Securitizations and Variable Interest Entities - Additional information (Detail) - JPY (¥) ¥ in Billions	6 Months Ended
Sep. 30, 2025	Sep. 30, 2024	Mar. 31, 2025
Variable Interest Entity [Line Items]
Cash proceeds from SPEs in new securitizations	¥ 247	¥ 305
Debt securities issued by SPEs with an initial fair value	359	270
Cash inflows from third parties on the sale of debt securities	449	330
Cumulative balance of financial assets transferred to SPEs	7,596		¥ 7,123
Retained interests	190		¥ 250
Cash inflows from the SPEs on the retained interests	¥ 18	¥ 13

Cash inflow (outflow) from SPEs on retained interests continuously held by entity.

No definition available.

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- Definition

Cumulative Balance of Financial Assets Transferred to Spes

+ References

No definition available.

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- Definition

Debt Securities Issued by Special Purpose Entities Initial Fair Value

+ References

No definition available.

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- Definition

The carrying amount (fair value) as of the balance sheet date of the transferor's interests in transferred financial assets (typically securitized receivables, generally not involved in the collection of principal) following transfer of significant portions of such financial instruments to other parties. Such interests could be ancillary cash flows and interest-only strips.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 860
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-Name Accounting Standards Codification
-Section 50
-Paragraph 4
-Subparagraph (a)(3)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481326/860-20-50-4

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- Definition

Amount of cash inflow from sale of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 320
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- Definition

The cash inflow from the securitization of loans held for investment. Securitization is the structured process whereby interests in loans and other receivables are packaged, underwritten, and sold in the form of asset-backed securities.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
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- Definition

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

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