Commitments and contingencies - Additional Information (Detail) - USD ($) $ in Millions |
Jun. 30, 2025 |
Dec. 31, 2024 |
|---|---|---|
| Loss Contingencies [Line Items] | ||
| Commitments to extend credit to commercial customers | $ 12,600 | $ 12,700 |
| Maximum credit risk for recourse associated with loans sold under Federal National Mortgage Association Delegated Underwriting and Servicing program | 4,300 | 4,200 |
| Loss contingency accrual | 108 | $ 157 |
| Minimum | ||
| Loss Contingencies [Line Items] | ||
| Range of reasonably possible losses | 0 | |
| Maximum | ||
| Loss Contingencies [Line Items] | ||
| Range of reasonably possible losses | $ 25 |
| X | ||||||||||
- Definition Commitments to extend credit to commercial customers. No definition available.
|
| X | ||||||||||
- Definition Maximum credit risk for recourse associated with loans sold under Federal National Mortgage Association Delegated Underwriting and Servicing program. No definition available.
|
| X | ||||||||||
- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. Reference 1: http://www.xbrl.org/2003/role/disclosureRef
|
| X | ||||||||||
- Definition Amount of loss contingency liability. Reference 1: http://www.xbrl.org/2003/role/disclosureRef
|
| X | ||||||||||
- Definition Reflects the estimated amount of loss from the specified contingency as of the balance sheet date. Reference 1: http://www.xbrl.org/2003/role/disclosureRef
|
| X | ||||||||||
- Details
|
| X | ||||||||||
- Details
|