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

Fair Value, Estimate Not Practicable, Cash And Cash Equivalents

No definition available.

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

No definition available.

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

No definition available.

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

No definition available.

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

No definition available.

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

No definition available.

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

Fair Value, Estimate Not Practicable, Investment

No definition available.

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

Fair Value, Estimate not Practicable, Notes Receivable, Net

No definition available.

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

No definition available.

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

Fair Value Estimate Not Practicable Payable To Correspondent Brokers

No definition available.

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

No definition available.

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

No definition available.

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

No definition available.

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

Fair value estimate not practicable receivables from clearing organizations.

No definition available.

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

No definition available.

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

Fair Value Estimate Not Practicable Receivables From Other

No definition available.

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

Fair Value Estimate Not Practicable Receivables From Trade Date Payables

No definition available.

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

Fair Value Estimate Not Practicable Receivables From Trade Receivables

No definition available.

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

No definition available.

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

No definition available.

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

Fair Value,Estimate not Practicable, Securities sold under Agreements to Repurchase

No definition available.

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

[Line Items] for Financial Instruments, Estimate Not Practicable, Fair Value [Table]

No definition available.

Name:	opy_FinancialInstrumentsEstimateNotPracticableFairValueLineItems
Namespace Prefix:	opy_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

This item represents the amount that could be realized under a life insurance contract or contracts owned by the Entity as of the date of the statement of financial position. Such Entity-owned life insurance policies are commonly known as corporate-owned life insurance (COLI) or bank-owned life insurance (BOLI).

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 210
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(12))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480566/210-10-S99-1

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 210
-SubTopic 10
-Name Accounting Standards Codification
-Section S50
-Paragraph 4
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480657/210-10-S50-4

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 325
-SubTopic 30
-Name Accounting Standards Codification
-Section 25
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481612/325-30-25-1

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

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

Name:	us-gaap_FairValueByFairValueHierarchyLevelAxis=us-gaap_FairValueInputsLevel1Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_FairValueByFairValueHierarchyLevelAxis=us-gaap_FairValueInputsLevel2Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_FairValueByFairValueHierarchyLevelAxis=us-gaap_FairValueInputsLevel3Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: