Related party transactions - Summary of Related Party Transactions (Detail) - JPY (¥) ¥ in Millions |
12 Months Ended | ||
|---|---|---|---|
Mar. 31, 2026 |
Mar. 31, 2025 |
Mar. 31, 2024 |
|
| Disclosure of transactions between related parties [line items] | |||
| Sales revenues | ¥ 4,095,328 | ¥ 4,042,632 | ¥ 3,799,268 |
| Cost of products sold (purchases) | 14,239,543 | 12,972,740 | 12,501,811 |
| Associates [Member] | |||
| Disclosure of transactions between related parties [line items] | |||
| Sales revenues | 2,933,464 | 3,420,576 | 3,137,067 |
| Cost of products sold (purchases) | 14,090,055 | 12,889,776 | 12,426,770 |
| Joint ventures [Member] | |||
| Disclosure of transactions between related parties [line items] | |||
| Sales revenues | 1,161,865 | 622,056 | 662,202 |
| Cost of products sold (purchases) | ¥ 149,488 | ¥ 82,963 | ¥ 75,042 |