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Securities - Narrative (Details) | Dec. 31, 2023 USD ($) security | Dec. 31, 2022 USD ($) security
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Other than Temporary Impairment, Credit Losses Recognized in Earnings [Line Items] |  |
AFS and HTM, accrued interest | $ | $ 44,000,000 | $ 42,000,000
Number of available-for-sale debt securities in an unrealized loss position | security | 547 | 559
Allowance for credit loss | $ | $ 0 | $ 0
HTM securities allowance for credit loss | $ | 0 | 0
Asset Pledged as Collateral |  |
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Line Items] |  |
Amortized Cost | $ | $ 7,000,000,000 | $ 794,000,000
U.S. government agency and U.S. government-sponsored enterprise mortgage-backed securities |  |
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Line Items] |  |
Number of available-for-sale debt securities in an unrealized loss position | security | 255 | 263
Non-agency mortgage-backed securities |  |
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Line Items] |  |
Number of available-for-sale debt securities in an unrealized loss position | security | 99 | 100
Corporate debt securities |  |
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Line Items] |  |
Number of available-for-sale debt securities in an unrealized loss position | security | 66 | 68

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