Per Share Data - Additional Information (Detail) - shares	12 Months Ended
Mar. 31, 2024	Mar. 31, 2023	Mar. 31, 2022
Officer's Compensation Board Incentive Plan
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Number of shares held for incentive plans, to be deducted in calculation of the weighted-average shares for EPS computation	2,783,978	2,496,724	2,104,640
Employee Stock Option
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive shares excluded from calculation of diluted EPS	0	0	0

Securities (including those issuable pursuant to contingent stock agreements) that could potentially dilute basic earnings per share (EPS) or earnings per unit (EPU) in the future that were not included in the computation of diluted EPS or EPU because to do so would increase EPS or EPU amounts or decrease loss per share or unit amounts for the period presented.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 260
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482662/260-10-50-1

+ Details

Name:	us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
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_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Number of shares of treasury stock determined by relating the portion of time within a reporting period that treasury shares have been outstanding to the total time in that period. Treasury stock is stock that the Entity has issued but subsequently reacquired.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Topic 260
-SubTopic 10
-Section 45
-Paragraph 10
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482689/260-10-45-10

+ Details

Name:	us-gaap_WeightedAverageNumberOfSharesTreasuryStock
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	us-gaap_PlanNameAxis=ck0001070304_OfficersCompensationBoardIncentivePlanMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis=us-gaap_EmployeeStockOptionMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: