Commitments, contingencies and guarantees - Commitments outstanding (Detail) - JPY (¥) ¥ in Millions |
Mar. 31, 2026 |
Mar. 31, 2025 |
|---|---|---|
| Commitments [Line Items] | ||
| Commitments to extend credit | ¥ 2,665,196 | ¥ 3,238,123 |
| Commitments to invest | 66,952 | 25,677 |
| Liquidity facilities to central clearing counterparties [Member] | ||
| Commitments [Line Items] | ||
| Commitments to extend credit | 1,034,593 | 2,038,836 |
| Other commitments to extend credit [Member] | ||
| Commitments [Line Items] | ||
| Commitments to extend credit | ¥ 1,630,603 | ¥ 1,199,287 |