Income and Expenses Relating to Life Insurance Operations - Reinsurance Benefits and Reinsurance Premiums Included in Life Insurance Premiums (Detail) - JPY (¥) ¥ in Millions |
6 Months Ended | |
|---|---|---|
Sep. 30, 2026 |
Sep. 30, 2025 |
|
| Policyholders Account In Life Insurance Business [Abstract] | ||
| Reinsurance benefits | ¥ 10,433 | ¥ 9,170 |
| Reinsurance premiums | ¥ (2,608) | ¥ (2,593) |