Consolidated Statements of Operations - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
REVENUE
Commissions	$ 80,896	$ 82,850	$ 160,305	$ 166,257
Investment Advisory Fee Revenue	80,707	77,270	154,354	154,818
Investment banking	32,006	27,904	60,049	56,114
Proceeds from (Payments for) in Interest-bearing Deposits in Banks	31,830	28,853	65,798	54,150
Interest	13,550	13,056	26,277	25,283
Principal transactions, net	3,045	6,400	14,483	9,126
Other	8,901	6,223	21,439	11,338
Total revenue	250,935	242,556	502,705	477,086
EXPENSES
Compensation and related expenses	155,783	151,871	316,138	304,975
Communications and technology	20,499	17,997	40,585	36,685
Occupancy and equipment costs	15,573	14,901	30,846	30,329
Clearing and exchange fees	5,678	5,780	11,010	11,876
Interest	13,192	10,909	26,178	19,872
Other	22,819	28,581	44,505	51,211
Total expenses	233,544	230,039	469,262	454,948
Operating Income (Loss)	17,391	12,517	33,443	22,138
Income Tax Expense (Benefit)	5,016	3,662	9,874	6,578
Net income attributable to Oppenheimer Holdings Inc.	$ 12,375	$ 8,855	$ 23,569	$ 15,560
Net income per share
Net loss per share (in dollars per share)	$ 0.95	$ 0.67	$ 1.81	$ 1.17
Earnings Per Share, Diluted [Abstract]
Net loss per share (in dollars per share)	$ 0.89	$ 0.63	$ 1.70	$ 1.11
Weighted average shares
Basic (in shares)	12,976,235	13,248,812	12,998,168	13,244,245
Diluted (in shares)	13,861,753	14,050,573	13,857,616	14,005,556