Employee benefits - Summary of Fair Value of Plan Assets Japanese Plans (Detail) - Japanese Defined Benefit Plans [Member] - JPY (¥) ¥ in Millions |
Mar. 31, 2026 |
Mar. 31, 2025 |
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|---|---|---|---|---|---|---|---|---|---|---|---|
| Disclosure of fair value of plan assets [line items] | |||||||||||
| Cash and cash equivalents | ¥ 4,755 | ¥ 12,192 | |||||||||
| Equity securities | [1] | 51,815 | 54,103 | ||||||||
| Fixed income: | |||||||||||
| Government bonds | 3,773 | 11,565 | [2] | ||||||||
| Corporate bonds | [3] | 5,241 | |||||||||
| Commingled funds | [4] | 274,752 | 278,892 | ||||||||
| Private equity | 36,814 | 35,115 | |||||||||
| Hedge funds | 46,544 | 42,835 | |||||||||
| Total | 418,453 | 439,943 | |||||||||
| Quoted Market Prices in Active Market [Member] | |||||||||||
| Disclosure of fair value of plan assets [line items] | |||||||||||
| Cash and cash equivalents | 4,755 | 12,192 | |||||||||
| Equity securities | [1] | 43,662 | 48,624 | ||||||||
| Fixed income: | |||||||||||
| Government bonds | 3,773 | 382 | [2] | ||||||||
| Corporate bonds | [3] | 18 | |||||||||
| Total | 52,190 | 61,216 | |||||||||
| Unquoted Market Prices in Active Market [Member] | |||||||||||
| Disclosure of fair value of plan assets [line items] | |||||||||||
| Equity securities | [1] | 8,153 | 5,479 | ||||||||
| Fixed income: | |||||||||||
| Government bonds | 0 | 11,183 | [2] | ||||||||
| Corporate bonds | [3] | 5,223 | |||||||||
| Commingled funds | [4] | 274,752 | 278,892 | ||||||||
| Private equity | 36,814 | 35,115 | |||||||||
| Hedge funds | 46,544 | 42,835 | |||||||||
| Total | ¥ 366,263 | ¥ 378,727 | |||||||||
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