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Commitments, Contingent Liabilities and Guarantees - Additional Information (Details) - USD ($) shares in Millions, $ in Millions | 3 Months Ended | 6 Months Ended |  |  |  |  |  |  |
--- | --- | --- | --- | --- | --- | --- | --- | --- | ---
Jun. 30, 2026 | Jun. 30, 2025 | Jun. 30, 2026 | Jun. 30, 2025 | Mar. 31, 2026 | Feb. 01, 2026 | Dec. 31, 2025 | Sep. 30, 2025 | Mar. 31, 2025 | Dec. 31, 2024 | Dec. 31, 2008
Loss Contingencies |  |  |  |  |  |  |  |  |  |  |
Margin account balance held by the brokerage clearing agent | $ 17 |  | $ 17 |  |  |  | $ 13 |  |  |  |
Derivative Liabilities | 2,666 |  | 2,666 |  |  |  | 2,034 |  |  |  |
Delegated Underwriting and Servicing | Commercial mortgage loans |  |  |  |  |  |  |  |  |  |  |
Loss Contingencies |  |  |  |  |  |  |  |  |  |  |
Loss share guarantee liability | 3 |  | 3 |  |  |  |  |  |  |  |
Servicing of residential mortgage loans for other investors | 1,700 |  | 1,700 |  |  |  |  |  |  |  |
Total Return Swap |  |  |  |  |  |  |  |  |  |  |
Loss Contingencies |  |  |  |  |  |  |  |  |  |  |
Derivative Liabilities | 70 |  | 70 |  |  |  | 124 |  |  |  |
Comerica Incorporated | Total Return Swap |  |  |  |  |  |  |  |  |  |  |
Loss Contingencies |  |  |  |  |  |  |  |  |  |  |
Business Combination, Recognized Liability Assumed, Financial Liability |  |  |  |  |  | $ 6 |  |  |  |  |
Visa |  |  |  |  |  |  |  |  |  |  |
Loss Contingencies |  |  |  |  |  |  |  |  |  |  |
Visa IPO, shares of Visa's Class B common stock received (in shares) |  |  |  |  |  |  |  |  |  |  | 10.1
Visa Class B shares carryover basis |  |  |  |  |  |  |  |  |  |  | $ 0
Escrow deposit | 250 |  | 250 |  | $ 125 |  | 500 | $ 500 | $ 375 | $ 8,115 | $ 3,000
Residential mortgage loans |  |  |  |  |  |  |  |  |  |  |
Loss Contingencies |  |  |  |  |  |  |  |  |  |  |
Fair value of liability | 5 |  | 5 |  |  |  |  |  |  |  |
Repurchase demand request | 9 | $ 8 | 18 | $ 17 |  |  |  |  |  |  |
Outstanding repurchase demand inventory | 6 |  | 6 |  |  |  | 5 |  |  |  |
Servicing of residential mortgage loans for other investors | 85,900 |  | 85,900 |  |  |  | 87,800 |  |  |  |
Swap |  |  |  |  |  |  |  |  |  |  |
Loss Contingencies |  |  |  |  |  |  |  |  |  |  |
Derivative Liabilities | 70 | $ 145 | 70 | $ 145 |  |  |  |  |  |  |
Secured Debt |  |  |  |  |  |  |  |  |  |  |
Loss Contingencies |  |  |  |  |  |  |  |  |  |  |
Fully and unconditionally guaranteed certain long-term borrowing obligations issued by wholly-owned issuing trust entities | 62 |  | 62 |  |  |  | 62 |  |  |  |
Standby Letters of Credit |  |  |  |  |  |  |  |  |  |  |
Loss Contingencies |  |  |  |  |  |  |  |  |  |  |
Reserve for unfunded commitments | $ 24 |  | $ 24 |  |  |  | $ 9 |  |  |  |
Standby letters of credit as a percentage of total letters of credit | 99.00% |  | 99.00% |  |  |  | 99.00% |  |  |  |
Standby Letters of Credit | Secured Debt |  |  |  |  |  |  |  |  |  |  |
Loss Contingencies |  |  |  |  |  |  |  |  |  |  |
Standby letters of credit as a percentage of total letters of credit | 77.00% |  | 77.00% |  |  |  | 77.00% |  |  |  |
Derivatives, Fair Value, by Balance Sheet Location [Axis]: us-gaap:OtherLiabilities |  |  |  |  |  |  |  |  |  |  |
Loss Contingencies |  |  |  |  |  |  |  |  |  |  |
Reserve for unfunded commitments | $ 230 |  | $ 230 |  |  |  | $ 157 |  |  |  |
Derivatives, Fair Value, by Balance Sheet Location [Axis]: us-gaap:OtherLiabilities | Residential mortgage loans |  |  |  |  |  |  |  |  |  |  |
Loss Contingencies |  |  |  |  |  |  |  |  |  |  |
Outstanding balances on residential mortgage loans sold with representation and warranty provisions | $ 4 |  | $ 4 |  |  |  | $ 4 |  |  |  |

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