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Investment Securities - Narrative (Details) | Sep. 30, 2025 USD ($) security | Dec. 31, 2024 USD ($)
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Certain Loans Acquired in Transfer Accounted for as Debt Securities Accretable Yield Movement Schedule [Line Items] |  |
Number of investment securities in a loss position for less than twelve months | security | 1 |
Number of investment securities in a loss position for twelve months or longer | security | 220 |
AFS allowance for credit loss | $ 0 |
Held-to-maturity, allowance for credit loss, measurement input | 0 |
Collateral Pledged |  |
Certain Loans Acquired in Transfer Accounted for as Debt Securities Accretable Yield Movement Schedule [Line Items] |  |
AFS pledged to secure deposits | 2,240,000,000 | $ 2,830,000,000
HTM pledged to secure deposits | $ 1,570,000,000 | $ 2,450,000,000

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