Securities - Summary of securities (Details) - JPY (¥) ¥ in Millions |
Mar. 31, 2026 |
Mar. 31, 2025 |
|---|---|---|
| Securities [Line Items] | ||
| Securities | ¥ 1,736,835 | ¥ 1,075,748 |
| Payment Segment | ||
| Securities [Line Items] | ||
| Securities | 65,612 | 35,953 |
| Financial Service Segment | ||
| Securities [Line Items] | ||
| Securities | 1,671,223 | 1,039,795 |
| Japanese Government Securities | ||
| Securities [Line Items] | ||
| Securities | 713,244 | 329,062 |
| Japanese Government Securities | Payment Segment | ||
| Securities [Line Items] | ||
| Securities | 65,612 | 35,953 |
| Corporate and Other Debt Securities | Financial Service Segment | ||
| Securities [Line Items] | ||
| Securities | 416,121 | 295,707 |
| Asset Backed Securities | Financial Service Segment | ||
| Securities [Line Items] | ||
| Securities | 337,685 | 282,333 |
| Exchange Traded Funds | Financial Service Segment | ||
| Securities [Line Items] | ||
| Securities | 202,879 | 132,509 |
| Equity Securities | Financial Service Segment | ||
| Securities [Line Items] | ||
| Securities | ¥ 1,294 | ¥ 184 |