Fair Value Asset And Liabilities Measured On Recurring Basis [Line Items]

No definition available.

Name:	ck0001070304_FairValueAssetAndLiabilitiesMeasuredOnRecurringBasisLineItems
Namespace Prefix:	ck0001070304_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of transfer of financial instrument classified as an asset into level 3 of the fair value hierarchy.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)(3)
-URI http://asc.fasb.org/extlink&oid=117815213&loc=d3e19207-110258

+ Details

Name:	us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetTransfersIntoLevel3
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount of transfer of financial instrument classified as an asset into (out of) level 3 of the fair value hierarchy.

+ References

No definition available.

+ Details

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

- Definition

Amount of transfers of financial instrument classified as an asset out of level 3 of the fair value hierarchy.

+ References

+ Details

Name:	us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetTransfersOutOfLevel3
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Details

Name:	us-gaap_FairValueByMeasurementFrequencyAxis=us-gaap_FairValueMeasurementsRecurringMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FairValueByAssetClassAxis=ck0001070304_JapanesePrefecturalAndForeignMunicipalBondSecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FairValueByAssetClassAxis=us-gaap_CorporateDebtSecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FairValueByAssetClassAxis=ck0001070304_CommercialMortgageBackedSecuritiesAndResidentialMortgageBackedSecuritiesInAmericasMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Fair Value Measurements - Additional Information (Detail) - Fair Value, Measurements, Recurring - JPY (¥)	12 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Mar. 31, 2018
Fair Value Asset And Liabilities Measured On Recurring Basis [Line Items]
Transfers in or out of Level 3			¥ 0
Japanese prefectural and foreign municipal bond securities
Fair Value Asset And Liabilities Measured On Recurring Basis [Line Items]
Transferred from level 2 to level 3		¥ 3,305,000,000
Corporate debt securities
Fair Value Asset And Liabilities Measured On Recurring Basis [Line Items]
Transferred from level 3 to level 2	¥ 2,991,000,000
CMBS and RMBS in the Americas
Fair Value Asset And Liabilities Measured On Recurring Basis [Line Items]
Transferred from level 3 to level 2		¥ 23,406,000,000