Premises and equipment-Summary of Premises and Equipment (Detail) - JPY (¥) ¥ in Millions |
Mar. 31, 2026 |
Mar. 31, 2025 |
|---|---|---|
| Property, Plant and Equipment [Line Items] | ||
| Premises and equipment, gross | ¥ 3,568,341 | ¥ 3,561,785 |
| Less: Accumulated depreciation and amortization | 1,745,321 | 1,748,107 |
| Premises and equipment—net | 1,823,020 | 1,813,678 |
| Land | ||
| Property, Plant and Equipment [Line Items] | ||
| Premises and equipment, gross | 562,520 | 570,626 |
| Buildings | ||
| Property, Plant and Equipment [Line Items] | ||
| Premises and equipment, gross | 673,974 | 741,887 |
| Equipment and furniture | ||
| Property, Plant and Equipment [Line Items] | ||
| Premises and equipment, gross | 409,053 | 392,780 |
| Leasehold improvements | ||
| Property, Plant and Equipment [Line Items] | ||
| Premises and equipment, gross | 217,966 | 212,741 |
| Construction in Progress | ||
| Property, Plant and Equipment [Line Items] | ||
| Premises and equipment, gross | 44,441 | 62,010 |
| Software | ||
| Property, Plant and Equipment [Line Items] | ||
| Premises and equipment, gross | ¥ 1,660,387 | ¥ 1,581,741 |