1 day | 2 months 29 days |
| U.S. Treasury Futures | 5 Year | ||
| Derivative [Line Items] | ||
| Notional | $ (1,574,300,000) | $ (1,047,400,000) |
| Carrying Value | $ 0 | $ 0 |
| Weighted Average Months to Expiration | 3 months 1 day | 2 months 29 days |
| U.S. Treasury Futures | 10 Year | ||
| Derivative [Line Items] | ||
| Notional | $ (55,100,000) | $ (115,700,000) |
| Carrying Value | $ 0 | $ 0 |
| Weighted Average Months to Expiration | 2 months 22 days | 2 months 18 days |
| U.S. Treasury Futures | 20 Year | ||
| Derivative [Line Items] | ||
| Notional | $ (90,100,000) | $ (283,300,000) |
| Carrying Value | $ 0 | $ 0 |
| Weighted Average Months to Expiration | 2 months 22 days | 2 months 18 days |
| Eris SOFR Swap Futures | 5 Year | ||
| Derivative [Line Items] | ||
| Notional | $ (1,216,000,000) | $ (1,200,000,000) |
| Carrying Value | $ 0 | $ 0 |
| Weighted Average Months to Expiration | 5 years 2 months 18 days | 5 years 2 months 17 days |
| Eris SOFR Swap Futures | 10 Year | ||
| Derivative [Line Items] | ||
| Notional | $ (830,000,000) | $ (830,000,000) |
| Carrying Value | $ 0 | $ 0 |
| Weighted Average Months to Expiration | 10 years 2 months 20 days | 10 years 2 months 19 days |