Fair Value Measurements (Recorded Amounts of Major Assets Measured at Fair Value on Nonrecurring Basis) (Detail) - JPY (¥) ¥ in Millions	Mar. 31, 2023	Mar. 31, 2022
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans held for sale	¥ 197,041	¥ 151,601
Certain investment in affiliates	2,511	0
Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Certain investment in affiliates	0
Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Certain investment in affiliates	0
Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Certain investment in affiliates	2,511
Fair Value, Measurements, Nonrecurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans held for sale	1,139	235
Real estate collateral-dependent loans (net of allowance for credit losses)	5,970	6,972
Investment in operating leases, property under facility operations, office facilities and other assets	4,568	59,847
Certain equity securities	11,794	9,451
Certain investment in affiliates	4,013	2,846
Certain reporting units including goodwill		192
Certain intangible assets acquired in business combinations		98,014
Assets measured at fair value on a nonrecurring basis	27,484	177,557
Fair Value, Measurements, Nonrecurring \| Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans held for sale	0	0
Real estate collateral-dependent loans (net of allowance for credit losses)	0	0
Investment in operating leases, property under facility operations, office facilities and other assets	0	0
Certain equity securities	0	0
Certain investment in affiliates	3,587	0
Certain reporting units including goodwill		0
Certain intangible assets acquired in business combinations		0
Assets measured at fair value on a nonrecurring basis	3,587	0
Fair Value, Measurements, Nonrecurring \| Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans held for sale	1,139	235
Real estate collateral-dependent loans (net of allowance for credit losses)	0	0
Investment in operating leases, property under facility operations, office facilities and other assets	31	262
Certain equity securities	11,794	9,451
Certain investment in affiliates	0	0
Certain reporting units including goodwill		0
Certain intangible assets acquired in business combinations		0
Assets measured at fair value on a nonrecurring basis	12,964	9,948
Fair Value, Measurements, Nonrecurring \| Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans held for sale	0	0
Real estate collateral-dependent loans (net of allowance for credit losses)	5,970	6,972
Investment in operating leases, property under facility operations, office facilities and other assets	4,537	59,585
Certain equity securities	0	0
Certain investment in affiliates	426	2,846
Certain reporting units including goodwill		192
Certain intangible assets acquired in business combinations		98,014
Assets measured at fair value on a nonrecurring basis	¥ 10,933	¥ 167,609

Certain intangible assets acquired in a business combination fair value.

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- Definition

Investment in operating leases, property under facility operations, office facilities and other assets.

+ References

No definition available.

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- Definition

Real estate collateral-dependent loans (net allowance probable loan losses).

+ References

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- Definition

Fair value portion of probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (a)
-URI https://asc.fasb.org/extlink&oid=126976982&loc=d3e19207-110258

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- Definition

Amount of investment in equity security measured at fair value with change in fair value recognized in net income (FV-NI).

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 45
-Paragraph 1A
-URI https://asc.fasb.org/extlink&oid=123594786&loc=SL75136599-209740

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(2))
-URI https://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

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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

No definition available.

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- Definition

Fair value portion of asset representing the future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (a)
-URI https://asc.fasb.org/extlink&oid=126976982&loc=d3e19207-110258

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- Definition

Fair value portion of investments in an entity not consolidated. Includes, but is not limited to, investments in an entity that is affiliated with the reporting entity by means of direct or indirect ownership, an entity in which the reporting entity shares control of the entity with another party or group, an entity which the company has significant influence, but does not have control and subsidiaries that are not required to be consolidated and are accounted for using the equity or cost method.

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- Definition

Fair value portion of loans held-for-sale including, but not limited to, mortgage loans and finance receivables.

+ References

No definition available.

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