Investment Securities (Narrative) (Detail) - JPY (¥) ¥ in Millions |
12 Months Ended | ||
|---|---|---|---|
Mar. 31, 2022 |
Mar. 31, 2021 |
Mar. 31, 2020 |
|
| Investment Securities [Line Items] | |||
| Gross realized gains on sales of Available-for-sale debt securities | ¥ 85,525 | ¥ 42,123 | ¥ 151,015 |
| Gross realized losses on sales of Available-for-sale debt securities | 36,698 | ¥ 48,606 | 44,662 |
| Corporate bonds | |||
| Investment Securities [Line Items] | |||
| Other-than-temporary impairment ("OTTI") losses of debt securities included in Investment securities gains (losses)—net | ¥ 47,281 | ¥ 1,590 | |