Contractual commitments and contingent liabilities - Additional Information (Detail) - JPY (¥) ¥ in Millions |
12 Months Ended | |
|---|---|---|
Mar. 31, 2025 |
Mar. 31, 2024 |
|
| Disclosure of contingent liabilities [line items] | ||
| Contractual commitments | ¥ 3,807,743 | ¥ 4,712,085 |
| Maximum potential amounts of future payment | ¥ 2,314,927 | 3,310,990 |
| Expiration Date of Concentration of Labor Supply In Employees under Agreeements | Aug. 31, 2027 | |
| Legacy certification cost | ¥ 281,140 | |
| Contingent liability for guarantees [Member] | ||
| Disclosure of contingent liabilities [line items] | ||
| Estimated liability for guarantees contract | ¥ 8,917 | ¥ 11,851 |
| Contingent liability for guarantees [Member] | Maximum [Member] | ||
| Disclosure of contingent liabilities [line items] | ||
| Guarantee period | 8 years | |
| Contingent liability for guarantees [Member] | Minimum [Member] | ||
| Disclosure of contingent liabilities [line items] | ||
| Guarantee period | 1 month |