Regulation and Capital Adequacy - Additional Information (Detail) $ in Millions |
Jun. 30, 2026
USD ($)
|
Dec. 31, 2025
USD ($)
|
|---|---|---|
| Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items] | ||
| Equity investment in subsidiaries | $ 143,320 | $ 143,110 |
| Minimum equity capital that is required to be maintained in regulated subsidiaries | $ 116,820 | $ 109,480 |
| "Well-capitalized" Requirements, SLR | 0.0375 | 0.050 |
| Reportable Legal Entities | ||
| Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items] | ||
| "Well-capitalized" Requirements, SLR | 0.060 |
| X | ||||||||||
- Definition Amount of restricted net assets of consolidated and unconsolidated subsidiaries as of the end of the most recently completed fiscal year. Reference 1: http://www.xbrl.org/2003/role/disclosureRef
|
| X | ||||||||||
- Definition Ratio of minimum Tier 1 risk-based capital to total leverage exposure categorized as well capitalized as defined by regulatory framework for prompt corrective action. Reference 1: http://www.xbrl.org/2003/role/disclosureRef
|
| 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/2009/role/commonPracticeRef
|
| X | ||||||||||
- Definition Amount of investment in equity method investee and investment in and advance to affiliate. Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
|
| X | ||||||||||
- Details
|