v3.26.1
Collateralized Transactions (Financial instruments owned and pledged where the counterparty has the right to repledge) (Details) - USD ($)
$ in Millions
Mar. 31, 2026
Dec. 31, 2025
Financial Instruments Owned and Pledged as Collateral [Line Items]    
Total financial instruments owned, at fair value $ 3,452 $ 4,982
Asset Pledged as Collateral with Right [Member] | Affiliated Entity [Member]    
Financial Instruments Owned and Pledged as Collateral [Line Items]    
Stocks 87 47
U.S. and foreign government securities 70 62
Total financial instruments owned, at fair value $ 157 $ 109