Short-term borrowings and long-term debt - Summary of Pledged Assets as Collateral (Detail) - JPY (¥) ¥ in Millions |
Mar. 31, 2025 |
Mar. 31, 2024 |
|---|---|---|
| Certain Assets Pledged As Collateral For Short Term Borrowings And Long Term Debt [Line Items] | ||
| Securities | ¥ 332,867 | ¥ 0 |
| Securities | 140,212 | 77,524 |
| Securities [member] | ||
| Certain Assets Pledged As Collateral For Short Term Borrowings And Long Term Debt [Line Items] | ||
| Financial assets pledged as collateral for liabilities or contingent liabilities | 1,595,016 | 1,597,034 |
| Housing Loans in The Banking Business [member] | ||
| Certain Assets Pledged As Collateral For Short Term Borrowings And Long Term Debt [Line Items] | ||
| Financial assets pledged as collateral for liabilities or contingent liabilities | ¥ 961,286 | ¥ 883,882 |