Lease Income (Operating Lease) (Parenthetical) (Detail) - JPY (¥) ¥ in Millions	6 Months Ended
Sep. 30, 2024	Sep. 30, 2023
Lessor, Lease, Description [Line Items]
Gains on sales of operating lease assets	¥ 44,646	¥ 27,792
Real Estate Asset
Lessor, Lease, Description [Line Items]
Gains on sales of operating lease assets	23,587	10,066
Operating Lease Assets Other than Real Estate
Lessor, Lease, Description [Line Items]
Gains on sales of operating lease assets	¥ 21,059	¥ 17,726

The net gain (loss) arising from the lessor's sale of assets held- or available-for-lease under contractual arrangements classified as operating leases.

Reference 1: http://fasb.org/us-gaap/role/ref/otherTransitionRef
-Topic 840
-SubTopic 30
-Name Accounting Standards Codification
-Section 40
-Paragraph 8
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481222/840-30-40-8

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 360
-SubTopic 10
-Name Accounting Standards Codification
-Section 40
-Paragraph 3A
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482161/360-10-40-3A

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration