Investment in Securities (Information About Impairment and Upward or Downward Adjustments Resulting From Observable Price Changes) (Detail) - Equity security - JPY (¥) ¥ in Millions |
6 Months Ended | ||
|---|---|---|---|
Sep. 30, 2026 |
Sep. 30, 2025 |
Mar. 31, 2026 |
|
| Schedule Of Gain Loss On Investments Held At Cost Balance Sheet and Income Statement Reported Amounts Summary [Line Items] | |||
| Carrying value | ¥ 109,482 | ¥ 112,283 | |
| Accumulated impairments and downward adjustments | (16,796) | (17,028) | |
| Accumulated upward adjustments | 16,537 | ¥ 16,071 | |
| Impairments and downward adjustments | (79) | ¥ (858) | |
| Upward adjustments | ¥ 766 | ¥ 12,363 | |