Commitments, Contingencies and Guarantees (Narrative) (Details) - USD ($) $ in Millions |
Sep. 30, 2024 |
Dec. 31, 2023 |
|---|---|---|
| Long-term Purchase Commitment [Line Items] | ||
| Fannie Mae DUS Servicing Portfolio, Amount | $ 6,700 | $ 6,200 |
| Fannie Mae Servicing Portfolio, Other, Amount | 634 | 653 |
| Maximum Quantifiable Fannie Mae Loss Share Guarantee | $ 2,300 | $ 2,300 |