Condensed Consolidating Financial Information - Condensed Consolidating Statement of Operations (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
REVENUES
Commissions	$ 103,833	$ 109,695
Advisory fees	66,026	70,966
Investment banking	12,383	27,305
Interest	13,379	11,035
Principal transactions, net	1,531	18,555
Other	21,542	8,005
Total revenue	218,694	245,561
EXPENSES
Compensation and related expenses	151,413	163,091
Communications and technology	17,781	17,168
Occupancy and equipment costs	14,978	15,778
Clearing and exchange fees	6,921	6,402
Interest	5,088	3,910
Other	30,510	29,361
Total expenses	226,691	235,710
Income (loss) before income tax provision (benefit)	(7,997)	9,851
Income tax provision (benefit)	(4,088)	3,730
Equity in earnings of subsidiaries	0	0
Net income (loss) for the period	(3,909)	6,121
Less net income (loss) attributable to noncontrolling interests	(62)	402
Net income (loss) attributable to Oppenheimer Holdings Inc.	(3,847)	5,719
Other comprehensive income (loss)	873	(567)
Comprehensive income (loss) attributable to Oppenheimer Holdings Inc.	(2,974)	5,152
Eliminations [Member]
REVENUES
Commissions	0	0
Advisory fees	(353)	(454)
Investment banking	0	0
Interest	(2,567)	(2,564)
Principal transactions, net	0	(54)
Other	(78)	(75)
Total revenue	(2,998)	(3,147)
EXPENSES
Compensation and related expenses	0	0
Communications and technology	0	0
Occupancy and equipment costs	(78)	(75)
Clearing and exchange fees	0	0
Interest	(2,567)	(2,564)
Other	(353)	(508)
Total expenses	(2,998)	(3,147)
Income (loss) before income tax provision (benefit)	0	0
Income tax provision (benefit)	0	0
Equity in earnings of subsidiaries	4,042	(14,544)
Net income (loss) for the period	4,042	(14,544)
Less net income (loss) attributable to noncontrolling interests	0	0
Net income (loss) attributable to Oppenheimer Holdings Inc.	4,042	(14,544)
Other comprehensive income (loss)	0	0
Comprehensive income (loss) attributable to Oppenheimer Holdings Inc.	4,042	(14,544)
Parent Company [Member]
REVENUES
Commissions	0	0
Advisory fees	0	0
Investment banking	0	0
Interest	0	0
Principal transactions, net	0	0
Other	0	0
Total revenue	0	0
EXPENSES
Compensation and related expenses	387	312
Communications and technology	28	25
Occupancy and equipment costs	0	0
Clearing and exchange fees	0	0
Interest	3,281	3,281
Other	673	288
Total expenses	4,369	3,906
Income (loss) before income tax provision (benefit)	(4,369)	(3,906)
Income tax provision (benefit)	(1,714)	(1,480)
Equity in earnings of subsidiaries	(1,192)	8,145
Net income (loss) for the period	(3,847)	5,719
Less net income (loss) attributable to noncontrolling interests	0	0
Net income (loss) attributable to Oppenheimer Holdings Inc.	(3,847)	5,719
Other comprehensive income (loss)	0	0
Comprehensive income (loss) attributable to Oppenheimer Holdings Inc.	(3,847)	5,719
Guarantor Subsidiaries [Member]
REVENUES
Commissions	0	0
Advisory fees	0	0
Investment banking	0	0
Interest	2,557	2,566
Principal transactions, net	30	0
Other	78	95
Total revenue	2,665	2,661
EXPENSES
Compensation and related expenses	0	0
Communications and technology	0	0
Occupancy and equipment costs	0	0
Clearing and exchange fees	0	0
Interest	0	0
Other	3	68
Total expenses	3	68
Income (loss) before income tax provision (benefit)	2,662	2,593
Income tax provision (benefit)	1,004	847
Equity in earnings of subsidiaries	(2,850)	6,399
Net income (loss) for the period	(1,192)	8,145
Less net income (loss) attributable to noncontrolling interests	0	0
Net income (loss) attributable to Oppenheimer Holdings Inc.	(1,192)	8,145
Other comprehensive income (loss)	0	0
Comprehensive income (loss) attributable to Oppenheimer Holdings Inc.	(1,192)	8,145
Non-Guarantor Subsidiaries [Member]
REVENUES
Commissions	103,833	109,695
Advisory fees	66,379	71,420
Investment banking	12,383	27,305
Interest	13,389	11,033
Principal transactions, net	1,501	18,609
Other	21,542	7,985
Total revenue	219,027	246,047
EXPENSES
Compensation and related expenses	151,026	162,779
Communications and technology	17,753	17,143
Occupancy and equipment costs	15,056	15,853
Clearing and exchange fees	6,921	6,402
Interest	4,374	3,193
Other	30,187	29,513
Total expenses	225,317	234,883
Income (loss) before income tax provision (benefit)	(6,290)	11,164
Income tax provision (benefit)	(3,378)	4,363
Equity in earnings of subsidiaries	0	0
Net income (loss) for the period	(2,912)	6,801
Less net income (loss) attributable to noncontrolling interests	(62)	402
Net income (loss) attributable to Oppenheimer Holdings Inc.	(2,850)	6,399
Other comprehensive income (loss)	873	(567)
Comprehensive income (loss) attributable to Oppenheimer Holdings Inc.	$ (1,977)	$ 5,832