Consolidated Statements of Operations - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
REVENUE
Commissions	$ 83,407	$ 86,717
Advisory fees	77,548	69,409
Investment banking	28,210	18,021
Proceeds from (Payments for) in Interest-bearing Deposits in Banks	25,297	14,126
Interest	12,227	10,565
Principal transactions, net	2,726	5,373
Other	5,115	9,050
Total revenue	234,530	213,261
EXPENSES
Compensation and related expenses	153,104	143,878
Communications and technology	18,688	17,706
Occupancy and equipment costs	15,428	15,272
Clearing and exchange fees	6,096	5,854
Interest	8,963	5,356
Other	22,626	32,220
Total expenses	224,905	220,286
Income (Loss) before income taxes from continuing operations	9,625	(7,025)
Income Tax Expense (Benefit)	2,916	(1,687)
Net income (loss) from continuing operations	6,709	(5,338)
Income from discontinued operations	0	976
Income taxes	0	389
Net income from discontinued operations	0	587
Net income (loss)	6,709	(4,751)
Less net income attributable to non-controlling interest, net of tax	4	96
Net income (loss) attributable to Oppenheimer Holdings Inc.	$ 6,705	$ (4,847)
Basic net income (loss) per share attributable to Oppenheimer Holdings Inc.
Continuing operations (in dollars per share)	$ 0.51	$ (0.40)
Discontinued operations (in dollars per share)	0.00	0.04
Net loss per share (in dollars per share)	0.51	(0.36)
Earnings Per Share, Diluted [Abstract]
Continuing operations (in dollars per share)	0.48	(0.40)
Discontinued operations (in dollars per share)	0.00	0.04
Net loss per share (in dollars per share)	$ 0.48	$ (0.36)
Weighted average shares
Basic (in shares)	13,239,628	13,399,250
Diluted (in shares)	13,977,492	13,399,250