Stock-Based Compensation - Additional Information (Detail) ¥ in Millions	12 Months Ended
Mar. 31, 2022 JPY (¥) Point	Mar. 31, 2021 JPY (¥)	Mar. 31, 2020 JPY (¥)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Points settled for individuals retired	190,966
Points outstanding	1,866,248
Stock Compensation Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Points granted	444,374
Stock-based compensation costs recognized \| ¥	¥ 1,191	¥ 885	¥ 417

Share Based Compensation Arrangement By Share Based Payment Award Points Grants In Period

No definition available.

Name:	ck0001070304_ShareBasedCompensationArrangementByShareBasedPaymentAwardPointsGrantsInPeriod
Namespace Prefix:	ck0001070304_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

Share Based Compensation Arrangement By Share Based Payment Award Points Outstanding Number

+ References

No definition available.

+ Details

Name:	ck0001070304_ShareBasedCompensationArrangementByShareBasedPaymentAwardPointsOutstandingNumber
Namespace Prefix:	ck0001070304_
Data Type:	xbrli:decimalItemType
Balance Type:	na
Period Type:	duration

- Definition

Share Based Compensation Arrangement By Share Based Payment Award Points Settled In Period

+ References

No definition available.

+ Details

Name:	ck0001070304_ShareBasedCompensationArrangementByShareBasedPaymentAwardPointsSettledInPeriod
Namespace Prefix:	ck0001070304_
Data Type:	xbrli:decimalItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of expense for award under share-based payment arrangement. Excludes amount capitalized.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=120381028&loc=d3e5047-113901

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SAB Topic 14.F)
-URI http://asc.fasb.org/extlink&oid=122041274&loc=d3e301413-122809

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (h)(1)(i)
-URI http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901

+ Details

Name:	us-gaap_AllocatedShareBasedCompensationExpense
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- 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.

+ Details

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	us-gaap_AwardTypeAxis=us-gaap_StockCompensationPlanMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: