Retirement Benefits - Weighted Average Durations of Defined Benefit Plans (Detail) |
12 Months Ended | ||
|---|---|---|---|
Mar. 31, 2026 |
Mar. 31, 2025 |
Mar. 31, 2024 |
|
| Lump-sum severance indemnity plans [member] | |||
| Disclosure of defined benefit plans [Line Items] | |||
| Weighted average durations of defined benefit plans | 10 years 7 months 6 days | 11 years 2 months 12 days | 12 years |
| Defined benefit pension plans [member] | |||
| Disclosure of defined benefit plans [Line Items] | |||
| Weighted average durations of defined benefit plans | 14 years 2 months 12 days | 15 years 4 months 24 days | 16 years 4 months 24 days |