Severance Indemnities and Pension Plans (Aggregated Accumulated Benefit Obligations) (Detail) - JPY (¥) ¥ in Millions |
Mar. 31, 2022 |
Mar. 31, 2021 |
|---|---|---|
| Domestic, Japan | Pension benefits and SIPs | ||
| Defined Benefit Plan Disclosure [Line Items] | ||
| Aggregated accumulated benefit obligations | ¥ 1,663,543 | ¥ 1,719,798 |
| Foreign offices and subsidiaries | Pension benefits and other benefits | ||
| Defined Benefit Plan Disclosure [Line Items] | ||
| Aggregated accumulated benefit obligations | ¥ 596,153 | ¥ 554,375 |