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Document and Entity Information (USD $) In Millions, except Share data	9 Months Ended
	Sep. 30, 2011	Jun. 30, 2010	Oct. 31, 2011 Class A non-voting common stock	Oct. 31, 2011 Class B voting common stock
Entity Information [Line Items]
Entity Registrant Name	OPPENHEIMER HOLDINGS INC
Entity Central Index Key	0000791963
Document Type	10-Q
Document Period End Date	Sep. 30, 2011
Amendment Flag	false
Document Fiscal Year Focus	2011
Document Fiscal Period Focus	Q3
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Filer Category	Accelerated Filer
Entity Public Float		$ 317.4
Entity Common Stock, Shares Outstanding			13,572,265	99,680