Net Trading Income - Summary of Net Trading Income (Detail) - JPY (¥) ¥ in Millions |
12 Months Ended | ||
|---|---|---|---|
Mar. 31, 2026 |
Mar. 31, 2025 |
Mar. 31, 2024 |
|
| Trading income (expense) [abstract] | |||
| Interest rate | ¥ (50,501) | ¥ (35,575) | ¥ 179,954 |
| Foreign exchange | (21,593) | (188,913) | 148,064 |
| Equity | (3,880) | 38,780 | 26,626 |
| Credit | (6,153) | (2,237) | (4,668) |
| Others | (1,940) | 1,257 | (456) |
| Total net trading income (loss) | ¥ (84,067) | ¥ (186,688) | ¥ 349,520 |