Equity and Other Equity Items - Disclosure of Classes of Share Capital (Detail) - Common stock issued [Member] - shares |
12 Months Ended | ||
|---|---|---|---|
Mar. 31, 2025 |
Mar. 31, 2024 |
Mar. 31, 2023 |
|
| Disclosure of classes of share capital [line items] | |||
| Balance at beginning of year | 16,314,987,460 | 16,314,987,460 | 16,314,987,460 |
| Changes during the year | (520,000,000) | 0 | 0 |
| Balance at end of year | 15,794,987,460 | 16,314,987,460 | 16,314,987,460 |