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Fair value measurements - Carrying Amounts and Estimated Fair Value for Financial Instrument Assets (Liabilities) (Detail) - USD ($) $ in Millions | Sep. 30, 2025 | Dec. 31, 2024
--- | --- | ---
Cash and cash equivalents |  |  |
Interest-bearing deposits at banks |  | $ 16,751 | $ 18,873
Investment securities held to maturity |  | 36,864 | 34,051
Net loans |  | 134,813 | 133,397
Financial liabilities: |  |  |
Short-term borrowings |  | 59 | 60
Loan facility carrying amount | [1] | 12,928 | 12,605
Level 1 |  |  |
Cash and cash equivalents |  |  |
Cash and cash equivalents |  | 1,811 | 1,749
Interest-bearing deposits at banks |  | 0 | 0
Investment securities held to maturity |  | 0 | 0
Net loans |  | 0 | 0
Financial liabilities: |  |  |
Time deposits |  | 0 | 0
Short-term borrowings |  | 0 | 0
Loan facility carrying amount |  | 0 | 0
Level 2 |  |  |
Cash and cash equivalents |  |  |
Cash and cash equivalents |  | 139 | 160
Interest-bearing deposits at banks |  | 16,751 | 18,873
Investment securities held to maturity |  | 11,879 | 12,909
Net loans |  | 7,113 | 6,806
Financial liabilities: |  |  |
Time deposits |  | 13,591 | 14,463
Short-term borrowings |  | 2,059 | 1,060
Loan facility carrying amount |  | 13,163 | 12,754
Level 3 |  |  |
Cash and cash equivalents |  |  |
Cash and cash equivalents |  | 0 | 0
Interest-bearing deposits at banks |  | 0 | 0
Investment securities held to maturity |  | 45 | 46
Net loans |  | 127,482 | 124,528
Financial liabilities: |  |  |
Time deposits |  | 0 | 0
Short-term borrowings |  | 0 | 0
Loan facility carrying amount |  | 0 | 0
Carrying Amount |  |  |
Cash and cash equivalents |  |  |
Cash and cash equivalents |  | 1,950 | 1,909
Interest-bearing deposits at banks |  | 16,751 | 18,873
Investment securities held to maturity |  | 12,711 | 14,195
Net loans |  | 134,813 | 133,397
Financial liabilities: |  |  |
Time deposits |  | 13,620 | 14,476
Short-term borrowings |  | 2,059 | 1,060
Loan facility carrying amount |  | 12,928 | 12,605
Estimated Fair Value |  |  |
Cash and cash equivalents |  |  |
Cash and cash equivalents |  | 1,950 | 1,909
Interest-bearing deposits at banks |  | 16,751 | 18,873
Investment securities held to maturity |  | 11,924 | 12,955
Net loans |  | 134,595 | 131,334
Financial liabilities: |  |  |
Time deposits |  | 13,591 | 14,463
Short-term borrowings |  | 2,059 | 1,060
Loan facility carrying amount |  | $ 13,163 | $ 12,754
[1] | Loans of $2.3 billion and $1.5 billion at September 30, 2025 and December 31, 2024, respectively, were held in special purpose trusts to settle the respective obligations of asset-backed notes issued by those trusts. The outstanding balances of those asset-backed notes issued to third party investors were included in Long-term borrowings and were $1.9 billion at September 30, 2025 and $1.2 billion at December 31, 2024.

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