Consolidated Statements of Operations - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
REVENUE
Commissions	$ 395,097	$ 320,114	$ 329,668
Investment Advisory Fee Revenue	455,261	353,671	314,349
Investment banking	222,298	126,211	115,353
Interest Income, Deposits with Financial Institutions	34,829	117,422	116,052
Interest	33,477	50,723	52,484
Principal transactions, net	27,874	30,094	14,461
Other	29,831	35,144	15,787
Total revenue	1,198,667	1,033,379	958,154
EXPENSES
Compensation and related expenses	770,997	657,714	607,192
Communications and technology	82,132	81,588	74,479
Occupancy and equipment costs	62,352	62,198	61,171
Clearing and exchange fees	22,978	21,962	22,985
Interest	15,680	45,687	46,396
Other	75,528	89,318	101,062
Total expenses	1,029,667	958,467	913,285
Operating Income (Loss), Total	169,000	74,912	44,869
Income Tax Expense (Benefit)	46,014	21,959	15,977
Net income (loss) attributable to Oppenheimer Holdings Inc.	$ 122,986	$ 52,953	$ 28,892
Earnings per share
Earnings Per Share, Basic	$ 9.73	$ 4.10	$ 2.18
Diluted earnings per share	9.30	3.82	$ 2.05
Dividends	$ 1.48	$ 0.46
Weighted average shares
Basic	12,642,576	12,904,397	13,248,876
Diluted	13,217,335	13,851,832	14,061,369
Class A Stock
Earnings per share
Dividends	$ 1.48	$ 0.46	$ 0.44
Retained Earnings [Member]
EXPENSES
Net income (loss) attributable to Oppenheimer Holdings Inc.	$ 122,986	$ 52,953	$ 28,892
Earnings per share
Dividends	$ 1.48	$ 0.46	$ 0.44