Severance Indemnities and Pension Plans (Aggregated Accumulated Benefit Obligations) (Detail) - JPY (¥) ¥ in Millions	Mar. 31, 2026	Mar. 31, 2025
Domestic, Japan \| Pension benefits and SIPs
Defined Benefit Plan Disclosure [Line Items]
Aggregated accumulated benefit obligations	¥ 1,177,021	¥ 1,292,334
Foreign offices and subsidiaries \| Pension benefits and other benefits
Defined Benefit Plan Disclosure [Line Items]
Aggregated accumulated benefit obligations	¥ 194,716	¥ 171,906

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.

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+ Details