Commitments, Guarantees, and Contingent Liabilities - Additional Information (Detail) (JPY ¥) In Millions, unless otherwise specified	3 Months Ended	9 Months Ended	12 Months Ended
Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2011	Dec. 31, 2010	Mar. 31, 2011
Commitments and Contingencies Disclosure [Line Items]
Commitments for purchase of equipment to be leased at cost			¥ 13,608		¥ 11,423
Total rental payments under operating lease agreements	1,845	2,022	5,684	6,113
Payments for computer systems under non-cancelable contracts	116	115	401	643
Estimated construction costs	93,831		93,831		135,567
Total unused credit and capital amount available	79,479		79,479		77,694
Guarantee Obligations Maximum Exposure	490,267		490,267		469,030
Guarantee Obligations Current Carrying Value	7,529		7,529		6,533
Investment in securities pledged for primarily collateral deposits	1,167,720		1,167,720		1,175,381
Securities Pledged as Collateral
Commitments and Contingencies Disclosure [Line Items]
Investment in securities pledged for primarily collateral deposits	27,358		27,358		58,607
Corporate loans
Commitments and Contingencies Disclosure [Line Items]
Guarantee Obligations Maximum Exposure	318,832		318,832		284,851
Guarantee Obligations Current Carrying Value	1,496		1,496		1,958
Corporate loans \| Performance Guarantee
Commitments and Contingencies Disclosure [Line Items]
Guarantee Obligations Maximum Exposure	1,288,700		1,288,700		1,265,000
Guarantee Obligations Current Carrying Value	¥ 684		¥ 684		¥ 755

Name:	ix_CommitmentsAndContingenciesDisclosureLineItems
Namespace Prefix:	ix_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

Total debt and equity financial instruments including: (1) securities held-to-maturity, (2) trading securities, (3) securities available-for-sale, and (4) non-marketable equity securities.

+ References

No definition available.

+ Details

Name:	ix_InvestmentSecurities
Namespace Prefix:	ix_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Lease office space under operating lease agreements which are primarily cancelable and made rental payments

+ References

No definition available.

+ Details

Name:	ix_OperatingLeasesRentExpenses
Namespace Prefix:	ix_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The current carrying amount of the liability for the freestanding or embedded guarantor's obligations under the guarantee or each group of similar guarantees.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 5

-Paragraph 9

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name FASB Interpretation (FIN)

-Number 45

-Paragraph 13

-Subparagraph c

+ Details

Name:	us-gaap_GuaranteeObligationsCurrentCarryingValue
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Maximum potential amount of future payments (undiscounted) the guarantor could be required to make under the guarantee or each group of similar guarantees before reduction for potential recoveries under recourse or collateralization provisions.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name FASB Interpretation (FIN)

-Number 45

-Paragraph 13

-Subparagraph b

+ Details

Name:	us-gaap_GuaranteeObligationsMaximumExposure
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The minimum amount the entity agreed to spend under the long-term purchase commitment.

+ References

No definition available.

+ Details

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

- Definition

The payments made in the period which reduced loss contingency reserves.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 5

-Paragraph 9, 10, 11, 12

+ Details

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

- Definition

Reflects the estimated amount of loss from the specified contingency as of the balance sheet date.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 5

-Paragraph 9, 10, 11, 12

+ Details

Name:	us-gaap_LossContingencyEstimateOfPossibleLoss
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

The floor amount as of the balance sheet date that the entity must expend to satisfy the terms of the disclosed arrangements (excluding long-term commitments) in which the entity has agreed to expend funds to procure goods or services from a supplier, or to commit resources to supply goods or services to a customer.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 25

-Article 5

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 03

-Paragraph 17

-Article 9

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 03

-Paragraph 19

-Article 7

+ Details

Name:	us-gaap_SignificantCommitmentRemainingMinimumAmountCommitted
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant