Revenue from services provided to customers - Schedule of Disaggregation of Asset Management Fees and Custody Fee (Detail) - JPY (¥) ¥ in Millions |
12 Months Ended | ||
|---|---|---|---|
Mar. 31, 2026 |
Mar. 31, 2025 |
Mar. 31, 2024 |
|
| Disaggregation Of Asset Management Fees And Custody Fee [Abstract] | |||
| Asset management fees | ¥ 311,710 | ¥ 235,893 | ¥ 193,468 |
| Administration fees | 120,570 | 109,092 | 88,201 |
| Custodial fees | 36,320 | 33,211 | 28,485 |
| Total | ¥ 468,600 | ¥ 378,196 | ¥ 310,154 |