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Derivatives - Derivatives Associated with Cash Flow Hedges and Mortgage Banking Hedges (Details) - Hedging Instruments And Hedged Items - USD ($) $ in Millions | Sep. 30, 2024 | Dec. 31, 2023
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Interest Rate Contract | Cash Flow Hedge |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |
Variability in cash flows related to debt instruments (primarily loans) | $ 5,000 | $ 5,200
Interest Rate Swap | Cash Flow Hedge |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |
Notional | 5,000 | 5,200
Assets | 0 | 0
Liabilities | 9 | 32
Option contracts written | Mortgage Banking Hedges |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |
Notional | 77 | 55
Assets | 1 | 1
Liabilities | 0 | 0
Forward contracts written | Mortgage Banking Hedges |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |
Notional | 123 | 93
Assets | 0 | 0
Liabilities | $ 0 | $ 1

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