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v3.7.0.1

Condensed Consolidating Financial Information - Narrative (Details) | 6 Months Ended
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Jun. 30, 2017
Condensed Financial Information of Parent Company Only Disclosure [Abstract] |
Interest owned by the holding company | 100.00%

X
- Definition The percentage of ownership the holding company owns the guarantors. + References No definition available. + Details
Name: | opy_InterestOwnershipByHoldingCompany
Namespace Prefix: | opy_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- References No definition available. + Details
Name: | us-gaap_CondensedFinancialInformationOfParentCompanyOnlyDisclosureAbstract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration