Clearing Operations (Investment Policy) (Details) - USD ($) $ in Millions |
Sep. 30, 2026 |
Dec. 31, 2025 |
|---|---|---|
| Clearing Operations [Line Items] | ||
| Default funds and margin deposits assets | $ 2,530 | $ 5,842 |
| Restricted cash and cash equivalents | ||
| Clearing Operations [Line Items] | ||
| Default funds and margin deposits assets | 755 | 3,120 |
| Demand deposits | ||
| Clearing Operations [Line Items] | ||
| Default funds and margin deposits assets | 715 | 3,011 |
| Central bank certificates | ||
| Clearing Operations [Line Items] | ||
| Default funds and margin deposits assets | 40 | 109 |
| Investments | ||
| Clearing Operations [Line Items] | ||
| Default funds and margin deposits assets | 1,775 | 2,722 |
| European government debt securities | ||
| Clearing Operations [Line Items] | ||
| Default funds and margin deposits assets | 417 | 292 |
| Reverse repurchase agreements | ||
| Clearing Operations [Line Items] | ||
| Default funds and margin deposits assets | 1,311 | 2,245 |
| Multilateral development bank debt securities | ||
| Clearing Operations [Line Items] | ||
| Default funds and margin deposits assets | $ 47 | $ 185 |