Lease Transactions (Narrative) (Detail) - JPY (¥) ¥ in Millions |
12 Months Ended | |
|---|---|---|
Mar. 31, 2025 |
Mar. 31, 2024 |
|
| Leases [Abstract] | ||
| Right-of-use assets of finance leases, in consolidated balance sheets line item | Premises and equipment—net (Notes 5 and 7) | Premises and equipment—net (Notes 5 and 7) |
| Right-of-use assets of finance leases | ¥ 21,035 | ¥ 24,430 |
| Lease liabilities of finance leases, in consolidated balance sheets line item | Long-term debt (including ¥234,909 and ¥153,742 measured at fair value under the fair value option in 2024 and 2025) (Notes 7, 9, 12 and 31) | Long-term debt (including ¥234,909 and ¥153,742 measured at fair value under the fair value option in 2024 and 2025) (Notes 7, 9, 12 and 31) |
| Lease liabilities of finance leases | ¥ 21,460 | ¥ 26,055 |
| Right-of-use assets of operating leases, in consolidated balance sheets line item | Other assets | Other assets |
| Right-of-use assets of operating leases | ¥ 247,221 | ¥ 235,548 |
| Lease liabilities of operating leases, in consolidated balance sheets line item | Other liabilities | Other liabilities |
| Amount on balance sheet | ¥ 341,499 | ¥ 329,267 |
| Operating Lease, Impairment Loss | 19,520 | 18,112 |
| Property, plant, and equipment separately for underlying assets under operating leases from owned assets subject to operating leases are carrying amount as | ¥ 142,964 | ¥ 99,005 |