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Investment Securities - Investment Securities, Narrative (Details) | 3 Months Ended | 6 Months Ended |
--- | --- | --- | ---
Jun. 30, 2024 USD ($) security | Mar. 31, 2024 USD ($) | Jun. 30, 2023 USD ($) | Jun. 30, 2024 USD ($) security | Jun. 30, 2023 USD ($) | Dec. 31, 2023 USD ($) security
Schedule of Investments [Line Items] |  |  |  |  |  |
Federal home loan bank stock | $ | $ 1,565,000,000 |  |  | $ 1,565,000,000 |  | $ 1,392,000,000
Federal reserve bank stock | $ | 218,000,000 |  |  | 218,000,000 |  | $ 203,000,000
Gross realized gains | $ | 1,000,000 |  |  | 1,000,000 |  |
Gross realized losses | $ | $ 1,000,000 |  |  | $ 1,000,000 |  |
Available-for-sale securities sold | $ |  |  | $ 0 |  | $ 0 |
Collateralized Debt Obligations |  |  |  |  |  |
Schedule of Investments [Line Items] |  |  |  |  |  |
Number of securities continuous unrealized loss position more than twelve months | 237 |  |  | 237 |  | 84
Capital trust notes |  |  |  |  |  |
Schedule of Investments [Line Items] |  |  |  |  |  |
Number of securities continuous unrealized loss position more than twelve months | 6 |  |  | 6 |  | 6
Asset-backed securities |  |  |  |  |  |
Schedule of Investments [Line Items] |  |  |  |  |  |
Number of securities continuous unrealized loss position more than twelve months | 6 |  |  | 6 |  | 8
Corporate bonds |  |  |  |  |  |
Schedule of Investments [Line Items] |  |  |  |  |  |
Number of securities continuous unrealized loss position more than twelve months | 12 |  |  | 12 |  | 12
Provision for credit loss | $ | $ 3,000,000 | $ 1,000,000 |  |  |  |
US Government Agencies Debt Securities |  |  |  |  |  |
Schedule of Investments [Line Items] |  |  |  |  |  |
Number of securities continuous unrealized loss position more than twelve months | 36 |  |  | 36 |  | 37
Mortgage-Related Debt Securities: |  |  |  |  |  |
Schedule of Investments [Line Items] |  |  |  |  |  |
Number of securities continuous unrealized loss position more than twelve months | 334 |  |  | 334 |  | 302
Mutual funds and common stock |  |  |  |  |  |
Schedule of Investments [Line Items] |  |  |  |  |  |
Number of securities continuous unrealized loss position more than twelve months |  |  |  |  |  | 1
Municipal bonds |  |  |  |  |  |
Schedule of Investments [Line Items] |  |  |  |  |  |
Number of securities continuous unrealized loss position more than twelve months | 1 |  |  | 1 |  | 1
Foreign notes |  |  |  |  |  |
Schedule of Investments [Line Items] |  |  |  |  |  |
Number of securities continuous unrealized loss position more than twelve months | 1 |  |  | 1 |  | 1
Private Collateralized Mortgage Obligations |  |  |  |  |  |
Schedule of Investments [Line Items] |  |  |  |  |  |
Number of securities continuous unrealized loss position more than twelve months | 2 |  |  | 2 |  |
Federal Home Loan Bank of New York |  |  |  |  |  |
Schedule of Investments [Line Items] |  |  |  |  |  |
Federal home loan bank stock | $ | $ 1,000,000,000 |  |  | $ 1,000,000,000 |  | $ 861,000,000
Federal Home Loan Bank of Indianapolis |  |  |  |  |  |
Schedule of Investments [Line Items] |  |  |  |  |  |
Federal home loan bank stock | $ | $ 329,000,000 |  |  | $ 329,000,000 |  | $ 329,000,000

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