Debt Securities in Issue - Summary of Movement in Subordinated Bonds (Detail) - JPY (¥) ¥ in Millions |
12 Months Ended | ||
|---|---|---|---|
Mar. 31, 2026 |
Mar. 31, 2025 |
Mar. 31, 2024 |
|
| Debt Securities In Issue [abstract] | |||
| Subordinated bonds at beginning of period | ¥ 1,274,554 | ¥ 1,444,192 | |
| Cash flows: | |||
| Proceeds from issuance of subordinated bonds | 513,967 | 252,506 | ¥ 274,551 |
| Redemption of subordinated bonds | (123,000) | (439,941) | |
| Non-cash changes: | |||
| Foreign exchange translations | 59,371 | (5,117) | |
| Others | (22,924) | 22,914 | |
| Subordinated bonds at end of period | ¥ 1,701,968 | ¥ 1,274,554 | ¥ 1,444,192 |