Commitments and Contingencies (Summary of Contractual Amounts with Regard to Undrawn Commitments) (Detail) - JPY (¥) ¥ in Billions |
Mar. 31, 2026 |
Mar. 31, 2025 |
|---|---|---|
| Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items] | ||
| Off-balance-sheet instruments, contractual amounts of the undrawn commitments | ¥ 132,615 | ¥ 121,562 |
| Commitments to Extend Credit | ||
| Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items] | ||
| Off-balance-sheet instruments, contractual amounts of the undrawn commitments | 130,737 | 119,733 |
| Commercial letters of credit | ||
| Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items] | ||
| Off-balance-sheet instruments, contractual amounts of the undrawn commitments | ¥ 1,879 | ¥ 1,829 |