Investment in Securities (Information About Impairment and Upward or Downward Adjustments Resulting From Observable Price Changes) (Detail) - Equity security - JPY (¥) ¥ in Millions |
12 Months Ended | |
|---|---|---|
Mar. 31, 2026 |
Mar. 31, 2025 |
|
| Schedule Of Gain Loss On Investments Held At Cost Balance Sheet and Income Statement Reported Amounts Summary [Line Items] | ||
| Carrying value | ¥ 112,313 | ¥ 89,554 |
| Accumulated impairments and downward adjustments | (17,028) | (16,955) |
| Accumulated upward adjustments | 16,071 | 3,643 |
| Impairments and downward adjustments | (1,789) | (1,438) |
| Upward adjustments | ¥ 13,276 | ¥ 1,485 |