Stock-based compensation - Additional Information (Detail) - JPY (¥) shares in Millions |
12 Months Ended | ||
|---|---|---|---|
Mar. 31, 2026 |
Mar. 31, 2025 |
Mar. 31, 2024 |
|
| Disclosure of terms and conditions of share-based payment arrangement [line items] | |||
| Expense from share-based payment transactions | ¥ 2,578,000,000 | ¥ 2,833,000,000 | ¥ 971,000,000 |
| Liabilities from share-based payment transactions | 195,000,000 | 142,000,000 | |
| Restricted Stock Plan [Member] | |||
| Disclosure of terms and conditions of share-based payment arrangement [line items] | |||
| Annual Share based Compensation Grant Limit Value | ¥ 4,000,000,000 | ||
| Annual Share based Compensation Grant Limit Shares | 4 | ||
| Weighted average fair value at measurement date, other equity instruments granted | ¥ 2,706 | 3,599 | ¥ 1,916.5 |
| Restricted Stock Unit Plan [Member] | |||
| Disclosure of terms and conditions of share-based payment arrangement [line items] | |||
| Weighted average fair value at measurement date, other equity instruments granted | ¥ 2,706 | ¥ 3,599 | |