Employee Benefits - Summary of Funding Requirement and Asset Ceiling (Detail) - Japanese Defined Benefit Plans [Member] - JPY (¥) ¥ in Millions |
12 Months Ended | |
|---|---|---|
Mar. 31, 2025 |
Mar. 31, 2024 |
|
| Disclosure of defined benefit plans [line items] | ||
| Beginning balance | ¥ 268,228 | |
| Interest income | 4,694 | |
| Change in asset ceiling excluding interest income | 299,185 | ¥ 268,228 |
| Ending balance | ¥ 572,107 | ¥ 268,228 |