Commitments, Contingencies and Guarantees (Narrative) (Details) - USD ($) $ in Millions	Mar. 31, 2024	Dec. 31, 2023
Long-term Purchase Commitment [Line Items]
Fannie Mae DUS Servicing Portfolio, Amount	$ 6,400	$ 6,200
Fannie Mae Servicing Portfolio, Other, Amount	580	$ 653
Maximum Quantifiable Fannie Mae Loss Share Guarantee	$ 2,300

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