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Fair Value Measurement - Assets and Liabilities Measured at Fair Value on Recurring Basis (Details) - USD ($) $ in Millions | 3 Months Ended |  |  |
--- | --- | --- | --- | ---
Mar. 31, 2024 | Dec. 31, 2024 | Dec. 31, 2023 | Dec. 31, 2022
Assets: |  |  |  |
Fair Value |  | $ 83,013 | $ 79,117 |
Loans held for sale |  | $ 87 | $ 347 |
Derivative Asset, Statement of Financial Position [Extensible Enumeration] |  | Other assets | Other assets |
Other assets: |  |  |  |
Derivative assets, gross amount |  | $ 2,232 | $ 2,675 |
Derivative Asset, netting adjustments |  | (1,056) | (1,005) |
Derivative asset |  | 1,176 | 1,670 |
Liabilities: |  |  |  |
Derivative liabilities, gross amount |  | 2,032 | 2,932 |
Derivative Liability, netting adjustments |  | (304) | (597) |
Derivative liability |  | $ 1,728 | $ 2,335 |
Derivative Liability, Statement of Financial Position [Extensible Enumeration] |  | Other liabilities | Other liabilities |
Net valuation allowance |  | $ 1 | $ 2 |
Level 1 |  |  |  |
Assets: |  |  |  |
Loans held for sale |  | 0 | 0 |
Level 2 |  |  |  |
Assets: |  |  |  |
Loans held for sale |  | 115 | 515 |
Level 3 |  |  |  |
Assets: |  |  |  |
Loans held for sale |  | 0 | 0 |
Recurring |  |  |  |
Assets: |  |  |  |
Fair Value |  | 83,013 | 79,117 |
Loans held for sale |  | 87 | 347 |
Other assets: |  |  |  |
Derivative asset |  | 1,176 | 1,670 |
Other |  | 723 | 627 |
Total |  | 84,999 | 81,761 |
Liabilities: |  |  |  |
Derivative liability |  | 1,728 | 2,335 |
Recurring | Level 1 |  |  |  |
Assets: |  |  |  |
Fair Value |  | 6,233 | 5,408 |
Loans held for sale |  | 0 | 0 |
Other assets: |  |  |  |
Derivative assets, gross amount |  | 510 | 788 |
Other |  | 689 | 589 |
Total |  | 7,432 | 6,785 |
Liabilities: |  |  |  |
Derivative liabilities, gross amount |  | 384 | 449 |
Deferred compensation plan assets |  | 688 | 578 |
Recurring | Level 2 |  |  |  |
Assets: |  |  |  |
Fair Value |  | 76,662 | 73,431 |
Loans held for sale |  | 87 | 347 |
Other assets: |  |  |  |
Derivative assets, gross amount |  | 1,039 | 1,001 |
Other |  | 0 | 3 |
Total |  | 77,788 | 74,782 |
Liabilities: |  |  |  |
Derivative liabilities, gross amount |  | 1,034 | 1,655 |
Recurring | Level 3 |  |  |  |
Assets: |  |  |  |
Fair Value |  | 118 | 278 |
Loans held for sale |  | 0 | 0 |
Other assets: |  |  |  |
Derivative assets, gross amount |  | 683 | 886 | $ 79
Other |  | 34 | 35 |
Total |  | 835 | 1,199 |
Liabilities: |  |  |  |
Derivative liabilities, gross amount |  | 614 | 828 | $ 74
Retained interests in securitizations |  | 34 | 35 |
Recurring | Fair Value Inputs Level 1 And Level 2 |  |  |  |
Liabilities: |  |  |  |
Equity securities |  | 1 | 14 |
Debt and equity securities, unrealized gain (loss) | $ 5 |  |  |
U.S. Treasury securities |  |  |  |
Assets: |  |  |  |
Fair Value |  | 6,110 | 5,282 |
U.S. Treasury securities | Recurring |  |  |  |
Assets: |  |  |  |
Fair Value |  | 6,110 | 5,282 |
U.S. Treasury securities | Recurring | Level 1 |  |  |  |
Assets: |  |  |  |
Fair Value |  | 6,110 | 5,282 |
U.S. Treasury securities | Recurring | Level 2 |  |  |  |
Assets: |  |  |  |
Fair Value |  | 0 | 0 |
U.S. Treasury securities | Recurring | Level 3 |  |  |  |
Assets: |  |  |  |
Fair Value |  | 0 | 0 |
Total RMBS |  |  |  |
Assets: |  |  |  |
Fair Value |  | 65,328 | 63,638 |
Total RMBS | Recurring |  |  |  |
Assets: |  |  |  |
Fair Value |  | 65,328 | 63,638 |
Total RMBS | Recurring | Level 1 |  |  |  |
Assets: |  |  |  |
Fair Value |  | 0 | 0 |
Total RMBS | Recurring | Level 2 |  |  |  |
Assets: |  |  |  |
Fair Value |  | 65,212 | 63,492 |
Total RMBS | Recurring | Level 3 |  |  |  |
Assets: |  |  |  |
Fair Value |  | 116 | 146 |
CMBS | Recurring |  |  |  |
Assets: |  |  |  |
Fair Value |  | 7,825 | 8,323 |
CMBS | Recurring | Level 1 |  |  |  |
Assets: |  |  |  |
Fair Value |  | 0 | 0 |
CMBS | Recurring | Level 2 |  |  |  |
Assets: |  |  |  |
Fair Value |  | 7,823 | 8,191 |
CMBS | Recurring | Level 3 |  |  |  |
Assets: |  |  |  |
Fair Value |  | 2 | 132 |
Other securities |  |  |  |
Assets: |  |  |  |
Fair Value |  | 3,750 | 1,874 |
Other securities | Recurring |  |  |  |
Assets: |  |  |  |
Fair Value |  | 3,750 | 1,874 |
Other securities | Recurring | Level 1 |  |  |  |
Assets: |  |  |  |
Fair Value |  | 123 | 126 |
Other securities | Recurring | Level 2 |  |  |  |
Assets: |  |  |  |
Fair Value |  | 3,627 | 1,748 |
Other securities | Recurring | Level 3 |  |  |  |
Assets: |  |  |  |
Fair Value |  | $ 0 | $ 0 |

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