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

Continuous prepayment rate used after specified loans prepayment penalty rate average.

+ References

No definition available.

+ Details

Name:	opy_ContinuousPrepaymentRateUsedAfterSpecifiedLoansPrepaymentPenaltyRateAverage
Namespace Prefix:	opy_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Continuous prepayment rate used after specified loans prepayment penalty rate maximum.

+ References

No definition available.

+ Details

Name:	opy_ContinuousPrepaymentRateUsedAfterSpecifiedLoansPrepaymentPenaltyRateMaximum
Namespace Prefix:	opy_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Continuous prepayment rate used after specified loans prepayment penalty rate minimum.

+ References

No definition available.

+ Details

Name:	opy_ContinuousPrepaymentRateUsedAfterSpecifiedLoansPrepaymentPenaltyRateMinimum
Namespace Prefix:	opy_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Continuous prepayment rate used before specified loans prepayment penalty rate.

+ References

No definition available.

+ Details

Name:	opy_ContinuousPrepaymentRateUsedBeforeSpecifiedLoansPrepaymentPenaltyRate
Namespace Prefix:	opy_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Estimated future cost to service loans on annual basis per loan average.

+ References

No definition available.

+ Details

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

- Definition

Loan held for sale period.

+ References

No definition available.

+ Details

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

- Definition

The carrying value, as of the balance sheet date, of loans held for sale.

+ References

No definition available.

+ Details

Name:	opy_LoansHeldForSaleCarryingValue
Namespace Prefix:	opy_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Loans prepayment penalty rate.

+ References

No definition available.

+ Details

Name:	opy_LoansPrepaymentPenaltyRate
Namespace Prefix:	opy_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Loans Receivable Held for Sale, Maximum Period Held for Sale

+ References

No definition available.

+ Details

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

- Definition

Maximum settlement period in case of delayed delivery of underlying instrument.

+ References

No definition available.

+ Details

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

- Definition

Securities committed to purchase period.

+ References

No definition available.

+ Details

Name:	opy_SecuritiesCommittedToPurchasePeriod
Namespace Prefix:	opy_
Data Type:	xbrli:gYearItemType
Balance Type:	na
Period Type:	duration

- Definition

Sensitivity analysis of fair value of interests continued to be held by transferor servicing assets or liabilities change in discount rate.

+ References

No definition available.

+ Details

Name:	opy_SensitivityAnalysisOfFairValueOfInterestsContinuedToBeHeldByTransferorServicingAssetsOrLiabilitiesChangeInDiscountRate
Namespace Prefix:	opy_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Valuation adjustment for the level 3 assets used for quantitative disclosure.

+ References

No definition available.

+ Details

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

- Definition

The interest (or dividend) rates earned on action market preferred securities (on an annual basis or APY) for the period reported.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21475-112644

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 02
-Paragraph 29
-Article 5

+ Details

Name:	us-gaap_AuctionMarketPreferredSecuritiesStockSeriesVariableInterestRateEarned
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Contractual interest rate for funds borrowed, under the debt agreement.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22(a)(1))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

Name:	us-gaap_DebtInstrumentInterestRateStatedPercentage
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

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

- Definition

Interest rate used to find the present value of an amount to be paid or received in the future as an input to measure fair value. For example, but not limited to, weighted average cost of capital (WACC), cost of capital, cost of equity and cost of debt.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (bbb)
-URI http://asc.fasb.org/extlink&oid=36462937&loc=d3e19207-110258

+ Details

Name:	us-gaap_FairValueInputsDiscountRate
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Fair value of financial instruments held by a broker-dealer for their own account (proprietary securities) for trading or investment purposes determined by management based upon quoted prices of a financial instrument with similar characteristics or on a valuation technique or model.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 10
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=49121117&loc=d3e13433-108611

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 940
-SubTopic 320
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=35711157&loc=d3e42546-110969

+ Details

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

- Definition

The hypothetical financial impact of a specified adverse percentage change in discount rate on the fair value of transferor's interests in transferred financial assets (including any servicing assets or servicing liabilities) as of the balance sheet date.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 860
-SubTopic 20
-Section 50
-Paragraph 4
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=51814546&loc=d3e107314-111719

+ Details

Name:	us-gaap_SensitivityAnalysisOfFairValueOfInterestsContinuedToBeHeldByTransferorServicingAssetsOrLiabilitiesImpactOfOtherThan10Or20PercentAdverseChangeInDiscountRate
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Details

