Fair value liabilities measured on recurring basis change in realized gain loss included in other income.

No definition available.

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

- Definition

Fair value measurement with unobservable inputs reconciliation recurring basis asset purchases sales issuances settlements.

+ References

No definition available.

+ Details

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

- Definition

Fair value measurement with unobservable inputs reconciliation recurring basis asset sales settlements.

+ References

No definition available.

+ Details

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

- Definition

Fair value measurement with unobservable inputs reconciliation recurring basis liabilities purchases issuances.

+ References

No definition available.

+ Details

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

- Definition

Fair value measurement with unobservable inputs reconciliation recurring basis liabilities sales settlements.

+ References

No definition available.

+ Details

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

- Definition

This item represents the amount of the total change in unrealized (holding) gains or losses for the period which are included in the statement of income (or changes in net assets) in other income. Such unrealized (holding) gains or losses relate to those assets still held at the reporting date for which fair value is measured on a recurring basis using significant unobservable inputs (Level 3).

+ 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 (d)

-URI http://asc.fasb.org/extlink&oid=7578670&loc=d3e19207-110258

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 157

-Paragraph 32

-Subparagraph d

-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

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

- Details

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

- Definition

This item represents the amount of the total change in unrealized (holding) gains or losses for the period which are included in the statement of income (or changes in net assets) in other income. Such unrealized (holding) gains or losses relate to those liabilities still held at the reporting date for which fair value is measured on a recurring basis using significant unobservable inputs (Level 3).

+ References

+ Details

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

- Details

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

- Definition

Amount of gain (loss) recognized in earnings, arising from assets measured at fair value on a recurring basis using unobservable inputs (level 3).

+ References

+ Details

Name:	us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInEarnings1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

This element represents [net] transfers in to and out of assets measured at fair value on a recurring basis using unobservable inputs (Level 3) which have taken place during the period.

+ References

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 157

-Paragraph 32

-Subparagraph c(3)

-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

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

- Definition

This element represents an asset measured at fair value using significant unobservable inputs (Level 3) which is required for reconciliation purposes of beginning and ending balances.

+ 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 (c)

-URI http://asc.fasb.org/extlink&oid=7578670&loc=d3e19207-110258

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 157

-Paragraph 32

-Subparagraph c

-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

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

- Definition

This element represents [net] transfers in to and out of liabilities measured at fair value on a recurring basis using unobservable inputs (Level 3) which have taken place during the period.

+ References

No definition available.

+ Details

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

- Definition

This element represents a liability measured at fair value using significant unobservable inputs (Level 3) which is required for reconciliation purposes of beginning and ending balances.

+ References

+ Details

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

Financial Instruments (Details 4) (Fair value on a recurring basis [Member], Level 3 [Member], USD $) In Thousands, unless otherwise specified	3 Months Ended			6 Months Ended		3 Months Ended	6 Months Ended			3 Months Ended	6 Months Ended	3 Months Ended		6 Months Ended		3 Months Ended		6 Months Ended		3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2012 Investments [Member]	Jun. 30, 2011 Investments [Member]	Jun. 30, 2012 Investments [Member]	Jun. 30, 2011 Investments [Member]	Jun. 30, 2012 Other [Member]	Jun. 30, 2012 Other [Member]	Jun. 30, 2011 Other [Member]	Dec. 31, 2010 Other [Member]	Jun. 30, 2012 Derivatives Contracts [Member]	Jun. 30, 2012 Derivatives Contracts [Member]	Jun. 30, 2012 Mortgage and other asset-backed securities [Member]	Jun. 30, 2011 Mortgage and other asset-backed securities [Member]	Jun. 30, 2012 Mortgage and other asset-backed securities [Member]	Jun. 30, 2011 Mortgage and other asset-backed securities [Member]	Jun. 30, 2012 Municipal obligations [Member]	Jun. 30, 2011 Municipal obligations [Member]	Jun. 30, 2012 Municipal obligations [Member]	Jun. 30, 2011 Municipal obligations [Member]	Jun. 30, 2012 Other [Member]	Jun. 30, 2011 Other [Member]	Jun. 30, 2012 Other [Member]	Jun. 30, 2011 Other [Member]
Assets:
Opening Balance		$ 13,132	$ 17,308	$ 12,482	$ 17,208							$ 98		$ 16	$ 14	$ 11,789	$ 2,165	$ 3,562	$ 1,787	$ 66,831	$ 36,582	$ 65,001	$ 35,909
Realized Gains (Losses)												(7)		(8)		(5)		(5)
Unrealized Gains (Losses)		(78)	1	437	(1)							(16)	3	1	3	586	(43)	(491)	(190)	738	1,966	(761)	(936)
Purchases, Issuances		3	426	127	552							3	102	83	102		1,882	9,305	2,407	4,425	27,575	14,725	34,150
Sales, Settlements		(297)	(1,607)	(297)	(1,607)							(64)		(79)	(14)	(2,250)	(175)	(2,250)	(175)	(7,350)	(3,025)	(14,321)	(6,025)
Transfers In/ Out			13	11	(11)							(2)		(2)
Ending Balance		12,760	16,141	12,760	16,141							12	105	12	105	10,120	3,829	10,120	3,829	64,644	63,098	64,644	63,098
Liabilities:
Opening Balance							50	(11)		3,907	2,347
Realize Gains (Losses)
Unrealized Gains (Losses)										(1,573)	(13)
Purchases, Issuances
Sales, Settlements													11
Transfers In/ Out
Ending Balance								$ (11)		$ 2,334	$ 2,334		$ 11		$ 11