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Derivatives - Gains/(Losses) on Derivatives Associated with Cash Flow Hedges and Mortgage Banking Hedges (Details) - USD ($) $ in Millions | 3 Months Ended | 9 Months Ended
--- | --- | ---
Sep. 30, 2025 | Sep. 30, 2024 | Sep. 30, 2025 | Sep. 30, 2024
Derivative Instruments, Gain (Loss) [Line Items] |  |  |  |
Loss expected to be reclassified to earnings in the next twelve months | $ (7) | $ (7) | $ (7) | $ (7)
Cash Flow Hedge | Hedging Instruments And Hedged Items |  |  |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |  |  |
Gains (losses), cash flow hedges | (4) | 45 | 21 | (13)
Gain (loss) reclassified from AOCI into interest income | 9 | 13 | 27 | 39
Interest rate contracts | Cash Flow Hedge | Hedging Instruments And Hedged Items |  |  |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |  |  |
Gains (losses), cash flow hedges | 7 | 77 | 64 | 35
Option contracts written | Mortgage Banking Hedges | Hedging Instruments And Hedged Items |  |  |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |  |  |
Gains (losses) on derivative instruments | 0 | 0 | 0 | 0
Forward contracts written | Mortgage Banking Hedges | Hedging Instruments And Hedged Items |  |  |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |  |  |
Gains (losses) on derivative instruments | $ 1 | $ 3 | $ 0 | $ (5)

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- Definition The estimated net amount of existing gains or losses on cash flow hedges at the reporting date expected to be reclassified to earnings within the next 12 months. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 815 -SubTopic 30 -Name Accounting Standards Codification -Section 50 -Paragraph 1 -Subparagraph (c) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480870/815-30-50-1 + Details
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