Consolidated Statements of Operations - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
REVENUE
Commissions	$ 78,627	$ 79,678	$ 238,932	$ 245,935
Investment Advisory Fee Revenue	80,887	78,154	235,241	232,972
Investment banking	21,798	28,328	81,847	84,442
Proceeds from (Payments for) in Interest-bearing Deposits in Banks	28,894	30,053	94,692	84,203
Interest	12,344	13,403	38,621	38,686
Principal transactions, net	7,606	(16)	22,089	9,110
Other	4,637	8,214	26,076	19,552
Total revenue	234,793	237,814	737,498	714,900
EXPENSES
Compensation and related expenses	151,284	152,846	467,422	457,821
Communications and technology	20,872	18,602	61,457	55,287
Occupancy and equipment costs	16,010	15,106	46,856	45,435
Clearing and exchange fees	5,469	5,378	16,479	17,254
Interest	11,531	12,915	37,709	32,787
Other	23,131	25,813	67,636	77,024
Total expenses	228,297	230,660	697,559	685,608
Operating Income (Loss)	6,496	7,154	39,939	29,292
Income Tax Expense (Benefit)	2,547	2,083	12,421	8,661
Net income attributable to Oppenheimer Holdings Inc.	$ 3,949	$ 5,071	$ 27,518	$ 20,631
Net income per share
Net loss per share (in dollars per share)	$ 0.31	$ 0.38	$ 2.13	$ 1.56
Earnings Per Share, Diluted [Abstract]
Net loss per share (in dollars per share)	$ 0.29	$ 0.36	$ 1.99	$ 1.47
Weighted average shares
Basic (in shares)	12,825,944	13,269,024	12,940,129	13,252,596
Diluted (in shares)	13,832,994	14,140,263	13,846,139	14,043,326