Actual percentage of net capital to aggregate customer related debit items.

No definition available.

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Period Type:	duration

- Definition

Percentage of net capital to aggregate indebtedness.

+ References

No definition available.

+ Details

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

- Definition

Required percentage of net capital to aggregate customer related debit items.

+ References

No definition available.

+ Details

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

- Definition

The amount of net capital in excess of the alternative minimum required net capital.

+ References

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

-Publisher SEC

-Name Rule 15c3

-Number 240

-Section 1

-Paragraph 1

-Subparagraph ii

-Article 15c3

-Subsection a

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of cash subject to withdrawal restrictions, restricted deposits held as compensating balances, and cash and securities segregated in compliance with regulations (such as cash deposited in a special reserve account for the exclusive benefit of customers).

+ References

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

-Publisher AICPA

-Name Audit and Accounting Guide (AAG)

-Number AAG-BRD

-Paragraph 80

-Subparagraph Exhibit 4-8, 3

-IssueDate 2006-05-01

-Chapter 4

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

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

-Publisher AICPA

-Name Audit and Accounting Guide (AAG)

-Number AAG-BRD

-Paragraph 21

-IssueDate 2006-05-01

-Chapter 4

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

+ Details

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

- Details

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

- Definition

The amount of net capital in excess of the minimum required net capital.

+ References

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

-Publisher SEC

-Name Rule 15c3

-Number 240

-Section 1

-Paragraph 1

-Subparagraph i

-Article 15c3

-Subsection a

+ Details

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

- Definition

Amount of minimum net capital required to be maintained to engage in securities transactions.

+ References

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

-Publisher SEC

-Name Rule 15c3

-Number 240

-Section 1

-Paragraph 1

-Subparagraph i

-Article 15c3

-Subsection a

+ Details

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

- Definition

Minimum amount of net capital required to be maintained by entity's broker-dealer subsidiary to engage in securities transactions.

+ References

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

-Publisher SEC

-Name Rule 15c3

-Number 240

-Section 1

-Paragraph 1

-Subparagraph i

-Article 15c3

-Subsection a

+ Details

Name:	us-gaap_MinimumNetCapitalRequiredForBrokerDealerSubsidiary1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Net capital is equal to the net worth of the broker dealer, less certain items such as exchange memberships, carrying value of securities not readily marketable, haircuts on marketable securities in proprietary accounts, furniture and equipment and other illiquid assets as defined.

+ References

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

-Publisher SEC

-Name Rule 15c3

-Number 240

-Section 1

-Paragraph 1

-Subparagraph ii

-Article 15c3

-Subsection a

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

-Publisher AICPA

-Name Audit and Accounting Guide (AAG)

-Number AAG-BRD

-Paragraph 80

-Subparagraph Exhibit 4-8

-IssueDate 2006-05-01

-Chapter 4

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

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

-Publisher AICPA

-Name Audit and Accounting Guide (AAG)

-Number AAG-BRD

-Paragraph 80

-Subparagraph Exhibit 4-8, 15

-IssueDate 2006-05-01

-Chapter 4

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

+ Details

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

Regulatory requirements - Additional Information (Detail) (USD $)			3 Months Ended
	Mar. 31, 2013	Dec. 31, 2012	Mar. 31, 2013 Oppenheimer [Member]	Mar. 31, 2013 Freedom [Member]	Mar. 31, 2013 Oppenheimer Europe Ltd [Member]	Mar. 31, 2013 Oppenheimer Investments Asia Ltd. [Member]
Regulatory Capital Requirements [Line Items]
Required percentage of net capital to aggregate customer-related debit items			2.00%
Net capital			$ 154,200,000	$ 4,700,000	$ 5,700,000	$ 917,000
Actual percentage of net capital to aggregate customer-related debit items			12.40%
Excess capital			129,300,000
Freedom maintain net capital equal to the greater				250,000
Aggregate indebtedness				6.67%
Excess capital				4,400,000	2,300,000	531,000
Cash and securities segregated for regulatory and other purposes	37,164,000	33,000,000	20,100,000	16,100,000
Regulatory capital required to be maintained					$ 3,400,000	$ 386,000