Collateralized Transactions (Financial instruments owned and pledged where the counterparty has the right to repledge) (Details) - USD ($) $ in Millions |
Jun. 30, 2025 |
Dec. 31, 2024 |
|---|---|---|
| Financial Instruments Owned and Pledged as Collateral [Line Items] | ||
| Total financial instruments owned, at fair value | $ 3,856 | $ 1,924 |
| Asset Pledged as Collateral with Right [Member] | Affiliated Entity [Member] | ||
| Financial Instruments Owned and Pledged as Collateral [Line Items] | ||
| Stocks | 32 | 25 |
| U.S. and foreign government securities | 47 | 52 |
| Total financial instruments owned, at fair value | $ 79 | $ 77 |