Other Assets and Liabilities (Narrative) (Detail) - JPY (¥)
¥ in Millions |
12 Months Ended |
Mar. 31, 2022 |
Mar. 31, 2021 |
Mar. 31, 2020 |
| Schedule of Equity Method Investments [Line Items] |
|
|
|
| Investments in equity method investees |
¥ 3,066,738
|
¥ 2,560,339
|
|
| Marketable equity securities included in investment in equity method investees, aggregated market values |
4,714,562
|
3,943,990
|
|
| Investment in equity method investees, recognized impairment losses of other-than-temporary declines in the value of investments in certain affiliated companies |
¥ 6,949
|
53,758
|
¥ 21,672
|
| Morgan Stanley |
|
|
|
| Schedule of Equity Method Investments [Line Items] |
|
|
|
| Equity method investment, Ownership percentage, approximately |
21.47%
|
|
|
| Marketable equity securities |
|
|
|
| Schedule of Equity Method Investments [Line Items] |
|
|
|
| Investments in equity method investees |
¥ 2,481,644
|
1,964,118
|
|
| Marketable equity securities | Morgan Stanley |
|
|
|
| Schedule of Equity Method Investments [Line Items] |
|
|
|
| Investments in equity method investees |
2,058,638
|
1,618,579
|
|
| Marketable equity securities | Morgan Stanley MUFG Securities, Co., Ltd. |
|
|
|
| Schedule of Equity Method Investments [Line Items] |
|
|
|
| Investments in equity method investees |
¥ 183,932
|
¥ 174,190
|
|