Loans and Allowance for Credit Losses (Financial Effect of Modifications) (Details) ¥ in Millions	12 Months Ended
Mar. 31, 2024 JPY (¥)
Commercial \| Domestic
Financing Receivable, Modifications [Line Items]
Weighted average interest rate decrease from modification	0.13%
Weighted average term increase from modificationn	1 year
Commercial \| Foreign
Financing Receivable, Modifications [Line Items]
Weighted average interest rate decrease from modification	0.46%
Weighted average term increase from modificationn	9 months 18 days
Residential
Financing Receivable, Modifications [Line Items]
Weighted average term increase from modificationn	1 year 7 months 6 days
Card
Financing Receivable, Modifications [Line Items]
Weighted average interest rate decrease from modification	15.22%
Weighted average term increase from modificationn	3 years
Decrease in loan principal from modification	¥ 809
Krungsri
Financing Receivable, Modifications [Line Items]
Weighted average interest rate decrease from modification	1.38%
Weighted average term increase from modificationn	2 years 3 months 18 days
Decrease in loan principal from modification	¥ 1,269
Other
Financing Receivable, Modifications [Line Items]
Weighted average interest rate decrease from modification	3.40%
Weighted average term increase from modificationn	3 years

Amount of increase (decrease) in amortized cost excluding accrued interest, of financing receivable modified for debtor experiencing financial difficulty.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 310
-SubTopic 10
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-Paragraph 42
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-Publisher FASB
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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 310
-SubTopic 10
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-Section 50
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Reference 2: http://www.xbrl.org/2003/role/disclosureRef
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Reference 3: http://www.xbrl.org/2003/role/exampleRef
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Reference 4: http://www.xbrl.org/2003/role/disclosureRef
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Percentage of decrease in weighted average contractual interest rate of financing receivable modified for debtor experiencing financial difficulty.

+ References

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Period of increase in weighted average maturity of financing receivable modified for debtor experiencing financial difficulty, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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