Income and Expenses Relating to Life Insurance Operations - Life Insurance Premiums and Related Investment Income (Parenthetical) (Detail) - JPY (¥) ¥ in Millions |
12 Months Ended | ||
|---|---|---|---|
Mar. 31, 2026 |
Mar. 31, 2025 |
Mar. 31, 2024 |
|
| Net Investment Income [Line Items] | |||
| Trading Securities, Unrealized Holding Gain (Loss) | ¥ 170,073 | ¥ 4,422 | ¥ 53,318 |
| Life insurance related investment income | |||
| Net Investment Income [Line Items] | |||
| Trading Securities, Unrealized Holding Gain (Loss) | ¥ 48,946 | ¥ 2,577 | ¥ 43,301 |