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Fair Value Measurement (Narrative) (Details) - USD ($) $ in Millions | 3 Months Ended | 9 Months Ended
--- | --- | ---
Sep. 30, 2025 | Sep. 30, 2024 | Sep. 30, 2025 | Sep. 30, 2024
Fair Value Disclosures [Abstract] |  |  |  |
Contractually Specified Servicing Fee, Late Fee, and Ancillary Fee Earned in Exchange for Servicing Financial Asset | $ 5 | $ 6 | $ 17 | $ 18
Unrealized gains (losses) arising during the period | (8) | (2) | 0 | 4
Changes in unrealized gains and losses on junior subordinated debentures carried at fair value, net of taxes | (6) | (1) | 0 | 3
Fair Value, Option, Quantitative Disclosures [Line Items] |  |  |  |
Net increase (decrease) in fair value | $ 4 | 9 | 11 | (3)
Residential Mortgage Banking Revenue |  |  |  |
Fair Value, Option, Quantitative Disclosures [Line Items] |  |  |  |
Net increase (decrease) in fair value |  | $ 1 | $ 1 | $ 1

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