Long-Duration Insurance Contracts Relating to Life Insurance Operations - Schedule of Liability For Future Policy Benefit, Weighted Average Duration (Detail) |
Sep. 30, 2026 |
Mar. 31, 2026 |
|---|---|---|
| Yen-denominated insurance (First Sector) | ||
| Liability for Future Policy Benefit, Activity [Line Items] | ||
| Liability for future policy benefit weighted average duration | 30 years 3 months 18 days | 30 years 7 months 6 days |
| Yen-denominated insurance (Third Sector) | ||
| Liability for Future Policy Benefit, Activity [Line Items] | ||
| Liability for future policy benefit weighted average duration | 33 years 4 months 24 days | 34 years 2 months 12 days |
| Foreign currency denominated insurance | ||
| Liability for Future Policy Benefit, Activity [Line Items] | ||
| Liability for future policy benefit weighted average duration | 28 years 2 months 12 days | 29 years 6 months |