Consolidated Statements of Operations - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
REVENUE
Commissions	$ 79,678	$ 77,635	$ 245,935	$ 248,204
Investment Advisory Fee Revenue	78,154	74,329	232,972	216,521
Investment banking	28,328	23,940	84,442	57,347
Proceeds from (Payments for) in Interest-bearing Deposits in Banks	30,053	21,146	84,203	52,992
Interest	13,403	12,952	38,686	36,346
Principal transactions, net	(16)	5,135	9,110	15,810
Other	8,214	11,083	19,552	28,145
Total revenue	237,814	226,220	714,900	655,365
EXPENSES
Compensation and related expenses	152,846	142,090	457,821	428,625
Communications and technology	18,602	17,781	55,287	53,886
Occupancy and equipment costs	15,106	15,288	45,435	45,721
Clearing and exchange fees	5,378	5,622	17,254	17,392
Interest	12,915	6,500	32,787	18,710
Other	25,823	27,111	77,046	87,865
Total expenses	230,670	214,392	685,630	652,199
Income before income taxes from continuing operations	7,144	11,828	29,270	3,166
Income Tax Expense (Benefit)	2,083	4,425	8,661	2,464
Net income from continuing operations	5,061	7,403	20,609	702
Income from discontinued operations	0	769	0	1,834
Income taxes	0	308	0	733
Net income from discontinued operations	0	461	0	1,101
Net income	5,061	7,864	20,609	1,803
Less net income (loss) attributable to non-controlling interest, net of tax	(10)	75	(22)	180
Net income attributable to Oppenheimer Holdings Inc.	$ 5,071	$ 7,789	$ 20,631	$ 1,623
Basic net income per share attributable to Oppenheimer Holdings Inc.
Continuing operations (in dollars per share)	$ 0.38	$ 0.56	$ 1.56	$ 0.05
Discontinued operations (in dollars per share)	0.00	0.03	0.00	0.07
Net loss per share (in dollars per share)	0.38	0.59	1.56	0.12
Earnings Per Share, Diluted [Abstract]
Continuing operations (in dollars per share)	0.36	0.54	1.47	0.05
Discontinued operations (in dollars per share)	0.00	0.03	0.00	0.07
Net loss per share (in dollars per share)	$ 0.36	$ 0.57	$ 1.47	$ 0.12
Weighted average shares
Basic (in shares)	13,269,024	13,213,139	13,252,596	13,290,399
Diluted (in shares)	14,140,263	13,763,516	14,043,326	13,790,136