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Investment Securities - Summary of Investment Securities (Details) - USD ($) $ in Millions | Mar. 31, 2025 | Dec. 31, 2024
--- | --- | ---
Debt securities available-for-sale |  |
Amortized Cost | $ 13,588 | $ 11,295
Gross Unrealized Gain | 66 | 39
Gross Unrealized Loss | 835 | 932
Cumulative Amount of Fair Value Hedging Adjustment | 7 |
Fair Value | 12,826 | 10,402
Interest receivable | $ 40 | $ 35
Debt Securities, Available-for-Sale, Accrued Interest, after Allowance for Credit Loss, Statement of Financial Position [Extensible Enumeration] | Other assets | Other assets
Mortgage-Related Debt Securities: |  |
Debt securities available-for-sale |  |
Amortized Cost | $ 10,506 | $ 9,155
Gross Unrealized Gain | 61 | 33
Gross Unrealized Loss | 551 | 615
Fair Value | 10,016 | 8,573
GSE CMOs |  |
Debt securities available-for-sale |  |
Amortized Cost | 9,096 | 7,724
Gross Unrealized Gain | 53 | 27
Gross Unrealized Loss | 405 | 447
Fair Value | 8,744 | 7,304
GSE certificates |  |
Debt securities available-for-sale |  |
Amortized Cost | 1,254 | 1,273
Gross Unrealized Gain | 1 | 0
Gross Unrealized Loss | 145 | 167
Fair Value | 1,110 | 1,106
Private Label collateralized mortgage obligations |  |
Debt securities available-for-sale |  |
Amortized Cost | 156 | 158
Gross Unrealized Gain | 7 | 6
Gross Unrealized Loss | 1 | 1
Fair Value | 162 | 163
Other Debt Securities: |  |
Debt securities available-for-sale |  |
Amortized Cost | 3,082 | 2,140
Gross Unrealized Gain | 5 | 6
Gross Unrealized Loss | 284 | 317
Cumulative Amount of Fair Value Hedging Adjustment | 7 |
Fair Value | 2,810 | 1,829
GSE debentures |  |
Debt securities available-for-sale |  |
Amortized Cost | 1,502 | 1,502
Gross Unrealized Gain | 0 | 0
Gross Unrealized Loss | 261 | 299
Fair Value | 1,241 | 1,203
U. S. Treasury obligations |  |
Debt securities available-for-sale |  |
Amortized Cost | 1,002 |
Gross Unrealized Gain | 0 |
Gross Unrealized Loss | 1 |
Cumulative Amount of Fair Value Hedging Adjustment | 7 |
Fair Value | 1,008 |
Corporate bonds |  |
Debt securities available-for-sale |  |
Amortized Cost | 259 | 314
Gross Unrealized Gain | 0 | 0
Gross Unrealized Loss | 10 | 6
Fair Value | 249 | 308
Asset-backed securities |  |
Debt securities available-for-sale |  |
Amortized Cost | 232 | 237
Gross Unrealized Gain | 0 | 1
Gross Unrealized Loss | 3 | 2
Fair Value | 229 | 236
Capital trust notes |  |
Debt securities available-for-sale |  |
Amortized Cost | 47 | 47
Gross Unrealized Gain | 5 | 5
Gross Unrealized Loss | 9 | 10
Fair Value | 43 | 42
Foreign notes |  |
Debt securities available-for-sale |  |
Amortized Cost | 35 | 35
Gross Unrealized Gain | 0 | 0
Gross Unrealized Loss | 0 | 0
Fair Value | 35 | 35
Municipal bonds |  |
Debt securities available-for-sale |  |
Amortized Cost | 5 | 5
Gross Unrealized Gain | 0 | 0
Gross Unrealized Loss | 0 | 0
Fair Value | $ 5 | $ 5

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