Financial Instruments - Schedule of Capital Adequacy Ratio, Core Capital, Total Capital and Risk-Weighted Assets (Details) - JPY (¥) ¥ in Millions |
Mar. 31, 2026 |
Mar. 31, 2025 |
|---|---|---|
| Disclosure of detailed information about financial instruments [abstract] | ||
| Capital adequacy ratio | 14.04% | 16.76% |
| Core capital | ¥ 157,147 | ¥ 145,215 |
| Total capital | 144,202 | 132,575 |
| Value at risk | ¥ 1,026,786 | ¥ 790,957 |