Fair value measurements - Fair value of financial instruments measured on recurring basis (Parenthetical) (Detail) - JPY (¥) ¥ in Millions |
Mar. 31, 2026 |
Mar. 31, 2025 |
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|---|---|---|---|---|---|---|---|---|
| Fair value measurements | ||||||||
| Other assets | ¥ 1,598,457 | ¥ 1,124,473 | ||||||
| Investments in equity securities | 123,191 | 98,401 | ||||||
| Listed Equity [Member] | ||||||||
| Fair value measurements | ||||||||
| Investments in equity securities | 97,173 | 72,184 | ||||||
| Unlisted Equity [Member] | ||||||||
| Fair value measurements | ||||||||
| Investments in equity securities | 26,018 | 26,217 | ||||||
| Recurring [Member] | ||||||||
| Fair value measurements | ||||||||
| Trading assets and private equity and debt investments | [1] | 23,345,000 | 20,483,000 | |||||
| Recurring [Member] | Other assets [Member] | ||||||||
| Fair value measurements | ||||||||
| Other assets | [2],[3] | 940,000 | 745,000 | |||||
| Recurring [Member] | Net asset value per share [Member] | ||||||||
| Fair value measurements | ||||||||
| Trading assets and private equity and debt investments | 104,000 | 73,000 | ||||||
| Recurring [Member] | Net asset value per share [Member] | Other assets [Member] | ||||||||
| Fair value measurements | ||||||||
| Other assets | ¥ 15,000 | ¥ 3,000 | ||||||
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