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Commitments and Contingencies - Additional Information (Detail) - USD ($) $ in Millions | 12 Months Ended
--- | ---
Dec. 31, 2024 | Dec. 31, 2023
Loss Contingencies [Line Items] |  |
Commitments to extend credit to commercial customers | $ 12,700 | $ 12,300
Maximum credit risk for recourse associated with loans sold under Federal National Mortgage Association Delegated Underwriting and Servicing program | 4,200 | 3,900
Estimate assessed losses | 34 | 197
Loss contingency accrual | 157 | $ 197
Minimum |  |
Loss Contingencies [Line Items] |  |
Range of reasonably possible losses | 0 |
Maximum |  |
Loss Contingencies [Line Items] |  |
Range of reasonably possible losses | $ 25 |

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- Definition Maximum Credit Risk For Recourse Associated With Loans Sold Under Federal National Mortgage Association Delegated Underwriting And Servicing Program + References No definition available. + Details
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