XML 17 R1.htm IDEA: XBRL DOCUMENT v3.20.4
Document and Entity Information - USD ($)
$ in Millions
 12 Months Ended
Dec. 31, 2020
Mar. 01, 2021
Jun. 30, 2020
Document Information [Line Items]      
Document Annual Report true    
Document Transition Report false    
Entity File Number 1-12043    
Entity Incorporation, State or Country Code DE    
Entity Tax Identification Number 98-0080034    
Entity Address, Address Line One 85 Broad Street,    
Entity Address, City or Town New York,    
Entity Address, State or Province NY    
Entity Address, Postal Zip Code 10004    
City Area Code 212    
Local Phone Number 668-8000    
Title of 12(b) Security Class A non-voting common stock    
Trading Symbol OPY    
Security Exchange Name NYSE    
Entity Central Index Key 0000791963    
Document Fiscal Year Focus 2020    
Document Fiscal Period Focus FY    
Amendment Flag false    
Entity Interactive Data Current Yes    
Entity Well-known Seasoned Issuer No    
Entity Voluntary Filers No    
Entity Current Reporting Status Yes    
Entity Filer Category Accelerated Filer    
Entity Small Business false    
Entity Emerging Growth Company false    
Document Type 10-K    
Document Period End Date Dec. 31, 2020    
Current Fiscal Year End Date --12-31    
Entity Registrant Name OPPENHEIMER HOLDINGS INC.    
Entity Public Float     $ 271.2
Entity Shell Company false    
ICFR Auditor Attestation Flag true    
Class A Stock      
Document Information [Line Items]      
Entity Common Stock, Shares Outstanding   12,580,734  
Class B Stock      
Document Information [Line Items]      
Entity Common Stock, Shares Outstanding   99,665