Document and Entity Information - shares		3 Months Ended
	May 01, 2020	Mar. 31, 2020
Document Information [Line Items]
Entity Registrant Name		OPPENHEIMER HOLDINGS INC
Entity Central Index Key		0000791963
Current Fiscal Year End Date		--12-31
Entity Filer Category		Accelerated Filer
Document Type		10-Q
Document Period End Date		Mar. 31, 2020
Document Fiscal Year Focus		2020
Document Fiscal Period Focus		Q1
Amendment Flag		false
Entity Small Business		false
Entity Emerging Growth Company		false
Entity Shell Company		false
Entity Current Reporting Status		Yes
Class A Stock
Document Information [Line Items]
Entity Common Stock, Shares Outstanding	12,619,081
Class B Stock
Document Information [Line Items]
Entity Common Stock, Shares Outstanding	99,665
Subsequent Event [Member]
Document Information [Line Items]
Subsequent Event, Date	May 01, 2020