Name:	us-gaap_RangeAxis=us-gaap_MaximumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_VariableRateAxis=opy_LIBORorTreasuryYieldMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis=us-gaap_AuctionRateSecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_SensitivityAnalysisOfFairValueOfInterestsContinuedToBeHeldByTransferorServicingAssetsOrLiabilitiesImpactOfAdverseChangeInAssumptionByTypeOfFinancialInstrumentAxis=opy_FairValueValuationScenarioTwoMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_SensitivityAnalysisOfFairValueOfInterestsContinuedToBeHeldByTransferorServicingAssetsOrLiabilitiesImpactOfAdverseChangeInAssumptionByTypeOfFinancialInstrumentAxis=opy_FairValueValuationScenarioOneMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis=opy_MortgageServicingRightsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_SecurityOwnedAndSoldNotYetPurchasedAtFairValueAxis=opy_AuctionRateSecuritiesPurchaseCommitmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_InvestmentTypeAxis=us-gaap_AuctionRatePreferredSecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_InvestmentTypeAxis=opy_AuctionRatePreferredSecurities01Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_SecurityOwnedAndSoldNotYetPurchasedAtFairValueAxis=opy_AuctionRateSecuritiesOwnedMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DeferredCompensationArrangementWithIndividualShareBasedPaymentsByTypeOfDeferredCompensationAxis=us-gaap_DeferredCompensationExcludingShareBasedPaymentsAndRetirementBenefitsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_SecurityOwnedAndSoldNotYetPurchasedAtFairValueAxis=us-gaap_EquitySecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Fair Value Measurements - Narrative (Details) - USD ($)	6 Months Ended
Fair Value Measurements - Narrative (Details) - USD ($)	Jun. 30, 2016	Dec. 31, 2015	Apr. 12, 2011
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Securities owned, including amounts pledged of $657,527 ($546,334 in 2015), at fair value	$ 951,906,000	$ 734,831,000
Auction rate securities, firm purchased and hold	90,700,000
Amount of ARS committed to purchase from clients	26,900,000
Valuation adjustment (unrealized loss) for ARS	$ 830,000
Interest rate	8.75%		8.75%
Loans held for sale period (in days)	60 days
Maximum period held for sale (in days)	90 days
Book value of loan held for sale	$ 1,600,000
Forward or delayed delivery of the underlying instrument with settlement (in days)	180 days
Maximum [Member] \| LIBOR or Treasury Yield [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Auction market preferred securities variable interest rate earned	200.00%
Auction Rate Securities [Member] \| Fair Value, Valuation Scenario Two [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Change in discount rate	50.00%
Decrease in fair value of ARS	$ 2,200,000
Auction Rate Securities [Member] \| Fair Value, Valuation Scenario One [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Change in discount rate	25.00%
Decrease in fair value of ARS	$ 1,100,000
Auction Rate Securities [Member] \| Maximum [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Commitment to purchase ARS period maximum	2020
Mortgage Servicing Rights [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Permanent and construction loans , discount rate	12.00%
Continuous prepayment rate used up to loans prepayment penalty rate hit 4%	0.00%
Continuous prepayment rate	4.00%
Continuous prepayment rate vast majority range minimum	10.00%
Continuous prepayment rate vast majority range maximum	15.00%
Continuous prepayment rate vast majority range average rate	12.00%
Estimated future cost to service loans on an annual basis per loan, average	$ 1,250
Auction Rate Securities Purchase Commitment [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Valuation adjustment (unrealized loss) for ARS	(769,000)
Auction Rate Securities Purchase Commitment [Member] \| Auction Rate Preferred Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Valuation adjustment (unrealized loss) for ARS	(911,000)
Auction Rate Securities Purchase Commitment [Member] \| Auction Rate Preferred Securities 01 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Valuation adjustment (unrealized loss) for ARS	$ 142,000
Auction Rate Securities Purchase Commitment [Member] \| Maximum [Member] \| Auction Rate Preferred Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Permanent and construction loans , discount rate	1.29%
Auction Rate Securities Purchase Commitment [Member] \| Maximum [Member] \| Auction Rate Preferred Securities 01 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Permanent and construction loans , discount rate	1.29%
Auction Rate Securities Owned [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Valuation adjustment (unrealized loss) for ARS	$ 1,599,000
Auction Rate Securities Owned [Member] \| Auction Rate Preferred Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Valuation adjustment (unrealized loss) for ARS	$ 1,156,000
Auction Rate Securities Owned [Member] \| Maximum [Member] \| Auction Rate Preferred Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Permanent and construction loans , discount rate	1.29%
Deferred Compensation, Excluding Share-based Payments and Retirement Benefits [Member] \| Equity Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Securities owned, including amounts pledged of $657,527 ($546,334 in 2015), at fair value	$ 13,700,000	$ 14,000,000