The total amount of ARS the firm purchased and hold.

No definition available.

Name:	opy_AmountOfAuctionRateSecuritiesFirmPurchasedAndHold
Namespace Prefix:	opy_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

The amount of ARS the firm committed to purchase from clients.

+ References

No definition available.

+ Details

Name:	opy_AuctionRateSecuritiesCommittedToPurchaseFromClient
Namespace Prefix:	opy_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Eligible investor subject to future buyback potential additional losses related to valuation adjustments.

+ References

No definition available.

+ Details

Name:	opy_EligibleInvestorSubjectToFutureBuybackPotentialAdditionalLossesRelatedToValuationAdjustments
Namespace Prefix:	opy_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Eligible Investor Subject To Future Buyback Principal Value

+ References

No definition available.

+ Details

Name:	opy_EligibleInvestorSubjectToFutureBuybackPrincipalValue
Namespace Prefix:	opy_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Period of auction rates security to be purchased from rendering of award.

+ References

No definition available.

+ Details

Name:	opy_PeriodOfAuctionRatesSecurityToBePurchasedFromRenderingOfAward
Namespace Prefix:	opy_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Purchase Commitments Outstanding, Auction Rate Securities Related to Settlements with Regulators

+ References

No definition available.

+ Details

Name:	opy_PurchaseCommitmentsOutstandingAuctionRateSecuritiesRelatedtoSettlementswithRegulators
Namespace Prefix:	opy_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of judgment or settlement awarded to (against) the entity in respect of litigation.

+ References

No definition available.

+ Details

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

- Definition

Amount of litigation expense, including but not limited to legal, forensic, accounting, and investigative fees.

+ References

No definition available.

+ Details

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

- Details

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

- Definition

The estimated maximum amount of possible loss from the contingency.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 450

-SubTopic 20

-Section 50

-Paragraph 4

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=25496072&loc=d3e14435-108349

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 450

-SubTopic 20

-Section 50

-Paragraph 9

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=25496072&loc=d3e14557-108349

+ Details

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

- Definition

The estimated minimum amount of possible loss from the contingency.

+ References

+ Details

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

- Definition

The amount of cash paid for the settlement of litigation or for other legal issues during the period.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 25

-Subparagraph (g)

-URI http://asc.fasb.org/extlink&oid=56944662&loc=d3e3536-108585

+ Details

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

- Details

Name:	us-gaap_LitigationCaseAxis=exch_FINR
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LitigationCaseAxis=opy_SECMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LitigationCaseAxis=opy_UnitedStatesDepartmentoftheTreasuryMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_StatementScenarioAxis=us-gaap_ScenarioForecastMember
Namespace Prefix:
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Contingencies - Narrative (Details) (USD $)	3 Months Ended	6 Months Ended	0 Months Ended
Contingencies - Narrative (Details) (USD $)	Mar. 31, 2015	Jun. 30, 2014	Feb. 17, 2015	Jan. 27, 2015	Feb. 09, 2015	Mar. 26, 2015	Jan. 27, 2017
Loss Contingencies [Line Items]
Litigation Settlement, Expense		$ 20,000,000us-gaap_LitigationSettlementExpense
Minimum estimated range of aggregate loss for legal proceedings	0
Maximum estimated range of aggregate loss for legal proceedings	34,000,000
Company purchased and holds auction rate securities	105,300,000
Amount of ARS committed to purchase from clients	14,200,000
Purchase Commitments Outstanding, Auction Rate Securities Related to Settlements with Regulators	2,000,000
Eligible investor subject to future buyback potential additional losses related to valuation adjustments	97,400,000
Eligible Investor Subject To Future Buyback Potential Additional Losses Related To Valuation Adjustments	0
Period of auction rates security to be purchased from rendering of the award	30 days
SEC [Member]
Loss Contingencies [Line Items]
Litigation Settlement, Amount				10,000,000
Payments for Legal Settlements			5,000,000
SEC [Member] \| Disgorgement [Member]
Loss Contingencies [Line Items]
Litigation Settlement, Amount				4,200,000
SEC [Member] \| Prejudgment Interest [Member]
Loss Contingencies [Line Items]
Litigation Settlement, Amount				753,500
SEC [Member] \| Civil Penalties [Member]
Loss Contingencies [Line Items]
Litigation Settlement, Amount				5,100,000
United States Department of the Treasury [Member]
Loss Contingencies [Line Items]
Litigation Settlement, Amount				10,000,000
Payments for Legal Settlements					5,000,000
FINRA [Member]
Loss Contingencies [Line Items]
Litigation Settlement, Amount						3,800,000
Forecast [Member] \| SEC [Member]
Loss Contingencies [Line Items]
Payments for Legal Settlements							$ 5,000,000