XML 10 R1.htm IDEA: XBRL DOCUMENT  v2.3.0.11
Document and Entity Information (USD $)
In Millions, except Share data
6 Months Ended
Jun. 30, 2011
Jun. 30, 2010
Jul. 29, 2011
Class A non-voting common stock
Jul. 29, 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 Jun. 30, 2011
Amendment Flag false      
Document Fiscal Year Focus 2011      
Document Fiscal Period Focus Q2      
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     13,570,945 99,680