Derivative financial instruments - Disclosure of Derivatives Notional Amount (Detail) - Derivative not designated as hedge [Member] - JPY (¥) ¥ in Millions |
Mar. 31, 2025 |
Mar. 31, 2024 |
|---|---|---|
| Disclosure of detailed information about hedges [line items] | ||
| The amount of underlying notional of derivatives | ¥ 37,749,645 | ¥ 36,042,835 |
| Interest rate and currency swap [Member] | ||
| Disclosure of detailed information about hedges [line items] | ||
| The amount of underlying notional of derivatives | 32,257,298 | 31,825,306 |
| Foreign exchange forward, option and other contracts [Member] | ||
| Disclosure of detailed information about hedges [line items] | ||
| The amount of underlying notional of derivatives | ¥ 5,492,347 | ¥ 4,217,529 |