Collateralized transactions - Securities transferred in repurchase agreements and securities lending transactions (Detail) - JPY (¥) ¥ in Billions |
Mar. 31, 2026 |
Mar. 31, 2025 |
||||||
|---|---|---|---|---|---|---|---|---|
| Financial Instruments Owned and Pledged as Collateral [Line Items] | ||||||||
| Repurchase agreements | [1],[2] | ¥ 51,275 | ¥ 45,747 | |||||
| Securities lending transactions | [1],[2] | 2,953 | 2,347 | |||||
| Total | [2] | 54,228 | 48,094 | |||||
| Equities and convertible securities [Member] | ||||||||
| Financial Instruments Owned and Pledged as Collateral [Line Items] | ||||||||
| Repurchase agreements | 442 | 401 | ||||||
| Securities lending transactions | 2,272 | 1,734 | ||||||
| Total | 2,714 | 2,135 | ||||||
| Japanese government, agency and municipal securities [Member] | ||||||||
| Financial Instruments Owned and Pledged as Collateral [Line Items] | ||||||||
| Repurchase agreements | 3,061 | 2,202 | ||||||
| Securities lending transactions | 163 | 1 | ||||||
| Total | 3,224 | 2,203 | ||||||
| Foreign government, agency and municipal securities [Member] | ||||||||
| Financial Instruments Owned and Pledged as Collateral [Line Items] | ||||||||
| Repurchase agreements | 38,182 | 34,569 | ||||||
| Securities lending transactions | 182 | 81 | ||||||
| Total | 38,364 | 34,650 | ||||||
| Bank and corporate debt securities [Member] | ||||||||
| Financial Instruments Owned and Pledged as Collateral [Line Items] | ||||||||
| Repurchase agreements | 5,598 | 3,881 | ||||||
| Securities lending transactions | 267 | 369 | ||||||
| Total | 5,865 | 4,250 | ||||||
| Commercial mortgage-backed securities ("CMBS") [Member] | ||||||||
| Financial Instruments Owned and Pledged as Collateral [Line Items] | ||||||||
| Repurchase agreements | 29 | |||||||
| Securities lending transactions | ||||||||
| Total | 29 | |||||||
| Residential mortgage-backed securities ("RMBS") [Member] | ||||||||
| Financial Instruments Owned and Pledged as Collateral [Line Items] | ||||||||
| Repurchase agreements | [3] | 3,635 | 4,466 | |||||
| Securities lending transactions | [3] | |||||||
| Total | [3] | 3,635 | 4,466 | |||||
| Collateralized debt obligations ("CDOs") and other [Member] | ||||||||
| Financial Instruments Owned and Pledged as Collateral [Line Items] | ||||||||
| Repurchase agreements | 346 | 177 | ||||||
| Securities lending transactions | ||||||||
| Total | 346 | 177 | ||||||
| Investment trust funds and other [Member] | ||||||||
| Financial Instruments Owned and Pledged as Collateral [Line Items] | ||||||||
| Repurchase agreements | 11 | 22 | ||||||
| Securities lending transactions | 69 | 162 | ||||||
| Total | ¥ 80 | ¥ 184 | ||||||
| ||||||||