Stock-based compensation plans - Additional Information (Detail) - JPY (¥) |
12 Months Ended | |||
|---|---|---|---|---|
Oct. 01, 2024 |
Mar. 31, 2025 |
Mar. 31, 2024 |
Mar. 31, 2023 |
|
| Statements [Line Items] | ||||
| Weighted-average stock price at the time when the stock acquisition rights were exercised during the fiscal years | ¥ 3,238 | ¥ 2,629 | ¥ 2,281 | |
| Weighted average stock price | ¥ 733 | ¥ 625 | ¥ 875 | |
| Expense from share-based payment transactions with employees | ¥ 29,416,000,000 | ¥ 21,657,000,000 | ¥ 15,781,000,000 | |
| Description of vesting requirements for share-based payment arrangement | The stock acquisition rights granted under the stock option plan primarily have a three-year vesting schedule | The stock acquisition rights granted under the stock option plan primarily have a three-year vesting schedule | The stock acquisition rights granted under the stock option plan primarily have a three-year vesting schedule | |
| Description of maximum term of options granted for share-based payment arrangement | exercisable up to 10 years from the date of grant. | exercisable up to 10 years from the date of grant. | exercisable up to 10 years from the date of grant. | |
| Shareholders stock split | five-for-one | |||
| Stock Option Plan [Member] | ||||
| Statements [Line Items] | ||||
| Shareholders stock split | five-for-one | |||
| Restricted share units [member] | ||||
| Statements [Line Items] | ||||
| Shareholders stock split | five-for-one | |||